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
We present the first synthesis of air/moisture-stable λ3-bromanes (9 and 10) by using a cyclic 1,2-benzbromoxol-3-one (BBX) strategy. X-ray crystallography and NMR and IR spectroscopy of N-triflylimino-λ3-bromane (12) revealed that the bromine(III) center is effectively stabilized by intramolecular R–Br–O hypervalent bonding. This strategy enables the synthesis of a variety of air-, moisture-, and
A simple method for direct metal-free C–H amination of unactivated hydrocarbons using easy-handling diacetoxy-λ3-bromane and triflylamide or sulfamate esters was developed.
Photoredox‐Catalyzed Site‐Selective α‐C(sp
<sup>3</sup>
)−H Alkylation of Primary Amine Derivatives
作者:Melissa A. Ashley、Chiaki Yamauchi、John C. K. Chu、Shinya Otsuka、Hideki Yorimitsu、Tomislav Rovis
DOI:10.1002/anie.201812227
日期:2019.3.18
tertiary amines to oxidatively generate α‐amino radicals is well established, however, primary amines remain challenging because of competitive side reactions. This report describes the site‐selective α‐functionalization of primary amine derivatives through the generation of α‐amino radical intermediates. Employing visible‐light photoredoxcatalysis, primary sulfonamides are coupled with electron‐deficient
Hypervalent N-triflylimino-lambda(3)-bromane undergoes direct and regioselective alpha-C-H amination of ethers at roomtemperature under transitionmetal-free conditions. Kinetic results, substituent and deuterium isotope effects suggest an asynchronous concerted organonitrenoid transition state with some hydride transfer character, analogous to that for alkane C-H insertions.