Sequential one-pot approach for the synthesis of functionalized phthalans via Heck-reduction–cyclization (HRC) reactions

Abstract

An efficient and practical method is described for the direct synthesis of 1,3-dihydroisobenzofurans, an important structural motif present in biologically active natural or synthetic compounds. The reaction was performed in an almost one-pot fashion via controlled [Pd]-catalyzed intermolecular Mizoroki–Heck coupling between 2-bromobenzaldehydes and allylic alcohols followed by reduction and treatment of crude diol with a Lewis acid to give 1,3-dihydroisobenzofurans. Significantly, the method enabled the synthesis of 1,3-dihydroisobenzofurans with simple to dense functionalities on the aromatic rings.

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Introduction

Development of new synthetic methods based on one-pot synthesis or sequential one-pot synthesis are considered as important methods for the synthesis of organic compounds.¹ Particularly, the sequential one-pot processes involved in multiple reactions are promoted by a metal-catalyst in a sequential fashion.² Moreover, such transformations could also be feasible via the sequential addition of reagents to accomplish a set of reactions.³ In addition, it would also be possible to develop such one-pot methods using a metal-catalyst to complete the initial reaction followed by the treatment of the resultant intermediate product with a reagent or vice versa.⁴ These types of processes can be classified into pseudo-domino, cascade⁵ and tandem-processes. Usually, the one-pot methods have certain advantages over conventional methods. For example, they reduce waste formation, save time, energy, resources and increase the efficacy.⁶ In general, the overall yields of such processes are found to be higher than those from the corresponding step-wise methods. Thus, the sequential one-pot processes that construct multiple bonds are of immense importance, particularly for the synthesis of cyclic structures because many cyclic systems constitute core or part-structures of biologically active natural or synthetic compounds.

Recently, transition-metal mediated one-pot processes have gained considerable attention due to their procedural advantages.^7,8 Among them, the domino Heck reactions under [Pd]-catalysis are well known,^9–11 although the reports on Heck coupling followed by reduction are limited.¹² In continuation of our interest in the development of synthetic methods by [Pd]-catalysis,¹³ we have observed the selective formation of β-aryl allylic alcohols 3 in a highly regio- and stereo-selective manner.^13b Surprisingly, this is not the expected product 3 under conventional Jeffery-Heck conditions. After a careful study of the literature, we realized that the usual Heck reaction followed by double bond isomerization to give the carbonyl compounds was observed for those substrates having no ortho-substituents on the aromatic ring of the allylic alcohols.¹⁴ Therefore, it was thought that the bromo substituent at the ortho-position on the aromatic moiety of the allylic alcohol plays a major role to confine the rotation around C–C bond of the PdCH–CH(OH)Ar intermediate (Scheme 1).

Scheme 1 Synthesis of β-aryl allylic alcohols 3.

Amongst the β-aryl allylic alcohols 3, those with aldehyde functionality on the aromatic ring appear to be a potential synthetic precursor for the synthesis of oxygen containing heterocyclic compounds (i.e., R³ = CHO and X = Br). Therefore, herein, we report a short and efficient synthesis of interesting cyclic ethers 1,3-dihydroisobenzofurans 6 by employing reduction and acid mediated intramolecular cyclization protocol on β-aryl allylic alcohols 3.

Oxygen containing heterocyclic compounds are widely assayed for their substantial therapeutic applications such as tetrahydroisobenzofuran motifs.^15,16 They are pervasive structural elements in biologically relevant small molecules (Fig. 1). For example, 3-deoxyisochracinic acid 8 that was isolated from Cladosporium species shows antibacterial activity by inhibiting the growth of Bacillus subtilis.^15a The cyclic ether pestacin 9 was obtained from microorganism Pestalotiopsis microspora, which exhibits antifungal, antimycotic and antioxidant activities.^15b FR 198248 10 was isolated from Aspergillus flavipes, which shows antibacterial activity and inhibitory activity against Staphylococcus aureus peptide deformylase and also exhibits anti-influenza activity.^15c–e 1,4-Dimethoxy-3-(3R-hydroxy-3R-methyl-1-tetralone)-1(3H)-isobenzofuran 11 was isolated from the broth of marine Streptomyces species M268 and identified to be cytotoxic against human cancer cell lines HL-60, A549 and BEL-7402.^15f 7-Bromo-1-(2,3-dibromo-4,5-dihydroxyphenyl)-5,6-dihydroxy-1,3-dihydroisobenzofuran 12 was isolated from a brown alga Leathesia nana, and it shows potential action on malignant tumors and cardiovascular diseases.^15g The (S)-(+)-enantiomer 13, known as escitalopram, seems to be more potent than the other (S)-(−)-enantiomer.^15h–l

Fig. 1 Representative examples of naturally occurring phthalans.

We thought that the process can be made more efficient by developing a sequential one-pot method for the direct synthesis of diol 5 starting from aryl allylic alcohols 2 and 2-bromobenzaldehydes 1. This can be achieved by [Pd]-catalysed coupling for the formation of β-aryl allylic alcohols 3 and in situ reduction of the aldehyde functionality. Thus, the [Pd]-catalyzed coupling of 2-bromobenzaldehyde 1c with ortho-bromo aryl allylic alcohol 1a followed by the reduction of 3ca with NaBH₄ gave the desired diol 5ca in a very good yield (Scheme 2). The idea behind this hypothesis is to minimize the number of steps and waste and to improve the overall yield of the reaction over the step-wise approach. However, the diol 5ca was not characterized due to its insolubility in CDCl₃, and hence it proceeded to the next reaction.

Scheme 2 Synthesis of diol 5.

With the required diol 5ca in hand, the acid promoted cyclization was subsequently explored under different sets of conditions, and the results are summarized in Table 1. Thus, the reaction carried out with a Lewis acid (BF₃·Et₂O) at 0 °C, as well as at −10 °C, leads to the decomposition of the starting material (Table 1, entries 1 and 2). Therefore, the reaction at a further low temperature (−20 °C), furnished the product 6ca in poor yield (30%, Table 1, entry 3). Interestingly, a further drop of temperature (−40 °C) gave the product 6ca in excellent yield (95%, Table 1, entry 4). However, exploring the reaction with different acids such as protic acid (p-TSA) or Lewis acid (AlCl₃) furnished the product 6ca in moderate to very good yields (Table 1, entries 5–7), whereas the reaction with H₂SO₄ gave the product in poor yield (20%, Table 1, entries 8).

Table 1 Optimization table for the synthesis of 1,3-dihydroisobenzofuran 6ca from the diol 5ca

Entry^a	Acid (equiv)	Solvent (5 mL)	Temp (°C)	Time min	Yield^b of 6ca (%)
a Reaction conditions: all the reactions carried out with diol 5ca (0.10 mmol) in DCM.b Isolated yields of chromatographically pure products.
1	BF3·Et2O (2.0)	DCM	0	15	—
2	BF3·Et2O (4.0)	DCM	−10	15	—
3	BF3·Et2O (5.0)	DCM	−20	15	30
4	BF3·Et2O (5.0)	DCM	−40	120	95
5	p-TSA (3.0)	DCM	−40	60	50
6	AlCl3 (1.2)	DCM	−40	10	70
7	AlCl3 (1.2)	DCE	−40	10	80
8	H2SO4 (3.0)	DCM	−40	30	20

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Having established the reaction conditions for the synthesis of 1,3-dihydroisobenzofuran 6, we thought that the method can still be made more efficient by performing cyclization directly on crude diol 5ca without the column purification. Interestingly, the reaction was found to be smooth on the crude diol 5ca (i.e., the crude diol, which was obtained after work-up followed by concentration under reduced pressure) and furnished the product in the overall yield of 48% (Scheme 3). The structure of the cyclic ether 6ca was confirmed from the spectroscopic data. ¹H-NMR data unambiguously confirmed the geometry of the double bond as trans by calculating the coupling constant (J = 15.5 to 15.6 Hz, see Experimental section and ESI†). Therefore, the other possibility for the formation of seven membered cyclic ether 7ca was ruled out because it must contain a cis double bond. In addition, the formation of five membered cyclic ether 6ca is geometrically favoured over the seven membered one.

Scheme 3 Sequential one-pot method for the synthesis of 6ca.

Now, with the optimized reaction conditions in hand, to check the scope and limitations of the method, we investigated this sequential one-pot method on various 2-bromobenzaldehydes 1a–1g in conjunction with ortho-bromo aryl allylic alcohols 2a–2h. Quite interestingly, the method was amenable on various systems possessing dense functionalities on both the aromatic rings and furnished the products 6aa–6gg in moderate yields (41–55%), as summarized in Fig. 2. It is worth mentioning that although the yields of the cyclic ether products 6 are moderate, they actually represent the overall yield of three individual reactions. Therefore, each step contributes to at least 75% yield, and thus the method still stands efficient.

Fig. 2 Synthesis of 1,3-dihydroisobenzofurans 6aa–6gg from 2-bromobenzaldehydes 1a–1g and aryl allylic alcohols 2a–2h. All reactions were carried out with 2-bromobenzaldehydes 1a–1g (0.50 mmol). Isolated yields of chromatographically pure products in parentheses.

After the successful synthesis of 1,3-dihydroisobenzofurans, we planned to increase the scope of this protocol by employing the allylic alcohols possessing a methyl/methoxy group in the ortho position. During the sequential one-pot approach, we observed the formation of the regular Jeffery-Heck product along with the Mizoroki–Heck product.^13b This (Jeffery-Heck product) interfered in the further steps and hindered the isolation of clean products. Thus, we proceeded in a step-wise approach and achieved the targeted 1,3-dihydroisobenzofurans 6ai and 6aj in a moderate overall yield (47% and 52%). It is worth mentioning that in these cases, we were also able to characterise diol 5 (Scheme 4).

Scheme 4 Step-wise approach for the synthesis of 1,3-dihydroisobenzofurans 6ai and 6aj from 2-bromobenzaldehyde 1a and aryl allylic alcohols 2i and 2j.

Experimental section

General considerations

IR spectra were recorded on a Bruker Tensor 37 (FT-IR) spectrophotometer. ¹H-NMR spectra were recorded on a Bruker Avance 400 (400 MHz) spectrometer at 295 K in CDCl₃; chemical shifts (δ in ppm) and coupling constants (J in Hz) are reported in standard fashion with reference to either internal standard tetramethylsilane (TMS) (δ_H = 0.00 ppm) or CHCl₃ (δ_H = 7.25 ppm). ¹³C-NMR spectra were recorded on a Bruker Avance 400 (100 MHz) spectrometer at 295 K in CDCl₃; chemical shifts (δ in ppm) are reported relative to CHCl₃ [δ_C = 77.00 ppm (central line of triplet)]. In ¹³C-NMR, the nature of carbons (namely, C, CH, CH₂ and CH₃) was determined by recording the DEPT-135 spectra, and it is given in parentheses and noted as s = singlet (for C), d = doublet (for CH), t = triplet (for CH₂) and q = quartet (for CH₃). In ¹H-NMR, the following abbreviations were used throughout: s = singlet, d = doublet, t = triplet, q = quartet, qui = quintet, m = multiplet and br. s = broad singlet, septd = septet of doublets. The assignment of signals was confirmed by ¹H, ¹³C CPD and DEPT spectra. High-resolution mass spectra (HR-MS) were recorded on an Agilent 6538 UHD Q-TOF using multimode source. X-ray crystal structure data were obtained using an Oxford Super Nova instrument. All the small scale dry reactions were carried out using the standard syringe-septum technique. Reactions were monitored by TLC on silica gel using a mixture of petroleum ether and ethyl acetate as eluents. Reactions were generally run under an argon or nitrogen atmosphere. All the solvents were distilled prior to use; petroleum ether with a boiling range of 60 to 80 °C, diethyl ether, dichloromethane (DCM), ethyl acetate, THF (with purity 99%), and acetonitrile (with purity 99.9%), which were purchased from locally available commercial sources were used. All aromatic aldehydes (with purity 98%), bromine (with purity 99%), iodine (with purity 99%), Bn(Et)₃NCl (with purity 99%), Pd(OAc)₂ (with purity 98%), 3-iodoanisole (with purity 99%), 2-bromoiodobenzene (with purity 99%), NaBH₄ (with purity 99%), K₂CO₃ (with purity 99%), and NaHCO₃ (with purity 99.5%) were purchased from Sigma-Aldrich, whereas vinylmagnesium bromide (with purity 99%), BF₃·Et₂O (with purity 48%) and iodobenzene (with purity 99%) were purchased from other commercial sources and used as received. The base NaHCO₃ was dried at 150–170 °C over an oil bath. Diethyl ether and toluene were dried over sodium/benzophenone, DCM and DCE were dried over calcium hydride, and acetonitrile was dried over P₂O₅. Acme's silica gel (60–120 mesh) was used for column chromatography (approximately 20 g per one gram of crude material).

ortho-Bromobenzaldehydes 1a–1h except 1a were synthesized from corresponding aromatic aldehydes using a bromination method reported in the literature.¹⁷ Among the bromo aryl allylic alcohols, 2a,¹⁸ 2g^13b and 2h^13b were reported in literature.

General procedure-1 for the synthesis of ortho-bromo aryl allylic alcohols (2a–2h). To a magnetically stirred solution of 2-bromobenzaldehydes 1a–1h (10 mmol) in THF (20 mL), in a round bottom flask at 0 °C, under nitrogen atmosphere, 1.0 M of vinylmagnesium bromide (20 mmol, 1.0 M in THF) was added, and the resultant reaction mixture was slowly allowed to reach room temperature and stirred for 1.5 h. The reaction mixture was quenched with saturated aq. NH₄Cl solution and extracted with diethyl ether (3 × 30 mL). The organic layer was washed with saturated NaCl solution, dried over anhydrous Na₂SO₄ and concentrated under reduced pressure. Purification of the residue on a silica gel column chromatography (petroleum ether/ethyl acetate 90 : 10 to 80 : 20) furnished ortho-bromo aryl allylic alcohols 2a–2h (80–92%).

General procedure-2 for the synthesis of 1,3-dihydroisobenzofurans (6aa–6gg). In an oven-dried Schlenk flask under nitrogen atmosphere, Pd(OAc)₂ (5 mol%), Bn(Et)₃NCl (0.50 mmol), NaHCO₃ (1 mmol), 2-bromobenzaldehydes 1a–1g (0.50 mmol) and ortho-bromo aryl allylic alcohol 2a–2h (0.60 mmol) were added, followed by the addition of dry acetonitrile (4 mL). The resulting reaction mixture was stirred for 24 h at 80 °C. Then, the reaction mixture was cooled to 0 °C and NaBH₄ (1.50 mmol) was added to it, and the mixture was stirred for two hours at room temperature. The reaction mixture was quenched with saturated aq. NH₄Cl solution and extracted with ethyl acetate (3 × 20 mL). The organic layer was washed with saturated NaCl solution, dried over anhydrous Na₂SO₄ and concentrated under reduced pressure. Traces of solvents were removed under high vacuum, and to the obtained crude, 20 mL of dry DCM was added, and then the mixture was cooled to −40 °C, BF₃·Et₂O (2.5 mmol) was added, and the reaction was stirred for 2 h at the same temperature. The reaction mixture was then quenched with saturated aqueous NaHCO₃ solution, and the aqueous layer was extracted with DCM (3 × 20 mL). The organic layers were dried over anhydrous Na₂SO₄, filtered, and concentrated under reduced pressure. Purification of the residue on a silica gel column chromatography (petroleum ether/ethyl acetate) furnished the product 6aa–6gg (40–55%).

General procedure-3 for the synthesis of 1,3-dihydroisobenzofurans (6ai and 6aj). In an oven-dried Schlenk flask under nitrogen atmosphere, Pd(OAc)₂ (5 mol%), Bn(Et)₃NCl (0.50 mmol), NaHCO₃ (1 mmol), 2-bromobenzaldehydes 1a (0.50 mmol) and ortho-bromo aryl allylic alcohol 2i–2j (0.60 mmol) were added, followed by the addition of dry acetonitrile (4 mL). The resulting reaction mixture was stirred for 24 h at 80 °C. The reaction mixture was quenched using saturated aq. NH₄Cl solution, and then compound was extracted in ethyl acetate and concentrated under reduced pressure. The aldehyde 3 was isolated by silica gel column chromatography (petroleum ether/ethyl acetate). The aldehyde 3 was cooled to 0 °C and NaBH₄ (1.50 mmol) was added and stirred for two hours at room temperature. The reaction mixture was quenched with saturated aq. NH₄Cl solution and extracted with ethyl acetate (3 × 20 mL). The organic layer was washed with saturated NaCl solution, dried over anhydrous Na₂SO₄ and concentrated under reduced pressure. Traces of solvents were removed under high vacuum, and to the obtained crude, 20 mL of dry DCM was added, and then the mixture was cooled to −40 °C, BF₃·Et₂O (2.5 mmol) was added, and the reaction mixture was stirred for 2 h at the same temperature. The reaction mixture was then quenched with saturated aqueous NaHCO₃ solution and the aqueous layer was extracted with DCM (3 × 20 mL). The organic layers were dried over anhydrous Na₂SO₄, filtered, and concentrated under reduced pressure. Purification of the residue on a silica gel column chromatography (petroleum ether/ethyl acetate) furnished the products 6ai & 6aj (47–52%).
1-[5-(Benzyloxy)-2-bromophenyl]prop-2-en-1-ol (2b). GP-1 was carried out and the product 2b (2.80 g, 88%) was furnished as a pale yellow liquid. [TLC control R_f(1b) = 0.60, R_f(2b) = 0.40 (petroleum ether/ethyl acetate 90 : 10, UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3371, 3032, 2920, 1592, 1571, 1462, 1291, 1380, 1291, 1233, 1163, 1010, 927, 736, 697 cm⁻¹. ¹H NMR (CDCl₃, 400 MHz): δ = 7.50–7.28 (m, 6H, Ar-H), 7.19 (d, 1H, J = 2.9 Hz, Ar-H), 6.78 (dd, 1H, J = 8.8 and 2.9 Hz, Ar-H), 5.99 (ddd, 1H, J = 15.6, 10.3 and 5.4 Hz, CH=CH₂), 5.54 (d, 1H, J = 5.4 Hz, ArCH–OH), 5.40 (td, 1H, J = 15.6 and 1.5 Hz, C=CH_aH_b), 5.22 (td, 1H, J = 10.3 and 1.5 Hz, C=CH_aH_b), 5.04 (s, 2H, PhCH₂O), 2.25 (d, 1H, J = 3.9 Hz, OH) ppm. ¹³C NMR (CDCl₃, 100 MHz): δ = 158.4 (s, Ar-C), 142.5 (s, Ar-C), 138.1 (d, CH=CH₂), 136.4 (s, Ar-C), 133.3 (d, Ar-CH), 128.6 (d, 2C, Ar-CH), 128.1 (d, Ar-CH), 127.5 (d, 2C, Ar-CH), 115.9 (d, Ar-CH), 115.7 (t, CH=CH₂), 114.2 (d, Ar-CH), 112.9 (s, Ar-C), 73.4 (d, Ar-CHOH), 70.2 (t, PhCH₂) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₆H₁₄BrO]⁺ = [(M + H)–H₂O]⁺: 301.0223; found 301.0213.
1-(2-Bromo-5-methoxyphenyl)prop-2-en-1-ol (2c). GP-1 was carried out and the product 2c (2.20 mg, 92%) was furnished as a pale yellow liquid. [TLC control R_f(1c) = 0.80, R_f(2c) = 0.50 (petroleum ether/ethyl acetate 80 : 20, UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3380, 2922, 2851, 1593, 1572, 1468, 1416, 1290, 1233, 1161, 1047, 1013, 928, 807, 771 cm⁻¹. ¹H NMR (CDCl₃, 400 MHz): δ = 7.39 (d, 1H, J = 8.8 Hz, Ar-H), 7.07 (d, 1H, J = 3.4 Hz, Ar-H), 6.69 (dd, 1H, J = 8.8 and 3.4 Hz, Ar-H), 5.99 (ddd, 1H, J = 17.1, 10.3 and 5.4 Hz, CH=CH₂), 5.53 (d, 1H, J = 5.4 Hz, ArCH–OH), 5.38 (td, 1H, J = 17.1 and 1.5 Hz, C=CH_aH_b), 5.21 (dd, 1H, J = 10.3 and 1.5 Hz, C=CH_aH_b), 3.78 (s, 3H, Ar-OCH₃), 2.34 (br. s, 1H, OH) ppm. ¹³C NMR (CDCl₃, 100 MHz): δ = 159.3 (s, Ar-C), 142.4 (s, Ar-C), 138.1 (d, CH=CH₂), 133.3 (d, Ar-CH), 115.7 (t, CH=CH₂), 115.2 (d, Ar-CH), 113.0 (d, Ar-CH), 112.7 (s, Ar-C), 73.4 (d, Ar-CHOH), 55.4 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₀H₁₀BrO]⁺ = [(M + H)–H₂O]⁺: 224.9910; found 224.9903.
1-[5-(Benzyloxy)-2-bromo-4-methoxyphenyl]prop-2-en-1-ol (2d). GP-1 was carried out and the product 2d (2.96 g, 85%) was furnished as a brownish viscous liquid. [TLC control R_f(1d) = 0.60, R_f(2d) = 0.30 (petroleum ether/ethyl acetate 90 : 10, UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3392, 2933, 2847, 1599, 1497, 1454, 1381, 1251, 1120, 1155, 1120, 1039, 1023, 861, 834, 696, 665 cm⁻¹. ¹H NMR (CDCl₃, 400 MHz): δ = 7.42 (dd, 2H, J = 7.3 and 6.8 Hz, Ar-H), 7.37 (t, 2H, J = 7.3 Hz, Ar-H), 7.31 (ddd, 1H, J = 7.3 and 6.8 Hz, Ar-H), 7.03 (s, 1H, Ar-H), 7.02 (s, 1H, Ar-H), 5.98 (ddd, 1H, J = 15.6, 10.3 and 4.9 Hz, CH=CH₂), 5.51 (d, 1H, J = 5.4 Hz, ArCH–OH), 5.38 (td, 1H, J = 15.6 and 1.5 Hz, C=CH_aH_b), 5.20 (td, 1H, J = 10.3 and 1.5 Hz, C=CH_aH_b), 5.09 (s, 2H, PhCH₂O), 3.38 (s, 3H, Ar-OCH₃), 2.29 (d, 1H, J = 2.9 Hz, OH) ppm. ¹³C NMR (CDCl₃, 100 MHz): δ = 149.4 (s, Ar-C), 148.1 (s, Ar-C), 138.5 (d, CH=CH₂), 136.3 (s, Ar-C), 134.0 (s, Ar-C), 128.6 (d, 2C, Ar-CH), 128.0 (d, Ar-CH), 127.3 (d, 2C, Ar-CH), 117.6 (d, Ar-CH), 115.3 (t, CH=CH₂), 112.1 (s, Ar-C), 110.7 (d, Ar-CH), 73.3 (d, Ar-CHOH), 71.2 (t, PhCH₂), 56.0 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₇H₁₆BrO₂]⁺ = [(M + H)–H₂O]⁺: 331.0328; found 331.0332.
1-[4-(Benzyloxy)-2-bromo-5-methoxyphenyl]prop-2-en-1-ol (2e). GP-1 was carried out and the product 2e (2.79 g, 80%) was furnished as a brownish viscous liquid. [TLC control R_f(1e) = 0.60, R_f(2e) = 0.30 (petroleum ether/ethyl acetate 90 : 10, UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3404, 3032, 3008, 2932, 1600, 1502, 1502, 1439, 1379, 1257, 1156, 1120, 1029, 925, 863, 777 cm⁻¹. ¹H NMR (CDCl₃, 400 MHz): δ = 7.42 (d, 2H, J = 7.3 Hz, Ar-H), 7.35 (dd, 2H, J = 7.3 and 6.8 Hz, Ar-H), 7.29 (t, 1H, J = 7.3 Hz, Ar-H), 7.06 (s, 1H, Ar-H), 7.00 (s, 1H, Ar-H), 5.90 (ddd, 1H, J = 15.6, 10.3 and 4.9 Hz, CH=CH₂), 5.49 (d, 1H, J = 5.4 Hz, ArCH–OH), 5.35 (td, 1H, J = 15.6 and 1.5 Hz, C=CH_aH_b), 5.31 (td, 1H, J = 10.3 and 1.5 Hz, C=CH_aH_b), 5.11 (d, 1H, J = 12.2 Hz, PhCH_aH_bO), 5.10 (d, 1H, J = 12.2 Hz, PhCH_aH_bO), 3.85 (s, 3H, Ar-OCH₃), 2.10 (d, 1H, J = 2.4 Hz, OH) ppm. ¹³C NMR (CDCl₃, 100 MHz): δ = 149.6 (s, Ar-C), 147.8 (s, Ar-C), 138.4 (d, CH=CH₂), 136.5 (s, Ar-C), 133.4 (s, Ar-C), 128.5 (d, 2C, Ar-CH), 128.0 (d, Ar-CH), 127.6 (d, 2C, Ar-CH), 115.7 (d, Ar-CH), 115.3 (t, CH=CH₂), 113.1 (s, Ar-C), 112.9 (d, Ar-CH), 73.2 (d, Ar-CHOH), 71.1 (t, PhCH₂), 56.2 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₇H₁₆BrO₂]⁺ = [(M + H)–H₂O]⁺: 331.0328; found 331.0334.
1-(6-Bromo-1,3-benzodioxol-5-yl)prop-2-en-1-ol (2f). GP-1 was carried out and the product 2f (2.0 g, 80%) was furnished as a colorless viscous liquid. [TLC control R_f(1f) = 0.60, R_f(2f) = 0.50 (petroleum ether/ethyl acetate 80 : 20, UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3346, 2897, 1501, 1471, 1407, 1230, 1107, 1035, 930, 840, 798 cm⁻¹. ¹H NMR (CDCl₃, 400 MHz): δ = 6.98 (s, 1H, Ar-H), 6.96 (s, 1H, Ar-H), 5.95 (d, 1H, J = 5.4 Hz, OCH_aH_bO), 5.94 (d, 1H, J = 5.4 Hz, OCH_aH_bO), 5.93 (ddd, 1H, J = 15.6, 10.3 and 5.4 Hz, CH=CH₂), 5.51 (d, 1H, J = 5.4 Hz, ArCH–OH), 5.37 (td, 1H, J = 15.6 and 1.5 Hz, C=CH_aH_b), 5.20 (td, 1H, J = 10.3 and 1.5 Hz, C=CH_aH_b), 2.26 (d, 1H, J = 2.9 Hz, OH) ppm. ¹³C NMR (CDCl₃, 100 MHz): δ = 147.8 (s, Ar-C), 147.7 (s, Ar-C), 138.4 (d, CH=CH₂), 134.8 (s, Ar-C), 115.3 (t, CH=CH₂), 112.8 (s, Ar-C), 112.5 (d, Ar-CH), 107.7 (d, Ar-CH), 101.7 (t, OCH₂O), 73.3 (d, Ar-CHOH) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₀H₉BrNaO₃]⁺ = [M + Na]⁺: 278.9627; found 278.9639.
1-[(E)-2-(2-Bromophenyl)vinyl]-1,3-dihydro-2-benzofuran (6aa). GP-2 was carried out and the product 6aa (83 mg, 55%) was furnished as a yellow viscous liquid. [TLC control R_f(1a) = 0.80, R_f(2a) = 0.70 and R_f(6aa) = 0.85 (petroleum ether/ethyl acetate 95 : 5, UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2922, 2852, 1588, 1465, 1437, 1357, 1284, 1246, 1158, 1122, 1107, 1021, 963, 747, 698, 665 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.53 (dd, 1H, J = 7.8 and 1.5 Hz, Ar-H), 7.50 (dd, 1H, J = 7.8 and 1.5 Hz, Ar-H), 7.35–7.15 (m, 5H, Ar-H), 7.10 (d, 1H, J = 15.6 Hz, ArCH=CH), 7.08 (ddd, 1H, J = 9.3, 7.8 and 1.5 Hz, Ar-H), 6.21 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.80 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.22 (d, 1H, J = 11.7 Hz, PhCH_aH_bOCHCH=CH), 5.14 (d, 1H, J = 11.7 Hz, PhCH_aH_bOCHCH=CH) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 140.6 (s, Ar-C), 139.1 (s, Ar-C), 136.4 (s, Ar-C), 132.9 (d, Ar-CH), 132.0 (d, Ar-CH), 130.5 (d, Ar-CH–CH=CH-Ar), 129.1 (d, Ar-CH–CH=CH-Ar), 127.8 (d, Ar-CH), 127.5 (d, Ar-CH), 127.4 (d, Ar-CH), 127.3 (d, Ar-CH), 123.8 (s, Ar-C), 122.0 (d, Ar-CH), 121.1 (d, Ar-CH), 85.0 (d, Ph-CHCH=CH), 72.9 (t, Ph-CH₂OCHCH=CH) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₆H₁₃BrNaO]⁺ = [M + Na]⁺: 323.0042; found 323.0041.
1-{(E)-2-[5-(Benzyloxy)-2-bromophenyl]vinyl}-1,3-dihydro-2-benzofuran (6ab). GP-2 was carried out and the product 6ab (92 mg, 45%) was furnished as a pale yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 95 : 5, R_f(1a) = 0.80, R_f(2b) = 0.50 and R_f(6ab) = 0.65 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2922, 2852, 1590, 1563, 1459, 1286, 1238, 1173, 1028, 1013, 963, 739, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.41 (d, 1H, J = 8.3 Hz, Ar-H), 7.39–7.20 (m, 8H, Ar-H), 7.19 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 7.14 (d, 1H, J = 2.9 Hz, Ar-H), 7.05 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.73 (dd, 1H, J = 8.8 and 2.9 Hz, Ar-H), 6.19 (dd, 1H, J = 15.6 and 7.3 Hz, ArCH=CH), 5.80 [d, 1H, J = 7.3 Hz, PhCH(O)CH=CH], 5.22 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.13 (dd, 1H, J = 12.2 and 1.0 Hz, PhCH_aH_bOCHCH=CH), 4.98 (s, 2H, PhCH₂O) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 158.0 (s, Ar-C), 140.5 (s, Ar-C), 139.1 (s, Ar-C), 137.1 (s, Ar-C), 136.4 (s, Ar-C), 133.4 (d, Ar-CH), 132.1 (d, Ar-CH), 130.5 (d, Ar-CH), 128.5 (d, 2C, Ar-CH), 128.0 (d, Ar-CH–CH=CH-Ar), 127.8 (d, Ar-CH–CH=CH-Ar), 127.5 (d, Ar-CH), 127.4 (d, 2C, Ar-CH), 122.0 (d, Ar-CH), 121.1 (d, Ar-CH), 116.2 (d, Ar-CH), 114.8 (s, Ar-C), 113.3 (d, Ar-CH), 84.8 (d, Ph-CHCH=CH), 72.8 (t, Ph-CH₂OCHCH=CH) 70.1 (t, PhCH₂O) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₃H₁₈⁷⁹BrO]⁺ = [(M + H)–H₂O]⁺: 389.0536; found 389.0545 and [C₂₃H₁₈⁸¹BrO]⁺ = [(M + H)–H₂O]⁺: 391.0515; found 391.0529.
1-[(E)-2-(2-Bromo-5-methoxyphenyl)vinyl]-1,3-dihydro-2-benzo furan (6ac). GP-2 was carried out and the product 6ac (80 mg, 48%) was furnished as a pale brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 95 : 5, R_f(1a) = 0.75, R_f(2c) = 0.35 and R_f(6ac) = 0.50 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2959, 2929, 1592, 1571, 1464, 1287, 1236, 1161, 1014, 802, 754, 733, 599 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.35 (d, 1H, J = 8.8 Hz, Ar-H), 7.30–7.05 (m, 4H, Ar-H), 7.01 (d, 1H, J = 15.5 Hz, ArCH=CH), 6.97 (d, 1H, J = 2.2 Hz, Ar-H), 6.62 (dd, 1H, J = 8.7 and 3.0 Hz, Ar-H), 6.13 (dd, 1H, J = 15.5 and 7.5 Hz, ArCH=CH), 5.74 [d, 1H, J = 7.5 Hz, PhCH(O)CH=CH], 5.16 (dd, 1H, J = 12.3 and 2.2 Hz, PhCH_aH_bOCHCH=CH), 5.08 (d, 1H, J = 12.3 Hz, PhCH_aH_bOCHCH=CH), 3.68 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 158.9 (s, Ar-C), 140.5 (s, Ar-C), 139.1 (s, Ar-C), 140.0 (s, Ar-C), 133.4 (d, Ar-CH), 132.0 (d, Ar-CH), 130.7 (d, Ar-CH), 127.8 (d, Ar-CH–CH=CH-Ar), 127.5 (d, Ar-CH–CH=CH-Ar), 122.0 (d, Ar-CH), 121.1 (d, Ar-CH), 115.7 (d, Ar-CH), 114.5 (s, Ar-C), 112.0 (d, Ar-CH), 84.9 (d, Ph-CHCH=CH), 72.9 (t, Ph-CH₂OCHCH=CH), 55.4 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₇H₁₄BrO]⁺ = [(M + H)–H₂O]⁺: 313.0223; found 313.0212, [C₁₇H₁₄⁸¹BrO]⁺ = [(M + H)–H₂O]⁺:315.0202; found 315.0189 and [C₁₇H₁₉BrNO₂]⁺ = [M + NH₄]⁺: 348.0594; found 348.0587.
1-{(E)-2-[5-(Benzyloxy)-2-bromo-4-methoxyphenyl]vinyl}-1,3-dihydro-2-benzofuran (6ad). GP-2 was carried out and the product 6ad (92 mg, 42%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1a) = 0.80, R_f(2d) = 0.20 and R_f(6ad) = 0.30 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2918, 2850, 1595, 1502, 1461, 1385, 1260, 1200, 1166, 1024, 861, 750, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.43 (d, 2H, J = 7.3 Hz, Ar-H), 7.38 (dd, 2H, J = 7.3 and 6.8 Hz, Ar-H), 7.35–7.25 (m, 4H, Ar-H), 7.22 (dd, 1H, J = 7.8 and 2.0 Hz, Ar-H), 7.06 (s, 1H, Ar-H), 7.04 (s, 1H, Ar-H), 7.03 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.13 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.81 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.25 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.14 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH), 5.10 (s, 2H, PhCH₂O) 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 149.1 (s, Ar-C), 148.6 (s, Ar-C), 140.7 (s, Ar-C), 139.2 (s, Ar-C), 136.2 (s, Ar-C), 130.7 (d, Ar-CH–CH=CH-Ar), 130.0 (d, Ar-CH–CH=CH-Ar), 128.8 (s, Ar-C), 128.6 (d, 2C, Ar-CH), 128.1 (d, Ar-CH), 127.8 (d, Ar-CH), 127.5 (d, Ar-CH), 127.4 (d, 2C, Ar-CH), 122.1 (d, Ar-CH), 121.1 (d, Ar-CH), 117.6 (d, Ar-CH), 114.4 (s, Ar-C), 109.6 (d, Ar-CH), 85.2 (d, Ph-CHCH=CH), 72.8 (t, Ph-CH₂OCHCH=CH), 71.1 (t, PhCH₂O), 56.1 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₄H₂₁BrNaO₃]⁺ = [M + Na]⁺: 459.0566; found 459.0583 and [C₂₄H₂₁BrNaO₃]⁺ = [M + Na]⁺: 461.0546; found 461.0561.
1-{(E)-2-[4-(Benzyloxy)-2-bromo-5-methoxyphenyl]vinyl}-1,3-dihydro-2-benzofuran (6ae). GP-2 was carried out and the product 6ae (100 mg, 45%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1a) = 0.80, R_f(2e) = 0.20 and R_f(6ae) = 0.35 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2957, 2920, 2851, 1503, 1462, 1441, 1379, 1261, 1206, 1163, 1026, 743 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.40 (d, 2H, J = 6.8 Hz, Ar-H), 7.34 (dd, 2H, J = 7.3 and 6.8 Hz, Ar-H), 7.31–7.24 (m, 4H, Ar-H), 7.20 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 7.08 (s, 1H, J = 9.3 Hz, Ar-H), 7.03 (s, 1H, J = 9.3 Hz, Ar-H), 7.00 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.02 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.78 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.23 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.13 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH), 5.06 (s, 2H, PhCH₂O) 3.86 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 150.2 (s, Ar-C), 147.7 (s, Ar-C), 140.8 (s, Ar-C), 139.2 (s, Ar-C), 136.5 (s, Ar-C), 130.6 (d, Ar-CH–CH=CH-Ar), 129.9 (d, Ar-CH–CH=CH-Ar), 128.6 (d, 2C, Ar-CH), 128.4 (s, Ar-C), 128.1 (d, Ar-CH), 127.8 (d, Ar-CH), 127.6 (d, 2C, Ar-CH), 127.5 (d, Ar-CH), 122.1 (d, Ar-CH), 121.1 (d, Ar-CH), 115.8 (d, Ar-CH), 115.2 (s, Ar-C), 112.1 (d, Ar-CH), 85.2 (d, Ph-CHCH=CH), 72.9 (t, Ph-CH₂OCHCH=CH), 71.3 (t, PhCH₂O), 56.2 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₄H₂₂BrO₃]⁺ = [M + H]⁺: 437.0747; found 437.0735 and [C₂₄H₂₂⁸¹BrO₃]⁺ = [M + H]⁺: 439.0726; found 439.0732.
5-Bromo-6-[(E)-2-(1,3-dihydro-2-benzofuran-1-yl)vinyl]-1,3-benzodioxole (6af). GP-2 was carried out and the product 6af (90 mg, 52%) was furnished as a pale yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1a) = 0.80, R_f(2f) = 0.30 and R_f(6af) = 0.65 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2901, 2852, 1502, 1474, 1412, 1247, 1229, 1116, 1034, 978, 961, 933, 863, 838, 750 cm⁻¹.¹H-NMR (CDCl₃, 400 MHz): δ = 7.35–7.23 (m, 3H, Ar-H), 7.19 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 7.03 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.99 (d, 2H, J = 2.4 Hz, Ar-H), 6.07 (dd, 1H, J = 15.5 and 7.8 Hz, ArCH=CH), 5.94 (s, 2H, OCH₂O), 5.78 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.22 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.13 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 148.1 (s, Ar-C), 147.6 (s, Ar-C), 140.7 (s, Ar-C), 139.1 (s, Ar-C), 130.5 (d, Ar-CH–CH=CH-Ar), 130.3 (d, Ar-CH–CH=CH-Ar), 129.6 (s, Ar-C), 127.8 (d, Ar-CH), 127.4 (d, Ar-CH), 122.0 (d, Ar-CH), 121.1 (d, Ar-CH), 115.0 (s, Ar-C), 112.6 (d, Ar-CH), 106.4 (d, Ar-CH), 101.7 (d, Ar-CH), 85.0 (d, Ph-CHCH=CH), 72.8 (t, Ph-CH₂OCHCH=CH) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₇H₁₃BrNaO₃]⁺ = [M + Na]⁺: 366.9940; found 366.9938 and [C₁₇H₁₃⁸¹BrNaO₃]⁺ = [M + Na]⁺: 368.9920; found 368.9918.
1-[(E)-2-(2-Bromo-4,5-dimethoxyphenyl)vinyl]-1,3-dihydro-2-benzofuran (6ag). GP-2 was carried out and the product 6ag (78 mg, 43%) was furnished as a yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1a) = 0.80, R_f(2g) = 0.15 and R_f(6ag) = 0.30 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2928, 2847, 1502, 1462, 1439, 1380, 1256, 1160, 1024, 751 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.30–7.15 (m, 4H, Ar-H), 7.00 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.99 (s, 1H, Ar-H), 6.98 (s, 1H, Ar-H), 6.10 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.78 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.21 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.13 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH), 3.83 (s, 3H, Ar-OCH₃), 3.81 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 149.4 (s, Ar-C), 148.4 (s, Ar-C), 140.6 (s, Ar-C), 139.1 (s, Ar-C), 130.6 (d, Ar-CH–CH=CH-Ar), 129.8 (d, Ar-CH–CH=CH-Ar), 128.2 (s, Ar-C), 127.7 (d, Ar-CH), 127.4 (d, Ar-CH), 122.0 (d, Ar-CH), 121.0 (d, Ar-CH), 115.2 (d, Ar-CH), 114.5 (s, Ar-C), 109.0 (d, Ar-CH), 85.2 (d, Ph-CHCH=CH), 72.8 (t, Ph-CH₂OCHCH=CH), 56.0 (q, Ar-OCH₃), 56.9 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₈H₁₇BrNaO₃]⁺ = [M + Na]⁺: 383.0253; found 383.0254.
1-[(E)-2-(2-Bromo-3,4,5-trimethoxyphenyl)vinyl]-1,3-dihydro-2-benzofuran (6ah). GP-2 was carried out and the product 6ah (90 mg, 46%) was furnished as a yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1a) = 0.80, R_f(2h) = 0.10 and R_f(6ah) = 0.25 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2923, 2851, 1559, 1480, 1426, 1391, 1325, 1201, 1166, 1106, 1009, 926, 753 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.45–7.15 (m, 4H, Ar-H), 7.10 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.87 (s, 1H, Ar-H), 6.13 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.81 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.23 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.14 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH), 3.88 (s, 3H, Ar-OCH₃), 3.87 (s, 3H, Ar-OCH₃), 3.82 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 152.7 (s, Ar-C), 150.8 (s, Ar-C), 143.0 (s, Ar-C), 140.6 (s, Ar-C), 139.1 (s, Ar-C), 131.9 (s, Ar-C), 131.2 (d, Ar-CH–CH=CH-Ar), 130.9 (d, Ar-CH–CH=CH-Ar), 127.8 (d, Ar-CH), 127.5 (d, Ar-CH), 122.1 (d, Ar-CH), 121.1 (d, Ar-CH), 110.8 (s, Ar-C), 105.6 (d, Ar-CH), 85.1 (d, Ph-CHCH=CH), 72.9 (t, Ph-CH₂OCHCH=CH), 61.1 (q, Ar-OCH₃), 61.0 (q, Ar-OCH₃), 56.1 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₉H₁₈BrO₃]⁺ = [(M + H)–H₂O]⁺: 373.0434; found 373.0416 and [C₁₉H₁₈⁸¹BrO₃]⁺ = [(M + H)–H₂O]⁺: 375.0413; found 375.0401.
5-(Benzyloxy)-1-{(E)-2-[5-(benzyloxy)-2-bromo-4-methoxy phenyl]vinyl}-1,3-dihydro-2-benzofuran (6bd). GP-2 was carried out and the product 6bd (111 mg, 41%) was furnished as a yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1b) = 0.70, R_f(2d) = 0.30 and R_f(6bd) = 0.50 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2956, 2922, 2852, 1600, 1500, 1455, 1383, 1260, 1166, 1025, 737, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.50–7.25 (m, 10H, Ar-H), 7.11 (d, 1H, J = 7.8 Hz, Ar-H), 7.06 (s, 1H, Ar-H), 7.05 (d, 1H, J = 8.3 Hz, Ar-H), 7.00 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.92 (d, 1H, J = 7.8 Hz, Ar-H), 6.87 (s, 1H, Ar-H), 6.10 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.75 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.18 (dd, 1H, J = 12.7 and 2.0 Hz, ArCH_aH_bOCHCH=CH), 5.12 (d, 1H, J = 12.7 Hz, ArCH_aH_bOCHCH=CH), 5.10 (s, 2H, PhCH₂O), 5.08 (s, 2H, PhCH₂O), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 159.1 (s, Ar-C), 149.1 (s, Ar-C), 148.6 (s, Ar-C), 140.9 (s, Ar-C), 136.8 (s, Ar-C), 136.2 (s, Ar-C), 133.0 (s, Ar-C), 130.4 (d, Ar-CH–CH=CH-Ar), 130.3 (d, Ar-CH–CH=CH-Ar), 128.8 (s, Ar-C), 128.6 (d, 3C, Ar-CH), 128.1 (d, Ar-CH), 128.0 (d, Ar-CH), 127.4 (d, 5C, Ar-CH), 122.9 (d, Ar-CH), 117.6 (d, Ar-CH), 114.6 (d, Ar-CH), 114.3 (s, Ar-C), 109.6 (d, Ar-CH), 107.3 (d, Ar-CH), 84.9 (d, Ar-CHCH=CH), 72.7 (t, Ar-CH₂OCHCH=CH), 71.1 (t, PhCH₂O), 70.3 (t, PhCH₂O), 56.0 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₃₁H₂₈BrO₄]⁺ = [M + H]⁺: 543.1165; found 543.1140 and [C₃₁H₂₈⁸¹BrO₄]⁺ = [M + H]⁺: 545.1145; found 545.1130, [C₃₁H₂₇BrNaO₄]⁺ = [M + Na]⁺: 565.0985; found 565.0959 and [C₃₁H₂₇⁸¹BrNaO₄]⁺ = [M + Na]⁺: 567.0964; found 567.0977.
5-(Benzyloxy)-1-{(E)-2-[4-(benzyloxy)-2-bromo-5-methoxy phenyl]vinyl}-1,3-dihydro-2-benzofuran (6be). GP-2 was carried out and the product 6be (119 mg, 44%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1b) = 0.70, R_f(2e) = 0.30 and R_f(6be) = 0.55 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2923, 2852, 1600, 1502, 1455, 1439, 1380, 1259, 1163, 1026, 737, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.50–7.20 (m, 10H, Ar-H), 7.09 (s, 1H, Ar-H), 7.05 (d, 1H, J = 7.8 Hz, Ar-H), 7.03 (s, 1H, Ar-H), 6.98 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.91 (dd, 1H, J = 8.3 and 2.0 Hz, Ar-H), 6.86 (d, 1H, J = 2.0 Hz, Ar-H), 6.09 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.74 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.17 (dd, 1H, J = 12.2 and 2.0 Hz, ArCH_aH_bOCHCH=CH), 5.10 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 5.07 (s, 2H, PhCH₂O), 5.07 (s, 2H, PhCH₂O), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 159.1 (s, Ar-C), 150.2 (s, Ar-C), 148.6 (s, Ar-C), 140.9 (s, Ar-C), 136.8 (s, Ar-C), 136.2 (s, Ar-C), 133.1 (s, Ar-C), 130.5 (d, Ar-CH–CH=CH-Ar), 130.2 (d, Ar-CH–CH=CH-Ar), 128.7 (d, 2C, Ar-CH), 128.6 (d, 2C, Ar-CH), 128.1 (s, Ar-C), 128.0 (d, 2C, Ar-CH), 127.4 (d, 2C, Ar-CH), 127.4 (d, 2C, Ar-CH), 122.9 (d, Ar-CH), 117.5 (d, Ar-CH), 114.6 (s, Ar-C), 114.4 (d, Ar-CH), 109.5 (d, Ar-CH), 107.3 (d, Ar-CH), 84.8 (d, Ar-CHCH=CH), 72.7 (t, Ar-CH₂OCHCH=CH), 71.1 (t, PhCH₂O), 70.3 (t, PhCH₂O), 56.1 (s, 3H, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₃₁H₂₈BrO₄]⁺ = [M + H]⁺: 543.1165; found 543.1142 and [C₃₁H₂₈⁸¹BrO₄]⁺ = [M + H]⁺: 545.1145; found 545.1126, [C₃₁H₂₇BrNaO₄]⁺ = [M + Na]⁺: 565.0985; found 565.0962 and [C₃₁H₂₇⁸¹BrNaO₄]⁺ = [M + Na]⁺: 567.0964; found 567.0987.
5-(Benzyloxy)-1-[(E)-2-(2-bromo-4,5-dimethoxyphenyl)vinyl]-1,3-dihydro-2-benzofuran (6bg). GP-2 was carried out and the product 6bg (108 mg, 47%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1b) = 0.70, R_f(2g) = 0.15 and R_f(6bg) = 0.40 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2922, 2851, 1600, 1503, 1462, 1439, 1259, 1162, 1027, 801, 737, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.42 (dd, 2H, J = 8.3 and 1.5 Hz, Ar-H), 7.38 (ddd, 2H, J = 8.3, 5.8 and 1.5 Hz, Ar-H), 7.33 (ddd, 1H, J = 8.3, 5.8 and 1.5 Hz, Ar-H), 7.11 (d, 1H, J = 8.3 Hz, Ar-H), 7.02 (d, 1H, J = 15.6 Hz, ArCH=CH), 7.01 (s, 1H, Ar-H), 7.00 (s, 1H, Ar-H), 5.91 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 6.86 (d, 1H, J = 2.0 Hz, Ar-H), 6.09 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.75 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.18 (dd, 1H, J = 12.2 and 2.4 Hz, ArCH_aH_bOCHCH=CH), 5.09 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 5.07 (s, 2H, PhCH₂O), 3.86 (s, 3H, Ar-OCH₃), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 159.1 (s, Ar-C), 149.4 (s, Ar-C), 148.5 (s, Ar-C), 140.9 (s, Ar-C), 136.8 (s, Ar-C), 133.1 (s, Ar-C), 130.4 (d, Ar-CH–CH=CH-Ar), 130.1 (d, Ar-CH–CH=CH-Ar), 128.5 (d, 2C, Ar-CH), 128.3 (s, Ar-C), 128.0 (d, Ar-CH), 127.4 (d, 2C, Ar-CH), 122.9 (d, Ar-CH), 115.2 (d, Ar-CH), 114.6 (d, Ar-CH), 114.5 (s, Ar-C), 109.1 (d, Ar-CH), 107.3 (d, Ar-CH), 84.9 (d, Ar-CHCH=CH), 72.7 (t, Ar-CH₂OCHCH=CH), 70.3 (t, PhCH₂O), 56.1 (q, Ar-OCH₃), 55.9 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₅H₂₄BrO₄]⁺ = [M + H]⁺: 467.0852; found 467.0824 and [C₂₅H₂₄⁸¹BrO₄]⁺ = [M + H]⁺: 469.0832; found 469.0817, [C₂₅H₂₃BrNaO₄]⁺ = [M + Na]⁺: 489.0672; found 489.0646 and [C₂₅H₂₃⁸¹BrNaO₄]⁺ = [M + Na]⁺: 491.0651; found 491.0649.
1-[(E)-2-(2-Bromophenyl)vinyl]-5-methoxy-1,3-dihydro-2-benzo furan (6ca). GP-2 was carried out and the product 6ca (79 mg, 48%) was furnished as a yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1c) = 0.70, R_f(2a) = 0.40 and R_f(6ca) = 0.50 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2956, 2924, 2854, 1610, 1493, 1466, 1275, 1117, 1025, 821, 748, 665 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.54 (d, 1H, J = 7.8 and 1.5 Hz, Ar-H), 7.51 (d, 1H, J = 7.8 and 1.5 Hz, Ar-H), 7.22 (dd, 1H, J = 7.8 and 1.5 Hz, Ar-H), 7.15–7.00 (m, 3H, Ar-H and ArCH=CH), 6.83 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 6.79 (d, 1H, J = 2.4 Hz, Ar-H), 6.19 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.75 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.18 (dd, 1H, J = 12.2 and 2.4 Hz, ArCH_aH_bOCHCH=CH), 5.09 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 3.81 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 160.0 (s, Ar-C), 140.9 (s, Ar-C), 136.4 (s, Ar-C), 132.9 (d, Ar-CH), 132.7 (s, Ar-C), 132.4 (d, Ar-CH), 130.3 (d, Ar-CH–CH=CH-Ar), 129.0 (d, Ar-CH–CH=CH-Ar), 127.4 (d, Ar-CH), 127.3 (d, Ar-CH), 123.8 (s, Ar-C), 122.8 (d, Ar-CH), 113.7 (d, Ar-CH), 106.3 (d, Ar-CH), 84.7 (d, Ar-CHCH=CH), 72.8 (t, Ar-CH₂OCHCH=CH), 55.6 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₇H₁₅BrNaO₂]⁺ = [M + Na]: 353.0148; found 353.0164.
1-[(E)-2-(2-Bromo-5-methoxyphenyl)vinyl]-5-methoxy-1,3-di hydro-2-benzofuran (6cc). GP-2 was carried out and the product 6cc (71 mg, 45%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1c) = 0.70, R_f(2c) = 0.50 and R_f(6cc) = 0.60 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2957, 2922, 2852, 1594, 1465, 1284, 1241, 1016, 804 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.42 (d, 1H, J = 8.8 Hz, Ar-H), δ = 7.10 (d, 1H, J = 8.3 Hz, Ar-H), δ = 7.04 (d, 1H, J = 3.3 Hz, Ar-H), 7.02 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.83 (dd, 1H, J = 8.3 and 1.9 Hz, Ar-H), 6.79 (d, 1H, J = 1.9 Hz, Ar-H), 6.69 (dd, 1H, J = 8.8 and 2.9 Hz, Ar-H), 6.18 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.75 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.19 (dd, 1H, J = 12.2 and 2.4 Hz, ArCH_aH_bOCHCH=CH), 5.10 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 3.81 (s, 3H, Ar-OCH₃), 3.76 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 160.0 (s, Ar-C), 158.9 (s, Ar-C), 140.9 (s, Ar-C), 137.1 (s, Ar-C), 133.5 (d, Ar-CH), 132.6 (s, Ar-C), 132.4 (d, Ar-CH–CH=CH-Ar), 130.5 (d, Ar-CH–CH=CH-Ar), 122.8 (d, Ar-CH), 115.7 (d, Ar-CH), 114.6 (s, Ar-C), 113.7 (d, Ar-CH), 112.0 (d, Ar-CH), 106.3 (d, Ar-CH), 84.7 (d, Ar-CHCH=CH), 72.8 (t, Ar-CH₂OCHCH=CH), 55.6 (s, Ar-OCH₃), 55.5 (s, Ar-OCH₃) ppm. HR-MS (ESI⁺) m/z calculated for [C₁₈H₁₆BrO₂]⁺ = [M + Na]: 343.0328; found 343.0314.
1-{(E)-2-[5-(Benzyloxy)-2-bromo-4-methoxyphenyl]vinyl}-5-methoxy-1,3-dihydro-2-benzofuran (6cd). GP-2 was carried out and the product 6cd (103 mg, 44%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1c) = 0.70, R_f(2d) = 0.30 and R_f(6cd) = 0.40 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2924, 2853, 1597, 1497, 1465, 1261, 1201, 1166, 1117, 1029, 813, 743, 698 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.42 (d, 2H, J = 7.3 Hz, Ar-H), 7.37 (dd, 2H, J = 7.8 and 7.3 Hz, Ar-H), 7.31 (t, 1H, J = 7.3 Hz, Ar-H), 7.10 (d, 1H, J = 8.3 Hz, Ar-H), 7.06 (s, 1H, Ar-H), 7.04 (s, 1H, Ar-H), 6.99 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.84 (dd, 1H, J = 8.3 and 2.0 Hz, Ar-H), 6.79 (d, 1H, J = 2.0 Hz, Ar-H), 6.10 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.75 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.19 (dd, 1H, J = 12.2 and 2.4 Hz, ArCH_aH_bOCHCH=CH), 5.10 (s, 2H, PhCH₂O), 5.09 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 3.83 (s, 3H, Ar-OCH₃), 3.81 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 159.9 (s, Ar-C), 149.1 (s, Ar-C), 148.6 (s, Ar-C), 140.9 (s, Ar-C), 136.2 (s, Ar-C), 132.7 (s, Ar-C), 130.4 (d, Ar-CH–CH=CH-Ar), 130.3 (d, Ar-CH–CH=CH-Ar), 128.8 (s, Ar-C), 128.6 (d, 2C, Ar-CH), 128.1 (d, Ar-CH), 127.4 (d, 2C, Ar-CH), 122.9 (d, Ar-CH), 117.5 (d, Ar-CH), 114.3 (s, Ar-C), 113.7 (d, Ar-CH), 109.5 (d, Ar-CH), 106.2 (d, Ar-CH), 84.9 (d, Ar-CHCH=CH), 72.7 (t, Ar-CH₂OCHCH=CH), 71.1 (t, PhCH₂O), 56.1 (q, Ar-OCH₃), 55.5 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₅H₂₄BrO₄]⁺ = [M + H]⁺: 467.0852; found 467.0826 and [C₂₅H₂₄⁸¹BrO₄]⁺ = [M + H]⁺: 469.0832; found 469.0812.
5-Bromo-6-[(E)-2-(5-methoxy-1,3-dihydro-2-benzofuran-1-yl) vinyl]-1,3-benzodioxole (6cf). GP-2 was carried out and the product 6cf (80 mg, 43%) was furnished as a pale yellow liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1c) = 0.70, R_f(2f) = 0.50 and R_f(6cf) = 0.55 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2921, 2852, 1605, 1500, 1474, 1235, 1106, 1036, 932, 870, 822 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.07 (d, 1H, J = 8.3 Hz, Ar-H), 6.99 (s, 2H, Ar-H), 6.98 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.82 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 6.77 (d, 1H, J = 2.4 Hz, Ar-H), 6.04 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.94 (s, 2H, OCH₂O), 5.72 [d, 1H, J = 7.8 Hz, ArCH(O)CH=CH], 5.17 (dd, 1H, J = 12.2 and 2.4 Hz, ArCH_aH_bOCHCH=CH), 5.08 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 3.81 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 160.0 (s, Ar-C), 148.1 (s, Ar-C), 147.6 (s, Ar-C), 140.8 (s, Ar-C), 132.7 (s, Ar-C), 130.6 (d, Ar-CH–CH=CH-Ar), 130.2 (d, Ar-CH–CH=CH-Ar), 129.7 (s, Ar-C), 122.7 (d, Ar-CH), 115.0 (s, Ar-C), 113.7 (d, Ar-CH), 112.6 (d, Ar-CH), 106.4 (d, Ar-CH), 106.2 (d, Ar-CH), 101.7 (t, OCH₂O), 84.7 (d, Ar-CHCH=CH), 72.7 (t, Ar-CH₂OCHCH=CH), 55.5 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₈H₁₆BrO₄]⁺ = [M + H]⁺: 375.0226; found 375.0212 and [C₁₈H₁₆⁸¹BrO₄]⁺ = [M + H]⁺: 377.0206; found 377.0189.
1-[(E)-2-(2-Bromo-3,4,5-trimethoxyphenyl)vinyl]-5-methoxy-1,3-dihydro-2-benzofuran (6ch). GP-2 was carried out and the product 6ch (86 mg, 41%) was furnished as a pale yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 80 : 20, R_f(1c) = 0.95, R_f(2h) = 0.25 and R_f(6ch) = 0.45 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2923, 2852, 1563, 1481, 1463, 1427, 1392, 1326, 1274, 1200, 1165, 1107, 1031, 1011, 926, 813 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.08 (d, 1H, J = 8.8 Hz, Ar-H), 7.06 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.86 (s, 1H, Ar-H), 6.83 (dd, 1H, J = 8.3 and 2.4 Hz, Ar-H), 6.78 (d, 1H, J = 2.4 Hz, Ar-H), 6.10 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.75 (d, 1H, J = 7.8 Hz, ArCH(O)CH=CH), 5.18 (dd, 1H, J = 12.2 and 2.4 Hz, ArCH_aH_bOCHCH=CH), 5.09 (d, 1H, J = 12.2 Hz, ArCH_aH_bOCHCH=CH), 3.88 (s, 3H, Ar-OCH₃), 3.87 (s, 3H, Ar-OCH₃), 3.82 (s, 3H, Ar-OCH₃), 3.80 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 160.0 (s, Ar-C), 152.6 (s, Ar-C), 150.8 (s, Ar-C), 143.0 (s, Ar-C), 140.8 (s, Ar-C), 132.6 (s, Ar-C), 131.9 (s, Ar-C), 131.5 (d, Ar-CH–CH=CH-Ar), 130.6 (d, Ar-CH–CH=CH-Ar), 122.8 (d, Ar-CH), 113.7 (d, Ar-CH), 110.8 (s, Ar-C), 106.2 (d, Ar-CH), 105.6 (d, Ar-CH), 84.7 (d, Ar-CHCH=CH), 72.7 (t, Ar-CH₂OCHCH=CH), 61.1 (q, Ar-OCH₃), 60.9 (q, Ar-OCH₃), 56.1 (q, Ar-OCH₃), 55.5 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₀H₂₁BrNaO₅]⁺ = [M + Na]⁺: 443.0465; found 443.0448.
5-{(E)-2-[5-(Benzyloxy)-2-bromophenyl]vinyl}-5,7-dihydrofuro [3,4-f][1,3]benzodioxole (6fb). GP-2 was carried out and the product 6fb (92 mg, 41%) was furnished as pale yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 90 : 10, R_f(1f) = 0.30, R_f(2b) = 0.45 and R_f(6fb) = 0.40 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2920, 2851, 1591, 1501, 1464, 1378, 1278, 1239, 1173, 1122, 1039, 939, 851, 737, 698 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.50–7.27 (m, 6H, Ar-H), 7.14 (d, 1H, J = 2.9 Hz, Ar-H), 7.01 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.76 (dd, 1H, J = 8.8 and 2.9 Hz, Ar-H), 6.68 (s, 1H, Ar-H), 6.62 (s, 1H, Ar-H), 6.14 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.97 (d, 1H, J = 2.9 Hz, OCH_aH_bO), 5.97 (d, 1H, J = 2.9 Hz, OCH_aH_bO), 5.70 (d, 1H, J = 7.8 Hz, ArCH(O)CH=CH), 5.12 (dd, 1H, J = 11.7 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 5.04 (d, 1H, J = 11.7 Hz, ArCH_aH_bOCHCH=CH), 5.01 (s, 2H, PhCH₂O) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 158.1 (s, Ar-C), 148.0 (s, Ar-C), 147.7 (s, Ar-C), 137.1 (s, Ar-C), 136.4 (s, Ar-C), 133.5 (d, Ar-CH–CH=CH-Ar), 133.4 (s, Ar-C), 132.3 (d, Ar-CH–CH=CH-Ar), 131.9 (s, Ar-C), 130.5 (d, Ar-CH), 128.6 (d, 2C, Ar-CH), 128.1 (d, Ar-CH), 127.4 (d, 2C, Ar-CH), 116.3 (d, Ar-CH), 114.8 (s, Ar-C), 113.3 (d, Ar-CH), 102.6 (d, Ar-CH), 101.6 (d, Ar-CH), 101.5 (t, OCH₂O), 84.9 (d, Ar-CHCH=CH), 72.9 (t, Ar-CH₂OCHCH=CH), 70.2 (t, PhCH₂O) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₄H₁₉BrNaO₄]⁺ = [M + Na]⁺: 473.0359; found 473.0330 and [C₂₄H₁₉⁸¹BrNaO₄]⁺ = [M + Na]⁺: 475.0338; found 475.0317.
5-{(E)-2-[4-(Benzyloxy)-2-bromo-5-methoxyphenyl]vinyl}-5,7-dihydrofuro[3,4-f][1,3]benzodioxole (6fe). GP-2 was carried out and the product 6fe (113 mg, 47%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 80 : 20, R_f(1f) = 0.70, R_f(2e) = 0.30 and R_f(6fe) = 0.50 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2956, 2924, 2853, 1598, 1502, 1439, 1259, 1162, 1033, 852, 803, 735, 698 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.41 (d, 2H, J = 7.3 Hz, Ar-H), 7.34 (dd, 2H, J = 7.8 and 7.3 Hz, Ar-H), 7.30 (t, 1H, J = 7.3 Hz, Ar-H), 7.07 (s, 1H, Ar-H), 7.02 (s, 1H, Ar-H), 6.95 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.68 (s, 1H, Ar-H), 6.60 (s, 1H, Ar-H), 6.96 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.97 (s, 2H, OCH₂O), 5.67 (d, 1H, J = 7.8 Hz, ArCH(O)CH=CH), 5.11 (dd, 1H, J = 11.7 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 5.07 (s, 2H, PhCH₂O), 5.02 (dd, 1H, J = 11.7 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 3.85 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 150.2 (s, Ar-C), 148.0 (s, Ar-C), 147.6 (s, 2C, Ar-C), 136.5 (s, Ar-C), 133.6 (s, Ar-C), 131.9 (s, Ar-C), 130.5 (d, Ar-CH–CH=CH-Ar), 130.0 (d, Ar-CH–CH=CH-Ar), 128.5 (d, 2C, Ar-CH), 128.3 (s, Ar-C), 128.0 (d, Ar-CH), 127.5 (d, 2C, Ar-CH), 115.7 (d, Ar-CH), 115.1 (s, Ar-C), 112.1 (d, Ar-CH), 102.6 (d, Ar-CH), 101.6 (d, Ar-CH), 101.5 (t, OCH₂O), 85.1 (d, Ar-CHCH=CH), 72.8 (t, Ar-CH₂OCHCH=CH), 71.2 (t, PhCH₂O), 56.2 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₅H₂₂BrO₅]⁺ = [M + H]⁺: 481.0645; found 481.0615 and [C₂₅H₂₂⁸¹BrO₅]⁺ = [M + H]⁺: 483.0625; found 483.0602, [C₂₅H₂₁BrNaO₅]⁺ = [M + Na]⁺: 503.0465; found 503.0438 and [C₂₅H₂₁Br⁸¹NaO₅]⁺ = [M + Na]⁺: 505.0444; found 505.0422.
5-[(E)-2-(2-Bromo-4,5-dimethoxyphenyl)vinyl]-5,7-dihydrofuro [3,4-f][1,3]benzodioxole (6fg). GP-2 was carried out and the product 6fg (85 mg, 42%) was furnished as a pale yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 80 : 20, R_f(1f) = 0.70, R_f(2g) = 0.30 and R_f(6fg) = 0.55 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2924, 2852, 1600, 1503, 1473, 1380, 1261, 1208, 1163, 1035, 937, 860, 736, 698, 665 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.00 (s, 2H, Ar-H), 6.98 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.67 (s, 1H, Ar-H), 6.63 (s, 1H, Ar-H), 6.06 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.97 (d, 1H, J = 2.9 Hz, OCH_aH_bO), 5.96 (d, 1H, J = 2.9 Hz, OCH_aH_bO), 5.69 (d, 1H, J = 7.8 Hz, ArCH(O)CH=CH), 5.11 (dd, 1H, J = 11.7 and 2.0 Hz, ArCH_aH_bOCHCH=CH), 5.02 (dd, 1H, J = 11.7 and 2.0 Hz, ArCH_aH_bOCHCH=CH), 3.86 (s, 3H, Ar-OCH₃), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 149.5 (s, Ar-C), 148.5 (s, Ar-C), 148.0 (s, Ar-C), 147.7 (s, Ar-C), 133.6 (s, Ar-C), 131.9 (s, Ar-C), 130.7 (d, Ar-CH–CH=CH-Ar), 130.0 (d, Ar-CH–CH=CH-Ar), 128.2 (s, Ar-C), 115.3 (d, Ar-CH), 114.6 (s, Ar-C), 109.1 (d, Ar-CH), 102.7 (d, Ar-CH), 101.6 (d, Ar-CH), 101.5 (t, OCH₂O), 85.2 (d, Ar-CHCH=CH), 72.8 (t, Ar-CH₂OCHCH=CH), 56.1 (q, Ar-OCH₃), 56.0 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₉H₁₇BrNaO₅]⁺ = [M + Na]⁺: 427.0152; found 427.0127 and [C₁₉H₁₇⁸¹BrNaO₅]⁺ = [M + Na]⁺: 429.0137; found 429.0121, HR-MS (ESI⁺) m/z calculated for [C₁₉H₁₈BrO₅]⁺ = [M + H]⁺: 405.0332; found 405.0304 and [C₁₉H₁₈⁸¹BrO₅]⁺ = [M + H]⁺: 407.0312; found 407.0294.
5-[(E)-2-(2-Bromo-3,4,5-trimethoxyphenyl)vinyl]-5,7-dihydro furo[3,4-f][1,3]benzodioxole (6fh). GP-2 was carried out and the product 6fh (98 mg, 45%) was furnished as a pale brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 80 : 20, R_f(1f) = 0.70, R_f(2h) = 0.20 and R_f(6fh) = 0.40 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2928, 2854, 1566, 1503, 1482, 1394, 1329, 1264, 1198, 1164, 1107, 1037, 1010, 934, 814, 739 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.05 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.86 (s, 1H, Ar-H), 6.68 (s, 1H, Ar-H), 6.64 (s, 1H, Ar-H), 6.07 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.96 (d, 1H, J = 2.9 Hz, OCH_aH_bO), 5.95 (d, 1H, J = 2.9 Hz, OCH_aH_bO), 5.69 (d, 1H, J = 7.8 Hz, ArCH(O)CH=CH), 5.11 (dd, 1H, J = 11.7 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 5.03 (dd, 1H, J = 11.7 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 3.88 (s, 3H, Ar-OCH₃), 3.87 (s, 3H, Ar-OCH₃), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 152.6 (s, Ar-C), 150.8 (s, Ar-C), 148.0 (s, Ar-C), 147.7 (s, Ar-C), 143.0 (s, Ar-C), 133.4 (s, Ar-C), 131.9 (s, Ar-C), 131.8 (s, Ar-C), 131.3 (d, Ar-CH–CH=CH-Ar), 130.8 (d, Ar-CH–CH=CH-Ar), 110.8 (s, Ar-C), 105.6 (d, Ar-CH), 102.6 (d, Ar-CH), 101.6 (d, Ar-CH), 101.5 (t, OCH₂O), 85.0 (d, Ar-CHCH=CH), 72.9 (t, Ar-CH₂OCHCH=CH), 61.1 (q, Ar-OCH₃), 60.9 (q, Ar-OCH₃), 56.1 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₀H₁₉BrNaO₆]⁺ = [M + Na]⁺: 457.0257; found 457.0257 and [C₂₀H₁₉⁸¹BrNaO₆]⁺ = [M + Na]⁺: 459.0237; found 459.0236.
1-{(E)-2-[5-(Benzyloxy)-2-bromo-4-methoxyphenyl]vinyl}-5,6-dimethoxy-1,3-dihydro-2-benzofuran (6gd). GP-2 was carried out and the product 6gd (116 mg, 47%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 70 : 30, R_f(1g) = 0.65, R_f(2d) = 0.55 and R_f(6gd) = 0.40 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2926, 2853, 1598, 1503, 1463, 1384, 1261, 1203, 1166, 1032, 859, 737, 698 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.41 (d, 2H, J = 7.3 Hz, Ar-H), 7.36 (dd, 2H, J = 7.8 and 7.3 Hz, Ar-H), 7.31 (t, 1H, J = 7.3 Hz, Ar-H), 7.05 (s, 2H, Ar-H), 7.00 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.77 (s, 1H, Ar-H), 6.69 (s, 1H, Ar-H), 6.10 (dd, 1H, J = 15.6 and 8.3 Hz, ArCH=CH), 5.75 (d, 1H, J = 8.3 Hz, ArCH(O)CH=CH), 5.18 (dd, 1H, J = 11.7 and 2.0 Hz, ArCH_aH_bOCHCH=CH), 5.10 (s, 2H, PhCH₂O), 5.07 (dd, 1H, J = 11.2 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 3.88 (s, 3H, Ar-OCH₃), 3.86 (s, 3H, Ar-OCH₃), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 149.3 (s, Ar-C), 149.1 (s, Ar-C), 149.0 (s, Ar-C), 148.6 (s, Ar-C), 136.2 (s, Ar-C), 132.1 (s, Ar-C), 130.6 (s, Ar-C), 130.6 (d, Ar-CH–CH=CH-Ar), 130.2 (d, Ar-CH–CH=CH-Ar), 128.7 (s, Ar-C), 128.6 (d, 2C, Ar-CH), 128.1 (d, Ar-CH), 127.3 (d, 2C, Ar-CH), 117.5 (d, Ar-CH), 114.4 (s, Ar-C), 109.5 (d, Ar-CH), 104.9 (d, Ar-CH), 103.9 (d, Ar-CH), 85.6 (d, Ar-CHCH=CH), 73.0 (t, Ar-CH₂OCHCH=CH), 71.1 (t, PhCH₂O), 56.2 (q, Ar-OCH₃), 56.1 (q, Ar-OCH₃), 56.0 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₆H₂₅BrNaO₅]⁺ = [M + Na]⁺: 519.0778; found 519.0753 and [C₂₆H₂₅⁸¹BrNaO₅]⁺ = [M + Na]⁺: 521.0757; found 521.0735.
1-[(E)-2-(2-Bromo-4,5-dimethoxyphenyl)vinyl]-5,6-dimethoxy-1,3-dihydro-2-benzofuran (6gg). GP-2 was carried out and the product 6gg (90 mg, 43%) was furnished as a brown viscous liquid. [TLC control (petroleum ether/ethyl acetate 70 : 30, R_f(1g) = 0.65, R_f(2g) = 0.45 and R_f(6gg) = 0.35 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2924, 2852, 1600, 1504, 1462, 1264, 1210, 1163, 1121, 1029, 863 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.02 (s, 1H, Ar-H), 7.01 (d, 1H, J = 15.6 Hz, ArCH=CH), 7.00 (s, 1H, Ar-H), 6.77 (s, 1H, Ar-H), 6.69 (s, 1H, Ar-H), 6.09 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.74 (d, 1H, J = 7.8 Hz, ArCH(O)CH=CH), 5.17 (dd, 1H, J = 11.2 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 5.07 (dd, 1H, J = 11.2 and 2.9 Hz, ArCH_aH_bOCHCH=CH), 3.88 (s, 3H, Ar-OCH₃), 3.86 (s, 6H, Ar-OCH₃), 3.83 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 149.5 (s, Ar-C), 149.4 (s, Ar-C), 149.1 (s, Ar-C), 148.5 (s, Ar-C), 132.2 (s, Ar-C), 130.7 (s, Ar-C), 130.6 (d, Ar-CH–CH=CH-Ar), 130.1 (d, Ar-CH–CH=CH-Ar), 128.3 (s, Ar-C), 115.3 (d, Ar-CH), 114.6 (s, Ar-C), 109.1 (d, Ar-CH), 105.0 (d, Ar-CH), 104.0 (d, Ar-CH), 85.6 (d, Ar-CHCH=CH), 73.0 (t, Ar-CH₂OCHCH=CH), 56.2 (q, Ar-OCH₃), 56.1 (q, Ar-OCH₃), 56.0 (q, Ar-OCH₃), 55.9 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₂₀H₂₁BrNaO₅]⁺ = [M + Na]⁺: 443.0465; found 443.0468.
(2E)-3-[2-(Hydroxymethyl)phenyl]-1-(2-methylphenyl)prop-2-en-1-ol (5ai). GP-3 was carried out and the product 5ai (65 mg, 97%) was furnished as a yellow colored viscous liquid. [TLC control (petroleum ether/ethyl acetate 70 : 30, R_f(3ai) = 0.70, R_f(5ai) = 0.30 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3330, 1485, 1459, 1006, 967, 753, 564 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.52–7.46 (m, 1H, Ar-H), 7.44 (d, 1H, J = 7.8 Hz, Ar-H), 7.32–7.10 (m, 6H, Ar-H), 6.98 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.21 (dd, 1H, J = 15.6 and 5.9 Hz, ArCH=CH), 5.47 [d, 1H, J = 5.9 Hz, PhCH(OH)CH=CH], 4.63 (d, 1H, J = 12.2 Hz, PhCH_aH_bOH), 4.62 (d, 1H, J = 12.2 Hz, PhCH_aH_bOH), 3.76 (br.s, 1H, OH), 3.29 (br.s, 1H, OH), 2.35 (s, 3H, Ar-CH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 140.4 (s, Ar-C), 137.5 (s, Ar-C), 135.8 (s, Ar-C), 135.2 (s, Ar-C), 133.2 (d, Ar-CH–CH=CH-Ar), 130.4 (d, Ar-CH), 128.7 (d, Ar-CH–CH=CH-Ar), 128.1 (d, Ar-CH), 127.6 (d, Ar-CH), 127.5 (d, Ar-CH), 126.9 (d, Ar-CH), 126.2 (2 × d, 2C, Ar-CH), 125.9 (d, Ar-CH), 71.4 (d, Ph-CHCH=CH), 63.1 (t, Ph-CH₂OH), 19.1 (q, Ar-CH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₇H₁₈NaO₂]⁺ = [M + Na]⁺: 277.1199; found 277.1197.
(2E)-3-[2-(Hydroxymethyl)phenyl]-1-(2-methoxyphenyl)prop-2-en-1-ol (5aj). GP-3 was carried out and the product 5aj (67 mg, 96%) was furnished as a colorless viscous liquid. [TLC control (petroleum ether/ethyl acetate 70 : 30, R_f(3aj) = 0.80, R_f(5aj) = 0.30 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 3320, 1597, 1489, 1461, 1244, 1023, 753 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.39 (ddd, 2H, J = 8.8, 7.8 and 1.5 Hz, Ar-H), 7.32–7.10 (m, 4H, Ar-H), 6.99 (d, 1H, J = 16.1 Hz, ArCH=CH), 6.87 (dd, 1H, J = 7.8 and 7.3 Hz, Ar-H), 6.82 (d, 1H, J = 8.3 Hz, Ar-H), 6.43 (dd, 1H, J = 16.1 and 5.9 Hz, ArCH=CH), 5.52 [d, 1H, J = 5.9 Hz, PhCH(OH)CH=CH], 4.66 (s, 2H, ArCH₂OH), 3.77 (s, 3H, Ar-OCH₃), 3.64 (br.s, 2H, 2 × OH) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 156.7 (s, Ar-C), 141.1 (s, Ar-C), 138.5 (s, Ar-C), 131.0 (d, Ar-CH–CH=CH-Ar), 130.0 (d, Ar-CH), 128.8 (d, Ar-CH–CH=CH-Ar), 128.3 (d, Ar-CH), 128.1 (d, Ar-CH), 127.8 (d, Ar-CH), 127.0 (d, Ar-CH), 125.5 (s, Ar-C), 125.4 (d, Ar-CH), 120.6 (d, Ar-CH), 110.8 (d, Ar-CH), 73.2 (d, Ph-CHCH=CH), 63.5 (t, Ph-CH₂OH), 55.4 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₇H₁₉O₃]⁺ = [M + H]⁺: 271.1329; found 271.1320.
1-[(E)-2-(2-Methylphenyl)vinyl]-1,3-dihydro-2-benzofuran (6ai). GP-3 was carried out and the product 6ai (50 mg, 84%) was furnished as a colorless viscous liquid. [TLC control (petroleum ether/ethyl acetate 95 : 5, R_f(5ai) = 0.15, R_f(6ai) = 0.80 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2924, 2853, 1731, 1460, 1029, 965, 747, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.45 (d, 1H, J = 8.3 Hz, Ar-H), 7.36–7.25 (m, 3H, Ar-H), 7.24–7.10 (m, 4H, Ar-H), 6.97 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.16 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.79 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.23 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.14 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH), 2.39 (s, 3H, Ar-CH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 141.0 (s, Ar-C), 139.2 (s, Ar-C), 135.7 (s, Ar-C), 135.5 (s, Ar-C), 130.3 (2 × d, 2C, Ar-CH–CH=CH-Ar and Ar-CH), 129.9 (d, Ar-CH), 127.7 (2 × d, 2C, Ar-CH–CH=CH-Ar and Ar-CH), 127.4 (d, Ar-CH), 126.0 (d, Ar-CH), 125.9 (d, Ar-CH), 122.0 (d, Ar-CH), 121.1 (d, Ar-CH), 85.5 (d, Ph-CHCH=CH), 72.8 (t, Ph-CH₂OCHCH=CH), 19.9 (q, Ar-CH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₇H₁₆NaO]⁺ = [M + Na]⁺: 259.1093; found 259.1099.
1-[(E)-2-(2-Methoxyphenyl)vinyl]-1,3-dihydro-2-benzofuran (6aj). GP-3 was carried out and the product 6aj (53 mg, 86%) was furnished as a colorless viscous liquid. [TLC control (petroleum ether/ethyl acetate 95 : 5, R_f(5aj) = 0.10, R_f(6aj) = 0.70 UV detection)]. IR (MIR-ATR, 4000–600 cm⁻¹): ν_max = 2904, 2838, 1489, 1461, 1244, 1028, 749, 697 cm⁻¹. ¹H-NMR (CDCl₃, 400 MHz): δ = 7.45 (dd, 1H, J = 7.8 and 1.5 Hz, Ar-H), 7.36–7.15 (m, 5H, Ar-H), 7.09 (d, 1H, J = 15.6 Hz, ArCH=CH), 6.91 (d, 1H, J = 7.3 Hz, Ar-H), 6.87 (d, 1H, J = 7.3 Hz, Ar-H), 6.30 (dd, 1H, J = 15.6 and 7.8 Hz, ArCH=CH), 5.78 [d, 1H, J = 7.8 Hz, PhCH(O)CH=CH], 5.23 (dd, 1H, J = 12.2 and 2.4 Hz, PhCH_aH_bOCHCH=CH), 5.13 (d, 1H, J = 12.2 Hz, PhCH_aH_bOCHCH=CH), 3.86 (s, 3H, Ar-OCH₃) ppm. ¹³C-NMR (CDCl₃, 100 MHz): δ = 156.9 (s, Ar-C), 141.2 (s, Ar-C), 139.2 (s, Ar-C), 129.4 (d, Ar-CH–CH=CH-Ar), 128.9 (d, Ar-CH), 127.6 (d, Ar-CH–CH=CH-Ar), 127.4 (d, Ar-CH), 127.1 (d, Ar-CH), 127.0 (d, Ar-CH), 125.4 (s, Ar-C), 122.1 (d, Ar-CH), 121.0 (d, Ar-CH), 120.5 (d, Ar-CH), 110.8 (d, Ar-CH), 85.9 (d, Ph-CHCH=CH), 72.7 (t, Ph-CH₂OCHCH=CH), 55.4 (q, Ar-OCH₃) ppm. HR-MS (ESI⁺): m/z calculated for [C₁₇H₁₇O₂]⁺ = [M + H]⁺: 253.1223; found 253.1219.

Conclusions

In summary, we have developed an efficient and practical method for the direct synthesis of 1,3-dihydroisobenzofurans, an important structural motif present in biologically active natural or synthetic compounds. [Pd]-catalyzed controlled intermolecular Mizoroki–Heck coupling and reduction were performed sequentially. The direct treatment of the resultant crude diol without further purification with BF₃·Et₂O gave 1,3-dihydroisobenzofurans. Significantly, the method enabled the synthesis of 1,3-dihydroisobenzofurans with simple to electron rich aromatic rings. Importantly, the protocol is also applicable for a wide range of ortho substituted allylic alcohols. It is worth mentioning that although the yields of the cyclic ether 1,3-dihydroisobenzofurans are moderate, it actually represents the overall yield of three individual reactions.

Acknowledgements

Council of Scientific and Industrial Research [(CSIR), 02(0018)/11/EMR-II], New Delhi, is gratefully acknowledged. JK and PN thank CSIR, New Delhi, for awarding the research fellowship.

Notes and references

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Footnote

† Electronic supplementary information (ESI) available. See DOI: 10.1039/c5ra00955c

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