BF3-promoted synthesis of diarylhexahydrobenzo[f]isoquinoline.

An easy and straightforward synthesis of 6,10b-diarylhexahydrobenzo[f]isoquinoline by the repeated treatment of boron trifluoride etherate (BF(3) x OEt(2)) is reported. The overall transformation from 4-arylpiperidin-3-one to benzo[f]isoquinoline proceeds via ring contraction, chain elongation, and intramolecular electrophilic cyclization in moderate yields. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.