Transition-Metal-Free Sonogashira-Type Coupling of <i>ortho</i>-Substituted Aryl and Alkynyl Grignard Reagents by Using 2,2,6,6-Tetramethylpiperidine-<i>N</i>-oxyl Radical as an Oxidant
作者:Modhu Sudan Maji、Sandip Murarka、Armido Studer
DOI:10.1021/ol1015702
日期:2010.9.3
Cross coupling of aryl, alkenyl, and alkynyl magnesium compounds by using 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO) as an environmentally benign organic oxidant is described. This coupling reaction can be performed without adding any transition metal on various ortho-substituted aryl and alkynyl Grignardreagents. Importantly, functional groups such as esters, amides, and cyanides are shown
Sonogashira Couplings of Aryl Bromides: Room Temperature, Water Only, No Copper
作者:Bruce H. Lipshutz、David W. Chung、Brian Rich
DOI:10.1021/ol801471f
日期:2008.9.1
Cross-coupling reactions between lipophilic terminal alkynes and arylbromides can be catalyzed by ligated Pd, in the absence of copper, in pure water at ambient temperatures. Small amounts of the nonionic amphiphile PTS assist by virtue of nanometer micelles formed spontaneously in an aqueous medium.
Sonogashira Coupling Using Bulky Palladium-Phenanthryl Imidazolium Carbene Catalysis
作者:Yudao Ma、Chun Song、Wei Jiang、Quansheng Wu、Yong Wang、Xueying Liu、Merritt B. Andrus
DOI:10.1021/ol035147k
日期:2003.9.1
[GRAPHICS]Bulky phenanthracenyl imidazolium-derived carbene ligands were investigated for copper-free Sonogashira coupling with terminal acetylenes. Aryl bromides and iodides gave coupled products in excellent yields from the Pd(PPh3)(2)Cl-2 complex with potassium t-butoxide and 18-crown-6 in THF. A remarkable dependence on the size of the ligand was found. The highest yields were obtained with the bulky 2,9-dicyclohexyl-10-phenanthryl ligand 5.