Search

Ethynylbenziodoxolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report that aryl‐substituted EBX reagents can be directly activated by visible light irradiation. They act as both oxidants and radical traps, alleviating the need for a photocatalyst in several reported EBX‐mediated processes, including decarboxylative and deboronative alkynylations, the oxyalkynylation of enamides and the C−H alkynylation of THF. Furthermore, the method could be applied to the synthesis of alkynylated quaternary centers from tertiary alcohols via stable oxalate salts and from tertiary amines via aryl imines. A photocatalytic process using 4CzIPN as an organic dye was also developed for the deoxyalkynylation of oxalates., Aryl ethynylbenziodoxolones (ArEBXs) can be directly activated by visible light irradiation. In the excited state, ArEBXs act as strong oxidants, alleviating the need for a photocatalyst in decarboxylative and deboronative alkynylations, the oxyalkynylation of enamides, and the C−H alkynylation of THF.

We report an organophotocatalytic 1,2-oxyalkynylation of ene-carbamates and enol ethers using Ethynyl BenziodoXolones (EBXs). 1-Alkynyl-1,2-amino alcohols and diols were obtained in up to 89% yield. Photocatalytic formation of radical cations led to Umpolung of the innate reactivity of the alkenes, enabling addition of a nucleophilic benzoate followed by radical alkynylation., Photocatalytic Umpolung with organic dyes overcoming the innate nucleophilicity of enecarbamates and enol ethers for oxyalkynylation with EBX reagents to access 1-alkynyl-1,2-amino alcohols and diols.

EthynylBenziodoXolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report their application in two complementary deoxygenation strategies allowing the synthesis of valuable alkynylated all-carbon quaternary centers from tertiary alcohols via stable oxalate salts. Our first approach involves a photocatalytic process using 4CzIPN as an organic dye to promote oxidative degradation of the oxalate and EBXs to trap the formed radical. In our second approach, we demonstrate the direct photoexcitation of an EBX, which then acts as both oxidant and radical trap, alleviating the need for a photocatalyst in several EBX-mediated alkynylation processes.

We report an atom-economical 1,2-oxyalkynylation of ene-carbamates and enol ethers based on the use of Ethynyl BenziodoXolone (EBX) as dual reagents for alkyne and oxygen transfer. The reaction occurs at room temperature under blue LED irradiation using an organic dye as a photocatalyst. A broad variety of 1-alkynyl-1,2-amino-alcohol and 1-alkynyl-1,2-diol scaffolds were obtained in up to 89% yield with anti-Markovnikov regioselectivity. The reaction is speculated to proceed via oxidation of the double bond to give a radical cation intermediate, enabling the selective difunctionalization of electron-rich alkenes.

Ethynylbenziodoxolones (EBXs) have recently emerged as potent reagents for the alkynylation of radicals. Their combination with photocatalysis allows the synthesis of valuable alkynes at room temperature. Herein, we discuss two photomediated strategies for the synthesis of internal alkynes. The first transformation is a 1,2-oxyalkynylation of N- and O-alkenes using 4ClCzIPN as a photocatalyst. The second strategy makes use of EBXs as strong photooxidants allowing the oxidation of a variety of substrates with no need for a photocatalyst.

Alkynyl sulfoxides are important building blocks with a unique reactivity in organic chemistry, but only a few reliable methods have been reported to synthesize them. A novel route to access alkynyl sulfoxides is reported herein by using ethynyl benziodoxolone (EBX) reagents to trap sulfenate anions generated in situ, via a retro-Michael reaction. The reaction takes place under metal-free and mild conditions. It is compatible with aryl, heteroaryl, and alkyl sulfoxides with up to 90% yield. This practical access to alkynyl sulfoxides is expected to facilitate the application of these useful building blocks in organic synthesis.