Iron-catalyzed aerobic oxidative aromatization of 1,3,5-trisubstituted pyrazolines
作者:Guddekoppa S. Ananthnag、Adithya Adhikari、Maravanji S. Balakrishna
DOI:10.1016/j.catcom.2013.09.002
日期:2014.1
A simple and high yielding method for the synthesis of tri-substituted pyrazoles via iron(III) catalyzed aerobic oxidative aromatization of pyrazolines has been reported. The process demonstrates a variety of functional group tolerance.
prepared by reacting pyrazolines with activated alkynes under neat conditions without a catalyst. The products were formed via unexpected ring opening of pyrazolines with the elimination of styrene/ethylene. These types of transformations are unknown and the products formed were confirmed using their spectral/analytical data. In addition, the structures of compounds 5e and 5n were confirmed by single-crystal
1 H -Pyrazole-4,5-dicarboxylates 和 chromenopyrazole carboxylates 是通过在没有催化剂的纯净条件下使吡唑啉与活化的炔烃反应制备的。产物是通过吡唑啉的意外开环和苯乙烯/乙烯的消除而形成的。这些类型的转化是未知的,并且使用它们的光谱/分析数据确认了所形成的产物。此外,化合物5e和5n的结构通过单晶X射线分析证实。进行了对照实验以支持所提出的反应机理。
Stereospecific Intramolecular C–H Amination of 1-Aza-2-azoniaallene Salts
作者:Daniel A. Bercovici、Matthias Brewer
DOI:10.1021/ja303054c
日期:2012.6.20
participate in intramolecularC-H amination reactions to provide pyrazoline products in good to excellent yield. This intramolecular amination occurs readily at both benzylic and tertiary aliphatic positions and proceeds at an enantioenriched chiral center without loss of enantiomeric excess. A competition reaction shows that insertion occurs more readily at an electron-rich benzylic position than an
Solid-Phase Synthesis of Pyrazolines and Isoxazolines with Sodium Benzenesulfinate as a Traceless Linker
作者:Yu Chen、Yulin Lam、Yee-Hing Lai
DOI:10.1021/ol0340888
日期:2003.4.1
text] The preparation of pyrazoline and isoxazoline derivatives with tracelesssolid-phase sulfone linker strategy is described. Key steps involved in the solid-phase synthetic procedure include (i) sulfinate S-alkylation, (ii) sulfone anion alkylation, (iii) gamma-hydroxy sulfone --> gamma-ketosulfone oxidation, and (iv) traceless product release via elimination-cyclization. A library of 12 pyrazolines
4-Substituted Hantzsch 1,4-dihydropyridines and 1,3,5-trisubstitutedpyrazolines were oxidized to the corresponding pyridines and pyrazoles, respectively, in high yields by molecular oxygen in the presence of catalytic amount of N-hydroxyphthalimide (NHPI) and Co(OAc)2 in acetonitrile at room temperature.