Chemistry of 1,2,3-thiadiazole. IV. Synthesis of [1]benzoxepino-[3,4-d][1,2,3]thiadiazole, [1]benzothiepino-[3,4-d][1,2,3]thiadiazole, [1]benzoxepino[4,3-d][1,2,3]thiadiazole, [1]benzoxepino[4,3-d]oxazole and [1]benzoxepino[4,3-d]oxazole. Four novel heterocycles

Starting from the readily available 4-bromomethy-5-carbethoxy 1,2,3-thiadiazole (V), 5-bromomethy-4-carbethoxy-1,2,3-thiadiazole (IX) and ethyl 2-aryl-5-bromomethyloxazole-4-carboxylate (XIV), 4,10-dihydro-10-oxo[1]benzoxepino[3,4-d][1,2,3]thiadiazole (Ia), 4,10-dihydro-10-oxo[1]benzothiepino[3,4-d][1,2,3]thiadiazole (Ib), 4,10-dihydro-4-oxo[1]benzothiepino[4,3-d] [1,2,3]thiazole (II), 2-aryl-4,10-dihydro-4-oxo[1]benzoxepino[4,3-d]oxazoles (XIXa-XIXc) and 2-aryl-4,10-dihydro-4-oxo[1]benzothiepino[4,3-d]oxazoles (XIXd-XIXf) were prepared.