Control of the Mode Selectivity (Ene Reaction versus [2 + 2] Cycloaddition) in the Photooxygenation of Ene Carbamates: Directing Effect of an Alkenylic Nitrogen Functionality
作者:Waldemar Adam、Sara G. Bosio、Nicholas J. Turro
DOI:10.1021/ja028407m
日期:2002.11.1
The geometry of the double bond in oxazolidinone-substituted ene carbamates controls the mode selectivity (ene reaction versus [2+2] cycloaddition) of singlet oxygen through stereoelectronic effects, whereas the chiral auxiliary provides high diastereoselectivity through steric shielding.
Chiral-Auxiliary-Controlled Diastereoselectivity in the Epoxidation of Enecarbamates with DMD and <i>m</i>CPBA
作者:Waldemar Adam、Sara G. Bosio、Barbara T. Wolff
DOI:10.1021/ol0273194
日期:2003.3.1
text] Chiral oxazolidinone-substituted enecarbamates 1 are epoxidized in a diastereoselectivity up to 93:7 for both DMD and mCPBA. The diastereofacial differentiation depends on the steric interaction between the R(1) substituent on the oxazolidinone ring and the incoming electrophile. The stereochemical course of epoxidation was assessed by chemical correlation with the known optically active diols