A facile intramolecular azido/amido reductive cyclization approach: synthesis of pyrrolobenzodiazepines and their dimers

A new synthetic pathway has been developed for the preparation of imine-containing pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) and their dimers. Selective reduction of aromatic azides as well as aliphatic amides in a single step leading to an intramolecular reductive cyclization process by employing LiAlH4 or LiBH4 provides the cyclized imines.