Cycloaddition of N-(2,2,2-trichloroethylidene)-substituted carboxamides and carbamates to 1,2,4-thiadiazol-5(2H)-imines

Abstract

1,2,4-Thiadiazol-5(2H)-imines 4 react with N-(2,2,2-trichloroethylidene)-substituted amides 5 to form [3 + 2]-cycloaddition products 6 featured by an extra coordination of the ring sulfur atom to the terminal nitrogen atom of the side 1,3-diazapropenylidene group, as established by X-ray diffraction investigation. This coordination evidently plays an important role in the alkylation of compounds 6 into 8 at the oxygen atom under mild conditions. The S-N bond "switch-over" restoring the original 1,2,4-thiadiazole ring occurs therewith. © 2003 Wiley Periodicals, Inc.