Stereoselective Access to Trisubstituted Cyclopentanols from Chiral Unsaturated Oxo Esters by Ketyl Radical Cyclization.

Substituted cyclopentanols with three contiguous stereocenters were prepared with impressive diastereocontrol through a samarium diiodide induced 5-exo-trig radical process. The chiral unsaturated oxo ester precursors were prepared with ee values up to 90 % from propionaldehyde through a two-step organocatalyzed aldolization and Wittig–Horner olefination reaction sequence.