Expedient Hydrofunctionalisation of Carbonyls and Imines Initiated by Phosphacyclohexadienyl Anions

The ability of phosphacyclohexadienyl anions [Li(1-R-PC5Ph3H2)] [R=Me (1 a), nBu (1 b), tBu (1 c), Ph (1 d) and CH2SiMe3 (1 e)] to initiate hydrofunctionalisation reactions was investigated and compared with simple, commercially available compounds, such as LiOtBu, KOtBu and nBuLi. All compounds are expedient catalysts for the hydroboration of a wide scope of substrates, ranging from aldehydes to imines and esters. In the hydroboration of carbon dioxide, however, only our system was observed to efficiently produce the desired methanol equivalents.