New routes to heterocycles via sulphenylation of unsaturated amides

Abstract

The reaction of manganese(III) acetate with diphenyl disulphide in dichloromethane-trifluoroacetic acid in the presence of N-allylacetamide, followed by hydrolysis, affords a vicinal hydroxy sulphide. Similarly, addition to N-allyltrifluoroacetamide affords hydroxy sulphide adducts, but with different regioselectivity. N-Allylbenzamide and other unsaturated benzamides under similar conditions give cyclic products, 4,5-dihydro-1,3-oxazoles. Homoallylic amides give 5,6-dihydro-4H-1,3-oxazines. Amides derived from pent-4-enylamine give substituted pyrrolidines by cyclisation through nitrogen, but N-hex-5-enylbenzamide gives only an acyclic adduct. Unsaturated carboxylic acids and unsaturated carboxamides are transformed in good yield into lactones under similar conditions.