An efficient synthesis of 5-phosphorylated 1,3,2-diazaphosphinines from beta-functionalized enamines derived from phosphine oxides and phosphonates

An easy and efficient synthesis of 1,3,2-P-III-diazaphosphininones (3, 4) s ubstituted with a phosphine oxide or a phosphonate group in the 5-position is described. The key step is a cyclocondensation reaction of substituted b eta-enamino amides (1) to phosphorus trichloride and phenylphosphonous dich loride. Subsequent treatment of 1,3,2-P-III-diazaphosphininones (3) with el emental sulfur, water or hydrogen peroxide afforded the substituted 2-thio- (7, 8) and 2-oxo-1,3,2-P-V-diazaphosphininones (5, 6, 9).