Biquan Xiong

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.

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.

DCC-assisted direct esterification of phosphinic and phosphoric acids with O-nucleophiles

GRAPHICAL ABSTRACT ABSTRACT A novel and efficient dicyclohexylcarbodiimide-promoted protocol for the selective and controllable esterification of P(O)OH compounds using O-nucleophiles (alcohols and phenols) as efficient esterification reagents is described. This method features a high efficiency and good functional-group tolerance, meaning a simple way to synthesize a broad spectrum of phosphinic and phosphoric acid esters from basic starting materials with moderate to excellent yields.

Bu4NI-Catalyzed Dehydrogenative Coupling of Diaryl Phosphinic Acids with C(sp3)–H Bonds of Arenes

An efficient phosphorylation of C(sp3)-H bonds of arenes with diaryl phosphinic acids via Bu4NI-catalyzed dehydrogenative coupling has been developed. This transformation proceeds efficiently under transition-metal-free reaction conditions and represents a straightforward method to prepare valuable organophosphorus compounds from readily available arenes and diaryl phosphinic acids.

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.