一种新的高度不对称的合控制的合合
Peter Nilsson1, Mats Larhed, Anders Hallberg
1Department of Organic Pharmaceutical Chemistry, Uppsala Biomedical Centre, Uppsala University, Sweden.
Journal of the American Chemical Society
|March 20, 2003
概括
一种新的非对称的赫克化方法可以产生具有高产率和优异的反选择性的性环丹. 这种高效的过程避免了恶劣的条件和阻断组,在不对称合成中取得了重大进展.
科学领域:
- 有机化学 有机化学
- 不对称的催化剂.
- 合成方法论 合成方法论
背景情况:
- 循环功能化的传统方法往往需要强大的基础或保护组.
- 在循环基的α-化过程中达到高的酶选择性仍然是一个挑战.
- 与乙烯酸盐的直接合可能会受到区域选择性问题的影响.
研究的目的:
- 开发一种新的,高度不对称的化控制的赫克化方法.
- 为了能够有效地合成基丰富的2--2-甲基环坦.
- 为了规避现有方法的局限性,例如需要强大的基础或阻断组.
主要方法:
- 开发一种新的化控制的赫克化反应.
- 使用N-甲基 pyrrolidin 醇以太作为基质.
- 优化反应条件的产量和酶选择性.
主要成果:
- 成功形成2--2-甲基环坦,具有良好的至非常好的两步收益率 (45-78%).
- 获得了优异的性丰富,其反体过量 (ee) 范围为90-98%.
- 该方法在不需要强基或阻断替代α-碳素的情况下运行.
结论:
- 开发的非对称的赫克化是一种强大的工具,用于合成性环坦.
- 一种拟议的化PI中间体有效地解释了观察到的高水平的性诱导.
- 这种方法为现有的合成路线提供了更有效和更温和的替代方案.
相关概念视频
Control Systems
Control systems are everywhere in contemporary society, influencing diverse applications from aerospace to automated manufacturing. These systems can be found naturally within biological processes, such as blood sugar regulation and heart rate adjustment in response to stress, as well as in man-made systems like elevators and automated vehicles. A control system is essentially a network of subsystems and processes that collaboratively convert specific inputs into desired outputs.
At the heart...
At the heart...
Open and closed-loop control systems
Control systems are foundational elements in automation and engineering. They are broadly categorized into open-loop and closed-loop systems. These classifications hinge on the presence or absence of feedback mechanisms, significantly influencing the system's performance, complexity, and application.
An open-loop control system operates without feedback from the output. It consists of two primary elements: the controller and the controlled process. The controller receives an input signal and...
An open-loop control system operates without feedback from the output. It consists of two primary elements: the controller and the controlled process. The controller receives an input signal and...
Feedback control systems
Feedback control systems are categorized in various ways based on their design, analysis, and signal types.
Linear feedback systems are theoretical models that simplify analysis and design. These systems operate under the principle that their output is directly proportional to their input within certain ranges. For instance, an amplifier in a control system behaves linearly as long as the input signal remains within a specific range. However, most physical systems exhibit inherent nonlinearity...
Linear feedback systems are theoretical models that simplify analysis and design. These systems operate under the principle that their output is directly proportional to their input within certain ranges. For instance, an amplifier in a control system behaves linearly as long as the input signal remains within a specific range. However, most physical systems exhibit inherent nonlinearity...
Controller Configurations
Controller configurations are crucial in a car's cruise control system because they manage speed over time to maintain a consistent pace regardless of road conditions, thereby meeting design goals. In traditional control systems, fixed-configuration design involves predetermined controller placement. System performance modifications are known as compensation.
Control-system compensation involves various configurations, most commonly series or cascade compensation, in which the controller aligns...
Control-system compensation involves various configurations, most commonly series or cascade compensation, in which the controller aligns...
PD Controller: Design
In automotive engineering, car suspension systems often employ Proportional Derivative (PD) controllers to enhance performance. PD controllers are utilized to adjust the damping force in response to road conditions. A controller, acting as an amplifier with a constant gain, demonstrates proportional control, with output directly mirroring input.
Designing a continuous-data controller requires selecting and linking components like adders and integrators, which are fundamental in Proportional,...
Designing a continuous-data controller requires selecting and linking components like adders and integrators, which are fundamental in Proportional,...
Load-frequency control
Load-frequency control (LFC) is vital for maintaining power system stability, ensuring that frequency and power flows remain within acceptable limits during load changes. Turbine-governor control eliminates rotor accelerations and decelerations following load changes. However, a steady-state frequency error persists when the change in the turbine-governor reference setting is zero. In an interconnected power system, each area agrees to export or import a scheduled amount of power through...


