Solvent-Free Asymmetric Alkylzinc Additions to Ketones

Significance

This is a new important contribution in the field of the catalytic asymmetric addition of organozinc to carbonyl compounds. Besides a number of advantages of the solvent-free methodology, the performance of the reaction at high concentration allowed reducing the amount of the catalyst from 10 mol% to 1 mol% and in some cases to even 0.1 mol% without a significant loss of stereoselectivity. For a variety of ketones as well as functionalized organozinc compounds, excellent enantioselectivities with moderate to good yield of the products were achieved. After the addition reaction, the titanium alcoholates formed can be epoxidized in situ with TBHP, affording the epoxy-alcohols with almost 100% diastereoselectivity. The whole sequence can be performed ‘in one pot’.