Highly regioselective amination of unactivated alkanes by hypervalent sulfonylimino-λ³-bromane.

Amination of alkanes has generally required metal catalysts and/or high temperatures. Here we report that simple exposure of a broad range of alkanes to N-triflylimino-λ(3)-bromane 1 at ambient temperature results in C-H insertion of the nitrogen functionality to afford triflyl-substituted amines in moderate to high yields. Marked selectivity for tertiary over secondary C-H bonds was observed; primary (methyl) C-H bonds were inert. Addition of hexafluoroisopropanol to inhibit decomposition of 1 dramatically improved the C-H amination efficiencies. Second-order kinetics, activation parameters (negative activation entropy), deuterium isotope effects, and theoretical calculations suggest a concerted asynchronous bimolecular transition state for the metal-free C-H amination event.

Direct transfer of the sulfonylimino group of imino-lambda3-bromane to N-heterocycles and trialkylamines: synthesis of N-iminoammonium ylides under metal-free conditions.

Exposure of N-heterocycles and aliphatic trialkylamines to trifluoromethanesulfonylimino-lambda(3)-bromane at room temperature results in direct transfer of the sulfonylimino group to the nitrogen atoms and affords a variety of iminoammonium ylides under transition-metal-free conditions. The imino-lambda(3)-bromane probably serves as an active nitrenoid species without any activation and produces the ammonium ylides via a bimolecular nucleophilic substitution process.