The<scp>S</scp>kraup Synthesis of Quinolines

Manske, Richard H. F.; Kulka, Marshall

doi:10.1002/0471264180.or007.02

Cited by 40 publications

(35 citation statements)

References 227 publications

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“…Simultaneouly, the nitro group was reduced to amino group. This intramolecular oxidation-reduction was similar to Skraup reaction, in which nitrobenzene served as the oxidizing agent to remove the hydrogen of dihydroquinoline and itself was reduced to aniline [25]. However, the reaction of 1c and 3-AT afforded the normal product 2c, which is of interest for further investigation.…”

Section: Chemistrymentioning

confidence: 83%

Synthesis and biological evaluation of novel steroidal[17,16-d][1,2,4]triazolo[1,5-a]pyrimidines

Huang

Zheng

et al. 2012

Steroids

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Section: Chemistrymentioning

confidence: 83%

Synthesis and biological evaluation of novel steroidal[17,16-d][1,2,4]triazolo[1,5-a]pyrimidines

Huang

Zheng

et al. 2012

Steroids

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“…(11)) [148] Various types of quinolines have been synthesized for application to pharmaceuticals, dyes, and feed additives. The Skraup synthesis is of great general utility and has been applied to many aromatic amines combined with glycerol or acrolein [149], because the route is straightforward, readily available starting material are used, and the procedure is simple. Reaction of aniline with acetone to yield 1,2-dihydro-2,2,4-trimethylquinoline is a modification of the Skraup synthesis, in which strong acids (pKa < 2) or halogens are used as the catalyst.…”

Section: Alkylation With Estermentioning

confidence: 99%

Catalytic Reactions over Halide Cluster Complexes of Group 5–7 Metals

Nagashima

Kamiguchi

Chihara

2014

Metals

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Halide clusters of Group 5-7 metals develop catalytic activity above 150-250 °C, and the activity is retained up to 350-450 °C by taking advantage of their thermal stability, low vapor pressure, and high melting point. Two types of active site function: the solid Brønsted acid site and a coordinatively unsaturated site that catalyzes like the platinum metals do. Various types of catalytic reactions including new reactions and concerted catalyses have been observed over the clusters: hydrogenation, dehydrogenation, hydrogenolysis, isomerization of alkene and alkyne, and alkylation of toluene, amine, phenol, and thiol. Ring-closure reactions to afford quinoline, benzofuran, indene, and heterocyclic common rings are also catalyzed. Beckmann rearrangement, S-acylation of thiol, and dehydrohalogenation are also catalyzed. Although the majority of the reactions proceed over conventional catalysts, closer inspection shows some conspicuous features, particularly in terms of selectivity. Halide cluster catalysts are characterized by some aspects: cluster counter anion is too large to abstract counter cation from the protonated reactants, cluster catalyst is not poisoned by halogen and sulfur atoms. Among others, cluster catalysts are stable at high temperatures up to 350-450 °C. At high temperatures, apparent activation energy decreases, and hence weak acid can be a catalyst without decomposing reactants. OPEN ACCESSMetals 2014, 4 236

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“…A great deal of investigation has previously shown that the possible formation of 5-and 7-substituted quinolines during the well-known Skraup reaction with m-substituted anilines involves conflicting reports about the composition of the products from certain reactions (26)(27)(28)(29)(30).…”

Section: Introductionmentioning

confidence: 99%

An Efficient Two-step Selective Synthesis of 7-Methyl-8-nitroquinoline From m-Toluidine as a Key Starting Material in Medicinal Chemistry

2013

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Background: A major problem in the development of required chemical compounds in a variety of industries such as pharmaceutical, agricultural, paint and polymer industries is to easily access the chemical starting materials. One class of these materials is quinoline derivatives. Synthesis of these compounds, despite their simple chemical structures is relatively complicated and their synthesis design and purification are challenging. Quinoline derivatives were synthesized and explored for their anticancer, antitinephritic, antitumor, anti-inflammatory and analgesic activity, as antiallergetic agents for treating Alzheimer's disease (AD). Possible formation of 5-and 7-substituted quinolines during the Skraup reaction using m-substituted anilines is well understood. However, there are conflicting reports on the composition of the products from certain reactions. Objectives: As part of our research, we are interested in the development of synthetic strategies for preparation of 7-methyl-8nitroquinoline selectively from a prepared mixture of 5-and 7-methyl quinoline as a key material to study its biological activities as well as to develop other corresponding quinoline derivatives for our research purpose. Materials and Methods: Synthesis and characterization of 7-methylquinoline using the Skraup methodology was reported. A subsequent nitration reaction was also carried out using a mixture of 5-and 7-methylquinoline to obtain pure 7-methyl-8nitroquinoline selectively. In this project, in the first step, a mixture of 7-methylquinoline and 5-methylquinoline was prepared from the reaction of m-toluidine and glycerol. In the next step, 7-methyl-8-nitroquinoline was selectively synthesized and subsequently characterized using conventional methods such as NMR, IR, GC-MS and elemental analysis. Results: The compound 7-methyl-8-nitroquinoline was selectively synthesized in a two-step reaction with an excellent yield. Conclusions: 7-methyl-8-nitroquinoline as a key starting material was obtained through a two-step synthesis from m-toluidine. Skraup synthesis was employed to produce a mixture of 7-and 5-methylquinoline in a 2:1 ratio, which was then used for a nitration reaction using nitric acid and sulfuric acid without further purification. The final reaction selectively produced 7-methyl-8nitroquinoline with an excellent yield.

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TheSkraup Synthesis of Quinolines

Cited by 40 publications

References 227 publications

Synthesis and biological evaluation of novel steroidal[17,16-d][1,2,4]triazolo[1,5-a]pyrimidines

Synthesis and biological evaluation of novel steroidal[17,16-d][1,2,4]triazolo[1,5-a]pyrimidines

Catalytic Reactions over Halide Cluster Complexes of Group 5–7 Metals

An Efficient Two-step Selective Synthesis of 7-Methyl-8-nitroquinoline From m-Toluidine as a Key Starting Material in Medicinal Chemistry

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