Visible-Light-Mediated Fluoroalkylation of Isocyanides with Ethyl Bromofluoroacetates: Unified Synthesis of Mono- and Difluoromethylated Phenanthridine Derivatives

A practical and unified strategy has been described for the preparation of mono- and difluoromethylated phenanthridine derivatives using a visible-light-promoted alkylation and decarboxylation sequence from biphenyl isocyanides with ethyl bromofluoroacetate (EBFA) or ethyl bromodifluoroacetate (EBDFA). These reactions could be carried out at room temperature in good to excellent chemical yields. Both stepwise and one-pot procedures have been developed, which makes this strategy more attractive

Visible-Light-Promoted Remote C(sp³)–H Amidation and Chlorination

A visible-light-promoted C­(sp³)–H amidation and chlorination of <i>N</i>-chlorosulfonamides (NCSs) is reported. This remote C­(sp³)–H functionalization can be achieved in weak basic solution at room temperature with as little as 0.1 mol % of a photocatalyst. A variety of nitrogen-containing heterocycles (up to 94% yield) and chlorides (up to 93% yield) are prepared from NCSs. Late-stage C­(sp³)–H functionalization of complex and biologically important (−)-<i>cis</i>-myrtanylamine and (+)-dehydroabietylamine derivatives can also be achieved with excellent yields and regioselectivity

Synthesis of Isoquinolones Using Visible-Light-Promoted Denitrogenative Alkyne Insertion of 1,2,3-Benzotriazinones

A visible-light-promoted regioselective denitrogenative insertion of terminal alkynes into 1,2,3-benzotriazinones is reported. This mechanistically novel process allows the synthesis of substituted isoquinolones in satisfactory isolated yields (24 examples, 46–84% yield) at room temperature under visible-light irradiation with the assistance of a photocatalyst. The proposed single-electron-transfer pathway was supported by TEMPO trapping, radical clock experiments, and Stern–Volmer analysis

Direct Synthesis of Nitriles from Aldehydes Using an <i>O</i>‑Benzoyl Hydroxylamine (BHA) as the Nitrogen Source

The direct synthesis of nitriles from commercially available or easily prepared aldehydes has been achieved. <i>O</i>-(4-CF₃-benzoyl)-hydroxylamine (CF₃-BHA) was utilized as the nitrogen source to generate <i>O</i>-acyl oximes in situ with aldehydes, which can be converted to a nitrile with the assistance of a Brønsted acid. Several aliphatic, aromatic, and α,β-unsaturated nitriles that contain different functional groups were prepared in high yields (up to 94% yield). This method has notable advantages, such as simple and mild conditions, high yields, and good functional group tolerance

Visible-Light-Promoted and One-Pot Synthesis of Phenanthridines and Quinolines from Aldehydes and <i>O</i>‑Acyl Hydroxylamine

A one-pot synthesis of phenanthridines and quinolines from commercially available or easily prepared aldehydes has been reported. <i>O</i>-(4-Cyanobenzoyl)­hydroxylamine was utilized as the nitrogen source to generate <i>O</i>-acyl oximes in situ with aldehydes catalyzed by Brønsted acid. <i>O</i>-Acyl oximes were then subjected to visible light photoredox catalyzed cyclization via iminyl radicals to furnish aza-arenes. A variety of phenanthridines and quinolines have been prepared assisted by Brønsted acid and photocatalyst under visible light at room temperature with satisfactory yields

Isocyanide Insertion: De Novo Synthesis of Trifluoromethylated Phenanthridine Derivatives

A mechanistically new strategy has been described for the simple, practical, and environmentally friendly preparation of 6-(trifluoromethyl)phenanthridine derivatives using ionic isocyanide insertion from biphenyl isocyanide derivatives and Umemoto’s reagent. These reactions were promoted only by inorganic base in good-to-excellent chemical yields without any external stoichiometric oxidants and radical initiators

Radical Alkynyltrifluoromethylation of Alkenes Initiated by an Electron Donor–Acceptor Complex

Radical alkynyltrifluoromethylation of alkenes with actylenic triflones has been achieved. This radical chain reaction is initiated by a catalytic amount of an electron-donor–acceptor complex composed of Togni’s reagent and <i>N</i>-methylmorpholine. This transformation proceeds under exceptionally mild and operationally simple conditions. A variety of alkenes are compatible in this protocol including aliphatic alkenes, vinyl ethers, enecarbamates, styrenes, and even acrylates, providing diverse β- trifluoromethyl alkynes in good to excellent yields

Synthesis of Quinolines through Three-Component Cascade Annulation of Aryl Diazonium Salts, Nitriles, and Alkynes

An efficient and rapid synthesis of multiply substituted quinolines is described. This method is enabled by a three-component cascade annulation of readily available aryl diazonium salts, nitriles, and alkynes. This reaction is catalyst- and additive-free. Various aryl diazonium salts, nitriles, and alkynes can participate in this transformation, and the yields are up to 83%

Synthesis of Tetracyclic Quinazolinones Using a Visible-Light-Promoted Radical Cascade Approach

A practical approach for the synthesis of tetracyclic pyrroloquinazolines using photoredox strategy has been developed. The visible-light-promoted intramolecular single-electron-transfer process between photocatalyst and <i>N</i>-(2-iodobenzyl)-<i>N</i>-acylcyanamides is considered to be involved in this transformation. Targeted pyrroloquinazoline derivatives (15 examples) are presented in good isolated yields (30%–88%)

<i>De Novo</i> Synthesis of Polysubstituted Naphthols and Furans Using Photoredox Neutral Coupling of Alkynes with 2‑Bromo-1,3-dicarbonyl Compounds

A conceptually new strategy has been described for the mild, practical, and environmentally friendly preparation of naphthols and furans using a visible-light promoted photoredox neutral approach. These reactions between accessible electron-deficient bromides and commercially available alkynes could be carried out at room temperature in good-to-excellent chemical yields without any external stoichiometric oxidants