MECHANISM STUDY OF THE BASE-CATALYZED ETHER FORMATION INVOLVING ALPHA-(HYDROXYMETHYL)ACRYLATES

The formation of ethers from activated allyl alcohols under basic conditions is described. Tertiary amine is necessary for catalysis probably through O-H bond polarization and/or a proton relay mechanism. The latter would most likely involved a six-membered transition state in which Micheal-like oxygen attack at the beta-vinyl carbon occurs more-or-less stimultaneously with loss of the allyl OH to generate the vinyl group at the allyl CH2. Deuterium labeling, carbon-13 labeling, transetherification, and mixed ether formation all confirm the proposed mechanism. A similar process involving attack of an intermediate carbanion (from attack of DABCO on trifluoroethyl acrylate) leads to a 1,4-diene in which two acrylate groups are linked by a single methylene. Carbon-13 labeling shows intermediate of the alpha-(hydroxymethyl)-acrylate and its either before their conversion to the 1,4-diene. Synthetically these two processes make available new families of ether-linked diacrylates, mixed esters of these diacrylates, alpha-ether-substituted methacrylate esters, and diacrylates with a 1,4-diene structure.