Ring-Opening of 4-Isoxazolines: Competitive Formation of Enamino Derivatives and a,b-Enones
摘要:
Ring-opening of 3-substituted 4-isoxazolines, proceeding through the intermediate isoxazolinium salts, follows two competing reaction pathways leading to alpha,beta-enones and enamines respectively. The rearrangement courses can be controlled as a function of substitution pattern and experimental conditions.
Catalysis by L-Lysine: A Green Method for the Condensation of Aromatic Aldehydes with Acidic Methylene Compounds in Water at Room Temperature
作者:Yan Zhang、Cuizhi Sun、Jun Liang、Zhicai Shang
DOI:10.1002/cjoc.201090373
日期:2010.11
The condensation of aromaticaldehydes with acidic methylene compounds such as ethyl benzoylacetate, 2,4‐pentanedione and dimedone proceeded efficiently in pure water in the presence of L‐lysine at roomtemperature. Interestingly, there are two different reaction mechanisms taking place under the same green catalyst system. This provides a green and mild synthetic method for the preparation of these
Thiourea catalysed reduction of α-keto substituted acrylate compounds using Hantzsch ester as a reducing agent in water
作者:Guanglin Weng、Xiaobo Ma、Dongmei Fang、Ping Tan、Lijiao Wang、Linlin Yang、Yuanyuan Zhang、Shan Qian、Zhouyu Wang
DOI:10.1039/c7ra00995j
日期:——
The first method for the reduction of α-keto substituted acrylate compounds by Hantzsch ester in water under the catalysis of thiourea has been developed. The products were isolated in moderate to high yields (38–95%). These products are important intermediates in the synthesis of a series of natural products and other biologically active molecules.
Preparation of Tetrasubstituted Furans via Intramolecular Wittig Reactions with Phosphorus Ylides as Intermediates
作者:Tzu-Ting Kao、Siang-en Syu、Yi-Wun Jhang、Wenwei Lin
DOI:10.1021/ol101080q
日期:2010.7.2
functional furans can be efficiently generated in one step at room temperature within 10 min to 21 h in moderate to high yields (60−99%). The reaction was proposed to proceed via intramolecular Wittig-type reactions, using phosphorus ylides as intermediates.
Synthesis of Functionalized Furans via Chemoselective Reduction/Wittig Reaction Using Catalytic Triethylamine and Phosphine
作者:Chia-Jui Lee、Tzu-Hsiu Chang、Jhen-Kuei Yu、Ganapuram Madhusudhan Reddy、Ming-Yu Hsiao、Wenwei Lin
DOI:10.1021/acs.orglett.6b01781
日期:2016.8.5
An efficient protocol for the synthesis of highly functionalized furans via intramolecular Wittigreaction has been developed using catalytic amounts of phosphine and triethylamine. Silyl chloride served as the initial promoter to activate the phosphine oxide. Reduction of the activated phosphine oxide by hydrosilane resulted in generation of phosphine, while decomposition of Et3N·HCl resulted in regeneration