Rapid and efficient protic ionic liquid-mediated pinacol rearrangements under microwave irradiation
作者:Luke C. Henderson、Nolene Byrne
DOI:10.1039/c0gc00916d
日期:——
Several protic ionic liquids were tested as potential mediators for pinacol rearrangements employing microwave irradiation. Using hydrobenzoin as a model substrate, the optimal conditions were found to be heating at 80 °C for 5 min using H2SO4:triethylamine as the ionic liquid. A key feature of this reaction was to keep the microwave power low (20 W) to avoid ionic liquid degradation. Application of these conditions to triphenylethylene glycol gave rearrangement products in high yield and purity, while phenylethylene glycol and styrene oxide gave pinacol products that underwent a cascade aldol condensation. These conditions represent an efficient means by which pinacol rearrangements can be carried out while avoiding the use of strong Brønsted acids, high temperatures and extended reaction times.
Synthesis and reactions of donor cyclopropanes: efficient routes to cis - and trans -tetrahydrofurans
作者:Jonathan Dunn、Adrian P. Dobbs
DOI:10.1016/j.tet.2015.05.007
日期:2015.9
A detailed study on the synthesis and reactions of silylmethylcyclopropanes is reported. In their simplest form, these donor-only cyclopropanes undergo Lewis acid promoted reaction to give either cis- or trans-tetrahydrofurans, with the selectivity being reaction condition-dependant. The adducts themselves are demonstrated to be an important scaffold for structural diversification. The combination
A highly efficient and selective rearrangement reaction of bromohydrins to aldehydes mediated by CF3CO2ZnEt was described. The secondary and tertiary aldehydes were prepared under mild conditions in good to excellent yields (85–99%). The scope and limitations of this rearrangement process were also investigated.
描述了由CF 3 CO 2 ZnEt介导的溴代醇对醛类的高效选择性重排反应。仲醛和叔醛是在温和的条件下以良好至极佳的收率(85–99%)制备的。还研究了这种重排过程的范围和局限性。
Chichibabin pyridinium synthesis <i>via</i> oxidative decarboxylation of photoexcited α-enamine acids
Chichibabin pyridinium synthesis between α-amino acids and aldehydes was developed. When the in situ generated α-enamine acids were photoexcited, they were oxidized by aerobic oxygen to give radical cation species. After decarboxylation and further oxidation, the generated iminium undergoes Chichibabin cyclization to afford pyridiniums. This photochemical protocol enables the synthesis of various tetra-substituted
Manganese‐Catalyzed Dual‐Deoxygenative Coupling of Primary Alcohols with 2‐Arylethanols
作者:Yujie Wang、Zhihui Shao、Kun Zhang、Qiang Liu
DOI:10.1002/anie.201809333
日期:2018.11.12
herein is a general and efficient dual‐deoxygenative coupling of primary alcohols with 2‐arylethanols catalyzed by a well‐defined Mn/PNP pincer complex. This reaction is the first example of the catalytic dual‐deoxygenation of alcohols using a non‐noble‐metal catalyst. Both deoxygenative homocoupling of 2‐arylethanols (17 examples) and their deoxygenative cross‐coupling with other primary alcohols (20 examples)