A Convenient Approach for Access to Both Carbapentofuranoses and Carbahexopyranoses. Stereocontrolled Synthesis of Enantiopure Carba-<scp>d</scp>-ribofuranoses, Carba-<scp>d</scp>-arabinofuranoses and Carba-<scp>l</scp>-gulopyranose
作者:Subrata Ghosh、Tanurima Bhaumik、Niladri Sarkar、Abhijit Nayek
DOI:10.1021/jo061717t
日期:2006.12.1
key step involves ring-closing metathesis of dienols 6 derived from a (R)-(+)-glyceraldehyde derivative 4 to form the substituted cyclopentenol 9 and cyclohexenol 34a. Stereocontrolled addition of hydroxyl groups followed by conversion of the ketal unit to hydroxymethyl group in these intermediates led to carbapentoses and -hexoses. Stereoselectivity during introduction of hydroxyl groups arises through
报道了一种对映体纯净形式的Carcarbugars的新方法。关键步骤涉及衍生自(R)-(+)-甘油醛衍生物4的二烯醇6的闭环易位,以形成取代的环戊烯醇9和环己烯醇34a。在这些中间体中立体控制地添加羟基,然后将缩酮单元转化为羟甲基,导致产生碳戊糖和-己糖。在引入羟基的过程中,立体选择性是由烯丙基取代基构成的位阻引起的。本方法的显着特征是d-和l的可访问性系列的羧甲基戊糖,分别由β- d-和β- 1-碳氢呋喃呋喃糖酶17和20的合成说明。卡巴-α- d -ribofuranose 25,生物合成中间对抗生素芒霉素,也被从相同的环戊烯醇合成9。环戊烯醇9a中的官能团操纵也使能够获得呋喃糖呋喃糖32。本合成策略可以延长carbahexopyranose的合成,由卡巴-β-的合成如图升-gulopyranose 40B。