Conjugate Addition Reactions of α-Aminoalkylcuprates with α,β-Alkenyl-, α,β-Alkynyl-, α,β−β,γ-Allenyl-, and α,β−γ,δ-Dienyl Carboxylic Acid Derivatives, Nitriles, and Sulfoxides
暂无分享,去创建一个
α-Aminoalkylcuprates prepared from α-lithio carbamates and CuCN·2LiCl participate in 1,4-addition reactions with α,β-unsaturated esters, thiol esters, imides, and nitriles in poor to excellent yields depending upon the electron-withdrawing substituent and the substitution pattern of the unsaturated substrate. These reagents also undergo conjugate addition reactions with α,β-alkynyl esters, sulfoxides, and nitriles and with α,β−β,γ-unsaturated allenyl esters. Excellent stereocontrol is achieved in the conjugate additions of α-aminoalkylcuprates to the allenyl esters, while poor stereoselectivity results in the conjugate additions to the alkynyl derivatives. Deprotection and cyclization of the alkynyl adducts affords pyrrolin-2-ones, while similar treatment of the allenyl adducts affords 4-alkylidine- pyrrolidin-2-ones and pyrrolizidinones.