Diastereoselective Chelation-Controlled Radical Cyclization of Chiral Oxazolidinone-Derived 2-Alkenamides and Modeling of the Transition State

A good yield, but only modest diastereoselectivity (2:3 = 45:55) is achieved in the radical cyclization of 1 to give 2 and 3. MgBr2·Et2O was essential for good diastereoselectivity (2:3 = 82:18). Transition state modeling with a specifically developed “radical force-field” suggested that the observed diastereoselectivities can be ascribed to van der Waals attractive interactions between arenes.