Synthesis and Dienophilic Behavior of Enantiomerically Pure (<i>Z</i>)-3-<i>p</i>-Tolylsulfinylacrylonitriles
作者:Jose L. García Ruano、Antonio Esteban Gamboa、Ana M. Martín Castro、Jesús H. Rodríguez、M. Isabel López-Solera
DOI:10.1021/jo9721002
日期:1998.5.1
The syntheses of enantiomerically pure (Z)-3-p-tolylsulfinylacrylonitrile (1b) and its 2-n-butyl (1a), 2-tert-butyl (1c), and 2-benzyl(ld) derivatives, by stereoselective hydrocyanation with Et2AlCN of their corresponding alkynylsulfoxides, are described. Asymmetric Diels-Alder reactions of these dienophiles with cyclopentadiene are also reported, the most significant finding being their total pi-facial diastereoselectivity, controlled by the sulfur configuration, which can be readily invented by using BF3 as a catalyst. The endo selectivity is very high for Ib under thermal and catalytic (ZnBr2) conditions and complete in the presence of BE3 whereas la and Id only exhibit a complete endo selectivity in the presence of BF3.
Asymmetric Synthesis of Chiral Organofluorine Compounds: Use of Nonracemic Fluoroiodoacetic Acid as a Practical Electrophile and Its Application to the Synthesis of Monofluoro Hydroxyethylene Dipeptide Isosteres within a Novel Series of HIV Protease Inhibitors
作者:Andrew G. Myers、Joseph K. Barbay、Boyu Zhong
DOI:10.1021/ja010113y
日期:2001.8.1
(diastereomeric ratios 12:1-84:1), efficient and stereoselectiveroutes to each of the four targeted inhibitors were achieved. The optimized syntheticroute to the most potent inhibitor (syn,syn-4, K(i) = 2.0 nM) proceeded in seven steps (87% average yield per step) from aminoindanol hydrocinnamide 40 and (S)-fluoroiodoacetic acid, and allowed for the preparation of more than 1 g of this compound. The inhibition
描述了一系列 HIV 蛋白酶非对映异构体抑制剂(默克 HIV 蛋白酶抑制剂茚地那韦的单氟化类似物)的两种立体选择性途径。这两条路线的特点是通过不对称烷基化反应立体选择性地构建氟化核心亚基。第一代合成基于来自伪麻黄碱 α-氟乙酰胺的烯醇锂与硝基烯烃 12 的共轭加成,这是一种适度的非对映选择性转化。开发了一种更实用的第二代合成路线,该路线基于一种不对称合成有机氟化合物的新方法,通过使用光学活性氟碘乙酸作为亲电子试剂与手性酰胺烯醇化物相结合进行烯醇化物烷基化。用麻黄碱拆分氟碘乙酸可提供 > 或 = 96% ee 的亲电子试剂的对映体形式。与这种稳定且可储存的手性氟化前体的烷基化反应显示出以高度立体定向的方式进行。随着底物控制的 α-氟酮 44 和 45(非对映体比率 12:1-84:1)的顺式或反选择性还原的发展,实现了四种靶向抑制剂中每一种的有效和立体选择性途径。最有效抑制剂 (syn,syn-4
(<i>Z</i>)-3-<i>p</i>-Tolylsulfinylacrylonitriles as Chiral Dipolarophiles: Reactions with Diazoalkanes
作者:José L. García Ruano、Sergio A. Alonso de Diego、Daniel Blanco、Ana M. Martín Castro、M. Rosario Martín、Jesús H. Rodríguez Ramos
DOI:10.1021/ol016481o
日期:2001.10.1
[reaction: see text] The dipolarophilic reactivity of enantiopure (Z)-3-p-tolylsulfinylacrylonitriles (1) has been evaluated with diazoalkanes. 3-Cyanopyrazoles are obtained when R = H, but with R = alkyl (Bn, n-Bu, and t-Bu) only one cycloadduct (4 or 5) is formed in high yield under mild conditions, therefore evidencing a complete control of the regioselectivity and the endo/exo and pi-facial selectivities