Synthesis of Substituted Pyrazoles via Tandem Cross-Coupling/Electrocyclization of Enol Triflates and Diazoacetates
作者:David J. Babinski、Hector R. Aguilar、Raymond Still、Doug E. Frantz
DOI:10.1021/jo201042c
日期:2011.8.5
The synthesis of 3,4,5-trisubstituted pyrazoles via a tandem catalytic cross-coupling/electrocyclization of enoltriflates and diazoacetates is presented. The initial scope of this methodology is demonstrated on a range of differentially substituted acyclic and cyclic enoltriflates as well as an elaborated set of diazoacetates to provide the corresponding pyrazoles with a high degree of structural
Decarboxylative Fluorination of Electron-Rich Heteroaromatic Carboxylic Acids with Selectfluor
作者:Xi Yuan、Jian-Fei Yao、Zhen-Yu Tang
DOI:10.1021/acs.orglett.7b00335
日期:2017.3.17
A transition-metal-free decarboxylative fluorination of electron-rich five-membered heteroaromatics, including furan-, pyrazole-, isoxazole-, thiophene-, indole-, benzofuran- and indazolecarboxylic acids, with Selectfluor is reported. Fluorinated dimer products were observed for nitrogen-containing heteroaromatic carboxylicacids, such as indole and pyrazole. An effective method has been developed
富电子的五元杂芳族化合物(包括呋喃,吡唑,异恶唑,噻吩,吲哚,苯并呋喃和吲唑羧酸)与Selectfluor的无过渡金属脱羧氟化反应得到了报道。观察到氟化二聚体产物中含氮杂芳族羧酸,例如吲哚和吡唑。已经开发出有效的方法,以在低温下以Li 2 CO 3为碱合成2-和3-氟吲哚的单体。
New one-pot synthesis of pyrazole-5-carboxylates by 1,3-dipole cycloadditions of ethyl diazoacetate with α-methylene carbonyl compounds
A facile one-pot procedure for the synthesis of pyrazole-5-carboxylates by 1,3-dipolar cycloaddition of ethyldiazoacetate is described. Cycloadditions with α-methylene carbonyl compounds utilizing 1,8-diazabicyclo[5.4.0]undec-7-ene as base and acetonitrile as solvent provide pyrazoles with excellent regioselectivity and good yields. The reaction was found to proceed by a domino 1,3-dipolar cycloaddition-water
Synthesis of pyrazole-3-carboxylates and pyrazole-1,5-dicarboxylates by one-pot cyclization of hydrazone dianions with diethyl oxalate
作者:Tung T. Dang、Tuan T. Dang、Christine Fischer、Helmar Görls、Peter Langer
DOI:10.1016/j.tet.2007.12.024
日期:2008.2
The one-pot cyclization of hydrazone dianions with diethyl oxalate allows a convenient synthesis of pyrazole-3-carboxylates and pyrazole-1,5-dicarboxylates.