Experimental and Theoretical Studies on Stereo- and Regioselectivity in Intramolecular Nitrone−Alkene Cycloaddition of Hept-6-enoses Derived from Carbohydrates
作者:Tony K. M. Shing、Annie W. F. Wong、Taketo Ikeno、Tohru Yamada
DOI:10.1021/jo060348y
日期:2006.4.1
effect of blocking groups and stereochemistry of the substituents on the regio- and stereoselectivity in intramolecular nitrone−alkene cycloaddition (INAC) of hept-6-enoses are reported. l-ribo-Hept-6-enose 12 and d-lyxo-hept-6-enose 15, both containing a 2,3-O-isopropylidene blocking group, and l-xylo-hept-6-enose 23 and d-arabino-hept-6-enose 30, both with a 2,3-O-trans-diacetal blocking group, were
据报道,封端基团和取代基的立体化学对庚6烯醇分子内硝酮-烯烃环加成(INAC)的区域和立体选择性的影响。升-核糖-庚-6- enose 12和d - L-来苏-庚-6- enose 15,两者都含有2,3- ö异亚丙基保护基,和升-木糖-庚-6- enose 23和d -阿糖由d-核糖和d制得均带有2,3 - O-反式-二缩醛封闭基团的-hept-6-enose 30-阿拉伯糖分别。与N-烷基羟胺一起,乳糖醇12和15进行INAC反应,仅得到顺式稠合的异恶唑烷,而乳糖醇23和30产生顺式,反式稠合的异恶唑烷(环己醇)和桥联的异恶唑烷(环庚醇)的混合物。具有2,3 - O-反式-二缩醛保护基团,通过INAC环化的内模,首次由直链糖衍生物23和30合成了桥联的双环[4.2.1]异恶唑烷(环庚醇)。这些反应的立体化学结果在通过计算获得的过渡态能量的基础上得到了合理化。目前的INAC显示出微不足道