Substituted 1-(21-aminovinyl)pyrroles and pyrrolo[1,2-a]pyrazines from the reaction of a pyrazolium methanide 1,3-dipole with dialkyl acetylenedicarboxylates: a 1,2-carbon to nitrogen rearrangement in the pyrazole system
摘要:
Treatment of 1-ethoxycarbonylmethyl-2,3,4,5-tetraarylpyrazolium salts with base in the presence of dialkyl acetylenedicarboxylates provides a new route to substituted 1-(2(1)-aminovinyl)pyrroles and pyrrolo[1,2-a]pyrazines.
Facile One-Pot Synthesis of 1,3,5-Trisubstituted Pyrazoles from α,β-Enones
作者:Jin Yu、Ko Hoon Kim、Hye Ran Moon、Jae Nyoung Kim
DOI:10.5012/bkcs.2014.35.6.1692
日期:2014.6.20
efficient one-pot synthesis of 1,3,5-trisubstituted pyrazoles from α,β-enones and arylhydrazinehydrochlorides has been developed. The pyrazoles were formed via a tandem formation of the correspondingpyrazolines and an acid-catalyzed aerobic oxidation process.Key Words : Pyrazoles, One-pot synthesis, Aerobic oxidation, α,β-Enones Introduction1,3,5-Trisubstituted pyrazolines are important heterocycliccompounds
A robust protocol for Pd(ii)-catalyzed C-3 arylation of (1H) indazoles and pyrazoles: total synthesis of nigellidine hydrobromide
作者:Mengchun Ye、Andrew J. F. Edmunds、James A. Morris、David Sale、Yejia Zhang、Jin-Quan Yu
DOI:10.1039/c3sc50184a
日期:——
indazole and pyrazoles are privileged structural motifs in agrochemicals and pharmaceuticals. C-3 C-H arylation of (1H) indazole and pyrazole has been a significant challenge due to the poor reactivity of the C-3 position. Herein, we report a practical Pd(II)/Phen catalyst and conditions for direct C-3 arylation of indazole and pyrazole with ArI or ArBr without using Ag additives as halide scavengers. The
Multicomponent Pyrazole Synthesis from Alkynes, Nitriles, and Titanium Imido Complexes via Oxidatively Induced N–N Bond Coupling
作者:Adam J. Pearce、Robin P. Harkins、Benjamin R. Reiner、Alexander C. Wotal、Rachel J. Dunscomb、Ian A. Tonks
DOI:10.1021/jacs.9b13173
日期:2020.3.4
and pharmaceuticals. Pyrazole synthesis often requires hydrazine or related reagents where an intact N-N bond is conservatively installed into a pyrazole precursor fragment. Herein, we report the multicomponent oxidative coupling of alkynes, nitriles, and Ti imidos for the syn-thesis of multisubstituted pyrazoles. This modular method avoids potentially hazardous reagents like hydrazine, instead forming
吡唑是一类重要的杂环,广泛存在于各种生物活性化合物和药物中。吡唑合成通常需要肼或相关试剂,其中完整的 NN 键保守地安装到吡唑前体片段中。在此,我们报告了炔烃、腈和 Ti 亚氨基的多组分氧化偶联,用于合成多取代吡唑。这种模块化方法避免了潜在危险的试剂,如肼,而是在最后一步通过 Ti 上的氧化诱导耦合形成 NN 键。这种转变的机理已经通过关键的二氮杂钛基环己二烯中间体的化学计量反应进行了深入研究,该中间体可以通过 Ti 亚氨基与腈和炔烃的多组分偶联、2-亚氨基-2H-氮丙啶的开环、或通过 4-氮杂二烯-1-胺衍生物的直接金属化。该反应的关键转变是 Ti 上的 2 电子氧化诱导的 NN 耦合。这是金属中心上正式 NN 耦合的罕见例子,它可能通过类似于纳扎罗夫环化的电循环机制发生。方便的是,这些 2-电子氧化的二氮杂钛基环己二烯中间体可以通过 1-电子氧化物质的歧化获得,这允许利用弱氧化剂,如 TEMPO。
Arylchlorocarbenes in the synthesis of heterocycles containing two nitrogen atoms
作者:Yuri N. Romashin、Michael T. H. Liu、Satnam S. Nijjar、Orazio A. Attanasi
DOI:10.1039/b002940h
日期:——
Substituted pyrazoles and pyrrolo[1,2-c]pyrimidines were prepared from the reaction of arylchlorocarbenes with 1,2-diazabuta-1,3-dienes and 4-vinylpyrimidines, respectively.
Cycloaddition of hydrazones and 1, 2-diarylalkynes promoted by t-BuOK/DMF: A convenient synthesis of tetraarylpyrazoles
作者:Lang Tong、Zhifeng Mao、Xiangzheng Tang、Xuejing Zhang、Ming Yan
DOI:10.1016/j.cclet.2018.06.018
日期:2019.2
Abstract A facile synthesis of tetraarylpyrazoles has been developed via t- BuOK/DMF promoted intermolecular cycloaddition of hydrazones and 1,2-diarylalkynes. A possible reaction pathway via a hydrazone radical is proposed.