Organic reactions mediated by stoichiometric phosphines play a key role in modern organic synthesis as testified by the classic Wittig, Mitsunobu, Staudinger and Appel reactions. Mechanistically these reactions are usually driven by the strong oxophilicity of tertiary phosphines. As a result, the formation of phosphine oxide as a concomitant byproduct represents a drawback which impacts heavily on the atom economy and large-scale applicability of these reactions. To tackle the “phosphine-oxide” issue, considerable efforts have been recently engaged in how to convert a stoichiometric phosphine-mediated reaction into a catalytic one, which has stimulated much research interest in organic chemistry community. In this mini-review, recent developments on catalytic approaches to stoichiometric phosphine-mediated reactions primarily including in situ reduction and activation strategies are summarized.
Keywords: Appel reaction, catalysis, phosphine, reduction, Staudinger reaction, Wittig reaction.