Visible-Light-Photocatalyzed Dicarbofunctionalization of Conjugated Alkenes with Ketone-Based Dihydroquinazolinones

A visible-light-photocatalyzed 1,2-arylalkylation of N-(arylsulfonyl)acrylamides with ketone-based dihydroquinazolinones is described. The formal C-C bond cleavage of aliphatic ketones is unified with tandem radical alkylation/1,4-aryl migration/desulfonylation to forge two different types of vicinal C-C bonds and construct an all-carbon quaternary α-stereocenter, thus enhancing the carbogenic complexity and tolerating diverse functionalities. Additional to telescopic synthesis and product diversification, this method features a radical dicarbofunctionalization of conjugated N-(arylsulfonyl)acrylamides with a nucleophilic alkyl radical precursor (dihydroquinazolinone) utilizing oxygen as a green oxidant at ambient temperature.

Visible-light-induced cascade reaction: a sustainable approach towards molecular complexity

Photoredox catalysis has demonstrated rapid evolution in the field of synthetic organic chemistry. On the other hand, the splendour of cascade reactions in providing complex molecular architectures renders them a cutting-edge research area. Therefore, the merging of photocatalysis with cascade synthesis brings out a synthetic paradigm with immense potential. The development of photocascade catalysis for a target molecule with a particular molecular skeleton and stereochemical framework presents certain challenges but provides a robust and environmentally benign synthetic alternative. This comprehensive review assembles all the accomplishments and highlights of visible-light-induced cascade reactions with literature coverage up to October 2022.

SO2-Extrusive 1,4-(Het)Aryl Migration: Synthesis of α-Aryl Amides and Related Reactions

(Het)aryl migration has emerged as a key synthetic tool and has particularly been exploited for the synthesis of α-aryl amides. This method overcomes the existing α-arylation methods, which are not always compatible with the introduction of (het)aryl groups possessing bulky or electrophilic substituents. This review focuses on SO2-extrusive (het)aryl migration in the frame of α-aryl amide synthesis. Anion- and radical-mediated transformations are reported, including the synthesis of polycyclic compounds through cascade reactions.

1 Introduction

2 Anionic Aryl Migration

3 Radical Aryl Migration

4 Conclusion

Copper-Catalyzed Aminoarylation of Alkenes via Aminyl Radical Addition and Aryl Migration

We describe a new strategy for aminoarylation of alkenes by copper-catalyzed smiles rearrangement using O-benzoylhydroxylamines as the amine reagent. This method affords various β-amino amide derivatives possessing a quaternary carbon center with wide functional group tolerance and high regioselectivity. The mechanistic studies indicate that the transformation can involve aminyl radical intermediates under acid-free condition.

Desulfonylation via Radical Process: Recent Developments in Organic Synthesis

As the "chemical chameleon", sulfonyl-containing compounds and their variants have been merged with various types of reactions for the efficient construction of diverse molecular architectures by taking advantage of their incredible reactive flexibility. Currently, their involvement in radical transformations, in which the sulfonyl group typically acts as a leaving group via selective C-S, N-S, O-S, S-S, and Se-S bond cleavage/functionalization, has facilitated new bond formation strategies which are complementary to classical two-electron cross-couplings via organometallic or ionic intermediates. Considering the great influence and synthetic potential of these novel avenues, we summarize recent advances in this rapidly expanding area by discussing the reaction designs, substrate scopes, mechanistic studies, and their limitations, outlining the state-of-the-art processes involved in radical-mediated desulfonylation and related transformations. With a specific emphasis on their synthetic applications, we believe this review will be useful for medicinal and synthetic organic chemists who are interested in radical chemistry and radical-mediated desulfonylation in particular.

Cobalt-Catalyzed 1,4-Aryl Migration/Desulfonylation Cascade: Synthesis of α-Aryl Amides

A cobalt-catalyzed 1,4-aryl migration/disulfonylation cascade applied to α-bromo N-sulfonyl amides was developed. The reaction was highly chemoselective, allowing the preparation of α-aryl amides possessing a variety of functional groups. The method was used as the key step to synthesize an alkaloid, (±)-deoxyeseroline. Mechanistic investigations suggest a radical process.

Generation and precise control of sulfonyl radicals: visible-light-activated redox-neutral formation of sulfonates and sulfonamides

An efficient protocol to direct sulfonamidation or sulfonation of electron-deficient alkenes for furnishing alkylsulfonamides or sulfonates has been achieved.

Visible-light-induced intramolecular radical cascade of α-bromo-N-benzyl-alkylamides: a new strategy to synthesize tetracyclic N-fused indolo[2,1-a]isoquinolin-6(5H)-ones

Polycyclic indole scaffolds are ubiquitous in pharmaceuticals and natural products and in materials science. Here, we present a visible-light-initiated intramolecular aryl migration/desulfonylation/cyclization cascade reaction for the synthesis of tetracyclic indolo[2,1-a]isoquinolin-6(5H)-ones. This protocol not only exhibited a wide substrate scope but also provided a mild route to access a variety of tetracyclic N-fused indoles.

Visible-light-induced sulfonylation/cyclization of vinyl azides: one-pot construction of 6-(sulfonylmethyl)phenanthridines

A facile and efficient protocol has been developed for sulfonylation/cyclization of vinyl azides under photoredox conditions.

CF3SO2X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF3SO2Cl

The recent progresses of the application of trifluoromethanesulfonyl chloride, CF₃SO₂Cl, in the formation of C–CF₃, C–SCF₃, C–SOCF₃, and C–Cl bonds are summarised in this second part of a two-part review published back-to-back on both sodium trifluoromethanesulfinate, CF₃SO₂Na, (Part 1) and trifluoromethanesulfonyl chloride, CF₃SO₂Cl (Part 2). There are many reactions in common between these two reagents but it should be noted that CF₃SO₂Cl reacts under reductive conditions while CF₃SO₂Na requires oxidative conditions. Electrophilic chlorination is obviously the exclusive preserve of CF₃SO₂Cl that has been exploited with emphasis in enantioselective chlorination.

Intermolecular cascade annulations of N-(arylsulfonyl)acrylamides with dual C(sp3)–H bonds: divergent access to indanes and pyrrolidin-2-ones

A new divergent cascade annulation reaction of N-(arylsulfonyl)acrylamides and dual alkyl C(sp³)–H bonds for selectively producing indanes and pyrrolidin-2-ones is presented.

CuBr-mediated radical cascade difluoroacetamidation of acrylamides using α,α-difluoro-α-(TMS)-acetamides

Radical cascade difluoroacetamidation of N-(arylsulfonyl)acrylamides with α,α-difluoro-α-(TMS)-acetamides has been achieved for the first time.