Cu<sub>1.5</sub>
PMo<sub>12</sub>
O<sub>40</sub>
-catalyzed condensation cyclization for the synthesis of substituted pyrazoles
作者:Guo-Ping Yang、Xing He、Bing Yu、Chang-Wen Hu
DOI:10.1002/aoc.4532
日期:2018.11
A convenient and direct approach has been developed for the preparation of pyrazole derivatives by the condensationcyclization of hydrazines/hydrazide and 1,3‐diketones in the presence of Cu1.5PMo12O40 (0.33 mol%) under mild conditions (r.t.‐60 °C, 10–30 min). Notably, the reaction was found to be scalable as 99% yield was obtained when the reaction was performed at a 5‐mmol scale. This solvent‐free
在温和的条件下(rt-60),在Cu 1.5 PMo 12 O 40(0.33 mol%)存在下,通过肼/酰肼和1,3-二酮的缩合环化反应,已经开发了一种方便直接的方法来制备吡唑衍生物。°C,10–30分钟)。值得注意的是,当反应在5 mmol规模下进行时,发现该反应可扩展,产率为99%。这种无溶剂和无卤素的催化体系代表了吡唑的一种有效的经济和环保方法。
Cellulose sulfuric acid as a bio-supported and efficient solid acid catalyst for synthesis of pyrazoles in aqueous medium
作者:Mohammad Ali Nasseri、Mehri Salimi、Abbas Ali Esmaeili
DOI:10.1039/c4ra11440j
日期:——
A convenient and practical method was described for the regioselective synthesis of pyrazoles from hydrazines/hydrazides and 1,3-dicarbonyl compounds via the Knorr synthesis in water with cellulose sulfuricacid (CSA) as a biopolymer-based solidacidcatalyst. Various hydrazines and hydrazides were reacted with 1,3 diketones and the desired pyrazoles were obtained in high yields. The reaction of less
A mild and efficient method for halogenation of 3,5-dimethyl pyrazoles by ultrasound irradiation using N-halosuccinimides
作者:Hélio A. Stefani、Claudio M.P. Pereira、Roberta B. Almeida、Rodolpho C. Braga、Karla P. Guzen、Rodrigo Cella
DOI:10.1016/j.tetlet.2005.08.027
日期:2005.10
The 4-halo-3,5-dimethyl pyrazoles have been synthetisized in good yields in short reaction times in the absence of a catalyst by reaction of 3,5-dimethyl pyrazoles with N-halosuccinimides (NBS, NCS and NIS) under ultrasound irradiation. Finally, the halogenation of pyrazoles with Br2, ICl and I2 was showed in similar conditions.
Magnetic Nanoparticle-Supported Glutathione as a Sustainable Organocatalyst
申请人:Varma Rajender S.
公开号:US20110054180A1
公开(公告)日:2011-03-03
This invention relates to the use of nano-organocatalysts, and, more specifically, to the use of magnetic nanomaterial-supported organocatalysts. It is an object of the present invention to provide “green” catalysts and protocols. According to one embodiment of the invention, a nano-organocatalyst in the form of a magnetic nanomaterial-supported organocatalyst is provided. According to other embodiments of the invention, glutathione and cysteine are provided as organocatalysts and magnetic nanomaterial-supported glutathione and magnetic nanomaterial-supported cysteine are provided for use as nano-organocatalysts. According to another embodiment of the invention, a method of using a recyclable magnetic nanomaterial-supported organocatalyst using a totally benign aqueous protocol, without using any organic solvent in the reaction or during the workup, is provided. According to a further embodiment of the invention, a recyclable magnetic nanomaterial-supported organocatalyst for various organocatalytic reactions, including but not limited to Paal-Knorr reactions, aza-Michael addition and pyrazole synthesis, is provided.
A mild halogenation of pyrazoles using sodium halide salts and Oxone
作者:Kathryn L. Olsen、Matthew R. Jensen、James A. MacKay
DOI:10.1016/j.tetlet.2017.09.042
日期:2017.10
A mild, inexpensive, and operationally simple pyrazole halogenation method utilizing Oxone and sodium halide salts is reported. This work documents 17 examples of alkyl, aryl, allyl, and benzyl substituted 4-chloro and 4-bromopyrazoles, obtained in up to 93% yield. Reactions are performed in water under ambient conditions and generation of organic byproducts is avoided.