<sup>13</sup>C-NMR. Spectral Differences between Corresponding Methyl Esters, Phenyl Esters and 2-Substituted Chromones
作者:Urs Séquin
DOI:10.1002/hlca.19810640824
日期:1981.12.16
The 13C-NMR. spectra of 2-substitutedchromones (3) are compared with the data of the analogous methyl and phenylesters (1 and 2). The chemical shift differences found are most prominent for the C-atoms in β-position to the ester carbonyl and chromone C(2), respectively. These shift differences are discussed in terms of conformational differencesbetween the esters 1 and 2 and the analogous chromones
Rh(III)‐Catalyzed Aldehydic C−H Functionalization Reaction between Salicylaldehydes and Sulfoxonium Ylides
作者:Guo‐Dong Xu、Kenneth L. Huang、Zhi‐Zhen Huang
DOI:10.1002/adsc.201900276
日期:2019.7.11
A novel aldehydic C−H functionalization reactionbetween salicylaldehydes and sulfoxonium ylides has been developed under rhodium(III) catalysis, affording coupling products in moderate to good yields. A plausible mechanism involving aldehydic C(sp2)−H activation by rhodium(III) and rhodium(III) catalyzed carbene insertion is also proposed. It was also found that the aldehydic C−H functionalization
Enantioselective Synthesis of Chromanones through Organocatalytic Tandem Reactions
作者:Mengxue Lu、Xin Wang、Zongli Xiong、Jingxiang Duan、Wen Ren、Weijun Yao、Yi Xia、Zhen Wang
DOI:10.1002/adsc.202001031
日期:2020.12.8
An enantioselective approach to lactone‐fused chromanone derivatives from 1‐(2‐hydroxyaryl)‐1,3‐diketones and α,β‐unsaturated aldehydes under mild conditions has been developed, which included organocatalytic stepwise Michaeladdition/ cycloketalization/hemiacetalization and followed by oxidation reaction. In the presence of chiral amine organocatalyst and an additional salicylic acid, a wide range
作者:Xiaoyi Li、Zihao Li、Rong Zhang、Zhen Zhou、Yonghui Zhang、Yi Xia、Weijun Yao、Zhen Wang
DOI:10.1021/acs.orglett.3c00705
日期:2023.4.21
organocatalyzed stereoselective domino reaction as a facile approach to multicyclic spirooxindolederivatives bearing two stereogenic quaternary carbon atoms is reported. The alkyl-substituted chiral thiourea catalyst was efficient for the reaction to tolerate a wide range of substrates, furnishing a new class of spirooxindolederivatives bearing an O,O-acetal-fused tricyclic skeleton or tetrahydroxanthone moiety
Rapid Construction of Tricyclic Furanobenzodihydropyrans by Asymmetric Tandem Reaction
作者:Yulong Zhang、Jingxiang Duan、Yuqiao Zhou、Xiaoyi Li、Weijun Yao、Zhen Wang
DOI:10.1021/acs.joc.2c02228
日期:2023.2.3
A process based on the organocatalyzed Mannich/cycloketalization/transesterification tandemreaction of 1-(2-hydroxyaryl)-1,3-diketones and β,γ-alkynyl α-imino esters has been developed, delivering a variety of tricyclic furanobenzodihydropyrans with excellent results (up to 99% yield, 99% ee, and >19:1 dr).