Synthesis and characterization of 4,5‐dihydro‐1H‐pyrazolo[3,4b][1,4]azaphosphinines

Abstract

1,3,

One-Pot Synthesis of (5-Aminopyrazol-4-yl)-phosphonicAcid Derivatives from 1-Aryl-5-arylcarboxamidopyrazoles throughPyrazolo[4,3-c][1,5,2]-oxazaphosphinines

“…3 Besides this, it was established that 5-aminopyrazoles bearing electron-withdrawing groups in the 4 position including 4-phosphorylated 5aminopyrazoles have herbicidal properties. 4 Continuing our research in the direct phosphorylation of pyrazoles with phosphorus(III) halides, [5][6][7][8][9] we have given special consideration to the synthesis of derivatives of 4-phosphorylated 5-aminopyrazoles.…”

“…We suggest that heterocyclization runs through the acyclic O-phosphorylated intermediate 2 (Scheme 1). 8,13,14 Pyrazolooxazaphosphinines 3-5, crystalline substances, stable under inert atmosphere, are formed in a high yield.…”