Nataliya N. Makhmudiyarova*,
Kamil R. Shangaraev,
Irina R. Ishmukhametova,
Askhat G. Ibragimov and
Usein M. Dzhemilev
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, 141 Prospekt Oktyabrya, 450075 Ufa, Russian Federation. E-mail: natali-mnn@mail.ru
First published on 21st January 2021
Co(OAc)2-catalyzed ring transformation reaction of 10-aryl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecanes with α,ω-dithiols (ethane-1,2-, propane-1,3-, butane-1,4-, pentane-1,5-, and hexane-1,6-dithiols, 3,6-dioxaoctane-1,8-dithiol) giving 3-aryl-1,5,3-dithiazacyclanes was studied.
It was shown by preliminary experiments that the reaction of 10-phenyl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecane 1 with ethane-1,2-dithiol 2 does not proceed without a catalyst. The reaction of azadiperoxide 1 with ethane-1,2-dithiol 2 catalyzed by Sm(NO3)3·6H2O, H2SO4 or BF3·Et2O in THF as a solvent affords 3-phenyl-1,5,3-dithiazepane 8 in 10–15% yield (Scheme 1, Table 1). It was found that the yield of 3-phenyl-1,5,3-dithiazepane12 is affected by the nature of the catalyst. When the reaction is carried out in a polar solvent (MeOH) in the presence of catalytic amounts of Sm(NO3)3·6H2O, H2SO4 or BF3·Et2O, the yield of the target product 8 increases to 30%. In the presence of the Co(OAc)2 catalyst, the yield of heterocycle 8 is 85%. When AlCl3 or CuCl catalysts are used, the yields of heterocycle 8 are 55% and 75%, respectively (Table 1). Under these conditions, cyclohexanone is formed and O2 is released (Scheme 1). All reactions were carried out at room temperature for 20 h.
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Scheme 1 Ring transformation reaction of 10-phenyl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecane with α,ω-dithiols. |
No. | Compound | [Cat] | Solvent | Yield, % |
---|---|---|---|---|
1 | 8 | AlCl3 | THF | 45 |
2 | 8 | AlCl3 | MeOH | 55 |
3 | 8 | Co(OAc)2 | THF | 79 |
4 | 8 | Co(OAc)2 | MeOH | 85 |
5 | 8 | BF3·OEt2 | THF | 15 |
6 | 8 | BF3·OEt2 | MeOH | 30 |
7 | 8 | CuCl | THF | 68 |
8 | 8 | CuCl | MeOH | 75 |
9 | 8 | H2SO4 | THF | 13 |
10 | 8 | H2SO4 | MeOH | 25 |
11 | 8 | Sm(NO3)3·6H2O | THF | 10 |
12 | 8 | Sm(NO3)3·6H2O | MeOH | 20 |
13 | 8 | — | THF | — |
14 | 8 | — | MeOH | — |
15 | 9 | Co(OAc)2 | MeOH | 87 |
16 | 10 | Co(OAc)2 | MeOH | 79 |
17 | 11 | Co(OAc)2 | MeOH | 83 |
18 | 12 | Co(OAc)2 | MeOH | 89 |
19 | 13 | Co(OAc)2 | MeOH | 91 |
A probable pathway to the synthesis of 3-phenyl-1,5,3-dithiazepane 8 from 10-phenyl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecane 1 includes13 coordination of the peroxide oxygen atom to the central atom of the catalyst, nucleophilic addition of ethane-1,2-dithiol to the resulting carbocation,14,15 and the subsequent ring closure giving heterocycle 8 (Scheme 2).
Under conditions including 5 mol% of Co(OAc)2, 20 °C, MeOH, and 20 h, 10-phenyl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecane 1 was allowed to react with propane-1,3- 3, butane-1,4- 4, pentane-1,5- 5, and hexane-1,6-dithiols 6, which furnished the corresponding 3-phenyl-1,5,3-dithiaazacycloalkanes16 9–12 in 83–89% yields (Table 1). The ring transformation reaction of azadiperoxide 1 with 3,6-dioxa-1,8-octanedithiol 7 (monooxa derivative is shown in the scheme) under the conditions described above resulted in the synthesis of 6-phenyl-1,11-dioxa-4,8-dithia-6-azacyclotridecane16 12 in 91% yield (Scheme 1).
The discovered ring transformation reaction of azadiperoxide 1 with ethane-1,2-dithiol 2 was also carried out for 10-aryl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecanes 14–24, which produced 3-aryl-1,5,3-dithiazepanes12 25–35 in 76–90% yields (Scheme 3).
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Scheme 3 Ring transformation reaction of 10-aryl-7,8,12,13-tetraoxa-10-azaspiro[5.7]tridecanes with ethane-1,2-dithiol. |
In conclusion, we demonstrated that on treatment with α,ω-alkanedithiols and the Co(OAc)2 catalyst, azadiperoxides are converted to N-aryl-substituted 1,5,3-dithiazamacroheterocycles in high yields.
Footnote |
† Electronic supplementary information (ESI) available. See DOI: 10.1039/d0ra09758f |
This journal is © The Royal Society of Chemistry 2021 |