An Unexpended Stereocontrolled Rearrangement of Ethyl 4-Hydroxy-4-(substituted phenyl)-2-butynoate to Tetrasubstituted Alkenes with MeSOCl2

Tetrasubstituted alkene derivatives are synthetically important compounds and one of the important research areas in organic chemistry. Stereoselective synthesis of all-carbon tetrasubstituted alkenes is a challenging problem in chemical synthesis because of the uncontrolled Z/E stereoselectivity. Here we described an unexpended stereocontrolled rearrangement for the synthesis of tetrasubstituted alkenes, each group different from the other. The reaction of ethyl 4-hydroxy-4-(substituted phenyl)-2-butynoate derivatives with methanesulfonyl chloride and triethylamine gave in an interesting manner syn-selective tetrasubstituted alkene, containing the sulfonate ester and the chlorine atom. The Z-configuration of the chlorovinyl sulfonate esters was determined by X-ray crystal analysis. The parameters (such as amount of equivalent, solvent, and temperature) that will affect product formation were examined and the optimum conditions for formation were determined.