Photoredox-Catalyzed Decarboxylative Cross-Coupling of α-Amino Acids with Nitrones

Visible-Light Mediated Carbamoylation of Nitrones under a Continuous Flow Regime

“…In accordance with our experimental observations and previous reports, − a plausible mechanism is proposed (see the SI for details). Stern–Volmer experiments with 4CzIPN and Ir photocatalysts indicate an effective luminesce quenching in the presence of DHP 2a .…”

“…For example, the Huang group disclosed an enantioselective Lewis acidmediated reductive cross-coupling of nitrones with aldehydes, 11 and a decarboxylative α-amino radical addition toward nitrones leading to valuable vicinal diamine-containing molecules. 12 Moreover, Dilman and co-workers reported a single-electron reductive fluoralkylation of nitrones affording the respective hydroxylamines (Scheme 1c). 13 While these methods rely on the installation of alkyl C(sp 3 )-centered radicals, we speculated whether we could expand the chemical space of functionalized nitrones utilizing photogenerated C(sp 2 )-carbamoyl radicals under a continuous flow protocol.…”

Overcoming Back Electron Transfer in the Electron Donor–Acceptor Complex-Mediated Visible Light-Driven Generation of α-Aminoalkyl Radicals from Secondary Anilines

“…Examples include silyl and carboxyl groups. Several reports of the use of N -aryl glycines as the α-aminoalkyl radical precursor in combination with photocatalysts have been reported in the literature. − Previous methods providing α-aminoalkyl radicals from amino acids, using an EDA complex approach, include the use of activated esters as acceptors. ,, …”

Carbamoylation of Azomethine Imines via Visible-Light Photoredox Catalysis

“…Recently, the use of nitrones in photoredox protocols has been reported in (3 + 2) cycloadditions 17 and in radical addition reactions. 18 Considering the importance of this structure to easily access nitrogen-containing compounds and the presence of N-hydroxylamines in pharmaceuticals, 19 we were curious if nitrone derivatives could be amenable to our optimized reaction conditions. To our delight, the carbamoylation proceeded well for all cases, affording the respective phenylglycine amide derivatives 17−19 in good yields (Scheme 3).…”