The main products from the title reactions were 7H-thiazolo [3, 2-a] pyrimidin-7-ones (IV) and 2H-pyrimido-[2, 1-b] benzothiazol-2-ones (V). Treatment of some of these with primary and secondary aliphatic amines yielded 2-(β-aminoacryloyl) imino-Δ4-thiazolines (X) and the corresponding benzo-analogues (XI).