Expansive Rearrangement of N-Vinylthiazolidines to 2,3,4,7-Tetrahydro-1,4-thiazepines and Their Transformation in 3-Thia-6-azabicyclo[3.2.1]oct-6-enes.

3-(2-Cyano-1-methylvinyl)-N-methoxy-N-methylthiaz-olidine-4-carboxamide was transformed in 1H,3H-pyrrolo[1,2-c]thiazoles by means of a modified Knorr synthesis or in 6-cyano-N-methoxy-N,5-dimethyl-2,3,4,7-tetrahydro-1,4-thiazepine-3-carboxamide by simple thermal treatment. The latter led to 8-hydroxy-3-thia-6-azabicyclo[3.2.1]oct-6-ene-l-carbonitrile derivatives when it reacted with Grignard or organolithium compounds.