Lewis Acid Catalyzed Synthesis of 1-Aryl-1,2-dihydro-naphtho[1,2-e][1,3]oxazin-3-ones under Solvent Free Conditions: A Mechanistic Approach.

Lewis acids catalyzed highly efficient one-pot three component coupling of β-naphthol, benzaldehydes and urea to produce 1-aryl-1,2-dihydro-naphtho[1,2-e][1,3]oxazin-3-one derivatives under solvent free conditions is described. Mechanistic studies confirmed that product formation is possible only at very high temperature (140-150°C) and at lower temperature (90-100°C) formation of 14-aryl-14 H-dibenzo(a,j)xanthenes was observed. Among the nine Lewis acids screened, iodine, P2O5 and Yb(OTf)3 are found to be most effective catalyst for this multicomponent reaction. [ABSTRACT FROM AUTHOR]