Reductive N-heterocyclization

Wantanabe and co-workers used an intermolecular reductive N-heterocyclization approach to generate quinazoline. Treatment of 2-nitro benzaldehyde with palladium(II) and molybdenum(V) complexes as catalysts in the presence of carbon monoxide under high pressure generated quinazoline in 29% yield. 

Since Watanabe s synthesis of 4(3H)-quinazolinones in 1993 via transition-metal catalyzed reductive N-heterocychzation [ 181 ], several catalytic methods for quinazoline synthesis have been developed [182-186]. For example, palladium-catalyzed cyclocarbonylations of halides with appropriate reactants provided regioselective synthesis of 4(3H)-quinazolinone derivatives [182] and indoloquinazolines [184]. Also selenium-catalyzed reductive N-heterocyclization to quinazolinones has been developed by Sonoda et al. [183]. Copper-catalyzed heteroannulation with alkynes has been developed as highly region- and stereoselective route to 2-(2-arylvinyl)-l,2,3,4-tetrahydroquinazolin-4-ones 64 by Kimdu et al. [ 185] (Scheme 12). Recently, condensation of anthranylamide with various aldehydes to 4-quinazotinones has been found to give excellent yields in the presence of cupric chloride [186]. 

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