Diastereoselective synthesis of 3,4-disubstituted 5-(p-tolylsulfinyl)-5,6-dehydropiperidin-2-ones: chirality transfer in the enantioselective synthesis of ethyl (+)-(3S,4aS,7aS)-1-oxo-octahydro-1H-cyclopenta[c]pyridine-3-carboxylate
摘要:
The base-mediated reaction of enantiomerically pure alpha-sulfinylketimine (+)-1 with (E)-alpha,beta-disubstituted propenoate esters afforded 3,4-disubstituted-5-(p-tolylsulfinyl)-5,6-dehydropiperidin-2-ones 9 alpha-13 alpha and 14 with high or complete diastereoselectivity. A sole diastereomer of the four possible ones, with regard to the nature of ester, was isolated, which revealed the stereocontrol of the chiral sulfinyl group in the Michael reaction and transenolization steps. In addition, the enantioselective synthesis of ethyl (+)(3S,4aS,7aS)-1-oxo-octahydro-H-1-cyclopenta[c]pyridine-3-carboxylates (+)-17 alpha is described (five steps; 47% yield; ee >= 97%). The absolute configuration of stereocentres introduced in (+)-17 alpha was assigned on the basis of H-1 NMR data. (c) 2005 Elsevier Ltd. All rights reserved.
Continuous Flow Magnesiation or Zincation of Acrylonitriles, Acrylates, and Nitroolefins. Application to the Synthesis of Butenolides
作者:Maximilian A. Ganiek、Matthias R. Becker、Marthe Ketels、Paul Knochel
DOI:10.1021/acs.orglett.6b00086
日期:2016.2.19
Scalable continuousflow procedures are reported for the metalation and downstream functionalization of β-substituted acrylates. The flow conditions allow the metalation of acrylonitriles, acrylates, and nitroolefins at 0.25–2.50 mmol/min conversion rates. Magnesiations can be performed with short residence times (1–20 min) and near-ambient temperature using TMPMgCl·LiCl. Further, high temperature
Preparation of New 2,3-Diphenylpropenoic Acid Esters – Good Yields Even for the More Hindered Z Isomers
作者:László Boros、Károly Felföldi、István Pálinkó
DOI:10.3390/90400256
日期:——
appropriate alkyl halides at room temperature. In this way 10 previously undescribed esters of these acids were synthesised and characterised. Excellent yields were observed for most of the E isomers and the more hindered Z esters were also obtained in good yields, far better than those obtained applying the classical acid-catalysed esterification reaction.
原位制备的 E- 和 Z-2,3- 二苯基丙烯酸钾盐可以在 DMSO 中与适当的烷基卤在室温下有效酯化。以这种方式合成并表征了这些酸的 10 种以前未描述的酯。观察到大多数 E 异构体的产率很高,并且也以良好的产率获得了更多受阻的 Z 酯,远好于应用经典酸催化酯化反应获得的产率。
Defluorinative Esterification and 1,3-Dietherification of (Trifluoromethyl)alkenes with Alcohols: Controlled Synthesis of α-Arylacrylates and 1,3-Diethers
作者:Hengyuan Li、Chuanle Zhu
DOI:10.1021/acs.joc.2c02568
日期:——
(trifluoromethyl)alkenes with alcohols are achieved, delivering various useful α-arylacrylates and 1,3-diethers in high yields. Remarkably, this reaction enables the cleavage of three C–F bonds in a CF3 group, and it is transition-metal free and catalyst-free, has simple operation, features mild conditions, is gram-scalable, and has broad substrate scope and valuable functional group tolerance. Mechanism studies
实现了(三氟甲基)烯烃与醇的纯化控制脱氟酯化和 1,3-二醚化,以高收率提供各种有用的 α-芳基丙烯酸酯和 1,3-二醚。值得一提的是,该反应可使CF 3基团中的三个C-F键断裂,且无过渡金属、无催化剂、操作简单、条件温和、克级可扩展、底物适用范围广等特点,有价值的官能团耐受性。机理研究表明,分离的单氟烯烃修饰的 1,3-二醚是中间体,硅胶的酸性有助于这些 1,3-二醚脱氟转化为以 H 2 O 为氧源的 α-芳基丙烯酸酯。
Phosphine-Catalyzed Stereoselective Ring-Opening Addition of Cyclopropenones with Nucleophiles
A phosphine-catalyzed ring-opening additionreaction of cyclopropenones with a variety of nucleophiles (NuH), including oxygen-, nitrogen-, sulfur-, and carbon-based ones, has been investigated, which produces potentially useful α,β-unsaturated carbonyl derivatives in high yields (up to 99%), high regioselectivity, and exclusive E-selectivity. The reaction proceeds in high efficiency under very mild