Photocatalytic Chemodivergent Synthesis of α‐gem‐Dihalovinyl Ketones and Chromen‐2‐Ones from Monoalkynes

AbstractA general photocatalytic substrate‐controlled chemodivergent strategy starting from monoalkynes with polyhalomethanes such as BrCCl3 and CBr4 was develop, enabling Kharasch‐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.magnified image