(PERHALOGENMETHYLTHIO)-HETEROCYCLEN, XV. Saeure- und basekatalysierte Umsetzungen von Furan, Selenophen und Pyridin

Article abstract of DOI:10.1016/S0022-1139(00)85137-4

In the presence of Lewis acids furan reacts with CF3SCl to form 2-trifluoromethylmercaptofuran 1 in yields of less than 1 percent.The yield is increased to 35 percent, if the reaction is carried out in the presence of pyridine. 2-Methyl-5-chlorofluoromethylmercaptofuran 4b-d were prepared similarly.Oxidation of 1 with m-chloroperbenzoic acid leads to the formation of 2-trifluoromethylsulfinyl- 5 and 2-trifluoromethylsulfonylfuran 6 in low yield.Cyclisation of 2,5-hexanedione in the presence of CF_nCl_3-nSCl gives 2,5-dimethyl-3-CF_nCl_3-nS-furan (for n = 3, 7a; n = 2, 7b) and 1-chlorodifluoromethylmercapto-2,5-hexanedione 8 for n = 2.Selenophene reacts with CF3SCl in the presence of SnCl4 to give 2-trifluoromethylmercaptoselenophene 9, which, with the aid of CF3SO3H, can be disubstituted to 2,5-bis(trifluoromethylmercapto)selenophene 10. 3,5-Bis(trifluoromethylmercapto)pyridine 12 can be isolated in small amounts as a byproduct obtained during the syntheses of 3-trifluoromethylmercaptopyridine 11.