Synthesis of pyrrolo[2,1-c][1,4]benzodiazepines via reductive cyclization of ω-azido carbonyl compounds by TMSI: an efficient preparation of antibiotic DC-81 and its dimers

ω-Azido carbonyl compounds on reaction with trimethylsilyl iodide (in situ prepared from TMSCl/NaI) led to the formation of diazepine imines in good yields under mild conditions. This methodology has been applied to the parent unsubstituted pyrrolobenzodiazepine, the natural product DC-81 and its dimers.