Divergent Synthesis of 1<i>H</i>-Indazoles and 1<i>H</i>-Pyrazoles from Hydrazones<i>via</i>Iodine-Mediated Intramolecular Aryl and<i>sp</i><sup>3</sup>C-H Amination
by condensation of hydrazines with the corresponding ketones. In the presence of potassium iodide, I2-mediated oxidative cyclization of diaryl and tert-butyl aryl ketone hydrazones produced 1H-indazoles via direct aryl C–H amination. Under similar reaction conditions, primary and secondary alkyl ketone hydrazones were transformed into 1H-pyrazole products in a reaction involving sp3 C–H amination. This
Synthesis, Structure, and Reactivity of a Palladium Hydrazonato Complex: A New Type of Reductive Elimination Reaction To Form C−N Bonds and Catalytic Arylation of Benzophenone Hydrazone
A rare, structurally characterized μ1 ,η1 -hydrazonato complex is a probable intermediate in the Pd-catalyzed N-arylation of hydrazones. Starting from aryl halides the reaction proceeds efficiently and under mild conditions with chelating phosphane ligands (L2 ); even Cs2 CO3 can be used as the base [Eq. (a)]. R=alkyl, aryl, MeCO, MeO; X=Br, I.
一种罕见的,结构上的特征μ 1,η 1个-hydrazonato复杂是腙的Pd催化的N-芳基化的可能的中间。从芳基卤化物开始,反应在螯合膦配体(L 2)的温和条件下有效地进行。甚至Cs 2 CO 3也可以用作碱[式。(一种)]。R =烷基,芳基,MeCO,MeO; X = Br,我。
A Palladium-Catalyzed Method for the Preparation of Indoles via the Fischer Indole Synthesis
作者:Seble Wagaw、Bryant H. Yang、Stephen L. Buchwald
DOI:10.1021/ja992077x
日期:1999.11.1
benzophenone hydrazones are converted to indole products via an in situ hydrolysis/Fischer cyclization protocol. A procedure that extends this methodology to the synthesis of N-alkylindoles via the intermediacy of N-aryl-N-alkyl benzophenone hydrazones is described. Additionally, the Pd-catalyzed preparation of diaryl benzophenone hydrazones, followed by a hydrolysis/Fischer cyclization protocol, affords N-arylindole
Industrial-Scale Palladium-Catalyzed Coupling of Aryl Halides and Amines –A Personal Account
作者:Stephen L. Buchwald、Christelle Mauger、Gerard Mignani、Ulrich Scholz
DOI:10.1002/adsc.200505158
日期:2006.1
The palladium-catalyzedcoupling of amines and arylhalides or aryl alcohol derivatives has matured from an exotic small-scale transformation into a very general, efficient and robust reaction during the last ten years. This article reports several applications of this method from an industrial vantage point, including ligand synthesis, synthesis of arylpiperazines, arylhydrazines and diarylamines
A simple, practical, and highly efficient synthesis of pyrazoles and indazoles via copper-catalyzed direct aerobic oxidative C(sp2)–H amination has been reported herein. This process tolerated a variety of functional groups under mild conditions. Further diversification of pyrazoles was also investigated, which provided its potential for drug discovery.