Photoredox-Catalyzed C-H Functionalization Reactions

Abstract

The fields of C-H functionalization and photoredox catalysis have garnered enormous interest and utility in the past several decades. Many different scientific disciplines have relied on C-H functionalization and photoredox strategies including natural product synthesis, drug discovery, radiolabeling, bioconjugation, materials, and fine chemical synthesis. In this Review, we highlight the use of photoredox catalysis in C-H functionalization reactions. We separate the review into inorganic/organometallic photoredox catalysts and organic-based photoredox catalytic systems. Further subdivision by reaction class─either sp² or sp³ C-H functionalization─lends perspective and tactical strategies for use of these methods in synthetic applications.

Scheme 1.

Table of Common Photoredox Catalysts, Abbreviations, and Excited-State Redox Values (vs SCE)^,,,

Scheme 2.

A General Mechanism of a Photoredox-Mediated Minisci-Type Radical Addition into Heteroarenes with a Sacrificial Reductant

Scheme 3.

Intramolecular Heteroaryl C–H Alkylation

Scheme 4.

Scope of the Intermolecular Heteroaryl C–H Alkylation using Ir(ppy)₃ with Respect to the Heteroarene

Scheme 5.

Scope of Alkyl Bromides for an Intermolecular Heteroaryl C–H Alkylation Using Ir(ppy)₃

Scheme 6.

Alkylation of Aniline Derivatives through α-Bromoketones as sp³ Carbon-Centered Radical Precursors

Scheme 7.

Dimeric Gold Complexes in Heteroaryl C–H Functionalizations with Alkyl Bromides

Scheme 8.

Heteroaryl C–H Fluoroalkylation

Scheme 9.

Mechanism of (Hetero)arene C–H Trifluoromethylation Using Sulfonyl Chlorides as Carbon-Centered Radical Precursors

Scheme 10.

Scope of (Hetero)aryl C–H Trifluoromethylation Using Trifluoromethyl Sulfonyl Chloride

Scheme 11.

Trifluoromethyl Radical Addition/Cascade of Arylpropiolates for the Synthesis of Coumarin Derivatives

Scheme 12.

α-Heteroarylation of Ethers through the Generation of α-Oxy Radicals

Scheme 13.

Minisci-Type C–H Functionalization Using Alcohols as Coupling Partners

Scheme 14.

Mechanism of Minisci-Type C–H Functionalization Using Alcohols as Coupling Partners

Scheme 15.

Mechanistic Support for a Spin-Centered Shift in the Minisci-Type C–H Functionalization Using Alcohols as Coupling Partners

Scheme 16.

Hydroxymethylation of (Hetero)arenes

Scheme 17.

Heteroaryl C–H Functionalization Using Carboxylic Acids as Carbon-Centered Radical Precursors

Scheme 18.

Peroxides Serving as Carbon-Centered Radical Precursors for a Minisci-Type C–H Functionalization

Scheme 19.

Mechanism for the Minisci-Type C–H Functionalization Using Acylperoxides as Radical Precursors

Scheme 20.

Decarboxylative C–H Functionalization for the Synthesis of Oxindoles

Scheme 21.

C–H Trifluoromethylation with Perfluoroarene Iodine(III) Trifluoroacetates as the Trifluoromethyl Radical Source

Scheme 22.

Addition of α-Amino Radicals in a Minisci-Type C–H Functionalization Reactions

Scheme 23.

Mechanism for an Asymmetric Minisci-Type Radical Addition of α-Amino Radicals

Scheme 24.

Scope of the Asymmetric Minisci-Type Radical Addition of α-Amino Radicals

Scheme 25.

General Mechanism for the C–H Functionalization of Heteroarenes by Aryl Radicals Accessed via Aryldiazoniums

Scheme 26.

Early Reports of C–H Cyclization through Aryl Diazoniums

Scheme 27.

Dual Palladium-Photoredox-Catalyzed Intermolecular C–H Functionalization Using Aryl Diazoniums

Scheme 28.

Mechanism of the Dual Palladium/Photoredox-Catalyzed Intermolecular C–H Functionalization Using Aryl Diazoniums

Scheme 29.

C–H Functionalization Using Aryl Diazoniums in Water

Scheme 30.

Diaryliodonium as Aryl Radical Precursors for (Hetero)aryl C–H Functionalization

Scheme 31.

Three-Component 1,2-Diarylation of Styrenes with Aryl Diazoniums as Radical Precursors

Scheme 32.

Pyridinium Salts as Radical Precursors for (Hetero)aryl C–H Functionalization

Scheme 33.

Sulfonyl Chlorides as Aryl Radical Precursors in a Cascade C–H Functionalization Reaction

Scheme 34.

C2 Arylation of Heteroarenes using Sulfonyl Chlorides

Scheme 35.

Aryl Halides as Aryl Radical Precursors for (Hetero)arene C–H Functionalizations

Scheme 36.

Generation of Vinylic Radicals in a Cascade C–H Functionalization Reaction for the Synthesis of Polycylic Heteroarenes

Scheme 37.

Minisci-Type Acylation Using Acyl Radicals

Scheme 38.

Dual Palladium and Photoredox Catalysis for C–H Acylation of Indoles

Scheme 39.. Site Selectivity for C–H Acylation of Pyridinium Salts^a

^aConditions: 1.0 mol % [Ir(dF(CF₃)ppy)₂bpy]PF₆, 1.2 equiv NaOAc, DCE, bLED

Scheme 40.

Mechanism for C2-Selective C–H Acylation of Pyridinium Salts

Scheme 41.

Dual Nickel and Photoredox Catalysis for a C–H Acylation Using Carboxylic Acids

Scheme 42.

Synthesis of Fluorenones by a Pschorr-like Acyl Radical Cyclization

Scheme 43.

Cascade Acyl Radical Addition to Amides for the Synthesis of 2-Oxoindoles

Scheme 44.

Alkynes as Acyl Radical Precursors in a C–H Acylation of Heteroarenes

Scheme 45.

General Mechanism for the Addition of a Nitrogen-Centered Radical to Aromatics

Scheme 46.

N-Acyloxyphthalimides as Nitrogen-Centered Radical Precursors for C–H Functionalization

Scheme 47.

Other Nitrogen-Centered Radical Precursors for Photoredox Catalyzed (Hetero)aryl C–H Functionalization

Scheme 48.

Alkyl Amines as Nitrogen-Centered Radical Precursors for C–H Functionalization

Scheme 49.

Synthesis of Phenanthridinones and Quinolinones through the Intramolecular Addition of a Nitrogen-Centered Radical

Scheme 50.

Synthesis of Substituted Pyridines through an Intramolecular Addition of a Nitrogen-Centered Radical

Scheme 51.

Benzoyloxylation through an Oxygen-Centered Radical

Scheme 52.

Synthesis of Benzothiazoles from the Addition of a Sulfur-Centered Radical to an Aryl C–H

Scheme 53.

External Oxidant-Free Variant of the Sulfur-Centered Radical Cyclization for the Synthesis of Benzothiazoles

Scheme 54.

Mechanism for the Synthesis of Benzothiazoles through Sulfur-Centered Radicals

Scheme 55.

Sulfonyl Chlorides in a Heteroaryl C–H Sulfenylation

Scheme 56.

Aryl C–H Sulfonylation Using Sodium Sulfinates

Scheme 57.

Aryl C–H Sulfonylation Using Sulfonyl Chlorides

Scheme 58.

Alkoxy Aryl C–H Amination with Azole Nucleophiles via Aryl Cation Radical Intermediates

Scheme 59.

(Hetero)aryl C–H Phosphonylation through Aryl Cation Radicals

Scheme 60.

Mechanism of an Aryl C–H Amination via Pyridyl Cation Radicals υ

Scheme 61.

Scope of Aryl C–H Amination via Pyridyl Cation Radicals Developed by Carreira

Scheme 62.

Scope of Aryl C–H Amination via Pyridyl Cation Radicals Developed by Ritter

Scheme 63.

In Situ Generation of Pyridyl Cation Radicals for Aryl C–H Aminations

Scheme 64.

Coupling of Imines, Generated by α-Amido Sulfides, and Heteroarenes for C–H Functionalization

Scheme 65.

Indole C–H Functionalization with Photogenerated Iminium Ions

Scheme 66.

Heck-Type Reaction Using a Photoredox Catalyst as an Oxidant

Scheme 67.

Ortho-Selective C–H Olefination of Phenol Derivatives

Scheme 68.

Intramolecular C–H Ortho-Olefination for the Synthesis of Indole Derivatives

Scheme 69.

Dual Palladium and Photoredox Catalysis for an Intramolecular C–H Amination

Scheme 70.

Directed Meta-C–H Alkylation of Pyridyl-Substituted Arenes

Scheme 71.

General Pathways for α-Amino C–H Functionalization via the Generation of Electrophilic Iminium Ions or Nucleophilic α-Amino Radicals

Scheme 72.

Mechanism of the Aza-Henry Reaction for the C–H Alkylation of Tetrahydroisoquinolines

Scheme 73.

Scope of Elaborated Aza-Henry Reaction for the C–H Alkylation of Tetrahydroisoquinolines

Scheme 74.

Mannich Reaction for the C–H Alkylation of Tetrahydroisoquinolines

Scheme 75.

Mannich Reaction for the C–H Alkylation of Tetrahydroisoquinolines Using Silyl Enol Ethers as Nucleophiles

Scheme 76.

Other Nucleophiles for the Addition into Photoredox-Generated Iminiums for the C–H Functionalization of Tetrahydroisoquinolines

Scheme 77.

Dimeric Gold Complexes as Photoredox Catalysts in C–H Alkylation and Phosphonylation of Tetrahydroisoquinolines

Scheme 78.

C–H Alkylation and Subsequent Cyclization of Tetrahydroisoquinolines

Scheme 79.

[3 + 2] Cyclization of Photogenerated Iminium Ions with Alkynes

Scheme 80.

Intramolecular C–H Amination or Alkoxylation through Iminium Ions

Scheme 81.

NHC Catalysis for Stereoselective Addition into Iminium Ions

Scheme 82.

Chiral Ion Pairing for Stereoselective Addition into Iminium Ions

Scheme 83.

Chiral Copper Catalysis for Stereoselective Coupling with Iminium Ions

Scheme 84.

Amide-Derived Iminium Ions Couple with Electron-Rich Aromatics or Alcohols

Scheme 85.

α-Arylation of Glycine Derivatives via Photogenerated Iminium Ions

Scheme 86.

Intramolecular Sulfonamide Cyclization to Photogenerated Iminiums for the Synthesis of Tetrahydroimidazoles

Scheme 87.

C–H Cyanation of Tertiary Aliphatic Amine Derived Iminium Ions

Scheme 88.

Benzimidazole Synthesis through an Intramolecular C–H Amination of Iminium Ions

Scheme 89.

Stereoselective Alkylation of Tetrahydroisoquinolines Using Dual Organo- and Photoredox Catalysis

Scheme 90.

Asymmetric Mannich-Type Reaction for the C–H Alkylation of Glycine-Derived Iminium Ions

Scheme 91.

Synthesis of (±)-Tetrabenazine via a Photogenerated Tetrahydroisoquinoline Iminium Ion

Scheme 92.

Synthesis (±)-5-epi-Cermizine C and (±)-Epimyrtine via Iminium Ions

Scheme 93.

α-Amine Functionalization via Radical Trapping

Scheme 94.

α-Amino C–H Arylation with Cyanobenzenes

Scheme 95.

Mechanism of the α-Amino C–H Arylation with Cyanobenzenes

Scheme 96.

Diastereoselective α-Amino C–H Arylation with Cyanobenzenes

Scheme 97.

α-Amino C–H Alkylation by Trapping with Michael Acceptors

Scheme 98.

Mechanistic Support of the α-Amino C–H Alkylation with Electron-Deficient Alkenes

Scheme 99.

C–H Amination via an α-Amino Radical-Azodicarboxylate Radical Anion Coupling Reaction

Scheme 100.

α-Amino C–H Alkylation Reported by Yoon

Scheme 101.

Acrylates as α-Amino Radical Acceptors for C–H Alkylations

Scheme 102.

2,3-Allenoates as α-Amino Radical Acceptors for C–H Alkylations

Scheme 103.

Photoredox Gold Catalysis of the Alkynylation of Amines through an α-Amino Radical

Scheme 104.

Vinyl Azides as α-Amino Radical Acceptors for C–H Alkylations

Scheme 105.

α-Amino C–H Arylation through a Triple Catalytic System

Scheme 106.

Mechanism of the α-Amino C–H Arylation through a Triple Catalytic System

Scheme 107.

α-Hydroxy C–H Arylation through A Triple Catalytic System

Scheme 108.

α-Oxy C–H Arylation through a Triple Catalytic System Reported by Molander

Scheme 109.

α-Hetero C–H Alkylation

Scheme 110.

α-Amino C–H Arylation through Dual Nickel and Photoredox Catalysis Reported by Doyle

Scheme 111.

α-Oxy C–H Arylation Using Aryl Chlorides via Dual Nickel and Photoredox Catalysis

Scheme 112.

Coupling of 1,3-Dioxolane and Aryl Chlorides and Subsequent Hydrolytic Workup to Access the Formylated Arenes

Scheme 113.

α-Hetero C–H Alkylation with Maleate and Fumarate Radical Acceptors

Scheme 114.

α-Amino C–H Deuteration and Tritiation of Pharmaceutical Derivatives

Scheme 115.

C–H Methylation via Peroxide Sensitization and Nickel Radical Coupling

Scheme 116.

α-Hetero C–H Alkylation Using an Amidate HAT Reagent

Scheme 117.

α-Hetero C–H Acylation through Dual Nickel and Photoredox Catalysis

Scheme 118.

Enantioselective α-Amino C–H Acylation

Scheme 119.

Direct α-Hydroxy C–H Alkylation Using a Hydrogen-Bonding Co-catalyst to Activate α-C–H Bonds on Alcohols

Scheme 120.

Effect on the BDEs of the α-Hydroxy C–H with the Coordination of a Pentavalent Silicate Species as a Bond-Weakening Catalyst

Scheme 121.

Scope of the Direct α-Hydroxy C–H Alkylation using a Pentavalent Silicate Species as a Bond Weakening Catalyst

Scheme 122.

Borinic Acids and Tetrabutyl Ammonium Phosphate as Bond Weakening Catalysts for α-Hydroxy C–H Alkylations

Scheme 123.

Coupling of Alkynes with α-Oxo Radicals via Dual Nickel and Photoredox Catalysis

Scheme 124.

Mechanism of Nickel-Mediated α-Amino Cross-Couplings with Aryl Halides

Scheme 125.

C–H Monofluoroalkenylation of Dialkylamines

Scheme 126.

Mechanism of a Primary Amine C–H Alkylation and Lactamization through In Situ Generated Carbamates

Scheme 127.

Scope of Primary Amine C–H Alkylation and Lactamization through In Situ Generated Carbamates

Scheme 128.

Generation of α-Amino Radicals through 1,6-HAT: Synthesis of Indolines

Scheme 129.

C–H Alkylation of Aliphatic Secondary Amides

Scheme 130.

Conjugate Acids of Common Hydrogen Atom Abstracting Reagents and Corresponding BDEs

Scheme 131.

C–H Alkylation and Arylation of Amides

Scheme 132.

Chiral Ir-Mediated C–H Alkylation with Trifluoromethyl Aryl Ketones

Scheme 133.

Asymmetric Coupling of α-Amino Radicals with Aldimines

Scheme 134.

Hydroaminoalkylations through Dual Transition-Metal and Photoredox Catalysis

Scheme 135.

C–H α-Allylation of Amines Using Allylic Bromides

Scheme 136.

Asymmetric C–H α-allylation of Amines via Dual Palladium and Photoredox Catalysis

Scheme 137.

Asymmetric α-C–H Alkylation of Aldehydes Using Dual Photoredox and Organocatalysis

Scheme 138.

Mechanism of Asymmetric α-C–H Alkylation of Aldehydes Using Dual Photoredox and Organocatalysis

Scheme 139.

Asymmetric α-C–H Fluoroalkylation of Aldehydes using Dual Photoredox and Organocatalysis

Scheme 140.

Asymmetric Synthesis of Oxonitriles via α-C–H Functionalization of Aldehydes

Scheme 141.

Two Energetically Favored Transition States for Addition of Radicals to Chiral Imidazolidinone Derived Enamines

Scheme 142.

Asymmetric α-C–H Benzylation of Aldehydes Using Dual Photoredox and Organocatalysis

Scheme 143.

Asymmetric α-C–H Alkylation through a Chiral Ir Photoredox Catalyst

Scheme 144.

Compatible Nucleophiles for the Asymmetric α-C–H Functionalization of Aldehydes Using Chiral Ir or Rh Photoredox Catalysis

Scheme 145.

Asymmetric Coupling of Aldehydes and α-Amino Radicals Using a Chiral Rh Photoredox Catalyst

Scheme 146.

3πe⁻ Enaminyl Radical for Asymmetric Aldehyde C–H Functionalization

Scheme 147.

Photoredox-Mediated Asymmetric Coupling of Aldehydes and Xanthenes and Subsequent Reduction

Scheme 148.

α-Trifluoromethylation of Ketones

Scheme 149.

Aldehyde C–H Oxyamination with TEMPO

Scheme 150.

Aldehyde C–H Alkylation with Diazoacetate Coupling Partners

Scheme 151.

Ketimine C–H Alkylation Using Dual Photoredox and Nickel Catalysis

Scheme 152.

α-Allylation of 1,3-Dicarbonyls with Allyl Stannanes and Allyl Sulfones

Scheme 153.

Mechanism of β-Aldehyde C–H Arylation with Cyanobenzenes

Scheme 154.

Scope of β-Arylation of Aldehydes with Cyanobenzenes

Scheme 155.

β-C–H Arylation of Cyclohexanone with Cyanobenzenes

Scheme 156.

β-C–H Alkylation of Aldehydes with Electron-Deficient Alkene Radical Traps

Scheme 157.

Scope of β-Aldehyde C–H Arylation with Cyanobenzenes

Scheme 158.

Chiral Rh Photoredox Catalyst for β-Functionalization of Ketones

Scheme 159.

Asymmetric Difluoroalkylation of Aldehydes

Scheme 160.

β-Arylation of Ketones by Dual Palladium and Photoredox Catalysis with Aryl Diazoniums

Scheme 161.

Direct Aldehyde C–H Hydroxylation via Acyl Radicals

Scheme 162.

Synthesis of N-Hydroxyphthalimide Esters through Direct Aldehyde C–H Functionalization

Scheme 163.

Acyl Chlorides Generated from Acyl Radicals for the Synthesis of Amides

Scheme 164.

Synthesis of Trifluoromethyl Thioesters through Acyl Radicals

Scheme 165.

Mechanism of Direct Aldehyde C–H Arylation through a Triple Catalytic System

Scheme 166.

Scope of Direct Aldehyde C–H Arylation through a Triple Catalytic System

Scheme 167.

Direct Aldehyde C–H Alkylation with Electron-Deficient Alkenes and Arylation with Nickel Catalysis

Scheme 168.

Alkynylation of Aldehydes Using a Benziodoxolonyl Radical as a Hydrogen Abstractor

Scheme 169.

Hydrazone C–H Alkylations

Scheme 170.

Benzylic C–H Arylation with Cyanobenzenes and a Thiol Hydrogen-Atom Abstracting Reagent

Scheme 171.

Allylic C–H Arylation with Cyanobenzenes and a Thiol Hydrogen Atom Abstracting Reagent

Scheme 172.

Allylic Radicals Trapped with Aryl Ketones

Scheme 173.

Allylic Radicals Trapped with Imines

Scheme 174.

Benzylic or Allylic Radical Coupling with Cyanobenzenes using Sulfonamide as the HAT Catalyst

Scheme 175.

Benzylic Radical Coupling with Cyanopyridines by Photogenerated Benzyloxy Radicals

Scheme 176.

Benzylic Sulfoximidation Using a Nitrogen-Centered Radical as the HAT Reagent

Scheme 177.

Benzylic Sulfonylation through a Three-Component Coupling

Scheme 178.

Benzylic Fluorination Using TBADT as a Photoredox and HAT Catalyst

Scheme 179.

Benzylic Amination through the Nucleophilic Addition of Azoles to Benzylic Cations

Scheme 180.

Intramolecular Benzylic Amination and Alkoxylation

Scheme 181.

Benzylic Alkoxylation through Phosphate-Mediated Hydrogen Atom Abstraction

Scheme 182.

Benzylic and Aldehydic C–H Bond Coupling

Scheme 183.

Vinylic C–H Functionalization with Acyl Chlorides

Scheme 184.

Allylic Thiolation via Allylic Cations

Scheme 185.

Benzylic C–H Carbocylization for the Synthesis of Indene Derivatives

Scheme 186.

Mechanism of Diastereoselective Allylation of Aldehydes via Dual Photoredox and Chromium Catalysis

Scheme 187.

Scope of Diastereoselective Allylation of Aldehydes via Dual Photoredox and Chromium Catalysis

Scheme 188.

Diastereoselective Allylation of Aldehydes via Dual Photoredox and Chromium Catalysis Using Enol Ethers

Scheme 189.

Allylic Alkylation of Silyl Enol Ethers

Scheme 190.

C–H Fluorination Remote from Functional Groups Using TBADT as a Photoredox and HAT Catalyst

Scheme 191.

C–H Alkylation Remote from Functional Groups Using TBADT as a Photoredox and HAT Catalyst

Scheme 192.

Hydrocarbon C–H Functionalization Using Cerium Salts

Scheme 193.

C–H Alkylation and Amination of Alkanes Using Cerium Salts

Scheme 194.

Hydrocarbon C–H Alkylation Using TBADT in Flow

Scheme 195.

C–H Coupling with (Hetero)aryl Bromides Remote from Functional Groups Using Dual TBADT and Nickel Catalysis

Scheme 196.

Remote C–C Bond Formation Using Dual Nickel and Iridium Photoredox through Chloride Radical HAT

Scheme 197.

Remote C–H Trifluoromethylation through Dual TBADT and Copper Catalysis

Scheme 198.

Remote Radical C–H Coupling with Aldehydes through the Generation of Nucleophilic Organochromium Carbanions

Scheme 199.

Asymmetric C–H Alkylation with TBADT and a Chiral Phosphoric Acid

Scheme 200.

Remote C–H Heteroarylation via a Minisci-Type Reaction

Scheme 201.

Adamantyl C–H Alkylation with Activation through a Charge-Transfer Event

Scheme 202.

Remote C–H Trifluoromethylthiolation Using a Benzoyloxy Radical Hydrogen Atom Abstractor

Scheme 203.

General Scheme of a 1,5-HAT

Scheme 204.

Remote C–H Amidation and Chlorination via a 1,5 HAT of Chlorosulfonamides

Scheme 205.

Remote C–H Allylation and Alkenylation via a 1–5 HAT of N-Alkoxyphthalimides

Scheme 206.

Mechanism for the Remote C–H Functionalization of N-Alkyl Amides through a PCET-Initiated 1,5-HAT

Scheme 207.

Scope of the Remote C–H Functionalization of N-Alkyl Amides through a PCET-Initiated 1,5-HAT by Knowles and Rovis

Scheme 208.

γ-Alkylation of Carboxylic Acids through a 1,5-HAT

Scheme 209.

Allylic Chlorides as Radical Traps for the Allylation of Remote C–H Bonds

Scheme 210.

Allylic Chlorides as Radical Traps for the Allylation of Remote C–H Bonds

Scheme 211.

Remote C–H Vinylation of O-Acyloximes

Scheme 212.

Chiral Lewis Acid Catalysis for the Asymmetric Remote Alkylation of Imidazole Amides

Scheme 213.

Enantioselective C–H Bond Functionalization with Imidate Chiral Copper Catalysis

Scheme 214.

Enantioselective C–H Cyanation via Photoredox and Chiral Copper Catalysis

Scheme 215.

C–H Azidation, Thiocyanation, and Isothiocyanation for the Synthesis of γ-Substituted Alcohols

Scheme 216.

Generation of Aryl Radicals from Aryldiazoniums Using an Eosin Y Photoredox Catalyst for C–H Heteroarylation

Scheme 217.

[4 + 2] Benzannulation of Biaryldiazonium Salts with Alkynes through Aryl Radicals Generated by Aryldiazoniums

Scheme 218.

(Hetero)aryl Coupling through C–H Functionalization with Aryl Radicals Generated from Aryl Chlorides

Scheme 219.

Generation of Aryl Radicals from Aryl Sulfonyl Chlorides for Arene C–H Functionalization

Scheme 220.

Perfluoroalkylation of Arenes Using Sulfinates as Fluoroalkyl Radical Precursors

Scheme 221.

C–H Acylation of Acetanilides through Dual Photoredox and Palladium Catalysis

Scheme 222.

α-Oxo Acids as Acyl Radial Precursors for C–H Acylation

Scheme 223.

Decarboxylative Heck-Type Coupling of Aliphatic Acids and Vinyl (Hetero)arenes

Scheme 224.

Generation of Aryl Radicals through C–H Activation by an Interrupted Pummerer Activation Allows for a Direct C–H/C–H Coupling of (Hetero)arenes

Scheme 225.

N-Acyloxyphthalimides for the Generation of Nitrogen-Centered Radical in Heteroaryl C–H Functionalization

Scheme 226.

Synthesis of Phenanthridine Derivatives using o-2,4-Dinitrophenyloximes as NCR Precursors

Scheme 227.

Phenol C–H Dehydrogenative Coupling with Diarylamines

Scheme 228.

Quinoxalinone C–H Functionalization via Minisci-Type Addition of a Nitrogen-Centered Radical

Scheme 229.

Addition of Phosphate-Centered Radicals for Heteroaryl C–H Functionalization

Scheme 230.

Heteroaryl C–H Phosphonylation of Aminoquinolines

Scheme 231.

Intramolecular Lactonization of 2-Arylbenzoic Acids through a Benzyoyloxy Radical Cyclization

Scheme 232.

Sulfur-Centered Radicals for the Synthesis of Thiazoles

Scheme 233.

C3 Selective C–H Sulfenylation of Indoles through a Minisci-Type Reaction with Thiyl Radicals

Scheme 234.

C–H Sulfenylation of Heteroarenes through a Minisci-Type Reaction with Arylthiyl Radicals

Scheme 235.

C3 Thiocyanation of Indoles through a Minisci-Type Reaction with Thiocyanate Radical

Scheme 236.

C3 Thiocyanation of Imidazoles through a Minisci-Type Reaction with Thiocyanate Radical

Scheme 237.

Heteroaryl C–H Sulfenylation Using Sulfinic Acids

Scheme 238.

DCN-Catalyzed C–H Cyclizations through Arene Cation Radicals

Scheme 239.

Intramolecular C–H Amination and Application to the Synthesis of Mitomycin Precursors

Scheme 240.

Arene C–H Amination with Benzotriazole Nucleophiles

Scheme 241.

Arene C–H Functionalization with Alcohol, Fluoride, and Bromide as a Nucleophile

Scheme 242.

Proposed Mechanism of Aryl C–H Functionalization with QuCN⁺ as the Photooxidant

Scheme 243.

Aryl C–H Bromination with an Acridinium Salt as the Photooxidant

Scheme 244.

Chlorination of Trialkoxyarenes with an Acridinium Salt as the Photooxidant

Scheme 245.

Arene C–H Amination with Azole Nucleophiles

Scheme 246.

Proposed Mechanism of Arene C–H Amination with Azole Nucleophiles

Scheme 247.

Predicted Site-Selectivity of Arene C–H Amination with Azole Nucleophiles

Scheme 248.

Aryl C–H Amination and Hydroxylation with QuCN⁺ as the Photooxidant

Scheme 249.

Arene C–H Functionalizations with Radiofluoride, Cyanide, and Primary Amines as the Nucleophiles

Scheme 250.

Synthesis of Styrene Derivatives through a Dehydrogenative Coupling of Arenes and Styrenes through Dual Photoredox and Cobaloxime Catalysis

Scheme 251.

Mechanism of an Arene C–H Alkylation Using Diazoacetates as Polar Nucleophiles Catalyzed by an Acridinium Salt

Scheme 252.

Thiophene C2-Selective C–H Amination with DDQ

Scheme 253.

Arene C–H Sulfoximidation Catalyzed by an Acridinium Salt

Scheme 254.

Selective C2 Sulfonamidation of Pyrroles Catalyzed by an Acridinium Salt

Scheme 255.

Mechanism of Arene C–H Sulfonamidation by Dual Photoredox and Cobaloxime Catalysis

Scheme 256.

Arene C–H Bromination, Amination, Amidation, and Nitration via Arene Cation Radicals

Scheme 257.

Arene C–H Phosphonylation through Addition to an Arene Cation Radical

Scheme 258.

Indole C–H Formylation through Nitrogen Cation Radicals

Scheme 259.

Arene C–H Bromination through Activation of NBS by Generation of an Amine Cation Radical

Scheme 260.

Directed Aryl C–H and N–H Bond Annulation of Aryl Amides with Alkynes

Scheme 261.

Mechanism of the Directed Aryl C–H and N–H Bond Annulation of Aryl Amides with Alkynes

Scheme 262.

Synthesis of Phenanthrenes through Aryl C–H by an α-Keto Radical

Scheme 263.

Arene C–H Chlorination via an In Situ Ipso-Halogen Exchange

Scheme 264.

C–H Alkylation of Amines through Photogenerated Iminiums

Scheme 265.

C–H Alkylation of Amines through Photogenerated Iminiums with Diazoacetates

Scheme 266.

C–H Cyanation and Trifluoromethylation of Amines through Photogenerated Iminiums

Scheme 267.

C–H α-Alkylation of Amines with Silyl Enol Ethers

Scheme 268.

Synthesis of Quinolines through a Cascade EAS and Olefin Addition to the Photogenerated Iminium Ion

Scheme 269.

In Situ C–H Alkylation of Tetrahydroisoquinolines and Subsequent 6π Electrocyclization

Scheme 270.

Asymmetric α-C–H Alkylation of Tetrahydroisoquinolines through a Chiral β-ICD Acrolein Complex

Scheme 271.

Oxocarbenium Ion Generation for the C–H Alkylation of Isochromans

Scheme 272.

C–H Alkylation of Tetrahydroisoquinolines through a Radical–Radical Coupling from Alkyl Selenides

Scheme 273.

Chemodivergent C–H Functionalization of Tetrahydroisoquinolines

Scheme 274.

α-Carbamyl C–H Alkylation of Piperidines with an Acridinium Salt as the Photooxidant

Scheme 275.

Mechanism of α-Carbamyl C–H Alkylation of Piperazines with an Acridinium Salt as the Photooxidant

Scheme 276.

Site-Selective Piperazine C–H Alkylation with an Acridinium Salt as the Photooxidant

Scheme 277.

α-Hetero C–H Alkylation with Eosin Y as the Photooxidant

Scheme 278.

Carbocarboxylation of Alkenes via α-Hetero Radicals

Scheme 279.

α-Heteroatom C–H Arylation with Aryl Bromides through a Benzaldehyde Photosensitization and HAT

Scheme 280.

α-Oxo C–H Arylation and Alkylation Reactions with Benzophenones as a Photoredox and HAT Catalyst

Scheme 281.

α-Hetero C–H Alkynylation, Alkenylation, and Allylations Using a Diarylketone

Scheme 282.

α-Amino Alkylation for the Synthesis of 1,4-Dicarbonyls

Scheme 283.

α-C–H Alkylation of Unprotected Amines through an Azidyl Radical HAT

Scheme 284.

Sulfonamides as HAT Catalysts for α-Hetero C–H Alkylations

Scheme 285.

α-Alkylation of Aldehydes with Alkyl Bromides Using Eosin Y as Photocatalyst

Scheme 286.

Generation of Acyl Radicals for a Radical Cascade with Alkynes and Arenes to Produce 3-Acyl-4-arylcoumarins

Scheme 287.

Direct Aldehyde C–H Alkylation through Acyl Radical Coupling to Olefins

Scheme 288.

Amide Synthesis from Aldehydes with a Phenazine Ethosulfate

Scheme 289.

Dual Chromium and Photoredox Catalysis for the Synthesis of Homoallylic Alcohols

Scheme 290.

Synthesis of α-Keto Amides through an Acyl Radical

Scheme 291.

Dual Eosin Y Photoredox and Chiral Rh Lewis Acid Catalysis for the Asymmetric Synthesis of 1,4-Dicarbonyls

Scheme 292.

Benzylic C–H Amination via HAT by Stabilized Nitrogen-Centered Radicals

Scheme 293.

Benzylic C–H Mono- or Difluorination Using 9-Fluorenone and Xanthone as the Photoredox Catalysts

Scheme 294.

Intramolecular Benzylic C–H Amination and Oxidation for the Synthesis of 3-Hydroxyisoindolinones

Scheme 295.

Benzylic C–H Carboxylation

Scheme 296.

Intramolecular Benzylic C–H Alkoxylations with DCN

Scheme 297.

Intramolecular Benzylic C–H Alkoxylations with a Pyrylium Salt for the Synthesis of Ethers and Lactones

Scheme 298.

Benzylic C–H Trifluoromethylation through an Inner-Sphere Hydrogen-Atom-Transfer Mechanism

Scheme 299.

Mechanism for a Benzylic C–H Trifluoromethylation through an Inner-Sphere Hydrogen-Atom-Transfer Mechanism

Scheme 300.

Benzylic C–H Alkylations through Radical Addition to Radical Acceptors

Scheme 301.

Benzylic C–H Arylation with Cyanoarenes

Scheme 302.

Benzylic C–H Arylation through Dual Triplet Excited Diaryl Ketone and Nickel Catalysis

Scheme 303.

Allylic C–H Alkylation of Alkenes Using an Acridnium Salt as the Photoredox Catalyst

Scheme 304.

Allylic C–H Arylation and Vinylation through Dual Nickel and Acridinium Photoredox Catalysis

Scheme 305.

Mechanism of Allylic C–H Arylation and Vinylation through Dual Nickel and Acridinium Photoredox Catalysis

Scheme 306.

Dual Enzymatic and Photoredox Catalysis for an Asymmetric Benzylic C–H Hydroxylation

Scheme 307.

Remote C–H Halogenation with Organic Photoredox Catalysts through HAT Events

Scheme 308.

Cycloalkane C–H Functionalization with Persulfate Radical Anions as the Hydrogen Atom Abstracting Agent

Scheme 309.

Dialkylation of Alkenes with Two Distinct C–H bonds by Dual Photoredox and Iron Catalysis

Scheme 310.

Remote C–H Functionalization with a Phosphate Salt as the Hydrogen Atom Abstracting Agent

Scheme 311.

Chlorine Radicals as HAT Catalysts for C–H Alkylations

Scheme 312.

1,5-HAT for the Alkylation of Amide Derivatives with Boronic Acid Acceptors

Scheme 313.

1,5-HAT for the Alkylation of Amide Derivatives with Allyl Sulfone Acceptors

Scheme 314.

Aryl Radical Translocation by a 1,5-HAT Event for the Arylation of Amide Derivatives

Scheme 315.

1,5-HAT for the Functionalization of Amides and Amines with Various Radical Traps

Scheme 316.

1,5-HAT for the Remote Halogenation of Imine and Ketone Derivatives

Scheme 317.

Remote Pyridiylation via a 1,5-HAT Radical Translocation of N-Alkoxypyridinium Salts

Scheme 318.

Intramolecular Amination through a 1,5-HAT event for the Synthesis of Pyrrolidines

Scheme 319.

Summary of the Reactive Intermediates Accessed via Inorganic and Organic Photoredox Catalysis for C–H Bond Functionalizations