Expedient Hydrofunctionalisation of Carbonyls and Imines Initiated by Phosphacyclohexadienyl Anions

Abstract

The ability of phosphacyclohexadienyl anions [Li(1-R-PC 5 Ph 3 H 2 )] [R = Me (1 a), nBu (1 b), tBu (1 c), Ph (1 d) and CH 2 SiMe 3 (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.

Implication of a Silyl Cobalt Dihydride Complex as a Useful Catalyst for the Hydrosilylation of Imines

“…Over the past few decades, impressive hydroelementation strategies have been developed using main group catalysts (s-block and p-block), including strong Lewis acids, frustrated Lewis pairs (FLPs), commercially available bases, and even catalyst-free conditions . In the field of catalyst-free hydroelementation, hydrosilylation reactions are less studied than hydroboration. , Moreover, regarding the reduction of imines, aryl-imines are most commonly investigated with rare examples of alkyl ketimines. , Obviously, earth-abundant metals such as Fe, Ni, Cu, Zn, and Co have also emerged as good alternative catalysts (Scheme a). Using these metals, very good results were obtained for the reduction of aldimines, and harsher conditions were generally necessary for the reduction of ketimines.…”

“…7e,g Moreover, regarding the reduction of imines, aryl-imines are most commonly investigated with rare examples of alkyl ketimines. 7,8 Obviously, earth-abundant metals such as Fe, Ni, Cu, Zn, and Co have also emerged as good alternative catalysts (Scheme 1a). Using these metals, very good results were obtained for the reduction of aldimines, and harsher conditions were generally necessary for the reduction of ketimines.…”