Lithiation of Pivaloylamino Derivatives of Dibenzofuran and 9-Methylcarbazole

Abstract

2-, 3- and 4-Pivaloylamino derivatives of dibenzofuran [compounds (5), (4) and (6), respectively] and analogous 3-, 2- and 1-substituted derivatives of 9-methylcarbazole [compounds (8), (7) and (9), respectively] were subjected to lithiation at 0˚C and subsequent reaction with dimethylformamide. Aldehyde formation took place at positions α to δ to the heteroatom as follows: α for (4) and (7); δ for (5); δ and β (3 : 1) for (8); and α ′ for (6). No formylation occurred with (9).