1,3-Diketones from Acid Chlorides and Ketones: A Rapid and General One-Pot Synthesis of Pyrazoles
作者:Stephen T. Heller、Swaminathan R. Natarajan
DOI:10.1021/ol060570p
日期:2006.6.1
[reaction: see text] 1,3-Diketones were synthesized directly from ketones and acidchlorides and were then converted in situ into pyrazoles by the addition of hydrazine. This method is extremely fast, general, and chemoselective, allowing for the synthesis of previously inaccessible pyrazoles and synthetically demanding pyrazole-containing fused rings.
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
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