Synthesis of Substituted Quinolines Using the Dianion Addition of N-Boc-anilines and α-Tolylsulfonyl-α,β-unsaturated Ketones

A short and versatile synthesis of substituted quinolines is provided. Alkylation of sodium tolylsulfinate with bromomethyl- or chloromethyl ketones generates beta-keto sulfones. Knoevenagel condensation of the beta-keto sulfones with an aldehyde provides alpha-tolylsulfonyl-alpha,beta-unsaturated ketones. Michael addition of the dianion of N-Boc-anilines in the presence of CuCN and LiCl with the unsaturated ketone generates a 1,4-adduct, which after deprotection of the Boc group and thermal elimination of the tolyl sulfone provides the quinoline.