SYNTHESIS AND CHARACTERIZATION OF ACYLATED CHIRAL OXAZOLIDINE-2-SELONES - SELONE CHIRAL DERIVATIZING AGENTS FOR THE DETECTION AND QUANTITATION OF REMOTELY DISPOSED CHIRAL CENTERS

摘要

Racemic and chiral carboxylic acids and acid chlorides are coupled cleanly to oxazolidine-2-selone chiral derivatizing agents (CDA's) with yields ranging from 85 to 99%. Se-77 NMR spectroscopy provides a highly sensitive method for the determination of the enantiomeric excesses of these remotely disposed chiral centers. The geometrical relationship between the selenocarbonyl and the adduct carbonyl (syn or anti) appears to have a profound effect on the chemical shift difference (Delta delta(Se)) observed for pairs of adduct diastereomers. Crystallographic and solution state NMR studies suggest that the syn orbital overlap enhances the Delta delta(Se). [References: 26]