A simple one-pot organometallic formylation/trapping sequence using N-formylcarbazole

Treatment of a range of sp3-, sp2- and sp-nucleophiles with N-formyl carbazole leads to the formation of the metastable anionic carbazole carbinols. In the presence of a second nucleophilic reagent such as phosphonoacetate or an organolithium, these collapse on warming to the aldehyde which is trapped in situ to afford the α,β-unsaturated esters or secondary carbinols respectively.