Copper-catalyzed aerobic aliphatic C-H oxygenation with hydroperoxides

Regioselective synthesis of isoquinolinonediones through remote unactivated C(sp3)-H bonds

Herein, a general strategy for the remote-site-selective cascade addition/cyclization of unactivated C(sp3)-H bonds in free alcohols and sulfonamides to build isoquinolinonedione skeletons is developed. The site selectivity occurs predominantly via a 1,5-hydrogen atom transfer (HAT) process, triggered by heteroatom-centred radicals generated directly under silver catalysis. A broad substrate scope and excellent regio-/chemo-selective control are demonstrated in this method.

Copper-catalyzed aerobic benzylic C(sp3)-H lactonization of 2-alkylbenzamides via N-centered radicals

Herein, we describe the copper-catalyzed aerobic C(sp³)-H functionalization of 2-alkylbenzamides for the synthesis of benzolactones. This reaction proceeds via 1,5-hydrogen atom transfer of N-centered radicals directly generated by N-H bond cleavage and does not require the synthesis of pre-functionalized N-centered radical precursors or the use of strong stoichiometric oxidants.

Iron-Catalyzed Photoinduced Remote C(sp3)-H Amination of Free Alcohols

We report a general photocatalytic protocol for the remote C(sp³)-H bond amination of free aliphatic alcohols. The electron transfer between the abundant and inexpensive catalyst FeCl₃ and simple alkanols under blue LED irradiation enables the alkoxy radical formation under mild redox-neutral conditions, with no need for additional oxidant and prefunctionalization. The subsequent selective 1,5-hydrogen atom transfer (HAT) and amination provide a simple and efficient way to access molecular complexity from readily available and bulk alcohols.

Remote C(sp3 )-H Arylation and Vinylation of N-Alkoxypyridinium Salts to δ-Aryl and δ-Vinyl Alcohols

The reaction of readily available and bench-stable N-alkoxypyridinium salts with arylboronic and vinylboronic acids afforded δ-aryl and δ-vinyl alcohols, respectively, in the presence of fac-Ir(ppy)₃ and Cu(OTf)₂ dual catalysts. The reaction takes place through a domino process involving the reductive generation of alkoxyl radicals, 1,5-hydrogen atom transfer (1,5-HAT) and the copper-catalyzed cross-coupling reaction of the resulting translocated carbon radicals with boronic acids. Complementary to the Minisci reaction, this method allows for the arylation of nucleophilic alkyl radicals with both electron-rich and electron-poor arenes under mild reaction conditions.

γ-Alkylation of Alcohols Enabled by Visible-Light Induced 1,6-Hydrogen Atom Transfer

Site-selective remote alkylation of alcohol is attractive but challenging in organic synthesis. Herein, we report a novel visible-light mediated γ-alkylation of alcohol derivatives via the formation of C_sp3-C_sp3 bond through C_sp3-H bond functionalization under mild conditions. The use of sulfamate esters enables the directed, otherwise rare 1,6-HAT to generate γ-selective C-centered radical, which is complementary to δ-selective 1,5-HAT of alcohols. This redox-neutral protocol provides a general and operationally simple method to access γ-alkylated alcohols.

Silver-catalyzed remote Csp3-H functionalization of aliphatic alcohols

Aliphatic alcohols are common and bulk chemicals in organic synthesis. The site-selective functionalization of non-activated aliphatic alcohols is attractive but challenging. Herein, we report a silver-catalyzed δ-selective Csp3-H bond functionalization of abundant and inexpensive aliphatic alcohols. Valuable oximonitrile substituted alcohols are easily obtained by using well-designed sulphonyl reagents under simple and mild conditions. This protocol realizes the challenging δ-selective C-C bond formation of simple alkanols.

Copper-catalyzed aerobic radical C-C bond cleavage of N-H ketimines

We report herein studies on copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines. Treatment of N–H ketimines having an α-sp³ hybridized carbon under Cu-catalyzed aerobic reaction conditions resulted in a radical fragmentation with C–C bond cleavage to give the corresponding carbonitrile and carbon radical intermediate. This radical process has been applied for the construction of oxaspirocyclohexadienones as well as in the electrophilic cyanation of Grignard reagents with pivalonitrile as a CN source.

Structure-reactivity relationship of trifluoromethanesulfenates: discovery of an electrophilic trifluoromethylthiolating reagent

A family of electrophilic trifluoromethanesulfenates was prepared. Structure-reactivity relationship studies showed that the substituted groups on the aryl ring of the trifluoromethylthiolating reagent did not have an obvious influence on their reactivities. A simplified electrophilic trifluoromethylthiolating reagent 1c was then identified that can react with a wide range of nucleophiles such as Grignard reagents, arylboronic acids, alkynes, indoles, β-ketoesters, oxindoles, and sodium sulfinates under mild reaction conditions. A variety of functional groups were tolerated under these conditions.

sp3 C–H oxidation by remote H-radical shift with oxygen- and nitrogen-radicals: a recent update

This review updates on recent advances in aliphatic sp³ C–H bond oxidation by remote H-radical abstraction with oxygen- and nitrogen-radicals classifying by the type of the radical precursors.