Visible-light promoted regioselective amination and alkylation of remote C(sp<sup>3</sup>)-H bonds.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32193371.
- Also identified by DOI 10.1038/s41467-020-15167-2 and PMC identifier 7081228.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The C-N cross coupling reaction has always been a fundamental task in organic synthesis. However, the direct use of N-H group of aryl amines to generate N-centered radicals which would couple with alkyl radicals to construct C-N bonds is still rare. Here we report a visible light-promoted C-N radical cross coupling for regioselective amination of remote C(sp<sup>3</sup>)-H bonds. Under visible light irradiation, the N-H groups of aryl amines are converted to N-centered radicals, and are then trapped by alkyl radicals, which are generated from Hofmann-Löffler-Freytag (HLF) type 1,5-hydrogen atom transfer (1,5-HAT). With the same strategy, the regioselective C(sp<sup>3</sup>)-C(sp<sup>3</sup>) cross coupling is also realized by using alkyl Hantzsch esters (or nitrile) as radical alkylation reagents. Notably, the α-C(sp<sup>3</sup>)-H of tertiary amines can be directly alkylated to form the C(sp<sup>3</sup>)-C(sp<sup>3</sup>) bonds via C(sp<sup>3</sup>)-H - C(sp<sup>3</sup>)-H cross coupling through the same photoredox pathway.