Process for the preparation of unsaturated alpha-chlorinated compounds of two electroattractive groups in the beta position

摘要

Preparation process for products of formula (Ia) or (Ib) wherein n represents an integer between 1 and 10 inclusive and X and Y, identical or different, each represents an electron-withdrawing group by the action of a halogenating agent on a product of general formula (IIa) or (IIb) wherein R, X and Y are defined as above, anionized with a base.