Abstract The β-isothiocyanato-ketone 1 reacts with substituted hydrazines (2) in alkaline solution to form 2-alkyl-5, 6-dihydro-(2 H)-1, 2, 4-triazepine-3 (4 H)-thiones (3); the intermediate thiosemicarbazide derivatives (6), formed by addition of the hydrazine derivatives to the isothiocyanate group, could be isolated. CH 3 I and BrCH 2 COOC 2 H 5 alkylate 3 at sulfur, and the fusedring compounds 14 and 16 were isolated.
![6,8,8-trimethyl-7H-[1,3]thiazolo[3,2-b][1,2,4]triazepin-3-one结构式](https://image.chemsrc.com/caspic/163/61781-24-6.png)