Photoredox-Catalyzed Decarboxylative Alkylation of Silyl Enol Ethers To Synthesize Functionalized Aryl Alkyl Ketones

Divergent Conversion of N-Acyl-isoxazol-5(2 H)-ones to Oxazoles and 1,3-Oxazin-6-ones Using Photoredox Catalysis

The fragmentation of N-acyl-isoxazol-5-ones using visible light photoredox catalysis has been disclosed. The catalyst-controlled divergent mechanisms, namely the oxidative and reductive quenching catalytic cycle, are utilized. Various oxazoles and 1,3-oxazin-6-ones are selectively obtained from the same isoxazol-5-one skeleton under mild conditions.

Photocatalytic decarboxylative alkylations mediated by triphenylphosphine and sodium iodide

Most photoredox catalysts in current use are precious metal complexes or synthetically elaborate organic dyes, the cost of which can impede their application for large-scale industrial processes. We found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light–emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals. Deaminative alkylation using Katritzky’s N-alkylpyridinium salts and trifluoromethylation using Togni’s reagent are also demonstrated. Moreover, the phosphine/iodide-based photoredox system catalyzes Minisci-type alkylation of N-heterocycles and can operate in tandem with chiral phosphoric acids to achieve high enantioselectivity in this reaction.

Photoinduced C(sp3 )-N Bond Cleavage Leading to the Stereoselective Syntheses of Alkenes

Herein we report a versatile Mizoroki-Heck-type photoinduced C(sp³ )-N bond cleavage reaction. Under visible-light irradiation (455 nm, blue LEDs) at room temperature, alkyl Katritzky salts react smoothly with alkenes in a 1:1 molar ratio in the presence of 1.0 mol % of commercially available photoredox catalyst without the need for any base, affording the corresponding alkyl-substituted alkenes in good yields with broad functional-group compatibility. Notably, the E/Z-selectivity of the alkene products can be controlled by an appropriate choice of photoredox catalyst.

Deaminative (Carbonylative) Alkyl-Heck-type Reactions Enabled by Photocatalytic C-N Bond Activation

The palladium-catalyzed Heck reaction is a well-known, Nobel Prize winning transformation for producing alkenes. Unlike the alkenyl and aryl variants of the Heck reaction, the alkyl-Heck reaction is still underdeveloped owing to the competitive side reactions of alkyl-palladium species. Herein, we describe the development of a deaminative alkyl-Heck-type reaction that proceeds through C-N bond activation by visible-light photoredox catalysis. A variety of aliphatic primary amines were found to be efficient starting materials for this new process, affording the corresponding alkene products in good yields under mild reaction conditions. Moreover, this strategy was successfully applied to deaminative carbonylative alkyl-Heck-type reactions.

Electrochemically induced oxidative S–O coupling: synthesis of sulfonates from sulfonyl hydrazides and N-hydroxyimides or N-hydroxybenzotriazoles

A variety of sulfonates were synthesized from sulfonyl hydrazides and N-hydroxy compounds via electrochemically induced oxidative S–O bond formation.

Photoredox-promoted alkyl radical addition/semipinacol rearrangement sequences of alkenylcyclobutanols: rapid access to cyclic ketones

Two photo-catalytic tandem alkyl radical addition/semipinacol rearrangement reactions of cycloalkanol-substituted styrenes with N-acyloxyphthalimides and O-acyl oximes have been documented. These protocols provide efficient access to functionalized cyclic ketones, and feature mild conditions (i.e., visible light irradiation, redox neutral and room temperature), broad substrate scope and excellent functional group tolerance.

Switchable Decarboxylative Heck-Type Reaction and Oxo-alkylation of Styrenes with N-Hydroxyphthalimide Esters under Photocatalysis

The switchable visible-light-mediated decarboxylative Heck-type reaction and oxo-alkylation reaction of N-hydroxyphthalimide esters under photocatalysis were developed. Disubstituted or trisubstituted alkenes were obtained in good yield with high E-selectivity in the presence of Brønsted acid as the additive, while ketones resulted in the absence of the acidic additive.

Visible-Light-Driven Decarboxylative Alkylation of C-H Bond Catalyzed by Dye-Sensitized Semiconductor

A decarboxylative alkylation of benzylic C(sp³)-H bonds of N-aryl tetrahydroisoquinolines under the irradiation of blue light is reported, featuring a broad substrate scope, low cost, heavy-metal-free, and mild conditions. A preliminary mechanistic study indicated that radical intermediates are involved during the course of the reaction.

A Desulfurative Strategy for the Generation of Alkyl Radicals Enabled by Visible-Light Photoredox Catalysis

Herein, we present a new desulfurative method for generating primary, secondary, and tertiary alkyl radicals through visible-light photoredox catalysis. A process that involves the generation of N-centered radicals from sulfinamide intermediates, followed by subsequent fragmentation, is critical to forming the corresponding alkyl radical species. This strategy has been successfully applied to conjugate addition reactions that features mild reaction conditions, broad substrate scope (>60 examples), and good functional-group tolerance.

Visible-Light-Mediated Synthesis of Ketones by the Oxidative Alkylation of Styrenes

The oxidative coupling of photogenerated alkyl radicals with readily available styrenes is disclosed. This visible-light-mediated method allows rapid access to a wide range of α-alkyl-acetophenones in good yields and with high functional group tolerance. In addition, the developed protocol features room temperature conditions, low photocatalyst loadings, and the use of dimethyl sulfoxide as nontoxic and mild terminal oxidant.

Merging visible-light photoredox and micellar catalysis: arylation reactions with anilines nitrosated in situ

A micellar photocatalytic system has been disclosed, which enables arylation reactions with anilines nitrosated in situ to run in water.

Regiospecific alkyl addition of (hetero)arene-fused thiophenes enabled by a visible-light-mediated photocatalytic desulfuration approach

A unique photoredox desulfuration approach enabling the regiospecific alkyl addition of (hetero)arene-fused thiophenes is presented.

Photoredox-catalyzed cascade annulation of methyl(2-(phenylethynyl)phenyl)sulfanes and methyl(2-(phenylethynyl)phenyl)selanes with sulfonyl chlorides: synthesis of benzothiophenes and benzoselenophenes

A photoredox-catalyzed cascade annulation of methyl(2-(phenylethynyl)phenyl)sulfanes and methyl(2-(phenylethynyl)phenyl)selanes with sulfonyl chlorides was developed.