Stereoselective Synthesis of ()- and ()-Cyclopropyl-Fused Carbocyclic Nucleosides Using Stereoselective Cyclopropanation.

To determine which sugar conformation is favorable in binding to peroxisome proliferator-activated receptors, the conformationally locked south () and north () analogues were asymmetrically synthesized using a bicyclo[3.1.0]hexane template. The ()-conformer was synthesized by employing "reagent-controlled" Charette asymmetric cyclopropanation in a 100% stereoselective manner, whereas the ()-conformer was stereoselectively synthesized by using "substrate-controlled" hydroxyl-directed Simmons-Smith cyclopropanation as a key step.