Condensed Heterocycles; Xl. Synthesis of 1,2,5-Thia(selena)diazolo[3,4-<i>b</i>]quinolines and 1,2,5-Thia(selena)diazolo[3,4-<i>h</i>]quinolines

Sharma, Komal; Kumari, S.; Singh, Ram Phul

doi:10.1055/s-1981-29435

Cited by 33 publications

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“…2-Chloro-3-nitroquinoline (13) was prepared from quinoline in three steps. 23 This intermediate was subjected to the same chemical transformation sequence as for the previously described 2-chloro-3-nitropyridine (6). Suzuki coupling with phenylboronic acid led almost quantitatively to the desired 3-nitro-2-phenylquinoline (14).…”

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confidence: 99%

First Synthesis of Benzopyridoiodolium Salts and Twofold Buchwald-Hartwig Amination for the Total Synthesis of Quindoline

Letessier¹,

Detert²

2011

Synthesis

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The first synthesis of cyclic benzopyridoiodolium salts is described. These hypervalent iodine intermediates are used in an efficient strategy for the construction of the d-carboline core. This novel approach involves a twofold palladium-catalyzed BuchwaldHartwig reaction between these unprecedented reagents and a primary amine. Our methodology successfully provides the expected N-substituted d-carboline core and is efficiently applied in the total synthesis of quindoline.Pyrido [x,y-b]indoles, better known under the common name carbolines, are divided into four different classes according to the position of the nitrogen atom in the pyridine ring. Whereas a large group of alkaloids is based on the bcarboline core, 1,2 d-carbolines belong to a much less represented group of pyridoindoles, in nature as well as in synthetic chemistry.A small number of d-carbolines have been isolated from natural sources, they are all benzo-fused and also known as quindolines 3 1-5 ( Figure 1). All these indolo[3,2-b]quinolines were extracted from Cryptolepis Sanguinolenta and Justica betonica, two indigenous plants from west Africa and India. Extracts of these plants are used in the dyeing of leather and textiles, as well as in traditional medicine in West and Central Africa, including the treatment of malaria, and infections of the respiratory and urinary tracts. 3,4 Recently, we reported that b-and g-carbolines can be efficiently synthesized via rhodium-or ruthenium-catalyzed [2+2+2] cycloadditions of nitriles to alkynyl-ynamides. 5 However, this synthetic strategy does not allow the synthesis of the isomeric a-and d-carbolines.Only a few synthetic strategies for the construction of the d-carboline core are described the literature. One of the first applied synthetic routes is based on the GraebeUllmann reaction. 6 Similarly to the synthesis of carbazoles, 1-pyridin-3-yl-1H-1,2,3-benzotriazoles are used as intermediates to obtain d-carboline derivatives. Other strategies are based on the combination of two palladiumcatalyzed reactions: an amination reaction of halogenobenzenes with b-aminopyridines followed by ring closure. 7-10 Herein we report the synthesis of a new class of iodolium heterocycles and their application in a novel strategy to construct the d-carboline core.As part of our interest in carbazoles and related heterocycles, 1,11 we applied Olofsson and Merritt's synthesis of diaryliodonium triflates 12 to the preparation of dibenzoiodolium salts. 13 The oxidation of an o-iodobiphenyl with m-chloroperoxybenzoic acid to an iodoso derivative followed by protonation with triflic acid results in remote functionalization of the o¢-position, giving the desired dibenzoiodolium salt with non-nucleophilic triflate as an anion. N-Substituted carbazoles are obtained in twofold palladium-catalyzed aminations with primary amines. 13Applying this methodology to 3-iodo-2-phenylpyridine (9), we were able to obtain benzopyridoiodolium triflate 10. To the best of our knowledge, these are the first examples of aza-analogous benzoiodoli...

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First Synthesis of Benzopyridoiodolium Salts and Twofold Buchwald-Hartwig Amination for the Total Synthesis of Quindoline

Letessier¹,

Detert²

2011

Synthesis

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“…In the course of studies aimed at development of new reactions of heterocyclic N -oxides 6 we had to prepare multigram quantities of various compounds of this class. A survey of the literature showed that current approaches to heterocyclic N -oxides are largely limited to stoichiometric oxidations by peroxyacids, either generated in situ from large excess of hydrogen peroxide in acetic or trifluoroacetic acids at elevated temperatures, 7 or as a commercially available reagent ( e.g. meta -chloroperbenzoic acid).…”

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confidence: 99%

Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles

et al. 2014

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A Mo/P catalytic system for an efficient gram-scale oxidation of a variety of nitrogen heterocycles to N-oxides with hydrogen peroxide as terminal oxidant has been investigated. Combined spectroscopic and crystallographic studies point to the tetranuclear Mo4P peroxo complex as one of the active catalytic species present in the solution. Based on this finding an optimized catalytic system has been developed. The utility and chemoselectivity of the catalytic system has been demonstrated by the synthesis of over 20 heterocyclic N-oxides.

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“…In our continuous effort to develop new chemotherapeutics with enhanced activities against resistant bacterial strains 17,18 , we introduced a new class of tricyclic compounds, namely thiadiazoloquinolones 19 . In our methodology, we took advantage of many known benzothiadiazoles ( Figure 2) with diverse biopharmaceutical activities [20][21][22][23][24][25][26] and we hybridized the thiadiazole moiety with the fluoroquinolone structure to introduce the new compound 9-cyclopropyl-4-fluoro-6-oxo-6,9-dihydro [1,2,5]thiadiazolo [3,4-h]quinoline carboxylic acid (16). The latter compound was tested against several clinical isolate bacterial strains and did prove to be quite active compared to the drugs used in the market 19 .…”

Section: Introductionmentioning

confidence: 99%

Design synthesis and antibacterial activity studies of new thiadiazoloquinolone compounds

Al‐Qawasmeh

Abadleh

Zahra

et al. 2014

Journal of Enzyme Inhibition and Medicinal Chemistry

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New 9-(alkyl/aryl)-4-fluoro-6-oxo [1,2,5]thiadiazolo [3,4-h]quinoline-5-carboxylic acids and their esters were designed and synthesized. A detailed discussion of the reactions utilized in the preparation of the intermediate and target compounds is reported. All the newly synthesized compounds were fully characterized using all the physico-chemical means needed. All the intermediates and the final esters and acids were tested against bacterial and fungal strains. The acids 25a and 25c proved to be very active against Gram positive and Gram negative bacteria with MIC 0.15-3 mg/mL. The structure-activity relationship of antibacterial thiadiazoloquinolones shows that compounds 25a and 25c are twice less potent than the corresponding cyclopropyl derivative 16. Therefore, the cyclopropyl moiety on N-9 seems to be the most suitable substituent.

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Condensed Heterocycles; Xl. Synthesis of 1,2,5-Thia(selena)diazolo[3,4-b]quinolines and 1,2,5-Thia(selena)diazolo[3,4-h]quinolines

Cited by 33 publications

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First Synthesis of Benzopyridoiodolium Salts and Twofold Buchwald-Hartwig Amination for the Total Synthesis of Quindoline

First Synthesis of Benzopyridoiodolium Salts and Twofold Buchwald-Hartwig Amination for the Total Synthesis of Quindoline

Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles

Design synthesis and antibacterial activity studies of new thiadiazoloquinolone compounds

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