A squaramide and tertiary amine: an excellent hydrogen-bonding pair organocatalyst for living polymerization

Abstract

A hydrogen-bond motif based on a squaramide and sparteine efficiently promoted the ring-opening polymerization of L-lactide at ambient temperature. Narrowly dispersed polymers with precise molar masses (Đ = 1.05, M_n = 16 240 g mol⁻¹) were obtained in a short reaction time (98% conv., 11 h) and with retention of stereochemistry. Experimental data and computational results indicated that the squaramide and sparteine pair is a competent H-bond donor–acceptor catalyst in living polymerization.