Convergent synthesis of 6-substituted phenanthridines via anionic ring closure

Org Lett. 2002 Jan 24;4(2):257-9. doi: 10.1021/ol0170051.

Abstract

[reaction: see text] The addition of organometallic derivatives to the cyano group of 2-(2-fluorophenyl)benzonitrile followed by intramolecular nucleophilic substitution produces 6-substituted phenanthridines. Alkyllithiums, aryllithiums, and sterically nondemanding lithium amides reacted at -78 degrees C to produce the 6-substituted phenanthridines in 82-98% yield upon warming to room temperature. The addition of the corresponding Grignard reagents requires an excess of the organometallic reagent and extented reaction times at elevated temperature.