Novel Synthesis of Phosphinates by the Microwave-Assisted Esterification of Phosphinic Acids

Abstract

1-Hydroxy-3-phospholene oxides (1 and 3) and phenyl-H-phosphinic acid (6) are converted to the corresponding phosphinic esters (2, 4, and 7, respectively) by reaction with simple alcohols on microwave irradiation. Under traditional heating conditions, the esterification does not take place, as in the cases of 1 and 3, or is highly incomplete, as in the case of 6. Steric hindrance in diphenylphosphinic acid prevents efficient microwave-assisted esterification.

Keywords:

• Esterification
• green chemistry
• microwave synthesis
• phosphinates
• phosphinic acids

ACKNOWLEDGMENTS

G. K. is grateful to Professor Harry R. Hudson (London Metropolitan University) for his advice. The authors thank the Hungarian Scientific and Research Fund for support (OTKA No. T067679).

Notes

^a After flash column chromatography (silica gel, 3% MeOH in chloroform).

^a On the basis of relative ³¹P NMR intensities.

^b After flash column chromatography (silica gel, 5% MeOH in chloroform).

^a After flash column chromatography (silica gel, 3% MeOH in chloroform).

^a After flash column chromatography (silica gel, 3% MeOH in chloroform).