Deconstructing α-Amidoalkyl Sulfones as Dual -Sulfonyl/-Azomethine Synthons: Synthesis of 3-Sulfonylmethylindole Aminals.

α-Amido sulfones () are widely applied as electrophilic aminoalkylation reagents. However, nonproductive sulfinate species are formed alongside. Here, we report that ethyl propiolate-promoted coupling of and gramines provides 3-sulfonylmethylindole aminals smoothly, thus establishing α-amido sulfones as dual donor/acceptor reagents with full atom incorporation on the target molecule. Simple adjustment of reactants loading allows one to revert the reaction outcome, leading to exclusive formation of 3-sulfonylmethylindoles instead.