Fused poly cyclic nitrogen-containing heterocycles 13.* Synthesis of 6-phenyl-2-phenylimino-6H-l,3,4-thiadiazine-5-carboxylic acid and its intermolecular cyclodehydration accompanied by sulfur extrusion to form dipyrazolo[l,5-a,l',5'-d]pyrazine

摘要

Condensation of methyl phenylchloropyruvate with 4-phenylthiosemicarbazide proceeds as the Bose reaction to form 5-methoxycarbonyl-6-phenyl-2-phenylimino-6H-l,3,4-thia-diazine,which is hydrolyzed to give carboxylic acid.In the presence of polyphosphoric acid,the latter undergoes intermolecular cyclodehydration accompanied by sulfur extrusion to yield dipyrazolo[l,5-a,l',5'-d]pyrazme.