Sulfoxide-controlled S(N)2 ' displacements between cyanocuprates and epoxyvinyl sulfoxides

Two short and convergent routes have been devised for the preparation of en antiomerically. pure acyclic epoxy vinyl sulfoxides. These substrates under go highly regio- and stereoselective S(N)2', displacements with lithium cya nocuprates to give alpha'-alkylated, gamma-oxygenated Z alpha,beta-unsatura ted sulfoxides in moderate to good yields and with good to excellent diaste reoselectivities. The absolute configuration of the newly formed carbon-car bon bond is primarily controlled by the chiral sulfur atom, which in a nonr einforcing situation can override the intrinsic anti tendency of the vinyl oxirane moiety and forces the cuprate to undergo syn addition. The hydroxy vinyl sulfoxide functionality of the resulting adducts should allow for sub sequent asymmetric; transformations thus enhancing the synthetic usefulness of this methodology.