Unexpected result of thiophosphorylation of 6-aminopyrano[2,3-c]pyrazole-5-carbonitrile derivative

Abstract

The reaction of 6-amino-3-methyl-4-(2,4-dichlorophenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile with phosphorus sulfide in boiling pyridine unexpectedly leads to the formation of a not previously described heterocyclic system—[1,2]oxaphosphinino[6,5-c]pyrazole derivative. Structure of the obtained compound was proved using 2D NMR spectroscopy and X-ray diffraction analysis