Photocatalytic Chemodivergent Synthesis of α-gem-Dihalovinyl Ketones and Chromen-2-ones from Monoalkynes

Zi-Yang Xu, Yin-Ping Liu, Xin Liu, Rong Fu, Wen-Juan Hao,* Shu-Jiang Tu,* Bo Jiang*

A general photocatalytic substrate-controlled chemodivergent strategy starting from monoalkynes with polyhalomethanes such as BrCCl₃ and CBr₄ was develop, enablingKharasch-type addition/nucleophilic substitution cascade to selectively produce α-gem-dihalovinyl ketones and chromen-2-ones with moderate to good yields. Use of monoalkynes without additional nucleophilic sites furnished α-gem-dihalovinyl ketones through a Kharasch-type addition and intermolecular allylic substitution cascade whereas the latter transformation of 2-ethynylphenols allowed the full breaking of carbon-halogen bonds of BrCX₃ to access functionalized chromen-2-ones. The late-stage application of these resulting α-gem-dihalovinyl ketones demonstrates the versatility of their derivatization. 

Adv. Synth. Catal. 2022, 364, 2666-2672; DOI: 10.1002/adsc.202200422