Highly diastereoselective nucleophilic additions using a novel myrtenal-derived oxathiane as a chiral auxiliary
作者:Federico Martı́nez-Ramos、Marı́a Elena Vargas-Dı́az、Luis Chacón-Garcı́a、Joaquı́n Tamariz、Pedro Joseph-Nathan、L.Gerardo Zepeda
DOI:10.1016/s0957-4166(01)00545-6
日期:2001.12
The synthesis of novel oxathiane 3 and its acetyl derivative 12, from commercially available (-)myrtenal 4, is described. The addition of several nucleophilic reagents to 12 furnished the corresponding tertiary carbinols in highly diastereomeric excess. The hydrolysis of 11a, b yielded the expected alpha-hydroxycarbonyl compounds in excellent enantiomeric excess. (C) 2002 Elsevier Science Ltd. All rights reserved.
Preparation of Substituted Enol Derivatives From Terminal Alkynes and Their Synthetic Utility
作者:John R. DeBergh、Kathleen M. Spivey、Joseph M. Ready
DOI:10.1021/ja803480b
日期:2008.6.1
trapping with carboxylic anydrides or silyl triflates yields trisubstituted enol esters or silanes, respectively. The tandem carbometalation/oxygenation tolerates free and protected alcohols, heterocycles, olefins, and nitriles. Stereodefined enol esters can undergo asymmetric dihydroxylation to yield optically active alpha-hydroxy aldehydes. Reduction with NaBH4 provides the diols of 1,1-disubstituted olefins
醛的立体定义的烯醇衍生物由末端炔烃制备。具体而言,已知末端炔烃会经历 Cp2ZrCl2 催化的甲基铝化。在这里,我们表明所得的乙烯丙烷可以用过氧锌物质氧化以生成三取代的烯醇化物。用羧酸酐或甲硅烷基三氟甲磺酸酯进行亲电捕获分别产生三取代的烯醇酯或硅烷。串联碳金属化/氧化耐受游离和受保护的醇、杂环、烯烃和腈。立体定义的烯醇酯可以进行不对称二羟基化以产生光学活性的 α-羟基醛。用 NaBH4 还原以优异的 ee 提供 1,1-二取代烯烃的二醇。介绍了这种方法在昆虫信息素额蛋白的对映选择性合成中的应用。最后,显示 α-羟基醛经过同系化到末端炔、还原胺化、氧化和烯化。初步结果表明串联碳金属化/胺化可以用偶氮二羧酸盐完成。以这种方式,以极好的收率形成烯-肼。