Chlorotrimethylsilane-mediated Michael addition reactions of chiral benzylic anions derived from η6-chromiumtricarbonyl complexes

The Michael addition of chiral organolithiums, resulting from benzylic metallation of certain η6-chromiumtricarbonyl complexes, to α,β-unsaturated ketones and esters, is strongly influenced by the presence of chlorotrimethylsilane. In most cases yields of Michael adducts are greatly improved in the presence of Me3SiCl. Some further transformations of the Michael adducts were carried out, including a ring expansion process of a cyclohexanone derivative and a SmI2 mediated cyclisation of a complex bearing an acyclic ketone appendage.