Lithiation of Pivaloylamino Derivatives of Dibenzofuran and 9-Methylcarbazole

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 a to d to the heteroatom as follows: a for (4) and (7); d for (5); d and ß (3 : 1) for (8); and a ' for (6). No formylation occurred with (9).