Alkylation of phosphinite/phosphonite-boranes via temporary protection of the P-H bond

Article abstract of DOI:10.1055/s-0040-1707104

A new alkylation protocol for the synthesis of tertiary phosphonite-/phosphinite-boranes is developed. P-Alkylation products are obtained exclusively in moderate to very good yields from easily accessible (1-hydroxy-1-methylethyl)/(1-hydroxy-1-cyclohexyl) phosphonite/phosphinite-boranes upon reaction with a variety of electrophiles under mild conditions. The methodology opens up new synthetic routes for organophosphorus chemistry and offers access to valuable alkyl phosphonite/phosphinite-boranes. In contrast to previously reported oxidative removal-substitution sequences for the preparation of optically active phosphinite-boranes, our protocol provides a one-step procedure that occurs without loss of stereochemical information at phosphorus. This new approach provides a rather advantageous protocol when compared to direct alkylation methods (which may undergo P-epimerization) and occurs in a stereoselective manner even at 0 °C.