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. [ABSTRACT FROM AUTHOR]