Synthesis of pyrroloazepines. Facile synthesis of 2‐substituted pyrrole derivatives by the phosgene method

Abstract A highly convenient method for the synthesis of 2‐substituted pyrrole derivatives 7a‐c from pyrrole using phosgene was developed. Successively, 7‐methyl‐6,7‐dihydro‐1 H ,5 H ‐pyrrolo[2,3‐ c ]azepine‐4,8‐dione 1a and 6,7‐dihydro‐1 H ,5 H ‐pyrrolo[2,3‐ c ]azepine‐4,8‐dione 1b (aldisin) were synthesized by phosphorus pentoxide/methanesulfonate and polyphosphoric acid cyclization.