Parham cyclization

What is Parham cyclization?

The Parham cyclization, also known as the Parham reaction, is a synthesis method for aryl or heteroaryl ring-fused carbocycles or heterocycles. It was originally developed by Parham in 1975 and extended by Bradsher after Parham’s death in 1976.

Parham cyclization - general reaction scheme - Parham reaction
Parham cyclization

The Parham cyclization involves the intramolecular reaction between a side chain electrophile and an aryl or heteroaryllithium generated from lithium-halogen exchange. The Parham cyclization has proven to be very useful for the synthesis of alkaloids.