Stereoselective <i>C</i>-Glycosylation Reactions of Ribose Derivatives: Electronic Effects of Five-Membered Ring Oxocarbenium Ions
作者:Catharine H. Larsen、Brian H. Ridgway、Jared T. Shaw、Deborah M. Smith、K. A. Woerpel
DOI:10.1021/ja0524043
日期:2005.8.1
The factors controlling the highly alpha-selective C-glycosylation of ribose derivatives were determined by examining the stereoselective reactions of 18 ribose analogues differing in substitution at C-2, C-3, and C-4. The lowest energy conformers of the intermediate oxocarbeniumions display the C-3 alkoxy group in a pseudoaxial orientation to maximize electrostatic effects. To a lesser extent, the
O–H hydrogen bonding promotes H-atom transfer from α C–H bonds for C-alkylation of alcohols
作者:Jenna L. Jeffrey、Jack A. Terrett、David W. C. MacMillan
DOI:10.1126/science.aac8555
日期:2015.9.25
alcohols is selectively induced by using an H-bonding catalyst to bind the hydroxyl group of the alcohol. The adjacent C-H bonds now become susceptible to a reaction accelerated by another pair of catalysts. In combination, the trio of catalysts promotes C-C bond formation at the alcohol C within an array of competing sites. Science, this issue p. 1532 Hydrogen bonding confers siteselectivity in a carbon-carbon
三重奏有助于激活醇中的 CH 键酶可以通过位置良好的 H 键激活分子的特定部分来加速化学反应。杰弗里等人。在合成环境中展示氢键的力量。在这里,醇的 C 中心的反应性是通过使用 H 键催化剂来结合醇的羟基而选择性地诱导的。相邻的 CH 键现在变得容易受到另一对催化剂加速的反应的影响。组合起来,这三种催化剂促进了在一系列竞争位点内的醇 C 处形成 CC 键。科学,这个问题 p。1532 氢键在醇和烯烃之间的碳-碳键形成反应中赋予位点选择性。在存在多个潜在的氢原子供体和受体的情况下,从有机分子转移氢原子的效率和选择性通常难以控制。在这里,我们描述了一种催化活化模式的机理评估,该模式通过氢原子转移机制实现了醇与丙烯酸甲酯的高选择性光氧化还原 α-烷基化/内酯化。我们的研究表明,在烯丙基、苄基、α-C=O 和 α-醚 C-H 键存在的情况下,四正丁基磷酸铵在提高醇中 α C-H 键的选择性方面具有特
Novel prolinal derivatives
申请人:Ono Pharmaceutical Co., Ltd.
公开号:US04977180A1
公开(公告)日:1990-12-11
A novel prolinal derivative of general formula: ##STR1## wherein A represents alkylene group of from 1 to 4 carbon atom(s) or saturated hydrocarbon ring of from 3 to 7 carbon atoms, n represents a number 2, 3 or 4, D represents carbocyclic or heterocyclic ring unsubstituted or substituted by from one to three of halogen atom, alkyl or alkoxy group of from 1 to 4 carbon atom(s), nitro group or trifluromethyl group posses inhibitory activity on prolyl endopeptidase, and therefore are useful for treating and/or preventing agent for amnesia.
Enantioselective Synthesis of <i>syn</i>/<i>anti</i>-1,3-Amino Alcohols via Proline-Catalyzed Sequential α-Aminoxylation/α-Amination and Horner−Wadsworth−Emmons Olefination of Aldehydes
作者:Vishwajeet Jha、Nagendra B. Kondekar、Pradeep Kumar
DOI:10.1021/ol100856u
日期:2010.6.18
A novel and general method for asymmetric synthesis of both syn/anti-1,3-amino alcohols is described. The method uses proline-catalyzed sequential alpha-aminoxylation/alpha-amination and Horner-Wadsworth-Emmons (HWE) olefination of aldehydes as the key step. By using this method, a short synthesis of a bioactive molecule, (R)-1-((S)-1-methylpyrrolidin-2-yl)-5-phenylpentan-2-ol, is also accomplished.