An efficient and generally applicable protocol for decarboxylative coupling of α,α‐difluoroarylacetic acids with ethynylbenziodoxolone (EBX) reagents has been developed, affording α,α‐difluoromethylated alkynes bearing various functional groups in moderate to excellent yields. Remarkably, this potassium persulfate (K2S2O8)‐promoted reaction employs water as solvent under transition metal‐free conditions
已经开发出一种有效且普遍适用的方案,用于将α,α-二氟代芳酸与乙炔基苯并恶唑酮(EBX)试剂进行脱羧偶联,从而以中等至极好的收率提供带有各种官能团的α,α-二氟甲基化炔烃。值得注意的是,这种过硫酸钾(K 2 S 2 O 8)促进的反应在无过渡金属的条件下将水用作溶剂,从而为α,α-二氟甲基化炔烃提供了绿色的合成方法。
Decarboxylative Alkynylation of α-Keto Acids and Oxamic Acids in Aqueous Media
作者:Hua Wang、Li−Na Guo、Shun Wang、Xin-Hua Duan
DOI:10.1021/acs.orglett.5b01336
日期:2015.6.19
K2S2O8 promoted decarboxylativealkynylation of α-ketoacids and oxamic acids has been developed. This process features mild reaction conditions, a broad substrate scope, and good functional-group tolerance, therefore providing a new and efficient access to a wide range of ynones and propiolamides. Furthermore, this radical process could also be successfully applied to alkynylation of the Csp2–H bond
已经开发出温和的K 2 S 2 O 8促进α-酮酸和草酰胺酸的脱羧炔基化。该工艺具有温和的反应条件,广泛的底物范围和良好的官能团耐受性,因此提供了一种新型且有效的途径,可广泛使用炔酮和丙酰胺类化合物。此外,该自由基过程也可以成功地用于高价炔碘试剂对DMF中C sp 2 -H键的炔基化反应。
Ethynyl Benziodoxolones for the Direct Alkynylation of Heterocycles: Structural Requirement, Improved Procedure for Pyrroles, and Insights into the Mechanism
作者:Jonathan P. Brand、Clara Chevalley、Rosario Scopelliti、Jérôme Waser
DOI:10.1002/chem.201200200
日期:2012.4.27
accelerating effect of a methyl substituent in both the 3‐ and 6‐position of triisopropylsilylethynyl‐1,2‐benziodoxol‐3(1H)‐one (TIPS‐EBX) on the reaction rate was observed. Competitive experiments between substrates of different nucleophilicity, deuterium labeling experiments, as well as the regioselectivity observed are all in agreement with electrophilic aromatic substitution. Gold(III) 2‐pyridinecarboxylate
The stereoselective synthesis of cis‐β‐phenoxyvinyl benziodoxolones (cis‐β‐phenol‐VBXs) from an ethynyl benziodoxolone‐acetonitrile complex (EBX‐MeCN) and various phenols is reported herein. The reaction tolerates different phenol derivatives, including complex natural products, and can be conducted under mild conditions. The synthesis was performed in an aqueous solvent in the absence and presence
Transition metal-free coupling of terminal alkynes and hypervalent iodine-based alkyne-transfer reagents to access unsymmetrical 1,3-diynes
作者:J. Schörgenhumer、M. Waser
DOI:10.1039/c8ob02375a
日期:——
A variety of unsymmetrical 1,3-diynes can easily be accessed in good yields under catalyst- and transition metal-free conditions by reacting terminalalkynes with hypervalent iodine-based electrophilic alkyne-transfer reagents.