Solution Phase and Solid Supported Syntheses of End-Functionalized Poly(MMA) by Aldol-Type Reaction of Samarium(III) Enolate at the Chain End

Abstract

Aldol-type reactions of a samarium enolate at the propagating end of living anionic poly(MMA) with aldehydes were carried out. The enolate underwent aldol-type end-capping reaction with 3-phenylpropanal to give the corresponding samarium alkoxide at the polymer terminal. Successive treatment of the alkoxide with benzoyl chloride resulted in its benzoylation. End-capping reaction with 2-phenylpropanal also smoothly proceeded to give the poly(MMA) having the corresponding secondary alkoxide at the terminal. Its benzoylation was not successful; however, an intramolecular reaction of the terminal alkoxide with the methyl ester moiety of the penultimate MMA unit predominantly proceeded to give the corresponding poly(MMA) having a lactone moiety at its terminal. In addition, a terminal samarium enolate of a living poly(MMA), which was supported on polystyrene beads by a benzoyl ester-type linker, reacted with the aldehydes to afford the end-capped poly(MMA), which could be efficiently isolated from the beads by selective cleavage of the linker by trifluoroacetic acid treatment.