Fine-tuned organic photoredox catalysts for fragmentation-alkynylation cascades of cyclic oxime ethers

Abstract

Fine-tuned organic photoredox catalysts are introduced for the metal-free alkynylation of alkylnitrile radicals generated via oxidative ring opening of cyclic alkylketone oxime ethers.

A dual photoredox-nickel strategy for remote functionalization via iminyl radicals: radical ring-opening-arylation, -vinylation and -alkylation cascades

“…With these optimised reaction conditions, we evaluated the scope of the aromatic partner in conjunction with the cyclobutanone oxime 1 (Scheme 4). Pleasingly the process exhibited broad scope and tolerated a wide variety of common functionalities such as ketone (3 and 4), ester (5), nitrile (6), aldehyde 7, sulfone (8), triuoromethyl (9) as well as groups that can be used as a handle for further functionalization like pinacol boronic ester (10) and aryl chloride (11) albeit in lower yields. 17 Electron rich aryl bromides are a limitation of the protocol (12), possibly due to a more difficult oxidative addition process from the Ni(0) catalyst.…”

Radical‐Promoted C−C Bond Cleavage: A Deconstructive Approach for Selective Functionalization

“…This application represents ac lear example of directly modifying the core of small bioactive molecules,a nd could serve to simplify the preparation of molecular libraries used for biological screening.I n2 018, Waser and co-workers [60] reported arelated method, wherein aC À Cf ormation was achieved by using ethynylbenziodoxolones (EBX) reagents as the radicophile. In this particular case, AII is expected to be an ucleophilic radical, which reacts with ap olarised radicophile (X-Y) to generate aY C radical.…”

Radical‐Promoted C−C Bond Cleavage: A Deconstructive Approach for Selective Functionalization

“…This application represents a clear example of directly modifying the core of small bioactive molecules, and could serve to simplify the preparation of molecular libraries used for biological screening. In 2018, Waser and co‐workers reported a related method, wherein a C−C formation was achieved by using ethynylbenziodoxolones (EBX) reagents as the radicophile.…”