Scalable Synthesis of Bio-Based Functional Styrene: Protected Vinyl Catechol from Caffeic Acid and Controlled Radical and Anionic Polymerizations Thereof

Abstract

Naturally abundant caffeic acid, a cinnamic acid derivative with a catechol group in its structure, was quantitatively converted into a series of protected vinyl catechol (VC) derivatives via facile and scalable decarboxylation and protection reactions. Controlled radical polymerizations of the protected VCs proceeded well using the appropriate reversible addition–fragmentation chain transfer agent or alkoxyamine to generate well-defined polymers, although the reaction rates and molecular weight distributions of the obtained polymers were dependent on the protecting groups on the monomers. Anionic polymerizations of the VCs were also achieved with the appropriate protecting groups (−SiMe2tBu or −SiiPr3) using sec-butyllithium as an initiator in THF at −78 °C. Furthermore, the tacticities of the obtained polymers could be controlled by varying the conditions of the polymerizations and the protecting groups on the monomers in the anionic polymerization.