Superelectrophilic Activation of Crotonic/Methacrylic Acids: Direct Access to Thiochroman-4-ones from Benzenethiols by Microwave-Assisted One-Pot Alkylation/Cyclic Acylation
作者:Habiba Vaghoo、G. K. Surya Prakash、Arjun Narayanan、Rohit Choudhary、Farzaneh Paknia、Thomas Mathew、George A. Olah
DOI:10.1021/acs.orglett.5b03172
日期:2015.12.18
efficient microwave-assisted protocol for the synthesis of 2-/3-methylthiochroman-4-ones by superacid-catalyzed alkylation followed by cyclic acylation (cyclization via intramolecular acylation) is described. Using easily accessible benzenethiols and crotonic acid/methacrylic acid with triflic acid (as catalyst of choice for needed optimal acidity), the reaction was tuned toward the formation of the cyclized
Spectroscopic and Theoretical Identification of Two Thermal Isomerization Pathways for Bistable Chiral Overcrowded Alkenes
作者:Jos C. M. Kistemaker、Stefano F. Pizzolato、Thomas van Leeuwen、Thomas C. Pijper、Ben L. Feringa
DOI:10.1002/chem.201602276
日期:2016.9.12
higher temperatures for the thermal isomerization, namely a thermal E–Z isomerization (TEZI) and a thermal helix inversion (THI). These processes were also studied computationally whereby a new strategy was developed for calculating the TEZI barrier for second‐generation overcrowded alkenes. To demonstrate that these overcrowded alkenes can be employed as bistable switches, photochromic cycling was performed
Visible-Light-Driven Tunable Molecular Motors Based on Oxindole
作者:Diederik Roke、Metin Sen、Wojciech Danowski、Sander J. Wezenberg、Ben L. Feringa
DOI:10.1021/jacs.9b03237
日期:2019.5.8
presented. This novel class of motors can be easily synthesized via a Knoevenagel condensation, and the choice of different upper halves allows for the facile tuning of their rotational speed. The four-step rotational cycle was explored using DFT calculations, and the expected photochemical and thermal isomerization behavior was confirmed by NMR, UV/vis, and CD spectroscopy. These oxindole motors offer
Fluorine-Substituted Molecular Motors with a Quaternary Stereogenic Center
作者:Peter Štacko、Jos C. M. Kistemaker、Ben L. Feringa
DOI:10.1002/chem.201700581
日期:2017.5.11
A series of unprecedented second generation molecular motors featuring a quaternary stereogeniccenter substituted with a fluorine atom has been synthesized. It is demonstrated that a seemingly benign replacement of the stereogenic hydrogen for a fluorine atom, regarded as a common substituent in pharmacology, resulted in a dramatic change in the energetic profile of thermal helix inversion. The barrier
Coupled Rocking Motion in a Light-Driven Rotary Molecular Motor
作者:Cosima Stähler、Daisy R. S. Pooler、Romain Costil、Dhruv Sudan、Pieter van der Meulen、Ryojun Toyoda、Ben L. Feringa
DOI:10.1021/acs.joc.2c01830
日期:——
and its orientation toward the upper half of the motor scaffold. In addition to the commonly observed successive photochemical and thermal steps driving the rotation of the motor, we find that the motor undergoes photochemically driven rotation in three of the four steps of the rotation cycle. Hence, this result extends the scope of molecularmotors capable of photon-only rotary behavior.
耦合运动在自然界中无处不在,因为它构成了运动的方向、放大、传播和同步的基础。在此,我们提出了二氢蒽定子部分的摇摆运动与过度拥挤的基于烯烃的分子马达的光诱导旋转运动耦合的实验证据。电机被去对称化,将两个不同的烷基取代基引入到分子支架的定子部分,从而形成具有相反轴向手性的两种非对映体。两种异构体的结构通过核奥沃豪瑟效应光谱NMR和单晶X射线分析确定。去对称化使得能够通过1 H NMR 研究耦合运动,即旋转和振荡,这些发现得到了密度泛函理论计算的进一步支持。还引入了一种通过下半部功能化来调节电机转速的新手柄,因为发现热螺旋反转的热障很大程度上取决于烷基取代基及其朝向电机支架上半部的方向。除了常见的连续光化学和热步骤驱动电机旋转之外,我们发现电机在旋转周期的四个步骤中的三个中经历光化学驱动的旋转。因此,这一结果扩展了能够进行纯光子旋转行为的分子马达的范围。