Guanidine masked catechol initiator promoted ring-opening polymerization of sarcosine N-carboxyanhydride

The synthesis of catechol polymers often demands tedious protection and deprotection steps. In this work, the role of a guanidine base to subdue the catechol functions and promote the ring-opening polymerization (ROP) is suggested. Accordingly, guanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), was employed to mediate ROP of N-carboxyanhydride (NCA) from a catechol initiator. MTBD played a dual-role in ROP of sarcosine-NCA (Sar-NCA) and masking the catechol initiator concurrently. Catechol-ended polysarcosine (PSar) was synthesized with a predicted molecular weight (M_n,SEC = 3.5 kg mol⁻¹, M_n,NMR = 3.7 kg mol⁻¹) and narrow dispersities (Đ < 1.11). This one base two-function strategy showed a new path for the synthesis of catechol functionalized polymers.