Enantioselective total synthesis and correction of the absolute configuration of megislactone
作者:Guo-Bao Ren、Yikang Wu
DOI:10.1016/j.tet.2008.02.054
日期:2008.5
the trans isomer of the remote double bond in a long alkyl chain was clearly revealed in 1H and 13C NMR in the presence of a lactone ring. The present work unambiguously shows that the absolute configuration of the natural compound is the antipode of the one originally reported. Some errors in the previous 1H and 13C NMR signal assignments are also corrected.
以对映纯的形式合成了标题化合物,它是来自大叶鸢尾的成分之一。C-2和C-3的立体异构中心是通过使用手性辅助剂诱导的不对称醛醇缩合而构建的,而C-4是从相应的旋光性乳酸中衍生而来的。侧链中的碳-碳双键源自纯顺式使用Suzuki偶合与碘化乙烯基碘,其中烷基硼烷是由相应的末端烯烃原位形成的。在用CAN对TBS基团进行脱保护的过程中,观察到了长链中孤立的C-C双键的先前未知的(部分)顺式至反式转化。出乎意料的是,在内酯环存在下的1 H和13 C NMR中清楚地揭示了长烷基链中远端双键的反式异构体原本无法检测到的共存现象。本工作明确地表明,天然化合物的绝对构型是最初报道的一种的对映体。以前的1 H和13 C NMR信号分配中的某些错误也已得到纠正。
Formal Total Synthesis of (+)-Trehazolin. Application of an Asymmetric Aldol−Olefin Metathesis Approach to the Synthesis of Functionalized Cyclopentenes
作者:Michael T. Crimmins、Elie A. Tabet
DOI:10.1021/jo015568k
日期:2001.6.1
An asymmetric synthesis of the aminocyclopentitol pseudosugar of trehazolin has been completed. The synthesis hinges on an asymmetric aldol-ring closing metathesis strategy to construct the five-membered ring with control of both the relative and absolute stereochemistry.
Stereoselective synthesis of 10,14-dimethyloctadec-1-ene, 5,9-dimethyloctadecane, and 5,9-dimethylheptadecane, the sex pheromones of female apple leafminer
作者:Jhillu S. Yadav、Kamakolanu Uma Gayathri、Neetipalli Thrimurtulu、Attaluri R. Prasad
DOI:10.1016/j.tet.2009.01.093
日期:2009.4
The stereoselectivesynthesis of (10R,14R)-10,14-dimethyloctadec-1-ene (1), (5R,9R)-5,9-dimethyloctadecane (2), and (5R,9R)-5,9-dimethylheptadecane (3) the sexpheromone components of female apple leafminer was accomplished by reductive elimination tosyl and isonitrile groups of dialkylated tosylmethyl isonitrile. The key steps involved were dialkylation of TosMIC with 1-iodo 2-methyl alkanes, which
Several N-vinyl-1,3-oxazolidine-2-thione (N-vinyl OZT) were conveniently used as new dienophiles in Eu(fod)3-catalyzed reverse hetero-Diels-Alder reactions involving benzylidene pyruvic acid methyl ester. Simple chiral N-vinyl OZT analogues homogeneously led to moderate endo and facial diastereoselectivities, when compared to those obtained with the corresponding N-vinyl-1,3-oxazolidin-2-ones. In contrast, high diastereocontrols were observed with a sugar-derived N-vinyl OZT.
An Efficient, General Asymmetric Synthesis of Carbocyclic Nucleosides: Application of an Asymmetric Aldol/Ring-Closing Metathesis Strategy
作者:Michael T. Crimmins、Bryan W. King、William J. Zuercher、Allison L. Choy
DOI:10.1021/jo005535p
日期:2000.12.1
A general and efficient synthesis of carbocyclic and hexenopyranosyl nucleosides has been developed. The strategy combines three key transformations: an asymmetric aldol addition to establish the relative and absolute configuration of the pseudosugar, a ring-closing metathesis to construct the pseudosugar ring, and a Trost-type palladium(0)-mediated substitution to assemble the pseudosugar and the