Catalytic Intermolecular C(sp3)–H Amination: Selective Functionalization of Tertiary C–H Bonds vs Activated Benzylic C–H Bonds
Résumé
A catalytic intermolecular amination of non-activated tertiary C(sp 3)−H bonds (BDE of 96 kcal.mol-1) is reported for substrates displaying an activated benzylic site (BDE of 85 kcal.mol-1). The tertiary C(sp 3)−H bond is selectively functionalized to afford a,a,a-trisubstituted amides in high yields. This unusual site-selectivity results from the synergistic combination of Rh2(Stfpttl)4, a rhodium(II) complex with a well-defined catalytic pocket, with tert-butylphenol sulfamate (TBPhsNH2), which leads to a discriminating rhodium-bound nitrene species under mild oxidative conditions. This catalytic system is very robust and the reaction was performed on a 50 mmoles-scale with only 0.01 mol% of catalyst. The TBPhs group can be removed under mild conditions to afford the corresponding NH-free amines.
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