Preparation ofN-Glycosylhydroxylamines and Their Oxidation to Nitrones for the Enantioselective Synthesis of Isoxazolidines
作者:Stefano Cicchi、Marco Marradi、Massimo Corsi、Cristina Faggi、Andrea Goti
DOI:10.1002/ejoc.200300353
日期:2003.11
Subsequent oxidation occurred at the alkyl group, selectively affording the corresponding C-phenyl- and C-unsubstituted N-glycosylnitrones. C-phenyl-N-glycosylnitrones 10 and 13 underwent highly stereoselective 1,3-dipolar cycloaddition with dimethyl maleate, with the sugar moiety acting as a chiral auxiliary. Final removal of the glycosyl moiety afforded enantiopure enantiomeric isoxazolidines 17 and
N-苄基-和N-甲基-N-糖基羟胺3a-i可以通过糖与N-取代的羟胺根据新方法反应方便地获得。随后在烷基处发生氧化,选择性地提供相应的 C-苯基-和 C-未取代的 N-糖基硝酮。C-苯基-N-糖基硝酮 10 和 13 与马来酸二甲酯进行了高度立体选择性的 1,3-偶极环加成反应,其中糖部分作为手性助剂。糖基部分的最终去除得到对映体纯的对映异构异恶唑烷 17 和 ent-17,它们是脯氨酸二酯衍生物的氧杂类似物。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)