诸如硅之类的主族元素化合物是绿色且廉价催化剂的诱人候选物。为了使它们与最先进的过渡金属配合物竞争,必须解锁和控制新的反应模式,这可以通过应变来实现。使用三(2-炔基)甲基phosph([TSMPH 3 ] +)支架,我们制备了应变阳离子硅烷[TSMPSiH] +。与一般的氢键Si-H键形成鲜明对比的是,它在4.7–8.1的实验性p K a DMSO中呈酸性,低于苯酚,苯甲酸和少数报道的p K a的氢化硅烷。价值观。我们表明,环应变显着地促进了这种异常的酸度以及感应和静电作用。共轭碱TSMPSi在CH酸存在下活化THF分子,从而通过痕量的[TSMPSiH] +起到释放应变路易斯酸的作用,从而产生高通量的烷氧基硅烷。该反应涉及从Si II到Si IV的正式氧化态变化,与过渡金属介导的过程具有令人着迷的相似性。
Zinc Chloride Mediated Nucleophilic Substitution: Amination and Thioetherification of Alcohols at Room Temperature
作者:Ashima Singh、Shruti Gupta、Jitender M. Khurana
DOI:10.1080/00304948.2020.1716617
日期:2020.3.3
Catalytic chemistry is one of the focal points for the development of environmentally benign organic transformations. It is true that the employment of catalysts in organic transformations comes wi...
催化化学是开发环境友好型有机转化的重点之一。确实,在有机转化中使用催化剂是...
Equilibrium Acidities of Nitroalkanes in an Ionic Liquid
作者:Feixiang Gao、Pengju Ji、Jin-Pei Cheng
DOI:10.1021/acs.joc.8b02183
日期:2018.12.21
The acidity ladder scale in [BMPY][NTf2] was successfully expanded toward the weak acidity region for about five more pK units compared to the previously established one. This allows the acidities of a series of 13 aliphatic and aromatic nitroalkanes to be determined accurately by the UV–vis spectroscopic method. The acidity of nitroalkane in [BMPY][NTf2] covers ∼8 pK units and is significantly weaker
ALIPHATIC CHEMISTRY OF FLUORENE:PART IV. PREPARATION AND ALKYLATION OF SOME SULPHIDES AND SULPHONES
作者:P. M. G. Bavin
DOI:10.1139/v60-129
日期:1960.6.1
The preparations are described of some 9-fluorenyl sulphides which have been oxidized with peracetic acid to the corresponding sulphones.9-Fluorenyl p-tolyl sulphone has been alkylated with a range of alkyl halides; other sulphones, including 2-nitro-9-fluorenyl p-tolyl sulphone, have been methylated.Methyl fluorene-9-carboxylate anion was reduced by p-toluenesulphonyl chloride to dimethyl 9,9′-difluorenyl-9
Broensted correlations for electron transfer from carbanions to halomethyl phenyl sulfone and 1,1-dinitroalkane-type acceptors
作者:Frederick G. Bordwell、Anthony H. Clemens
DOI:10.1021/jo00134a003
日期:1982.6
(Thio)urea Organocatalyst Equilibrium Acidities in DMSO
作者:Gergely Jakab、Carlo Tancon、Zhiguo Zhang、Katharina M. Lippert、Peter R. Schreiner
DOI:10.1021/ol300307c
日期:2012.4.6
Bordwell's method of overlapping indicators was used to determine the pK(a) values of some of the most popular (thio)urea organocatalysts via UV spectrophotometric titrations. The incremental effect of CF3 groups on acidic strength was also investigated. The pic's are in the range of 8.5-19.6. The results may lead to a better understanding of noncovalent organocatalysis and may aid in future catalyst development.