Formamides are useful starting materials for pharmaceutical syntheses. Although various synthetic methods have been documented in this regard, the use of N-formylcarbazole as a formylation reagent for amines has not yet been reported. We report here the first examples of the use of N-formylcarbazole for the formylation of amines. The characteristic reactivity of N-formylcarbazole enables the selective formylation of sterically less hindered aliphatic primary and secondary amines. In contrast, sterically bulkier amines and weakly nucleophilic amines such as anilines are less reactive under the reaction conditions.
Keywords: carbazole; formylation; selectivity.