L,3,4,6-Oxatriazepine-5-thiones

Only two classes appear to be known. The 1,2,5,6-system (599) is said to result from the treatment of the semicarbazide (598) with iron(III) chloride (28JIC439), and more recently it has been shown that benzoyl isothiocyanate adds to the phenylhydrazones of benzaldehyde and several ketones to give the l,3,4,6-oxatriazepine-5-thione system (600) (67JCS(C)952, 76JCS(P1)2243). The products rearrange to give (601) quantitatively on treatment with acid. 

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