Optimization of Enantiocontrol for Carbon Hydrogen Insertion with Chiral Dirhodium (II) Carboxamidates. Synthesis of Natural Dibenzylbutyrolactone Lignans from 3 Aryl 1 propyl …

A= CH2, Rh2 (5S-MEPY) 4 A= 0, Rh2 (4S-MEOX) 4 A= NCOMe, Rh2 (4S-MACIM) 4 catalytic cyclopropanation reactions have been employed with increased frequency as key steps in the synthesis of natural products and/or physiologically active com-pounds. 9-11 Similar applications with inherently more complex intramolecular CH insertion reactions of primary alkyl diazoacetates have not been possible because of limitations in the existing complement of chiral dirhodium (II) carboxamidates for highly enantioselective and regioselective insertion into a remote, unactivated