A highly efficient and stereoselective synthesis of coumarin-, 1,3-cyclohexanedione-, and 1,4-naphthoquinone-fused 2,8-dioxabicyclo[3.3.1]nonanes is described. This was achieved via a sequential Michael addition/bicyclizationreaction from easily accessible 3-(2-hydroxyphenyl)-1-phenylprop-2-en-1-one derivatives. Three chemical bonds (one C–C bond and two C–O bonds), two six-membered cycles, and two
prepared by reacting pyrazolines with activated alkynes under neat conditions without a catalyst. The products were formed via unexpected ring opening of pyrazolines with the elimination of styrene/ethylene. These types of transformations are unknown and the products formed were confirmed using their spectral/analytical data. In addition, the structures of compounds 5e and 5n were confirmed by single-crystal
1 H -Pyrazole-4,5-dicarboxylates 和 chromenopyrazole carboxylates 是通过在没有催化剂的纯净条件下使吡唑啉与活化的炔烃反应制备的。产物是通过吡唑啉的意外开环和苯乙烯/乙烯的消除而形成的。这些类型的转化是未知的,并且使用它们的光谱/分析数据确认了所形成的产物。此外,化合物5e和5n的结构通过单晶X射线分析证实。进行了对照实验以支持所提出的反应机理。
Asymmetric Synthesis of 3,4-Dihydrocoumarins Bearing an α,α-Disubstituted Amino Acid Moiety
作者:Joanna Hejmanowska、Anna Albrecht、Jakub Pięta、Łukasz Albrecht
DOI:10.1002/adsc.201500598
日期:2015.12.14
An organocatalytic approach for the stereoselective synthesis of 3,4-dihydrocoumarins with an α,α-disubstituted amino acid moiety incorporated is presented. The developed methodology is based on the cascade reaction between α-substituted azlactones and 2-hydroxychalcones. It is initiated by a chiral Brønsted base-catalyzed enantio- and diastereoselective Michael reaction followed by the azlactone ring
One-Pot Synthesis of O-Heterocycles or Aryl Ketones Using an InCl<sub>3</sub>/Et<sub>3</sub>SiH System by Switching the Solvent
作者:Wenqiang Jia、Qiumu Xi、Tianqi Liu、Minjian Yang、Yonghui Chen、Dali Yin、Xiaojian Wang
DOI:10.1021/acs.joc.9b00140
日期:2019.5.3
An efficient one-pot synthesis of O-heterocycles or aryl ketones has been achieved using Et3SiH in the presence of InCl3 via a sequential ionic hydrogenation reaction by switching the solvent. This methodology can be used to construct C–O bonds and to prepare conjugate reduction products, including chromans, tetrahydrofurans, tetrahydropyrans, dihydroisobenzofurans, dihydrochalcones, and 1,4-diones
ZrCl<sub>4</sub>-Catalysed Synthesis of New 4-(2-hydroxyphenyl)Pyrazolo[3,4-b]Pyridine Derivatives
作者:Meilin Liu、Guodong Yin
DOI:10.3184/174751915x14296297811712
日期:2015.5
In the presence of a catalytic amount of zirconium(IV) chloride, an efficient synthesis of new 4-(2-hydroxyphenyl)pyrazolo[3,4-b]pyridines has been developed by the reaction 2-hydroxychalcones with 3-methyl-1-phenyl-1H-pyrazol-5-amine in refluxing ethanol. All these novel compounds have been characterised by 1H NMR, 13C NMR, HRMS, IR spectra and X-ray crystallographic analysis.