An easy, efficient, and completely stereoselective synthesis of (E)-alpha,beta-unsaturated esters via sequential aldol-type/elimination reactions promoted by samarium diiodide or chromium dichloride.

(E)-Alpha,beta-unsaturated esters can be obtained with complete stereoselectivity by reaction of different aldehydes and ethyl dibromoacetate promoted by SmI(2) or CrCl(2). The transformation takes place as two sequential reactions: an aldol-type reaction and a beta-elimination reaction.