Palladium-Catalyzed Cascade Synthesis of Pyrrolobenzazepines

Significance

Reported is a one-pot, multistep process which provides a simple synthesis of ­pyrrolobenzazepines. The mechanism proposed progresses via ortho-alkylation to tether the alkyl chain to the aromatic ring, alkyne carbo-palladation to form the six-membered ring, and finally C-H activation to form the seven-membered ring. In the case of the pyrrole-based systems, interesting byproducts A and B were formed. The amounts could be altered by increasing the equivalents of ­norbornene. No further optimization studies were conducted. This type of norbornene-mediated multistep reaction is having a major impact in ­synthetic organic chemistry.