Stereoselective Synthesis of Trisubstituted <i>E</i>-Iodoalkenes by Indium-Catalyzed <i>syn</i>-Addition of 1,3-Dicarbonyl Compounds to 1-Iodoalkynes

Indium-catalyzed addition of 1,3-dicarbonyl compounds to 1-iodo-1-alkynes takes place exclusively in a syn-fashion to produce E-iodoalkenes. The iodine atom serves both as an activating group and as a group that controls the regioselectivity of the addition. The E-alkenyl iodide product can be further derivatized using either a one-pot or a two-pot procedure into trisubstituted olefins in high overall yield with retention of the stereochemistry.