Solid-Phase Synthesis of a Library of Pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones with Potential Antitubercular Activity

A versatile combinatorial approach was developed and utilized for the rapid synthesis of pyrrolo[2,1-c][1,4]benzodiazepine-5,11-dione (PBD-5,11-dione) libraries 10, 15, and 19 containing 210 compounds with varied substitutions in A, B, and C rings. The key aspect of the synthetic strategy includes Staudinger, intermolecular aza-Wittig reaction followed by imine reduction and base-mediated cyclative cleavage results in the formation of final resin-free compounds. This strategy provides a highly efficient and practical protocol for the parallel synthesis of PBD-5,11-diones on solid support. The modifications in the C-ring of the PBD scaffold produced three types of sublibraries. Reactions were monitored by FT-IR spectroscopy on the resin beads. Further, from a generated library of 210 compounds, 142 compounds have been selected and evaluated for in vitro activity against Mycobacterium tuberculosis, and some of these compounds have exhibited promising activity.