1,2- versus 1,4-asymmetric addition of Grignard reagents to carbonyl compounds

The first copper(I)-catalysed conjugate addition of Grignard reagents to α,β-unsaturated carbonyl compounds was reported in 1941. Impressive developments have been made since then, with catalytic asymmetric additions representing the most remarkable achievement. The recent discovery that copper(I) is able to catalyse the asymmetric 1,2-addition of Grignard reagents to α,β-unsaturated, as well as aromatic ketones, was a true revelation. Recent progress in copper(I)- catalysed addition of Grignard reagents is reviewed throughout this chapter, comparing and contrasting the well-established 1,4-selectivity of Cu(I)-ligand complexes with the newly introduced 1,2-selectivity. Mechanistic insights towards the better understanding of the regiodivergence are also discussed.