Visible-light photoredox-catalyzed dual C-C bond cleavage: synthesis of 2-cyanoalkylsulfonylated 3,4-dihydronaphthalenes through the insertion of sulfur dioxide.

An efficient novel visible-light photoredox-catalyzed dual carbon-carbon bond cleavage of methylenecyclopropanes and cycloketone oximes for the synthesis of 2-cyanoalkylsulfonated 3,4-dihydronaphthalenes through the insertion of sulfur dioxide is established. This dual cleavage of carbon-carbon bonds involves a radical pathway and goes through a sequence of iminyl radical formation, carbon-carbon bond cleavage, sulfur dioxide insertion, sulfonyl radical addition, another carbon-carbon bond cleavage, and intramolecular cyclization.

Visible Light-Catalyzed Cascade Radical Cyclization of N-Propargylindoles with Acyl Chlorides for the Synthesis of 2-Acyl-9H-pyrrolo[1,2-a]indoles.

A novel and convenient visible light-catalyzed tandem radical cyclization of N-propargylindoles with acyl chlorides for accessing 2-acyl-9H-pyrrolo[1,2-a]indoles is established. This transformation involves sequential addition of the acyl radical to the carbon-carbon triple bond, intramolecular cyclization with the 2-position of indole, and isomerization of the carbon-carbon double bond. The experimental results show that this reaction contains a radical pathway and a radical chain process is not the major pathway for the formation of products.

Visible-light promoted one-pot synthesis of sulfonated spiro[4,5]trienones from propiolamides, anilines and sulfur dioxide under transition metal-free conditions.

A novel visible-light promoted sulfonylation/ipso-cyclization of N-arylpropiolamides with arylamines and DABCO·(SO2)2 to synthesize various sulfonated spiro[4,5]trienones is reported. This sulfonylation/ipso-cyclization reaction proceeds via a radical process and undergoes arylsulfonyl radical formation, sulfonylation, and ipso-cyclization. The experimental results indicate that H2O provides an oxygen atom for the construction of the carbonyl group.

Visible-Light-Catalyzed C-C Bond Difunctionalization of Methylenecyclopropanes with Sulfonyl Chlorides for the Synthesis of 3-Sulfonyl-1,2-dihydronaphthalenes.

A novel visible-light-catalyzed sulfonylation/arylation of carbon-carbon σ-bond with sulfonyl chlorides for the synthesis of 3-sulfonylated 1,2-dihydronaphthalenes is developed. This difunctionalization proceeds via a sequence of C═C bond sulfonylation, C-C σ-bond cleavage, and intramolecular cyclization, and the experiment result shows that the C-C σ-bond difunctionalization reaction includes a radical process. This strategy provides a simple and convenient route for difunctionalization of C-C bonds with an aromatic carbon and a sulfonyl radical by one-pot construction of a C-S bond and a new C-C bond.

Oxidative radical ring-opening/cyclization of cyclopropane derivatives.

The ring-opening/cyclization of cyclopropane derivatives has drawn great attention in the past several decades. In this review, recent efforts in the development of oxidative radical ring-opening/cyclization of cyclopropane derivatives, including methylenecyclopropanes, cyclopropyl olefins and cyclopropanols, are described. We hope this review will be of sufficient interest for the scientific community to further advance the application of oxidative radical strategies in the ring-opening/cyclization of cyclopropane derivatives.

Silver-mediated oxidative C-C bond sulfonylation/arylation of methylenecyclopropanes with sodium sulfinates: facile access to 3-sulfonyl-1,2-dihydronaphthalenes.

The novel AgNO3-mediated oxidative sulfonylation/arylation of a C-C σ-bond in methylenecyclopropanes with sodium sulfinates to synthesize various 3-sulfonylated 1,2-dihydronaphthalenes is reported. This sulfonylation/arylation transformation proceeds via a sequence of sulfonylation, C-C σ-bond cleavage and intramolecular cyclization, and the experimental results show that the C-C σ-bond difunctionalization reaction includes a radical process. This strategy provides a simple and convenient route for the difunctionalization of C-C bonds with a phenyl ring and a sulfonyl radical via the one-pot construction of a C-S bond and a new C-C bond.

Oxidative C-C Bond Functionalization of Methylenecyclopropanes with Aldehydes for the Formation of 2-Acyl-3,4-dihydronaphthalenes.

A new FeCl2- and DTBP (di- tert-butyl peroxide)-promoted oxidative ring-opening and cyclization of methylenecyclopropanes with aldehydes for the synthesis of 2-acyl-3,4-dihydronaphthalenes is presented. This oxidative cyclization reaction proceeds via a radical addition, ring-opening, and cyclization sequence facilitated by a Lewis acid, and it offers a practical and straightforward route for the oxidative cyclization of methylenecyclopropanes with an aromatic carbon and a C(sp2)-H bond by simultaneously forming two new carbon-carbon bonds.

Visible-Light-Mediated Ipso-Carboacylation of Alkynes: Synthesis of 3-Acylspiro[4,5]trienones from N-(p-Methoxyaryl)propiolamides and Acyl Chlorides.

A novel visible-light-mediated ipso-carboacylation of N-(p-methoxyaryl)propiolamides with acyl chloride has been established for the synthesis of diverse 3-acylspiro[4,5]trienones with high selectivity and efficiency. This method represents a new difunctionalization of alkynes through cross coupling of the acyl chloride C-Cl bonds with an ipso-aromatic carbon by simultaneously forming two new carbon-carbon bonds and one carbon-oxygen double bond.

Metal-Free Oxidative C-C Bond Functionalization of Methylenecyclopropanes with Ethers Leading to 2-Substituted 3,4-Dihydronaphthalenes.

A novel metal-free oxidative ring-opening/cyclization of methylenecyclopropanes with ethers was established for the synthesis of diverse 2-substituted 3,4-dihydronaphthalenes with high selectivity and efficiency. This oxidative cyclization is achieved by C(sp3)-H functionalization, ring-opening, and cyclization, and this method represents a new example of methylenecyclopropane oxidative cyclization with an aromatic carbon and a C(sp3)-H bond by simultaneously forming two new carbon-carbon bonds.