Functional regioregular (poly)urethanes from soft nucleophiles and cyclic iminocarbonates

The catalyst-free synthesis of urethanes from cyclic iminocarbonates, used as masked isocyanates, and soft nucleophiles (i.e. carboxylic acids and thiols) has been studied. Remarkably, the ring-opening reaction was fully site-selective (i.e. methylene). The disclosed method showed high functional group tolerance towards carboxylic acids bearing alkyl-, alkenyl-, ketone-, pyrone- and hydroxyl groups. This methodology was further applied for the construction of regioregular functional polyurethanes by step-growth copolymerization of cyclic bisiminocarbonates and dicarboxylic acids or dithiols. M-w up to 34 000 g mol(-1) was obtained in a fully atom-economical manner using an equimolar amount of both monomers.