Ring-contraction of hantzsch esters and their derivatives to pyrroles <i>via</i> electrochemical extrusion of ethyl acetate out of aromatic rings
作者:Xu Liu、Chang Liu、Xu Cheng
DOI:10.1039/d1gc00487e
日期:——
ring-contraction of HEs and theirs pyridinederivatives is developed to obtain polysubstituted pyrroles. This process provides an orthogonal utilization of Hantzsch esters for the well-documented application as side chain or hydrogen donors. The formal transformation shows an extrusion of ethyl acetate out of the pyridine ring in a single step. In addition to the novel transformation, we also discovered the Lewis
<b>Aromatization of Hantzsch 1,4-Dihydropyridine with Bismuth(III) Chloride Supported onto Wet HZSM-5 Zeolite Under Microwave Irradiation in Solventless System</b>
作者:Majid M. Heravi、Mitra Ghassemzadeh
DOI:10.1080/104265090508415
日期:2005.2
Abstract Hantzsch1,4-dihydropyridines (1,4 DHPs) can be aromatized to pyridines by bismuth(III) chloride supported onto wet HZSM-5 zeolite under microwave irradiation in high yields and in a short time.
Iodoxybenzoic Acid (IBX): An Efficient and Novel Oxidizing Agent for the Aromatization of 1,4-Dihydropyridines
作者:J. S. Yadav、B. V. Reddy、A. K. Basak、G. Baishya、A. Venkat Narsaiah
DOI:10.1055/s-2005-918519
日期:——
Hantzsch 1,4-dihydropyridines undergo smooth aromatization catalyzed by iodoxybenzoic acid (IBX) to afford the corresponding pyridine derivatives in high yields. All the reactions were carried out in DMSO solvent at 80-85 °C for a period of two to four hours to complete conversion of the substrates.
Old reagents, new results: Aromatization of Hantzsch 1,4-dihydropyridines with manganese dioxide and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
作者:Jean Jacques Vanden Eynde、Florence Delfosse、Annie Mayence、Yves Van Haverbeke
DOI:10.1016/0040-4020(95)00318-3
日期:1995.6
Hantzsch1,4-dihydropyridines are readily oxidized by manganese dioxide or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in dichloromethane at room temperature. With manganese dioxide loss of the 4-substituent, in addition to aromatization, occurs when it is a secondary alkyl or a benzylic group and sonication significantly reduces the reaction times. In contrast, loss of the 4-substituent is never
Aromatization of 1,4-dihydropyridines in the presence of methanesulfonic acid/NaNO<sub>2</sub>/wet SiO<sub>2</sub>under both heterogeneous and solvent free conditions
作者:Khodabakhsh Niknam、Seyed Mehdi Razavian、Mohammah Ali Zolfigol、Iraj Mohammahpoor-Baltork
DOI:10.1002/jhet.5570430131
日期:2006.1
A combination of methanesulfonic acid and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of 1,4-dihydropyridines to the corresponding pyridine derivatives under mild and heterogeneousconditions in excellent yields.