Aldol Condensation-Type Group Transfer Copolymerizations of Silyl (Di)Enolates

Abstract

Copolymerizations of two monomers among silyl dienolates, CH2=CR1—CH=CH—OSi(CH3)2R2 and silyl enolates CH2=CH—OSi(CH3)2R2 [R1=H, CH3; R2=CH3, C(CH3)3] were examined under conditions suitable for aldol condensation-type group transfer polymerization (aldol-GTP). Structures of the copolymers were determined mainly by their 1H NMR spectra and by partial desilylation. E-isomers of dienolates (R1=H) showed much higher copolymerizability than enolates, independent of R2 substituent on silicon. Methyl substituent at 3-carbon (R1=CH3) enhanced the copolymerizability of silyl dienolate further. Z-dienolates could hardly react with E-isomers but gave rise to copolymerization with the enolate monomer. 1:1 Aldol-adducts of the above monomers with benzaldehyde were prepared. The adducts were effective initiators for aldol-GTP of other monomers. The results provided evidence for the existence of cross-propagation on aldol group transfer copolymerization.