Application of the Stille coupling reaction to the synthesis of C2-substituted endo–exo unsaturated pyrrolo[2,1-c][1,4]benzodiazepines (PBDs)

The Stille coupling reaction has been used to introduce novel vinyl, alkynyl and heterocyclic substituents to the C2-position of pyrrolo[2,1-c][1,4]benzodiazepine dilactams. Sodium borohydride reduction followed by N10-SEM deprotection has provided five analogues (6b, 8a–d) that contain C2-endo/exo-unsaturation and novel C2-substituents. These analogues have significant multilog cytotoxicity profiles in the NCI 60-Cell Line screen, and provide new SAR data for the PBD family.