Cyanopyridines with Grignard reagents

Aromatization of a tetrahydroquinolizone (5) by means of acetic anhydride and sulfuric acid or acetic anhydride alone leads to the formation of a variety of mono- or di-substituted quinolizinium compounds. Glover and Jones 8 achieved the synthesis of a number of these derivatives starting from 2-cyanopyridine and condensing it with appropriate Grignard reagents followed by cyclization and aromatization as outlined in Eq. (2). An identical method was simultaneously worked out by Nesmeyanov and Rybinskaya9 for the specific synthesis of 2-substituted quinolizinium compounds. This... 

Xho cyano group in 2-chloro-4-cyanopyridine does, however, appear to react in the expected manner with the indole Grignard reagent (see Section III,B.7). 

---