Facile synthesis of 2-benzoxazoles via CuI/2,2'-bipyridine catalyzed intramolecular C-O coupling of 2-haloanilides

Development of newer methods for the synthesis of Benzoxazoles has of greater interest due to their wide range of biological activities and pharmaceutical importance. We herein report a facile and general method for the synthesis of 2-substituted Benzoxazoles via copper catalyzed intramolecular C-O cross-coupling of 2-haloanilides. A combination of CuI (5 mol%), 2,2'-bipyridine (10 mol%), Cs2CO3 (2 equiv.) in DMF solvent with 4 angstrom molecular sieves at 140 degrees C, illustrated the scope for tuning the reactivity of 2-haloanilides toward the selective formation of a series of 2-alkyl benzoxazole derivatives in moderate to good yields. This is the first systematic study using CuI/2,2'-Bipyridine as the catalytic system for the synthesis of 2-substituted Benzoxazoles. The outcome of the reaction was found to be significantly influenced by the aromatic and amide substituents of 2-haloanilides. [GRAPHICS]