Stereoselective synthesis of trisubstituted E-iodoalkenes by indium-catalyzed syn-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.