Photocatalytic Generation of π‐Allyltitanium Complexes via Radical Intermediates

The addition of π‐allylmetal complexes to carbonyls is the most important route to homoallylic alcohols. This study reports the first photocatalytic generation of π‐allyltitanium complexes by a radical strategy. This novel strategy enables the three‐component allylation of carbonyls with 1,3‐butadiene, providing rapid access to valuable homoallylic alcohols (over 60 examples). The exceptional regio‐ and diastereoselectivity provided by dual photoredox/Ti catalysis is comparable to that of the Cr‐catalyzed Nozaki–Hiyama–Kishi allylation reaction. This study reports the first photocatalytic generation of π‐allyltitanium complexes by a radical strategy. This novel strategy enables the three‐component allylation of various aldehydes and ketones with feedstock 1,3‐butadiene, providing access to a broad range of valuable homoallylic alcohols with over 60 examples of exceptional regio‐ and diastereoselectivities.