Selective Organocatalytic Ring-Opening Polymerization:  A Versatile Route to Carbohydrate-Functionalized Poly(ε-caprolactones)

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