DBU-promoted alkylation of alkyl phosphinates and H-phosphonates

The alkylation of alkyl phosphinates and some H-phosphonate diesters is promoted by the base DBU. Only more reactive alkyl halides react in preparatively useful yields. However, the method provides easy access to important H-phosphinate building blocks, without the need for a protecting group strategy or metal catalysts. The reaction is conveniently conducted at, or below, room temperature. The preparation of methyl-H-phosphinate esters is particularly interesting as it avoids the heretofore more common use of methyldichlorophosphine MePCl₂.