Superbase-promoted direct N-carbonylation of pyrrole with carbonic acid diesters

Carbonic acid diesters have been investigated as carbonylating agents in the direct reaction with pyrrole (HetNH). In the presence of superbases (DBU, P1-t-Bu, BTPP) as catalysts, the heteroaromatic substrate can be N-carbonylated by direct reaction with carbonic acid diesters under not-severe experimental conditions. The carbonylation reaction makes accessible pyrrole N-carbonyl derivatives (HetNC(O)OR, (HetN)2CO) selectively through a simple straightforward way, which offers a safe eco-friendly alternative to the traditional synthetic methods based on hazardous phosgene or phosgene-derivatives.