Engaging 1,7-diynes in a photocatalytic Kharasch-type addition/1,5-(S'')-substitution cascade toward β-gem-dihalovinyl carbonyls.

A new and general photocatalytic Kharasch-type addition/1,5-(SN'')-substitution cascade of 1,7-diynes with alkyl halides such as BrCCl3 and CBr4 was reported for the first time, and used to produce 65 hitherto unreported β-gem-dihalovinyl ketones/aldehydes with moderate to excellent yields in a highly regioselective manner. This reaction tolerates a wide scope of substrates, which offers a green and efficient entry to fabricate synthetically important β-gem-dihalovinyl carbonyl scaffolds. Notably, the late-stage application of these resulting β-gem-dihalovinyl carbonyls shows high and unique reactivity profiles and demonstrates the versatility of their derivatization.