Organophotocatalytic carbo-heterofunctionalization of unactivated olefins with pendant nucleophiles

Abstract

The difunctionalization of unactivated, terminal olefins through intermolecular addition of α-bromoketones, -esters, and -nitriles followed by formation of 4- to 6-membered heterocycles with pendant nucleophiles is reported.

Photo‐ and Cobalt‐Catalyzed Synthesis of Heterocycles via Cycloisomerization of Unactivated Olefins

“…Previously, we demonstrated the use of PC in olefin‐cyclopropanation and carbo‐heterofunctionalization reactions [9a,b] . Consequently, we sought to examine its utility in the cycloisomerization of amines.…”

The Multifaceted Opportunities Provided by the Pheomelanin-Inspired 1,4-Benzothiazine Chromophore: A Still-Undervalued Issue

“…Under visible-light irradiation, this complex would be promoted to the excited state and then undergo a single electron transfer from the nitrogen atom of the arylcyclopropylamine to the catalyst (Figure 11A) [58]. More recently, the same compound has also found applications as a robust photoredox catalyst (active at 0.5 mol%) for the difunctionalization of unactivated olefins through the intermolecular addition of α-bromoketones, -esters, or -nitriles, leading to the formation of 4-6 member heterocycles (Figure 11B) [59]. In this case, the catalytic cycle would involve the absorption of a photon by QXPT-NPh, which, in the excited state, would be able to reduce the α-bromoderivative to an alkyl radical species.…”

“…In this case, the catalytic cycle would involve the absorption of a photon by QXPT-NPh, which, in the excited state, would be able to reduce the α-bromoderivative to an alkyl radical species. This latter would then add to the olefin to lead to a radical, which would be oxidized by the oxidized photocatalyst to give a carbocation, which, after entrapment by bromide ions, would undergo a reaction with the nucleophile counterpart [59].…”

A DFT study of NHC-catalyzed reactions of [3+3] annulations of 2-bromoenals and thioamides: mechanisms and regio- and stereoselectivities

“…11,12 In addition to their utilization as effective ligands for organometallic catalysts, 13–17 NHCs also have application as organocatalysts. 18–22 The essence of NHC-catalyzed umpolung reactions lies in that the employed NHCs are able to convert the electrophiles (such as aldehydes and enals) to nucleophilic intermediates via nucleophilic attack of the NHCs on the carbonyl group, and then the reactive intermediates couple with other electrophiles, offering great potential for a variety of transformations, such as C–C 23–25 /C–X (X = O, N etc. ) 26–28 bond construction and C–X (X = H, F, Cl, OR, etc. )…”