REINVESTIGATION OF THE WADSWORTH-EMMONS REACTION INVOLVING LITHIUM DIFLUOROMETHYLENEPHOSPHONATE

Application of the published reaction conditions for the Wadsworth-Emm ons transformation of ketones or aldehydes into 1,1-difluoroolefins wi th lithium difluoromethylenephosphonate failed to give the expected pr oduct, affording instead phosphates of the general structure 9 in a ne arly exclusive fashion. As variations of the conditions did not bring any change to the unexpected course taken by the reaction, a new proce dure was worked out, that allows reproducible preparation of the desir ed difluoroolefins. Copyright (C) 1996 Published by Elsevier Science L td