Regio- and diastereoselective 1,2-hydroalkylation of 1,3-enynes via dual photoredox/Ti catalysis.

The selective 1,2-difunctionalization of 1,3-enynes represents a highly efficient strategy for synthesizing propargyl compounds-key structural motifs in organic synthesis. Herein, we present a novel photocatalysis strategy for the highly chemo-, regio-, and diastereoselective 1,2-difunctionalization of 1,3-enynes via cobalt-catalyzed MHAT and Ti-catalyzed reductive polar crossover. However, the reaction failed to proceed with aromatic aldehydes and ketones, likely due to steric hindrance or low electrophilicity. This approach enables the highly efficient preparation of homopropargylic alcohols with excellent diastereoselectivity (up to 20 : 1) and advances radical-based strategies for synthesizing complex active molecules.