Control of Diastereoselectivity in C=O/C=N Reductive Cyclizations Using an Intramolecularly Tethered Hydrazone

Cyclic hydrazones are efficient ketyl radical acceptors in reductive coupling cyclizations mediated by samarium diiodide, affording cyclic amino alcohols with controlled stereochemistry at the new aminated stereocenter. This approach has been successfully applied to the stereoselective synthesis of a fully functionalized trehazolin cyclitol starting from D-glucose, where the required cyclic hydrazone was directly obtained by partial hydrazynolysis of a 1,2-cyclic carbonate.