Synthesen mit 1,3-Dithietanen. XIV. Ringumwandlungen von substituierten Dihydropyrazolo[5, 1-b]thiazolcarbonsäureestern

Syntheses with 1,3-Dithietanes. XIV. Ring Transformations of Substituted Dihydropyrazolo 5,1-b]thiazolecarboxylates Dihydropyrazolo5,1-b]thiazolecarboxylates 2 react with aliphatic amines to give dihydrothiazolo2,3-g]1,2,4]triazepinecarboxylates 4 . Compounds 2c , d and o-phenylenediamine, o-amino-phenols or o-amino-thiophenol afford substituted ethyl benzimidazol-, benzoxazol- or benzothiazol-2-yl-acetates 6 . Hydrazine hydrate and compounds 2 yield derivatives of ethyl pyrazolidin-4-yliden-4-thiazoline-5-carboxylates 8 .