Synthesis of C1- and C8a-epimers of (+)-castanospermine from d-glucose derived γ,δ-epoxyazide: intramolecular 5-endo epoxide opening approach
作者:Navnath B. Kalamkar、Vedavati G. Puranik、Dilip D. Dhavale
DOI:10.1016/j.tet.2011.02.030
日期:2011.4
A concise synthesis of two diastereomers of (+)-castanospermine namely 1- and 8a-epi-castanospermine 1b and 1c, respectively, is reported from d-glucose. The methodology involves stereoselective cross metathesis of d-glucose derived alkene 2 with 4-bromo-1-butene followed by azide displacement and m-CPBA oxidation to afford diastereomeric γ,δ-epoxyazides 5a/5b. The Staudinger reaction of epoxyazide
从d-葡萄糖报道了两个(+)- castanospermine的非对映异构体的简明合成,分别是1-和8a- epi- castanospermine 1b和1c。该方法包括将d-葡萄糖衍生的烯烃2与4-溴-1-丁烯进行立体选择性交叉复分解,然后进行叠氮化物置换和m- CPBA氧化,得到非对映异构体γ,δ-环氧叠氮化物5a / 5b。环氧叠氮化物5a的Staudinger反应,然后与氯甲酸苄酯(CbzCl)反应,出乎意料地提供了1,3-恶二嗪-2-酮衍生物7其立体化学是通过单晶X射线建立的。这有助于在环氧化反应中分配立体化学。然后通过转移氢化进行5a / 5b还原,以提供γ,δ-环氧胺,同时进行分子内5-内-tet环化反应,得到带有糖骨架的羟基吡咯烷环骨架-粟精胺类似物1b / 1c的前体。