A novel and convenient preparation of hypophosphite esters

Only a few methods have been described for the preparation of hypophosphite esters (alkyl phosphinates, ROP(O)H-2). As a result, comparatively few applications have been reported, and these intermediates have not been widely exploited in organophosphorus chemistry despite their synthetic potential. Herein, we describe a very general, practical, and high-yielding synthesis of hypophosphite esters, based on the reaction of hypophosphorous acid and some of its salts with alkoxysilanes. This methodology solves a number of the problems associated with previously reported reactions. Our esterification takes place at moderate temperature in a variety of solvents. and under these conditions the esters are remarkably thermally stable. Furthermore, the reagents employed are inexpensive and do not have to be strictly anhydrous. The scope and limitations of the method are discussed. and representative synthetic applications for the preparation of monosubstituted phosphinate esters are described. (C) 2002 Elsevier Science B.V. All rights reserved.