The thiazolium ylides, derived from 3-(2-aryl-2-oxoethyl)-4-methylthiazolium bromides and triethylamine, gave with dimethyl acetylenedicarboxylate and dibenzoylacetylene derivatives of the lHi-pyrrolo [2, 1-c][1, 4] thiazine system that were formed by rearrangement of the intermediate 5, 7a-dihydropyrrolo [2, 1-b] thiazole system. With ethyl propiolate a 1, 2 adduct was formed by further reaction of a hydroxyl substituent in the thiazine system with ...
