24090-98-0Relevant articles and documents
Sequential [3+2] annulation reaction of prop-2-ynylsulfonium salts and hydrazonyl chlorides: Synthesis of pyrazoles containing functional motifs
Jia, Tingting,Liu, Shourong,Shao, Jiaan,Shi, Tao,Wu, Zhaoxiao,Zeng, Linghui,Zhang, Chong,Zhang, Jiankang,Zhu, Huajian,Zhuang, Rangxiao
supporting information, p. 8460 - 8463 (2021/09/08)
A novel sequential [3+2] annulation reaction has been developed using prop-2-ynylsulfonium salts and hydrazonyl chlorides, affording a series of pyrazoles with functional motifs that can be post modified in the preparation of various drugs or drug candidates. Further transformation and gram-scale operations could also be achieved efficiently. This journal is
The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- And 1,3,4,5-tetrasubstituted pyrazoles
Duan, Liancheng,Zhou, Hui,Gu, Yucheng,Gong, Ping,Qin, Mingze
supporting information, p. 16131 - 16137 (2019/11/03)
In the present work, an efficient regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles via a methanesulfonic acid (MSA)-catalyzed reaction of hydrazones with enaminones or enamines is reported. Mechanistically, the formation of the title compounds involves the [2+3] cycloaddition of hydrazones with enaminones or enamines followed by aromatization with acid and oxygen. This convenient method under mild conditions with various hydrazones, enaminones, and enamines was well-tolerated to afford products in good to excellent yields. Compared with the literature methods, this strategy has advantages such as materials that are available economically, metal-free catalysis, excellent regioselectivity, and high efficiency.
Facile One-Pot Transformation of Primary Alcohols into 3-Aryl- and 3-Alkyl-isoxazoles and -pyrazoles
Kobayashi, Eiji,Togo, Hideo
, p. 3723 - 3735 (2019/09/30)
Various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylisoxazoles in good yields in one pot by successive treatment with PhI(OAc) 2 in the presence of TEMPO, NH 2 OH, and then NCS, followed by reaction with alkynes in the presence of Et 3 N. Similarly, various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylpyrazoles in good yields in one pot by successive treatment with PhI(OAc) 2 in the presence of TEMPO, PhNHNH 2, and then NCS and decyl methyl sulfide, followed by reaction with alkynes in the presence of Et 3 N. Thus, both 3-aryl- and 3-alkylisoxazoles, and 3-aryl- and 3-alkylpyrazoles could be prepared from readily available primary alcohols in one pot under transition-metal-free conditions.
Synthesis, characterization and density functional theory study of low cost hydrazone sensitizers
Al-Sehemi, Abdullah G.,Irfan, Ahmad,Asiri, Abdullah M.,Ammar, Yousry Ahmed
, p. 137 - 148 (2015/01/30)
The 2-{4-[2-benzylidenehydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 1), 2-{4-[2-(1- naphthylmethylene)hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 2) and 2-{4-[2-(9-anthrylmethylene)- hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 3) were synthesized by direct tricyanovinylation of hydrazones. The bathochromic shift in absorption spectra has been observed by increasing the solvent polarity. The FTIR spectra of these new dyes exhibited three important absorption bands. The first band centered near 3260 cm-1 in System 1 while 3208 cm-1 and 3211 cm-1 in System 2 and System 3 for the vNH absorption, respectively. The second band is a sharp absorption band in the region of 2212-2209 cm-1, which was attributed to the cyano group absorption. The third is an absorption band in the region of 1611-1603 cm-1 ascribed for the C=N. Density functional theory (DFT) calculation of relative energies, relative enthalpies and free energies shows that E isomers are the most stable except System 3 in which the most stable is Z isomers. The conformational energy profile shows two maxima near (-90 and 90°) while three local minima observed at (-180, 0 and 180) for N1-N2-C1-C2 torsional angle. The highest occupied molecular orbitals (HOMOs) are localized on the whole molecules while lowest unoccupied molecular orbitals (LUMOs) are distributed on the tricarbonitrile.
Fast hydrazone reactants: Electronic and acid/base effects strongly influence rate at biological pH
Kool, Eric T.,Park, Do-Hyoung,Crisalli, Pete
supporting information, p. 17663 - 17666 (2014/01/06)
Kinetics studies with structurally varied aldehydes and ketones in aqueous buffer at pH 7.4 reveal that carbonyl compounds with neighboring acid/base groups form hydrazones at accelerated rates. Similarly, tests of a hydrazine with a neighboring carboxylic acid group show that it also reacts at an accelerated rate. Rate constants for the fastest carbonyl/hydrazine combinations are 2-20 M-1 s-1, which is faster than recent strain-promoted cycloaddition reactions.
A prototype continuous-flow liquid-liquid extraction system using open-source technology
O'Brien, Matthew,Koos, Peter,Browne, Duncan L.,Ley, Steven V.
body text, p. 7031 - 7036 (2012/10/08)
A prototype continuous-flow liquid-liquid extraction system is reported. By harnessing several open-source software libraries, a computer control script was written using the Python programming language. Using a 'computer-vision' approach, this allowed the computer to monitor the interface level between the organic and aqueous phases using a simple webcam setup and (by dynamically controlling pump flow rate) to keep this interface within defined limits. The system enabled the efficient 'inline' extraction of excess reagent in hydrazone formations, dithiane formations and epoxidations. The initial results of dispersion measurement are also presented.
Kinetics and Mechanism for the Formation of Phenylhydrazone from Benzaldehydes, Naphthaldehydes, and Formyl-1,6-methanoannulenes
Somera, Neusa M.,Stachissini, Antonia S.,Amaral, Antonia T. do,Amaral, Luciano do
, p. 1717 - 1722 (2007/10/02)
Formation of phenylhydrazone from benzaldehyde, 4-chlorobenzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde, 2-formyl-1,6-methanoannulene, and 3-formyl-1,6-methanoannulene in 50percent aqueous ethanol (v/v) at 25.0 deg C and ionic strength 0.20M occurs in two steps, (i) the formation of an aminomethanol intermediate and (ii) the dehydration of aminomethanol to give the products of reaction.Formation of the aminomethanol is the rate-determining step above pH 5-6.Both the reactions are subject to hydronium ion catalysis.The values of the catalytic constant are very similar with all the aldehydes.Formation of aminomethanol is subject to general acid catalysis by carboxylic acid.The α Bronsted exponents for catalysis of the intermediate formation reaction for the formyl-1,6-methanoannulenes are higher than those for the benzaldehydes and smaller than those for naphthaldehydes.Comparison of the general behaviour of the formyl-1,6-methanoannulenes with the benzaldehydes and naphthaldehydes provides strong evidence of the aromatic character of 1,6-methanoannulene ring.
