Selective monobenzylation of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) to yield an AB linear monomer and analogous linear oligomers

Abstract

The synthesis of a mono-benzylated AB monomer based on bis-MPA is explored and accomplished via a three-step synthesis without column chromatography. This optimized synthesis utilizes a generic acid-catalyzed esterification of bis-MPA to the ethyl ester. Subsequently, a selective mono-benzylation mediated by silver(I) oxide affords the monobenzyl ether of the ethyl ester. Finally, a simple base hydrolysis of monobenzyl ether ethyl ester yields 3-(benzyloxy)-2-(hydroxymethyl)-2-methylpropanoic acid, the AB monomer. This synthesis was utilized to generate gram quantities of the linear monomer (47% yield) and this monomer was used to produce a small amount of the linear polymer analogs. Although there are many branched analogs of bis-MPA, this is the first linear oligomer that has been confirmed.