Remarkable Effects of Chirality on Deslipping Reactions of Diastereomeric Rotaxanes and Relevant Mechanism Involving Pre-Equilibrium
作者:Keiji Hirose、Yamato Nakamura、Yoshito Tobe
DOI:10.1021/ol802571d
日期:2009.1.1
stereocenters of rotaxanes up to 8.4 times and unexpectedly large steric kineticisotope effect on the deslipping reaction (ca. 20%) were observed. On the basis of the kinetic parameters, steric kineticisotope effect, and 1H NMR spectra of the nondeuteriated and deuteriated rotaxanes, we propose a deslipping mechanism involving pre-equilibrium.
观察到轮滑的非对映体立体中心差异高达8.4倍,并且对脱脂反应的空间动力学同位素效应出乎意料地大(约20%),这对脱脂率产生了明显的区分。根据动力学参数,空间动力学同位素效应和未氘代和氘代轮烷的1 H NMR光谱,我们提出了一种涉及预平衡的脱脂机理。
Triazabicyclodecene: An Effective Isotope Exchange Catalyst in CDCl<sub>3</sub>
We describe the first effective H/D exchange reaction with acidic substrates in CDCl3 at room temperature. The particularly mild reaction conditions involved (solvent, base, and temperature) allow the chemoselective deuteration of ketones over esters. An NMR study was conducted with the aim of rationalizing the results obtained in the presence of TBD as catalyst.
Ruthenium-Catalyzed Formal Dehydrative [4 + 2] Cycloaddition of Enamides and Alkynes for the Synthesis of Highly Substituted Pyridines: Reaction Development and Mechanistic Study
作者:Jicheng Wu、Wenbo Xu、Zhi-Xiang Yu、Jian Wang
DOI:10.1021/jacs.5b06400
日期:2015.7.29
Reported herein is a ruthenium-catalyzed formal dehydrative [4 + 2] cycloaddition of enamides and alkynes, representing a mild and economic protocol for the construction of highly substitutedpyridines. Notably, the features of broad substrate scope, high efficiency, good functional group tolerance, and excellent regioselectivities were observed for this reaction. Density functional theory (DFT) calculations
One-Pot Sequential Hydrogen Isotope Exchange/Reductive Deuteration for the Preparation of α,β-Deuterated Alcohols using Deuterium Oxide
作者:Hengzhao Li、Zemin Lai、Mengqi Peng、Lei Ning、Qixin Dong、Yuxia Hou、Jie An
DOI:10.1021/acs.orglett.2c01940
日期:2022.7.29
An efficient one-pot sequential hydrogen isotope exchange (HIE)/reductive deuteration approach was developed for the preparation of α,β-deuterated alcohols using ketones as the precursors. The HIE step can also be used for the synthesis of α-deuterated ketones. This method has been applied in the synthesis of four deuterated drug and MS internal standards.