delta, beta'-Dihydroxy-beta,gamma-unsaturated esters were stereoselectively synthesized by aldol reaction of aldehydes with samarium enolates that were generated by epoxide-fragmentation of gamma,delta-oxiranyl-alpha,beta-unsaturated esters using two moles of samarium(II) iodide. This samarium(II) iodide-mediated aldol reaction was applied successfully to the enantioselective synthesis of C11-C17 segment of Mycinolide IV.