Themed collection Organic Chemistry Frontiers HOT articles for 2018

The direct aryl-conjugate addition to electron-deficient alkenes without prior stoichiometric formation of organometallic reagents in water catalyzed by copper represents an important but unresolved challenge.

The reductive difunctionalization strategy was successfully applied in the Ni-catalyzed 1,2-iminoacylation reaction of oxime ester-tethered olefins with electrophilic acylating reagents, providing an efficient entry to diverse pyrrolines under safe and mild reaction conditions.

A highly regioselective protocol has been developed for the synthesis of benzimidazo[l,2-c]quinazolin-6-ones via C–C bond cleavage and triple C–N bond formation.

A novel method has been developed for the desymmetrization of aromatic dicarboxylic acids by employing an esterification reaction/conjugate addition of a carboxyl group to ynoates, which can trigger a coupling reaction.

Described herein is an iridium(III)-catalyzed oxidative Ar–H/Ar–H cross-coupling of primary benzamides with thiophenes for the synthesis of (2-thienyl)benzamides.

An enantioselective formation of isoquinuclidines useful for alkaloid synthesis is achieved through an organocatalyzed Diels–Alder reaction of dihydropyridines with acrolein and a subsequent photoredox catalyzed oxidative deformylation reaction.

A model of a triple-functionalised metal centre for the discovery of unprecedented enantioselective reactions was exquisitely developed by using a Rh^I/(DHQ)₂PHAL catalyst system via multiple coordination interactions with different ligands and substrates.

A DFT study toward N-heterocyclic carbene-catalyzed [3 + 4] annulation reactions of 2-bromoenals has been performed for the first time.

A novel rearrangement of cycloketoxime esters to cyano-containing benzoates beyond the traditional Beckmann and Neber rearrangement process has been established in the presence of photocatalysis catalysis.

The potential energy curves show that (2,6-aza)Ind in aqueous solution undergoes a quadruple-proton transfer reaction with the assistance of three water molecules.

A new type of 2,4-dienal featuring a benzofulvene skeleton is utilised in asymmetric Diels–Alder cycloadditions with 3-olefinic oxindoles via trienamine catalysis.

Rh(III)-Catalyzed oxidative annulation of 2-aryl-2H-indazoles with alkynes and their photophysical studies are reported with high quantum yields.

A visible-light photocatalytic trifluoromethylthiolation of aryl amine through in situ generation of aryldiazonium salts with S-trifluoromethyl 4-methoxylbenzenesulfonothioate was developed.

An electro-generated trifluoromethyl radical mediated by a bromide ion is efficiently applied to the trifluoromethylarylation/cyclization of N-arylacrylamides.

An N-heterocyclic carbene-catalyzed reaction of aldehydes and butadienoates affording (E)-4-oxo-2-butenoates highly stereoselectively has been developed. Some key intermediates have been detected by an MS study.

The annulation of aryl iodides and epoxides to convergently access valuable 2,3-dihydrobenzofuran scaffolds was developed via a Catellani strategy.

An efficient Cu(I)-catalyzed stereoselective synthesis of trisubstituted Z-enol esters via interrupting the 1,3-O-transposition process is reported, which provided a convenient approach to highly functionalized Z-enol esters.

We developed a series of unsymmetrical CNN palladacycles with geometry-constrained iminopyridyl ligands, which were used as efficient precatalysts for preparing diarylalkanes through Suzuki coupling.

A Pd(II)-catalyzed [3 + 2] spiroannulation of α-aryl-β-naphthols with internal alkynes has been developed by relying on a C–H activation/arene dearomatization approach.

A chiral N,N′-dioxide/Mg(II) complex efficiently constructs spiroindolinones which include three adjacent atom chiralities and a tertiary carbon center at remote sites in up to 95% yield, with 99% ee and 20 : 1 dr.

A Cu-catalyzed synthesis of 5-arylsubstituted 1,2,3-triazoles via an oxidative interrupted click reaction with arylboronic acids in air at room temperature is disclosed.

Five dimeric polyketides with two novel skeletons, generated by the crucial [3 + 2] and [3 + 3] cycloadditions, were isolated from Aspergillus sp.

Twenty-one structurally diverse diterpenoids (1–21), wherein 1, 2, and 4 represented unprecedented architectures, were isolated from Isodon pharicus.

An efficient and green carbon disulfide surrogate via facile combination of potassium sulfide and chloroform has been developed.

Reported herein is a novel, mild, and practical protocol for the radical-mediated phosphinoyl-functionalization of unactivated alkenes through distal functional group migration.

A simple chiral primary amine catalyst was identified to enable effective catalysis in direct α-sulfenylation of acyclic and cyclic β-ketocarbonyls with good yields and excellent enantioselectivities.

Photoexcited perylene diimide radical anions exhibit remarkable substituent-dependent photocatalytic activities towards the reduction of aryl halides, which are mainly controlled by their excited-state reduction potentials and SOMO−1 energies.

Palladium-catalyzed regioselective electrocarboxylation of homostyrenyl acetates with CO₂ has been successfully developed, providing α-aryl carboxylic acids with good selectivity and yield.

An efficient three-component reaction for the synthesis of sulfonylated furans or imidazo[1,2-a]pyridines has been developed.

Dysohonin A (1), a meroditerpenoid incorporating an unprecedented architecture, along with three new biogenetically related meroditerpenoids as PTP1B inhibitors were reported in this paper.

The penta- to octa-saccharide fragments of Vi polysaccharide were synthesized efficiently, and the hexasaccharide might be the minimum epitope of Vi antigen based on ELISA analysis.

GpTx-1 and its analogue GpTx-71-1 were synthesized by a flexible and highly practical strategy via converging three segments based on C-terminal proline residues.

DFT studies revealed the detailed structure stereoselectivity relationship for cyclic secondary amine catalyzed asymmetric Mannich reactions.

An asymmetric [4 + 2] cycloaddition reaction with 2-benzyl-3-furfurals and α-cyano-chalcones was developed to afford chiral tetrahydrobenzofurans having dense substitutions.

A catalytic reductive addition of isocyanoacetates to tertiary lactams/amides has been developed. This one-pot procedure involves Ir-catalysed partial reduction of lactams/amides and sequential chemoselective addition of isocyanide group in isocyanoacetates and produces 5-methoxyoxazoles in moderate to excellent yields.

A three-component reaction of geminal bis(silyl) allyl silyl ether, aldehyde and electrophile has been developed to synthesize trisubstituted E-vinyl silyl anti-1,2-diols. The approach features a sequential [1,4]-O-to-O/[1,4]-C-to-O silyl migrations process.

After a serendipitous synthesis of a potentially effective chemotherapeutic agent for the treatment of colorectal carcinomas, a more reliable synthetic method is now described using our building blocks containing stereodefined stereochemistry at C-20.

Easy access to mono- and bis-sulfenylindoles using the SeO₂/I₂ system.

Asymmetric synthesis of chiral hydroxy amides has been successfully accomplished by asymmetric hydrogenation of prochiral α-, β-, γ-, δ-keto amides catalyzed by Ir/f-amphox with up to >99% conversion and >99% ee.

The Pd/Cu-catalyzed intramolecular C–H bond aminocarbonylation utilizing imines as the amine source has been developed. This transformation provides an efficient and straightforward protocol for the synthesis of phthalimides which widely exist in natural products, pharmaceutical and functional materials. Various functional groups are tolerated and the yields are up to 99%.

A novel azidoheteroarylation of unactivated olefins by means of intramolecular distal heteroaryl migration is herein reported.

Cyclic tripyrrin “locked” by a bridging benzyl moiety: enhancing the molecular rigidity and tuning aggregation and fluorescence via intermolecular halogen interactions.

New substitution patterns for rylene diimides by catalytic diamination.

We have developed an iridium-catalysed conjugated alkynylation of α,β-unsaturated amide.

An indium(I)–chiral phosphoric acid complex was found to catalyze the enantioselective [4 + 2] annulation reaction of β,γ-unsaturated α-keto esters with alkoxyallenes, affording cyclic O,O-acetals in good yields and with high regio- and stereo-selectivities.

A highly concise approach for the first asymmetric and gram-scale total syntheses of callistrilones B, G and J is reported.

A photoredox-catalyzed cascade annulation of methyl(2-(phenylethynyl)phenyl)sulfanes and methyl(2-(phenylethynyl)phenyl)selanes with sulfonyl chlorides was developed.

A facile synthetic method for the preparation of oxazole and 4-amino-isoquinolin-1(2H)-one derivatives has been developed from the reaction of N-(pivaloyloxy)-amides and ynamides by using different metal catalysts.

A silver-catalyzed ring-opening difluoromethylthiolation/trifluoromethylthiolation of cycloalkanols including cyclopropanols, cyclobutanols, cyclopentanols, cyclohexanols and cycloheptanols was described.

The mechanism of Rh₂(II)-catalyzed ring expansion of ortho-cyclobutanol-substituted aryl azides to access N-heterocycles was investigated by DFT calculations.

The total syntheses of teixobactin and a series of its stereoisomers at positions 2, 5, 6, 10 and 11 were achieved via a combined strategy of solution and solid phase peptide synthesis.

A highly enantioselective method to chiral α-substituted 6H-benzo[c]chromenes through chiral imidodiphosphoric acid-catalyzed asymmetric transfer hydrogenation of ketals has been established.

The gene cluster of two new labdanmycins was identified from an endophytic Streptomyces. The P450 enzyme LabE was confirmed to oxidize C-20 methyl of the biosynthetic intermediate 3 to afford labdanmycins.

A facile synthesis of 6H-1,3-oxazin-6-ones and 6H-1,3-thiazin-6-ones has been achieved in the base-promoted [3 + 3] cyclization of cyclopropenones and cyclopropenethiones with amides.

A wide range of functionalized 1,3-enynes undergo hydroboration with pinacolborane to produce enantiomerically enriched allenylboronates in the presence of a chiral copper catalyst.

Salviyunnanone A (1), a cytotoxic diterpenoid possessing an unprecedented architecture was characterized, and its 6-epi-isomer was synthetic achieved in 9 steps.

Based on dithieno[2,3-b:2′,3′-d]thiophene, three novel helicenes including helicene (rac-1), double helicene (rac-2), and benzohexathia[7]helicene (rac-3), and one bull's horn-shaped benzohexathienoacene (4) have been synthesized and reported in this paper.

A general and efficient Mn-catalyzed acceptorless dehydrogenative coupling of alcohols with hydroxides into carboxylates has been developed.

We report the first allylic isomerization of alcohols catalyzed by ⁿBu₄NOTf generated in situ from tetrabutylammonium triflate and potassium tert-butoxide.

An organocatalytic enantioselective 1,4-addition of phosphites to azadienes has been successfully developed using quinine as a catalyst, providing an efficient and facile route to optically active γ-aminophosphonates with up to 94% ee.

An efficient and straightforward protocol to complex indene-based polycyclic compounds via the cascade cyclization of propargylic alcohols and alkenes was developed. The catalyst FeCl₃, as an Earth-abundant and environment friendly transition metal salt, is attractive. This reaction proceeded through unusual C–C bond cleavage.

An enantioselective NHC-catalyzed desymmetrization reaction of diarylalkane-bisphenols with aldehydes was reported under the guidance of linear free energy relationships (LFERs).

An efficient method for the synthesis of poly-substituted naphthalenes/isoquinolines via Fe(III)/Zn(II)-catalyzed [4 + 2] cycloaddition of 2-(2-oxo-alkyl)benzketones is described.

Two rare new furan butanolides, sponalisolides A (1) and B (2), were isolated from the Beihai sponge Spongia officinalis, and fully characterized by extensive spectroscopic analysis and biomimetic total synthesis.

The catalytic activity of Ru(II) complexes in sustainable C–C and C–N bond formation is enhanced by using a functionalized 2,2′-bipyridine ligand.

Sulfoxonium ylides acts as a bifunctional C₂-synthon in Rh(III)-catalyzed redox-neutral annulative coupling with arenes for the synthesis of N-heterocycles and carbocycles.

A copper-catalyzed three-component phosphorylation–peroxidation of alkenes with P(O)–H compounds and TBHP has been developed.

A di-tert-butyl peroxide-promoted radical rearrangement of N-sulfonyl-N-aryl propynamides has been developed, giving 2-sulfonyl-3-aryl-2(1H)-quinolinones in moderate to good yields.

This method provides a visible-light-induced radical tandem cyclization for the synthesis of phosphorus phenanthridines with various nitrogen-containing substrates.

The hexameric resorcinarene capsule as an artificial enzyme to rule the regio and stereochemistry of a 1,3-dipolar cycloaddition.