Analyzing Site Selectivity in Rh2(esp)2-Catalyzed Intermolecular C–H Amination Reactions
نویسندگان
چکیده
Predicting site selectivity in C-H bond oxidation reactions involving heteroatom transfer is challenged by the small energetic differences between disparate bond types and the subtle interplay of steric and electronic effects that influence reactivity. Herein, the factors governing selective Rh2(esp)2-catalyzed C-H amination of isoamylbenzene derivatives are investigated, where modification to both the nitrogen source, a sulfamate ester, and substrate are shown to impact isomeric product ratios. Linear regression mathematical modeling is used to define a relationship that equates both IR stretching parameters and Hammett σ(+) values to the differential free energy of benzylic versus tertiary C-H amination. This model has informed the development of a novel sulfamate ester, which affords the highest benzylic-to-tertiary site selectivity (9.5:1) observed for this system.
منابع مشابه
Organocatalytic nitrenoid transfer: metal-free selective intermolecular C(sp3)–H amination catalyzed by an iminium salt† †Electronic supplementary information (ESI) available: Experimental procedures, characterization data for all new products, copies of NMR spectra. See DOI: 10.1039/c7sc03968a
This report details the first organocatalytic method for nitrenoid transfer and its application to intermolecular, site-selective C(sp)–H amination. The method utilizes a trifluoromethyl iminium salt as the catalyst, iminoiodinanes as the nitrogen source, and substrate as the limiting reagent. Activated, benzylic, and aliphatic substrates can all be selectively functionalized in yields up to 87...
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