Regio- and stereoselective divergent cross-coupling of alkynes and disubstituted alkenes via photoredox cobalt dual catalysis

Abstract

Achieving divergent synthesis from the same substrates quickly generating different products remains an attractive objective in synthetic chemistry and medicinal industry. Here, we report a discovery of highly selective divergent...

Expedient Synthesis of Axially and Centrally Chiral Diaryl Ethers via Cobalt-Catalyzed Photoreductive Desymmetrization

“…Owing to the cost-effectiveness and the favorable small radius of first-row transition metals in asymmetric catalysis, cobalt catalysis has been established as a powerful strategy in asymmetric synthesis . Inspired by the seminal reports of cobalt-catalyzed reductive coupling triggered by oxidative coupling by the Cheng, Xia, and Xiao groups, we envisioned that simultaneous introduction of both axial and central chirality could be achieved via selective functionalization of the aldehyde according to the proposed mechanism shown in Scheme c. The reaction is initiated by single-electron reduction of a cobalt­(II) complex to active cobalt­(I), followed by oxidative cyclization of an aldehyde unit with the alkyne to form an axially and centrally chiral cobaltacyclic intermediate, where this oxidative cyclization is considered to be both the enantio- and diastereo-determining step.…”

Dual Photoredox/Cobalt-Catalyzed Reductive Cyclization of Alkynals

“…Recent progress of photoredox/transition metal dual catalysis has made it an indispensable synthetic tool in organic chemistry . The progress includes photoredox/cobalt-catalyzed reductive functionalization of alkenes and alkynes using Co I as a catalytically active species. − One of the advantages of this dual catalysis is that protonation can facilitate catalyst turnover. However, most of the protonation step relies on the acidic proton of oxidized Hantzsch ester, − , which leads to the production of excess pyridine derivative as a waste.…”

Cyclization reactions of 1,6-dienes and 1,6-enynes by dual cobalt photocatalysis

“…4 c ,6 Recent studies demonstrate that dual cobalt photocatalysis can enable a variety of useful transformations such as dehydrogenative coupling, 7 dehydrogenative aromatization, 8 reduction, 9 isomerization and functionalization of alkenes and alkynes. 4 c ,10 Given these significant achievements, it can be expected that further investigations in this line would give rise to new powerful synthetic tools that may not be accessible in other ways.…”