Nucleophilic activation of alkenyl and aryl boronates by a chiral Cu(I)F complex: catalytic enantioselective alkenylation and arylation of aldehydes.

Daisuke Tomita, Motomu Kanai, Masakatsu Shibasaki

Index: Chem. Asian J. 1(1-2) , 161-6, (2006)

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Abstract

A new method for the catalytic enantioselective alkenylation and arylation of aldehydes involves the activation of alkenyl and aryl boronates by a catalytic amount of the Cu(I)F-DTBM-segphos complex through transmetalation, generating novel alkenyl and aryl copper species. These reagents act as the actual nucleophile. A range of aldehydes can be converted into optically active secondary allyl alcohols or diaryl methanols with excellent enantioselectivity. The appropriate choice of additives, depending on the substrate, is critical to ensure high yields of products. These additives possibly modulate the catalyst turnover step from copper alkoxide intermediates generated by the addition of organocopper reagents to aldehydes.