Heterocycles: 2—Regiospecific addition of methylhydrazine to acetylenic ketones
摘要:
AbstractThe reaction of 1‐p‐methoxyphenyl‐3‐phenyl‐2‐propen‐1‐one and 3‐p‐methoxyphenyl‐1‐phenyl‐2‐propen‐1‐one with methylhydrazine gave 1‐methyl‐3‐p‐methoxyphenyl‐5‐phenylpyrazoline and 1‐methyl‐3‐phenyl‐5‐p‐methoxyphenylpyrazoline, respectively. These compounds, on oxidation, gave 1‐methyl‐3‐p‐methoxyphenyl‐5‐phenylpyrazole(2) and 1‐methyl‐3‐phenyl‐5‐p‐methoxyphenylpyrazole, respectively. When methyl‐hydrazine was made to react with 1‐p‐methoxyphenyl‐3‐phenyl‐2‐propyn‐1‐one, a pyrazole was obtained which proved to be identical with 2. Confirmatory evidence for this identity was obtained from their spectral data.
Regioselective Synthesis of 1,3,5-Trisubstituted Pyrazoles from <i>N</i>-Alkylated Tosylhydrazones and Terminal Alkynes
作者:Yuanfang Kong、Meng Tang、Yun Wang
DOI:10.1021/ol403447g
日期:2014.1.17
An efficient synthesis of 1,3,5-trisubstitutedpyrazoles from N-alkylated tosylhydrazones and terminal alkynes was developed. The protocol was applied to a wide range of substrates and demonstrated excellent tolerance to a variety of substituents, including both electron-donating and -withdrawing groups. In comparison with the common approaches for substituted pyrazole syntheses, this methodology proceeded
One-Pot Coupling–Coupling–Cyclocondensation Synthesis of Fluorescent Pyrazoles
作者:Alissa C. Götzinger、Florian A. Theßeling、Corinna Hoppe、Thomas J. J. Müller
DOI:10.1021/acs.joc.6b01326
日期:2016.11.4
ondensation syntheses of pyrazoles and pyrimidines were developed by taking advantage of the provisional, sequentially Pd-catalyzed one-pot generation of alkynones from aryl iodides, ethynylmagnesium bromide, and acid chlorides. This one-pot methodology allows the concise, diversity-oriented generation of a set of donor-, acceptor-, and donor–acceptor-substituted pyrazoles, which are interesting fluorophores
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
consecutive tandem processes are described for the regioselective, two-step synthesis of 1,3,5-trisubstitutedpyrazoles from α-hydroxyketones. The first, a tandem MnO 2 -mediated oxidation/Ramirez olefination reaction, provides a facile route to β,β-dibromo-enones. These valuable 1,3-dicarbonyl synthons can then be converted into 1,3,5-trisubstitutedpyrazoles via a second tandem hydrazine condensation/Suzuki-Miyaura