Enantioselective Formation of Quaternary Centers with Dialkylzinc Reagents

Abstract

Benzylic quaternary centers are common in biologically active natural compounds or synthetic drugs. This is one of the first studies of the generation of all-carbon benzylic quaternary centers by catalytic enantioselective 1,4-addition. The starting Meldrum’s acid derivates are readily available by Knoevenagel condensation. The products are easily converted into a variety of functionalized compounds, bearing a quaternary chiral center. The phosphoramidite ligand used is commercially available or can be readily synthesized. Except for o-substituted arenes, the scope of the substrates is very broad. Usually, excellent yields and enantioselectivities are obtained.