Asymmetric Conjugate Additions of 3-Boronyl Unsaturated Esters

Significance

Organoboron reagents are extremely useful in organic synthesis due to the ­ability to functionalize the B-C bond. These functionalizations typically proceed with retention of stereochemistry at the carbon-bearing boron. With the advent of stereospecific cross-couplings of organoboron reagents, there is an increasing push to generate these reagents as single enantio­mers. The authors report a conceptually different approach in which a copper-catalyzed asymmetric conjugate addition is preformed on a 3-boronyl unsaturated ester. This method expands the scope of available chiral boron reagents via a ­novel strategy.