The δ C-H amination of unactivated, secondary C-H bonds to form a broad range of functionalized pyrrolidines has been developed via a triiodide (I3−)-mediated strategy. By in situ (i) oxidation of sodium iodide and (ii) sequestration of the transiently generated iodine (I2) as I3−, this approach precludes undesired I2− mediated decomposition that can otherwise limit synthetic utility to only weak C-H bonds. The mechanism of this triiodide-mediated cyclization of unbiased, secondary C-H bonds, via thermal or photolytic initiation, is supported by NMR and UV-Vis spectroscopic data and intercepted intermediates.

Asymmetric, radical C–H functionalizations are rare, yet powerful tools for solving modern synthetic challenges. Specifically, the enantio- and regio-selective C–H amination of alcohols to access medicinally valuable, chiral β-amino alcohols remains elusive. To solve this challenge, a radical relay chaperone strategy was designed, wherein an alcohol is transiently converted to an imidate radical that undergoes intramolecular H-atom transfer (HAT). This regioselective HAT was also rendered enantioselective by harnessing energy transfer catalysis to mediate selective radical generation and interception by a chiral copper catalyst. The successful development of this multi-catalytic, asymmetric, radical C–H amination enables broad access to chiral β-amino alcohols from a variety of alcohols containing alkyl, allyl, benzyl, and propargyl C–H bonds. Mechanistic experiments reveal triplet energy sensitization of a Cu-bound radical precursor facilitates catalyst-mediated HAT stereoselectivity – enabling the synthesis of several important classes of chiral β-amines by enantioselective, radical C–H amination.

A radical-mediated strategy for β C–H amination of alcohols has been developed. This approach employs a radical relay chaperone, which serves as a traceless director that facilitates selective C–H functionalization via 1,5-hydrogen atom transfer (HAT) and enables net incorporation of ammonia at the β carbon of alcohols. The chaperones presented herein enable direct access to imidate radicals, allowing their first use for H atom abstraction. A streamlined protocol enables rapid conversion of alcohols to their β-amino analogs (via in situ conversion of alcohols to imidates, directed C–H amination, and hydrolysis to NH2). Mechanistic experiments indicate HAT is rate-limiting, whereas intramolecular amination is product- and stereo-determining.

An iodine-catalyzed strategy for β C–H amination of alcohols is enabled by a chemo-, regio-, and stereo-selective H-atom transfer mechanism.