Synthesis and reactivity of thieno[2,3-b]quinoline derivatives (Part II)

As a continuation of our previous review entitled “Vilsmeier-Haack cyclisation as a facile synthetic route to thieno[2,3-b]quinolines (Part I).” This review describes the methods of preparation and the chemical reactivity of thieno[2,3-b]quinolines, which might show interesting biological activities.     

Recent progress on the chemistry of thieno[3,2-b]quinoline derivatives (part III)

This review describes the methods of preparation and the chemical reactivity of thieno[3,2-b]quinolines.     

1H-pyrazolo[3,4-d]thieno[2,3-b]pyridine and its derivatives

The synthesis of the parent ring system and some of the derivatives of 1H-pyrazolo[3,4-d]thieno[2,3-b]pyridine are described.     

A simple synthesis of thieno[2,3-b]pyrazine and thieno[2,3-b] pyridine

A facile synthesis of thieno[2,3-b]pyrazine (1) and thieno[2,3-b]pyridine (9) is reported. Furthermore, convenient preparations of a variety of synthetically useful compounds derived from these ring systems is also presented.     

Facile and convenient synthesis of new thieno[2,3-b]-thiophene derivatives

A facile and convenient synthesis of bis(2-(1H-benzo[d]imidazol-2(3H)-ylidene)-3-oxopropanenitrile), bis((3-amino-5-(methylthio)-1H-pyrazol-4-yl)methanone) and bis(2-thioxo-1,2-dihydropyrimidine-5-carbonitrile) derivatives incorporating a thieno- [2,3-b]thiophene moiety via versatile, readily accessible diethyl 3,4-dimethylthieno-[2,3-b]thiophene-2,5-dicarboxylate is described.     

Characteristic ortho-methoxycarboxylate fragmentation of yerrinquinone and its derivatives on electron impact

Mass Spectrometry of a natural product, yerrinquinone, isolated from fungal-infested Diospyros montana, and isomeric 1-tetralonecarboxylates has revealed fragmentation pathways characteristic of a methoxy group flanked by a carboalkoxy and a carbonyl group.     

General synthesis of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) derivatives

A new straightforward synthesis of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) derivatives from readily available 2-methoxynaphthalenes is described. Thus, newly developed derivatives of DNTT showed very high field effect mobility in the vapor-processed field-effect transistors up to 8 cm(2) V(-1) s(-1).     

Nitriles in heterocyclic synthesis: A novel synthesis of some thieno[2,3-d]pyrimidine and thieno[2,3-b]pyridine derivatives

A simple route to the synthesis of the pharmaceutically important thieno[2,3-d]pyrimidine derivatives and of thieno[2,3-b]pyridine derivatives via the use of 5-amino-3-phenylthiophene-2,4-dicarbonitrile (2) as a starting material is described. © 1996 John Wiley & Sons, Inc.     

The fragmentation of isotetronic acids under electron impact

The mass spectral fragmentation of eleven α-hydroxybutenolide compounds (isotetronic acids) are reported. The main features are carboxyl and consecutive carbon monoxide expulsions. Masses were determined using high resolution techniques, metastable transitions were detected by defocusing experiments, and pathways were further documented by isotopic labelling experiments.     

The fragmentation of 2-aminooxazoles under electron impact

The 70 eV electron impact mass spectra of six 2-aminooxazoles are discussed in detail with the aid of exact mass measurements, metastable ion detection in the defocused mode and labelling experiments. The fragmentation is markedly influenced by strong electron donating substituents at the 2-position. Some 2-acetylamino and 2-diacetylamino derivatives have also been considered, which lose ketene from [M]⁺? giving the corresponding aminooxazole molecular ions. The mass spectral behaviour is peculiar and the most important differences between the fragmentation pathways of these compounds and those reported in the literature for oxazole (alkyl and aryl) derivatives are outlined. The mass spectrum of 4-methyl-5-phenylimidazol-2-one is compared with that of the isomeric 4-methyl-5-phenyl-2-aminooxazole.     

DIPEA catalyzed step-by-step synthesis and photophysical properties of thieno[2,3-b]pyridine derivatives

A series of novel 5,6-disubstituted ethyl 3-amino-4-cyanothieno[2,3-b]pyridine-2-carboxylates was synthesized. The reaction conditions were thoroughly studied and intermediate ethyl 2-((3,4-dicyanopyridin-2-yl)thio)acetates were successfully isolated in good yields. For all synthesized compounds, spectral-fluorescent properties were carefully investigated and correlation thereof with chemical structure was found.     

Mass spectra of isomeric thieno [2,3-b]- and thieno[3,2-b]pyridines

The mass spectra of six isomeric thieno- and thionaphthenopyridines were studied for the first time, and the pathways of fragmentation of the molecular ions, which made it possible to isolate the peaks of the fragment ions that characterize the destruction of the pyridine and thiophene rings, were traced. It is shown that the character and type of conjugation of the heterorings can be distinguished by analyzing the mass-spectral data. The relationship between the intensity of the peak of the doubly charged molecular ion and the number of electrons in the system and the -donor character of the heteroring was illustrated by means of the literature data on the mass spectrometry of heteroaromatic systems with one heteroatom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 758–761, June, 1982.     

Utilization of potassium carbonate for the synthesis of 2-(organylsulfonyl)thieno[2,3-b]pyridine derivatives

Russian Chemical Bulletin - A novel preparative method for the synthesis of 2-(organylsulfonyl)thieno[2,3-b]pyridine derivatives has been developed, which allows one to obtain the desired products...     

The fragmentation behaviour of some spirobenzthiazoles under electron impact

The electron impact induced fragmentations of ten spiro-benzthiazoles have been studied. The principal decomposition reactions have been elucidated by metastable studies, exact mass measurements, and by deuterium exchange of the imino hydrogen. The primary fragmentation step is an α-cleavage reaction, which leads to ring opening of the ring fused to the benzthiazole moiety of the molecule. The subsequent decompositions resemble those of cyclohexylamines. They follow a general pattern, the details of which are discussed with respect to the nature and position of the heteroatom in the saturated ring.     

The synthesis of benzofuroquinolines. I. Some benzofuro[2,3-b]quinoline and benzofuro[3,2-c]quinoline derivatives

Benzofuro[2,3-b]quinoline ( Ia ) and its 11-methyl derivative ( Ib ) were synthesized by demethylcyclization of 3-(o-methoxyphenyl)-1,2-dihydroquinolin-2-ones (VIa,b). Benzofuro[2,3-b]quinoline-11-carboxylic acid (Id) was synthesized by chlorination followed by the action of potassium hydroxide of a lactone (IX) prepared by demethyl-cyclization of 3-(o-methoxyphenyl)-2-oxo-1,2-dihydroquinoline-4-carboxylic acid (VIII). Isomeric benzofuro[3,2-c]quinoline (Ha) and its 6-methyl derivative (IIb) were synthesized by demethyl-cyclization of 3-(o-methoxyphenyl)-1,4-dihydroquinolin-4-ones (XIa,b). Both the methyl derivatives (Ib and IIb) were converted to the carboxylic acids (Id and IId) through condensation with benzaldehyde followed by oxidation. The benzofuroquinolines (Ia,b,d and IIa,b) thus obtained were oxidized to the corresponding N-oxides (IIIa,b,d and IVa,b).     

Recent approaches to the synthesis of thieno[2,3-b]pyridines (microreview)

Chemistry of Heterocyclic Compounds - This microreview describes recent approaches to the synthesis of thieno[2,3-b]pyridine derivatives. Selected works published in 2015–2019 are reviewed.     

Photochemical properties of 2,2′-biquinoxalyl and thieno[2,3-b:4,5-b′]biquinoxalyl

2,2-biquinoxyalyl and thieno[2,3-b:4,5-b]biquinoxyalyl can be photoreduced in acidified alcoholic solutions and in aqueous solutions of acids. Quantum yields of the photochemical reaction have been determined. The fluorescence and phosphorescence spectra of these compounds have been recorded and the fluorescence quantum yields have been determined. A mechanism of the photoreduction has been proposed.

---

Photochemische Eigenschaften von 2,2-Bichinoxalyl und Thieno[2,3-b:4,5-b]bichinoxalyl

Zusammenfassung 2,2-Bichinoxalyl und Thieno[2,3-b:4,5-b]bichinoxalyl unterliegen photochemischer Reaktion in angesäuerten Alkohollösungen und in wäßrigen Säurelösungen. Es wurde die photochemische Quantenausbeute bestimmt. Außerdem wurden die Fluoreszenz- und Phosphoreszenz-Spektren aufgezeichnet und die Fluoreszenz-Quantenausbeuten bestimmt. Zugleich wurde ein Mechanismus zur Photoreduktion vorgeschlagen.

     

Indole and quinoline derivatives of 2,3-dihydro-l-benzothiepin-4(5H) one

By application of the Friedlander synthesis on 2,3-dihydro-l-benzothiepin-4(5H) one (4), the corresponding [4,5-b]quinoline derivatives 5a and 5b were obtained. Starting from the ketone (4) and by application of the Fischer indole synthesis, 1-benzolhiepino[4,5-b ]indole (6) and 1-benzothiepino[4,5-b]benzo[g]indole (7) were obtained. When β-naphthylhydrazine was used in the indolisation reaction, a mixture of 1-benzothiepino[4,5-b]benzo[e]indole ( 8 ) and 1-benzothiepino[4,3-b]benzo[e] indole (9) was obtained.