Y(OTf)3-Catalyzed Cascade Propargylic Substitution/Aza-Meyer–Schuster Rearrangement: Stereoselective Synthesis of α,β-Unsaturated Hydrazones and Their Conversion into Pyrazoles
concise method for the highly stereoselective synthesis of α,β-unsaturated hydrazones by the Y(OTf)3-catalyzed cascade propargylic substitution/aza-Meyer–Schuster rearrangement reaction of tertiary propargylic alcohols and p-toluenesulfonyl hydrazide under an air atmosphere is developed. A series of α,β-unsaturated hydrazones have been synthesized from simple and readily available starting materials
Highly Enantioselective Catalytic Alkynylation of Ketones – A Convenient Approach to Optically Active Propargylic Alcohols
作者:Gui Lu、Xingshu Li、Yue-Ming Li、Fuk Yee Kwong、Albert S. C. Chan
DOI:10.1002/adsc.200606078
日期:2006.9
The development of highly enantioselective catalysts involving Cu(OTf)2 and chiral camphorsulfonamides for the alkynylation of ketone is described. The influences of Lewis acids, reaction conditions and chiral ligands on the outcome of the reaction are discussed. The best enantioselectivity (up to 97 % ee) was obtained in the alkynylation of 2′-chloroacetophenone. The scope of the reaction is also
[3+2] Cycloaddition of Propargylic Alcohols and α‐Oxo Ketene Dithioacetals: Synthesis of Functionalized Cyclopentadienes and Further Application in a Diels–Alder Reaction
作者:Zhongxue Fang、Jianquan Liu、Qun Liu、Xihe Bi
DOI:10.1002/anie.201403014
日期:2014.7.7
organic synthesis and also ubiquitous as the Cp ligands in organometallic chemistry. As part of ongoing efforts to develop novel organic reactions that employ functionalized alkynes, a [3+2] cycloaddition of propargylic alcohols and ketene dithioacetals has been developed, which leads to fully substituted 2,5‐dialkylthio cyclopentadienes in good to excellent yields. In an unusual dethiolating Diels–Alder
4-phosphinoylcyanation of 1,3-enynes with diarylphosphine oxides and trimethylsilyl cyanide. The reaction produced various tetrasubstituted phosphinoyl- and cyano-containing allenes with high functional group compatibilities in good yields under mild reaction conditions. A preliminary reaction mechanism involving the formation of phosphinoyl radicals and their regioselective addition to 1,3-enynes was also proposed