Polar Effects. Part 15. Twin γ-substituent effects in the formation of adamantyl-1-cations
作者:Cyril A. Grob、Martin Gründel、Pawel Sawlewicz
DOI:10.1002/hlca.19880710615
日期:1988.9.28
adamant-1-yl ( = tricyclo[3.3.1.13,7]dec-1-yl) p-toluenesulfonates and bromides 2 identically substituted at C(3) and C(5) (twin substitution) have been determined and compared with the rates of the corresponding 3-monosubstituted compounds 1. As expected, the rate factors for twin substitution are much larger, but less than the square of the rate factors for single substitution. Also the rates factors
[EN] A PROCESS FOR THE PREPARATION OF UMECLIDINIUM BROMIDE AND INTERMEDIATES THEREOF<br/>[FR] PROCÉDÉ DE PRÉPARATION DE BROMURE D'UMÉCLIDINIUM ET DE SES INTERMÉDIAIRES
申请人:GBR LABORATORIES PVT LTD
公开号:WO2018163212A1
公开(公告)日:2018-09-13
Provided herein is a process for the preparation of umeclidinium bromide and intermediates thereof, wherein pure form of umeclidinium bromide is achieved by a two step process under mild conditions.
Hydrogen Bonding Shuts Down Tunneling in Hydroxycarbenes: A Gas-Phase Study by Tandem-Mass Spectrometry, Infrared Ion Spectroscopy, and Theory
作者:Mathias Paul、Thomas Thomulka、Wacharee Harnying、Jörg-Martin Neudörfl、Charlie R. Adams、Jonathan Martens、Giel Berden、Jos Oomens、Anthony J. H. M. Meijer、Albrecht Berkessel、Mathias Schäfer
DOI:10.1021/jacs.3c01698
日期:2023.6.7
current study on aliphatic trialkylammonio-tagged systems. Quite unexpectedly, the flexible 3-(trimethylammonio)propylhydroxycarbene turned out to be stable─no H-shift to either aldehyde or enol occurred. As supported by density functional theory calculations, this novel QMHT inhibition is due to intramolecular H-bonding of a mildly acidic α-ammonio C–H bonds to the hydroxyl carbene’s C-atom (C:···H–C)
羟基卡宾可以在气相中通过碰撞诱导的 α-酮基羧酸脱羧反应生成并进行结构表征,然后进行红外离子光谱分析。使用这种方法,我们之前已经表明,量子力学氢隧穿 (QMHT) 解释了电荷标记的苯基羟基卡宾在气相和室温以上异构化为相应的醛。在此,我们报告了我们目前对脂肪族三烷基氨标记系统的研究结果。出乎意料的是,柔性 3-(三甲基氨) 丙基羟基卡宾被证明是稳定的——没有 H 转移到醛或烯醇。在密度泛函理论计算的支持下,这种新型 QMHT 抑制作用是由于弱酸性 α-氨 C-H 键与羟基卡宾的 C 原子 (C: ···H-C)。为了进一步支持这一假设,合成了 (4-quinuclidinyl)hydroxycarbenes,其刚性结构阻止了这种分子内氢键。后一种羟基卡宾对醛进行“常规”QMHT,其速率与 Schreiner 等人研究的甲基羟基卡宾相当。虽然 QMHT 已被证明可用于许多生物 H 位移过程,但
Bank, Shelton; Cleveland, William K. S., Heterocycles, 1982, vol. 18, p. 145 - 148