Selective organocatalytic ring-opening polymerization:: A versatile route to carbohydrate-functionalized poly(∈-caprolactones)

Cationic catalysis using simple carboxylic acids to combine the ring-opening polymerization of c-caprolactone and the regioselective acylation of carbohydrates has been investigated. L-Lactic acid catalyzed the acylation of methyl beta-D-glucopyranoside and sucrose with epsilon-caprolactone in high yield by bulk polymerization at 120 degreesC. The main products were regioselectively acylated on the primary hydroxyl groups of the carbohydrate end groups. The overall conversion to methyl beta-D-glucopyranoside-functionalized poly(epsilon-caprolactone) was more than 90%, M-w 2000 and polydispersity index 1.5, with one major product methyl 6-O-poly(epsilon-caprolactone)-beta-D-glucopyranoside, in agreement with the corresponding Candida antarctica lipase B-catalyzed acylation.