A Stereoselective Synthesis of α,β-Unsaturated Ketones Involving the Reactions of Organocuprates with β-Alkylthio α,β-Enones

Article abstract of DOI:10.1021/jo00374a034

The substitution reactions of E and Z vinylogous thiol esters with organocuprates has been examined as a potential stereoselective synthetic route to α,β-enones.The stereoselectivities of the reactions were dependent upon substrate structure, cuprate reagent, cuprate transferable ligand, solvent, and temperature.The E vinylogous thiol esters all underwent reaction in THF with net retention of configuration except 26 which afforded net inversion with Me2CuLi.In diethyl ether, the E vinylogous thiol esters generally afforded net inversion of configuration and only gave retention for enone 9 and for sterically hindered enone/cuprate pairs.The Z vinylogous thiol esters uniformly afforded reaction with net retention in either THF or diethyl ether with the exception of enone 34 which gave inversion with Li2.These results can be explained in terms of an addition-elimination pathway and several possible mechanisms are discussed.