Microwave-Assisted Direct Esterification of Cyclic Phosphinic Acids

It is known that phosphinic acids do not undergo direct esterification under conventional conditions. However, the reaction may take place on microwave irradiation. 1-Hydroxy-3-phospholene 1-oxides, 1-hydroxy-phospholane 1-oxides, and a 1-hydroxy-1,2,3,4,5,6-hexahydrophosphinine 1-oxide were esterified with n-pentanol, i-pentanol, n-octanol, and i-octanol(2-ethylhexanol). The phosphinates prepared in 50%-94% yield are all new compounds, and a number of them are useful intermediates. (C) 2013 Wiley Periodicals, Inc.