Reduction of sulfonates and aromatic compounds with the NiCl2·2H2OLi-arene (cat.) combination
作者:Gabriel Radivoy、Francisco Alonso、Miguel Yus
DOI:10.1016/s0040-4020(99)00893-5
日期:1999.12
A series of alkyl mesylates, dimesylates and alkyl or aryl triflates have been reduced to the corresponding hydrocarbons with nickel(II) chloride dihydrate, an excess of lithium powder and a catalytic amount of DTBB (10 mol%) in THF at room temperature. This methodology applied to enol triflates allowed the preparation of olefins or alkanes depending on the amount of the Ni(II) salt used. The reduction
Reaction of Hydrazones with Methoxy(tosyloxy)iodobenzene (MTIB): Tosylate Formation under Oxidative Conditions
作者:Christopher Ramsden、Helen Rose
DOI:10.1055/s-1997-702
日期:——
Treatment of aromatic hydrazones 1 containing electron-withdrawing, reduction sensitive substituents with MTIB gives the corresponding tosylates 2 in high yield. When the tosylate is particularly reactive the thermodynamically more stable methyl ether 3 is isolated. Analogous reactions with DAIB give acetates 4 in high yield. Dialkyl hydrazones give olefinic products (e.g. 7 and 8). (+)-Camphor hydrazone 1k with either MTIB or DAIB gives both camphene 12 (major product) and tricyclene 11 (minor product) suggesting that a carbene pathway accounts for some of the material formed in these oxidations.
alternatives to Wittig chem-istry are needed to construct olefins from carbonyl compounds, but none have been developed to-date. Here we report an atom-economical olefination of carbonyls via aldol-decarbonylative coupling of aldehydes using robust and recyclable supported Pd catalysts, producing only CO and H2O as waste. The reaction affords homocoupling of aliphatic al-dehydes, as well as heterocoupling
需要新的原子经济替代 Wittig 化学来从羰基化合物构建烯烃,但迄今为止还没有开发出来。在这里,我们报告了使用坚固且可回收的负载型 Pd 催化剂通过醛的醛醇-脱羰基偶联实现羰基的原子经济烯化,仅产生 CO 和 H2O 作为废物。该反应提供了脂肪族醛的同偶联,以及脂肪族和芳香族醛的杂偶联。计算可以深入了解反应的选择性和热力学。串联羟醛脱羰反应为探索新的羰基反应以构建烯烃打开了大门。
Catalytic Ketone Hydrodeoxygenation Mediated by Highly Electrophilic Phosphonium Cations
作者:Meera Mehta、Michael H. Holthausen、Ian Mallov、Manuel Pérez、Zheng-Wang Qu、Stefan Grimme、Douglas W. Stephan
DOI:10.1002/anie.201502579
日期:2015.7.6
Ketones are efficiently deoxygenated in the presence of silane using highly electrophilic phosphonium cation (EPC) salts as catalysts, thus affording the corresponding alkane and siloxane. The influence of distinct substitution patterns on the catalytic effectiveness of several EPCs was evaluated. The deoxygenation mechanism was probed by DFT methods.
Fluorodecarboxylation, rearrangement and cyclisation: the influence of structure and environment on the reactions of carboxylic acids with xenon difluoride
作者:Christopher A. Ramsden、Maxine M. Shaw
DOI:10.1016/j.tetlet.2009.02.090
日期:2009.7
The reactions of structurally diverse carboxylic acids with XeF2 in both CH2Cl2/Pyrex® and CH2Cl2/PTFE have been studied. Pyrex® appears to be a very effective heterogeneous catalyst for an electrophilic mode of reaction of polarised XeF2, leading to rearrangement, cyclisation and cationic products. In CH2Cl2/PTFE, fluorodecarboxylation is the main mode of reaction, in accordance with previous studies