Substituent Effects on Regioselective Intramolecular Oxidation of Unactivated C—H Bonds: Stereoselective Synthesis of Substituted Tetrahydropyrans.

Abstract

Pyran derivatives Pyran derivatives R 0340Substituent Effects on Regioselective Intramolecular Oxidation of Unactivated C-H Bonds: Stereoselective Synthesis of Substituted Tetrahydropyrans. -It is found that substituents at the aliphatic carbon chain exhibit remarkable effects on the stereoselectivity of intramolecular oxidation reactions. Besides steric effects observed in the oxidation of ketones bearing methyl and phthalimido groups, an unexpected hydrogen bonding interaction plays an important role on the stereoselective outcome of oxidation of ketones having oxygen substituents. Starting from ketones containing β-oxygen substituents reversed stereoselectivity is observed. -(WONG, M.-K.; CHUNG, N.-W.; HE, L.; YANG*, D.; J.