Efficient one-pot synthesis of substituted pyrazoles
作者:Meng Tang、Fu-Min Zhang
DOI:10.1016/j.tet.2012.12.038
日期:2013.2
An efficient, one-potsynthesis of substituted pyrazoles from enones, hydrazides, and halides was developed. In comparison with the classical Knorr pyrazolesynthesis, this methodology gave a different type of product (R3≥R5). A range of substituted pyrazoles were prepared in good to high yields with complete regioselectivity.
Copper-Catalyzed Aerobic Intramolecular Dehydrogenative Cyclization of N,N-Disubstituted Hydrazones through C sp 3H Functionalization
作者:Guangwu Zhang、Yan Zhao、Haibo Ge
DOI:10.1002/anie.201209618
日期:2013.2.25
An aerobic activity: The title reaction proceeds through an oxidation/cyclization/aromatization sequence under an atmosphere of O2 (see scheme; DBU=1,8‐diazabicyclo[5.4.0]undec‐7‐ene, DCE=1,2‐dichloroethane, DMS=dimethylsulfide). This coupling reaction is the first to proceed via an iminium intermediate for a CH bond‐functionalization process, and provides an environmentally friendly and atom‐efficient
Aluminum Chloride Mediated Reactions of N-Alkylated Tosylhydrazones and Terminal Alkynes: A Regioselective Approach to 1,3,5-Trisubstituted Pyrazoles
作者:Meng Tang、Yun Wang、Hu Wang、Yuanfang Kong
DOI:10.1055/s-0035-1561646
日期:——
Abstract Aluminum chloridemediated reactions of N-alkylated tosylhydrazones and terminal alkynes are reported. The protocol is applied to a wide range of substrates, and demonstrates excellent functional group tolerance. A series of 1,3,5-trisubstituted pyrazoles is prepared in good to high yields with complete regioselectivity. Aluminum chloridemediated reactions of N-alkylated tosylhydrazones and
作者:Barrington Cross、Robert L. Arotin、Charles F. Ruopp
DOI:10.1002/jhet.5570170512
日期:1980.7
A rapid, convenient conversion of 1,2-dimethylpyrazolium salts (1) to 1-methylpyrazoles (2) is accomplished in piperidine or 3-methylpiperidine at temperatures ≥ 106°. This demethylation represents a particularly useful procedure for the synthesis of 3- and 5-substituted aminopyrazoles, which are not readily obtainable by other methods. The 50:50 mixture of piperidinopyrazole isomers 2b can be obtained
Verfahren zur Herstellung von N-substituierten Pyrazolen
申请人:BASF Aktiengesellschaft
公开号:EP0628563A1
公开(公告)日:1994-12-14
Verfahren zur Herstellung von N-substituierten Pyrazolen der allgemeinen Formel I
in der
R¹C₁- bis C₁₂-Alkyl oder C₇- bis C₂₀-Phenylalkyl und
R²,R³,R⁴unabhängig voneinander Wasserstoff, C₁- bis C₁₂-Alkyl, Phenyl, C₇- bis C₂₀-Alkylphenyl oder C₇- bis C₂₀-Phenylalkyl
bedeuten, durch Umsetzung von Pyrazolen der allgemeinen Formel II
in der R², R³ und R⁴ die obengenannten Bedeutungen haben, mit Verbindungen der allgemeinen Formel III
R¹ - O - R⁵ (III),
in der R¹ die obengenannten Bedeutungen hat und
R⁵Wasserstoff oder R¹ bedeuten,
in Gegenwart eines Katalysators bei Temperaturen von 200 bis 550°C und Drücken von 0,001 bis 50 bar, indem man als Katalysator einen Heterogenkatalysator einsetzt.