摘要
碳氢键的去质子官能化反应是碳碳键构建最常用的方法,是一种重要的碳氢键活化方式.近年来,碱催化碳碳键形成反应在含弱酸性碳氢键化合物作为亲核试剂的底物拓展方面取得了重要进展.强碱性试剂或催化剂是实现这些弱酸性碳氢键官能化反应的关键.根据酸碱平衡理论,相对较强的碱才能够对弱酸性碳氢键发生去质子化反应,形成较大浓度的碳负离子中间体,进而发生亲核反应.相对较弱的碱不足以对弱酸性碳氢键进行去质子化反应,然而尽管碳负离子中间体可能浓度很低,但应该仍然存在于反应体系中.如果可以选择性地进行热力学有利的化学转化,碳负离子中间体的浓度将会下降并引起去质子化平衡的重新构建.结合碳负离子中间体不可逆的转化和去质子平衡的重新构建,弱酸性碳氢键就可以在弱碱条件下实现缓慢却持续不断的去质子官能化反应.为区别于强碱条件下、通过热力学稳定碳负离子中间体的传统碳氢键去质子官能化反应,我们将这种在弱碱条件下、通过热力学不利的碳负离子中间体转化和酸碱平衡重新构建实现的弱酸性碳氢键的官能化反应称为动力学去质子官能化反应.本文总结了碳氢键去质子官能化反应研究现状和本研究团队近年来在弱碱条件下的动力学去质子官能化反应研究进展.
The C–H bond deprotonation and functionalization reaction represents the most frequently used method for C–C bond construction and also a vital mode of C–H bond activation. Great developments have been made recently in the catalytic C–C bond formation by using weakly acidic C–H compounds as nucleophiles. The strongly basic reagent or catalyst is the key factor in these reactions. If only the base is basic enough, the deprotonation of the weakly acidic C–H bonds, the formation of the carbanions and the following nucleophilic reactions occur according to the acid-base equilibrium theory. Even though a relative weak base is not strong enough for deprotonation, the carbanion still exists in the system, possibly in a very low concentration. Once the carbanion selectively undergoes a thermodynamically favoured transformation, its concentration goes down and thus starts the reestablishment of the deprotonation equilibrium. With the combination of the irreversible conversion of the carbanion and constant reestablishment of the equilibrium, the deprotonative functionalization of weakly acidic C–H bonds could be achieved slowly but continuously under relative weakly basic conditions. Distinct from the conventional deprotonative functionalization under strong base via a thermodynamically favoured carbanion intermediate, we suggest the descriptive name "kinetic deprotonative functionalization" for the reaction under relative weak conditions via the combination of the irreversible conversion of the carbanion and constant reestablishment of the equilibrium. Herein, we will briefly review the research status of deprotonative functionalization reactions and discuss the kinetic deprotonative functionalization reactions developed recently in our group.
作者
关冰涛
施章杰
Bing-Tao Guan;Zhang-Jie Shi(Department of Chemistry,Fudan University,Shanghai 200438,China)
出处
《中国科学：化学》
CAS
CSCD
北大核心
2021年第2期201-212,共12页
SCIENTIA SINICA Chimica
基金
国家自然科学基金(编号:21372123)
天津自然科学基金(编号:19JCYBJC20100)资助项目。
关键词
弱酸性碳氢键
去质子平衡
碳氢键官能化反应
相对弱碱
布朗斯特碱
动力学去质子官能化反应
weakly acidic C–H bonds
deprotonation equilibrium
C–H bond functionalization
relative weak base
Bronsted base
kinetic deprotonative functionalization
