Synthesis of β-keto- and vinyl phosphonates

Abstract

A convienient synthetic methods for the preparation of a variety of $\beta$-keto phosphonates and vinyl phosphonates were studied. Sodium diethyl phosphite were reacted with a wide range of epoxy sulfones to give $\beta$-keto phosphonates. In this reaction aryl epoxy sulfones appeared to be the synthetic equivalent for ketone equivalents with $\alpha$-cation reactivity. Unexpectedly, when 2-phenyl-2-(phenylsulfonyl)-1,2-epoxyethane was reacted, trans-styryl phosphonate was produced in about half yield. It is supposed that initially formed 1-formyl benzyl phosphonate reacts with additional sodium diethylphosphite. When 1-formyl benzyl phosphonate was reacted with dialkyl phosphite sodium salt in tetrahydrofuran at room temperature, corresponding dialkyl phenyl alkenephosphonates were produced in high yield. In this reaction, 1-formyl benzyl phosphonate could be used as trans styryl cation equivalent. However, when $\alpha$-formyl benzyl phosphonate which do not have $\alpha$-electron withdrawing group was reacted, alkenyl phosphonate did not form. Furthermore, from the reaction of 1-phenyl-2-diethyl phosphonyl ethanone with diethyl phosphite sodium salt, 2-phenyl ethene phosphonate were obtained with 2-hydroxy-2-phenyl ethane phosphonate.