Copper-catalyzed oxidative coupling of quinoxalin-2(1H)-ones with alcohols: access to hydroxyalkylation of quinoxalin-2(1H)-ones

An efficient protocol for the synthesis of hydroxyl-containing quinoxalin-2(1H)-ones has been developed via the copper-catalyzed cross-coupling reaction of quinoxalin-2(1H)-ones with alcohols with moderate to good yields.

Copper-catalyzed oxidative intermolecular 1,2-alkylarylation of styrenes with ethers and indoles

A new copper-catalyzed oxidative three-component intermolecular 1,2-alkylarylation of styrenes with ethers and indoles is disclosed.

Synthesis of benzyl hydrazine derivatives via amination of benzylic C(sp3)–H bonds with dialkyl azodicarboxylates

Copper(i)/Phen catalysed functionalization of benzylic C–H bonds with dialkyl azodicarboxylates.

Eosin Y-catalyzed, visible-light-promoted carbophosphinylation of allylic alcohols via a radical neophyl rearrangement

An eosin Y-catalyzed, visible-light-promoted phosphinylation-induced 1,2-rearrangement reaction of allylic alcohols to prepare various β-aryl-γ-ketophosphine oxides is presented.

Copper-catalyzed remote oxidation of alcohols initiated by radical difluoroalkylation of alkenes: facile access to difluoroalkylated carbonyl compounds

A Cu-catalyzed oxidation of alcohols triggered by the radical difluoroalkylation of alkenes has been developed.

Iron-Promoted Difunctionalization of Alkenes by Phenylselenylation/1,2-Aryl Migration

Iron-promoted difunctionalization of α,α-diaryl and α-aryl-α-alkyl allylic alcohols has been efficiently achieved by means of N-(phenylseleno)phthalimide (N-PSP) under mild conditions. An in situ generated phenylselenium cation (PhSe⁺) was added to the olefinic C═C bond to initiate the regioselective phenylselenylation with concomitant 1,2-aryl migration, following a migration preference contrary to the well-known radical pathway. Hydrazonation of the resultant alkene difunctionalization products, that is, α-aryl-β-phenylselenyl ketones, and subsequent copper-catalyzed dehydroselenylation efficiently afforded functionalized 2-pyrazoline derivatives.

Recent Advances in Radical C-H Activation/Radical Cross-Coupling

Research and industrial interest in radical C-H activation/radical cross-coupling chemistry has continuously grown over the past few decades. These reactions offer fascinating and unconventional approaches toward connecting molecular fragments with high atom- and step-economy that are often complementary to traditional methods. Success in this area of research was made possible through the development of photocatalysis and first-row transition metal catalysis along with the use of peroxides as radical initiators. This Review provides a brief and concise overview of the current status and latest methodologies using radicals or radical cations as key intermediates produced via radical C-H activation. This Review includes radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling of radicals with M-R groups, and coupling of radical cations with nucleophiles (Nu).

Combined Di-tert-butyl Peroxide and Inorganic Base Promoted α-Alkylation of Ethers with Arenesulfonylindoles

The di-tert-butyl peroxide (DTBP) induced coupling of arenesulfonylindoles with ethers such as 1,4-dioxane, tetrahydropyran, tetrahydrofuran, and 1,2-dimethoxyethane was studied. The distinguishing feature of this strategy was characterized by capturing in situ generated vinylogous imine intermediates for the C(sp³)-H bond alkylation of ethers. This general procedure presents the major advantages of its wide substrate scope and good functional group compatibility.

Direct alkylheteroarylation of alkenes via photoredox mediated C–H functionalization

The direct alkylheteroarylation of alkenes with cyclic and acyclic ethers via distal heteroaryl ipso-migration has been accomplished through the design of a photoredox-mediated C–H functionalization pathway.

An iron-catalyzed hydroalkylation reaction of α,β-unsaturated ketones with ethers

A general strategy for the hydroalkylation of vinyl ketones using ethers catalyzed by an iron catalyst is described.

Metal-free tandem oxidative C(sp3)–H bond functionalization of alkanes and dearomatization of N-phenyl-cinnamamides: access to alkylated 1-azaspiro[4.5]decanes

Metal-free tandem C(sp³)–H bond functionalization of simple alkanes/dearomatization of N-phenyl-cinnamamides is developed, providing 1-azaspiro[4.5]decanes with excellent regioselectivity and diastereoselectivity.

One-Pot Synthesis of Allylic Sulfones, Ketosulfones, and Triflyl Allylic Alcohols from Domino Reactions of Allylic Alcohols with Sulfinic Acid under Metal-Free Conditions

A metal-free tandem procedure by using a sulfonylation reaction of aryl allylic alcohols followed by an iodobenzenediacetate (PIDA)-promoted oxidative functionalization has been established. Allylic sulfones, γ-ketosulfones, and triflyl allylic alcohols have been constructed in a single operation. The methodology incorporates the sulfonyl (both aryl and triflyl) functionality with a simple work-up procedure.

Palladium-Catalyzed Cross-Coupling of α-Bromocarbonyls and Allylic Alcohols for the Synthesis of α-Aryl Dicarbonyl Compounds

The palladium-catalyzed coupling of olefins and organohalides is a versatile approach for synthesizing complex molecules from simple starting materials. We have developed a palladium-catalyzed coupling of α-bromocarbonyl compounds with allylic alcohols for the generation of acyclic aryl-substituted dicarbonyl compounds. The reaction proceeds via a tandem olefin insertion of an α-acyl radical followed by a 1,2-aryl migration. In addition to providing preliminary evidence for a free radical mediated mechanism, we demonstrate unprecedented levels of 1,3-stereoinduction for the 1,2-migration step.

Radical aryl migration reactions and synthetic applications

This review provides a comprehensive summary of radical aryl migration reactions, highlighting their mechanistic studies and synthetic applications.

Visible light-mediated arylalkylation of allylic alcohols through concomitant 1,2-aryl migration

A photocatalytic process for selective arylalkylation of allylic alcohols via unique 1,2-aryl migration with α-bromo diethyl malonate has been developed.

Oxidative radical 1,2-alkylarylation of alkenes with α-C(sp3)–H bonds of acetonitriles involving 1,2-aryl migration

The first access to acyclic molecules by metal-free oxidative 1,2-alkylarylation of alkenes with acetonitriles is presented.

Iodine-catalyzed ammoxidation of methyl arenes

A metal-free direct ammoxidation of readily available methyl arenes leading to nitriles was established under mild conditions.

Oxidative C(sp3)–H functionalization of acetonitrile and alkanes with allylic alcohols under metal-free conditions

Direct oxidative C(sp³)–H functionalization of acetonitrile and alkanes with α,α-diaryl allylic alcohols has been developed.

Direct construction of 2-alkylbenzo-1,3-azoles via C–H activation of alkanes for C–C and C–X (X = O, S) bond formation

2-Alkylated benzo(oxa)thiazoles were prepared directly from simple alkanes and aryl isocyanates/isothiocyanates in a one-pot procedure.

Alkylation/1,2-aryl migration of α-aryl allylic alcohols with α-carbonyl alkyl bromides using visible-light photoredox catalysis

A visible-light-induced alkene difunctionalization strategy is described for 1,5-dicarbonyl compound synthesis through alkylation and 1,2-aryl migration.

Synthesis of functionalized benzoxazines by copper-catalyzed C(sp3)–H bond functionalization of acetonitrile with olefinic amides

A Cu-mediated/catalyzed oxycyanomethylation reaction of olefinic amides with acetonitrile was developed for the synthesis of important benzoxazine derivatives.

DBU-promoted cyclization of vinyl isocyanides with ethers via the functionalization of a C(sp3)–H bond for the synthesis of isoquinolines

A DBU-promoted cascade functionalization of a C(sp³)–H bond adjacent to oxygen and a radical cyclization reaction of vinyl isocyanides was developed to easily access multi-functionalized isoquinolines.

Radical 1,2-aryl migration in α,α-diaryl allylic alcohols toward β-silyl ketones

A copper-catalyzed radical 1,2-aryl migration in α,α-diaryl allylic alcohols is developed, leading to β-silyl carbonyl compounds in moderate to good yields.

Metal-free oxidative C(sp3)–H bond functionalization of alkanes and alkylation-initiated radical 1,2-aryl migration in α,α-diaryl allylic alcohols

A C(sp³)–H bond functionalization of alkanes and 1,2-aryl migration of allylic alcohols was reported with up to 93% yields.

A nickel-mediated oxidative α-C(sp3)–H functionalization of amides with allylic alcohols terminated by radical 1,2-aryl migration

A Ni-mediated oxidative C(sp³)–H functionalization of N,N-substituted amides with α,α-diaryl allylic alcohols through a radical 1,2-aryl migration process has been developed. This process features a broad substrate scope and excellent functional group tolerance.