Photocatalytic Kharasch-Type Cyclization Cascade for Accessing Polyhalogenated 1-Indanones and Indenes

A new photocatalytic cascade involving Kharasch-type cyclization, 1,5-(S N ″)-substitution, and elimination has been developed for the reactions of secondary alcohol-tethered 1,6-diynes with polyhalomethanes such as BrCCl 3 and CBr 4 . This method affords a series of functionalized β- gem -dihalovinyl 1-indanones in good yields with high stereoselectivity. Moreover, when ene-diynes were employed as radical acceptors, the reaction proceeded readily to deliver polyhalogenated indenes in a completely stereoselective manner.