Stereoselection at the Steady State in Radical Cyclizations of Acyclic Systems Containing One Radical Acceptor and Two Precursors in a 1,5- Relationship under Pseudo-First-Order Conditions

The first example of a successive kinetic resolution of acyclic diastereomeric radical intermediates in a 1,5-relationship under pseudo-first-order conditions is reported. A mechanistic model involves nonselective generation of the radical intermediates followed by different partitioning of these between two different chemical pathways. The "2,5-cis" selectivity in the radical cyclization step arises from transition geometries with the substituents aligned in pseudoequatorial positions.