Cyclization of 2- and 3-indolythioalkanoic acids to novel indole-containing tricyclic ring systems

A series of 2- and 3-indolylthioalkanoic acids of various chain lengths were cyclized under dehydrative conditions affording tricyclic indole-containing ring systems wherein the third ring contains a sulfur atom attached to the 2- or 3-position of the indole ring. This methodology affords entry into the novel thiepino[3,2-b]indole, thiocino[2,3-b]indole and thiocino[3,2-b]indole ring systems.     

Thiophene systems. 11. The synthesis of novel thieno[4,3,2-de] tricyclic ring systems

The synthesis of thieno[4,3,2-de] tricyclic compounds is described. The N-1 alkylation of I produced the alkanoic ester precursors. After hydrolysis, the corresponding carboxylic acids were cyclized to the title compounds II . This cyclization step was accomplished with 1:10 phosphorus pentoxide-methanesulfonic acid. The ketones II were further modified to introduce additional functionality onto this novel tricyclic ring system.     

Some novel quinone-type dyes containing naphthoquinone and related fused ring systems

A variety of 1,4-thiazines, thiazoles, 1,4-dithines and 2,2′-bithiazoles containing fused naphthoquinone and related rings have been prepared. The compounds include several novel chromophoric heterocyclic system and their visible absorption spectra are discussed.     

Synthesis and antitumor activity of novel pyridazinone derivatives containing 1,3,4-thiadiazole moiety

Abstract

A series of novel pyridazinone derivatives containing the 1,3,4-thiadiazole moiety were synthesized and characterized by ¹H NMR, 13C NMR, spectroscopies HRMS and IR. Among them, the structure of compound 5c (2-(Tert-butyl)?4-chloro-5-((5-((2-ethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was unambiguously confirmed via single crystal X-ray diffraction analysis. The inhibitory activity of all the target compounds against MGC-803 and Bcap-37 was determined by MTT assay, with doxorubicin (the inhibition rates were 95.5?±?0.4% and 95.7?±?1.0% respectively) as a control. The preliminary results showed that the inhibitory activity of compound 5n (2-(Tert-butyl)?4-chloro-5-((5-((3-fluorophenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was superior to the others. The inhibition rates of MGC-803 and Bcap-37 cells were 86.3?±?2.2% and 92.3?±?0.6% at a concentration of 10?μmol/L, respectively. The preliminary structure-activity relationship showed that when the 2-position of the benzene ring was substituted by a methyl group, such as compound 5j (2-(Tert-butyl)?4-chloro-5-((5-((2,3-dimethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), it exhibited good anticancer activity on MGC-803 cells. Besides, introducing fluorine, chlorine, or trifluoromethyl group onto the benzene ring, such as compound 5?m (2-(Tert-butyl)?4-chloro-5-((5-((4-(trifluoromethoxy)phenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), displayed good anticancer activity on MGC-803 and Bcap-37 cells.     

Some reactions of systems containing the imidazole ring

Behavior towards sodamide is compared for 3-benzyl- and 3-methyl substituted naphth [1, 2-d] imidazole and imidazo [4, 5-f] quinoline derivatives. The following are synthesized: 2-amino derivatives of 3-benzylnaphtho- [1, 2-d] imidazole(by direct animation), and of 3-benzylimidazo [4, 5-f] quinoline (ammonolysis of a 2-chloro substituted compound).     

Synthesis of new tricyclic ring systems containing the pyrimido[5, 4-b][1, 4]oxazine skeleton

Synthesis of derivatives 4 and 6 of two novel tricyclic ring systems, 1, 2, 4-triazolo[3, 4-c]pyrimido[5, 4-b]-[1, 4]oxazine and imidazo[1, 2-c]pyrimido[5, 4-b][1, 4]oxazine, respectively is described. Although the parent pyrimido[5, 4-b]oxazines possess positive inotropic activity, the tricyclic compounds are practically inactive.     

Preparation of some tricyclic fused ring iminopyrido[3,2-e]pyrimidines

The preparation of a number of tricyclic fused ring iminopyrido[3,2-e]pyrimidines is described. Treatment of 2-chloronicotinonitrile with primary amines afforded the corresponding 2-amino derivative which was condensed with ethylenediamine or higher congeners to give substituted cyclic amidines. The latter on treatment with cyanogen bromide gave the desired imino-pyrido[3,2-e]pyrimidines. The preparation of diaminopyrido[2,3-d]pyrimidines and tricyclic quinazolines by related procedures is discussed.     

Synthesis of steroid compounds containing a pyridazinone moiety

Russian Chemical Bulletin - The reaction of 17-ketosteroids and glyoxylic acid followed by treatment with hydrazine affords steroid compounds condensed in the 16 and 17 positions with the...     

Transformations of bicyclic systems containing an isothiazole ring

Isothiazolium salts, which are readily hydrolyzed to heterocyclic o-formyl disulfides, were obtained by alkylating bicyclic systems containing an isothiazole ring. The initial isothiazole-containing systems are stable in water and react with nucleophiles such as the hydroxyl ion with opening of the isothiazole ring and formation of o-cyanodisulfides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 223–226, February, 1985.     

The synthesis of novel dipyridazinothiazine ring systems

The synthesis of several dipyridazinothiazines have been accomplished by: (a) cyclization in concentrated hydrochloric acid solution of the appropriate intermediates; and (b) via the Smiles rearrangement in either basic or glacial acetic acid solution of the appropriate intermediates. The following ring systems have been prepared and characterized: 10H-dipyridazino-[4,3-b:4′,5′-e]-1,4-thiazine, 5H-dipyridazino[3,4-b:4′,5′-e]-1,4-thiazine, 10H-dipyridazino[4,5-b:-4′,5′-e]-1,4-thiazine, 5Hdipyridazino[5,4-b:4′,3′-e]-1,4-thiazine, and 10H-dipyridazino[3,4-b:-3′,4′-e]-1,4-thiazine.     

Design,synthesis, and bioactivities of novel pyridazinone derivatives containing 2-phenylthiazole or oxazole skeletons

A series of novel pyridazinone derivatives were designed and synthesized by replacing 4-(tert-butyl)phenyl moiety of pyridaben with 2-phenylthiazole or oxazole fragments via activity substructure connecting approach. The structures of all target compounds were characterized through NMR, MS, and elemental analysis. Bioassay results exhibit that most compounds showed potent bioactivities against Aphis fabae, Tetranychus urticae, Erysiphe graminis, and/or Puccinia polysora. Among the newly synthesized compounds, 2-(tert-butyl)-4-chloro-5-(((2-phenylthiazol-4-yl)methyl)thio)pyridazin-3(2H)-one ( 12b ) displays remarkable insecticidal activity against A fabae. Its LC₅₀ value (2.73 mg/L) is better than that of pyridaben (5.46 mg/L), although inferior to that of imidacloprid (0.51 mg/L). In addition to its extraordinary insecticidal activity, compound 12b also exerts 96.9% fungicidal activities against P polysora at 500 mg/L in vivo, significantly superior to that of pyridaben (50.0%), while slightly lower than that of tebuconazole (100%). This article discusses the synthesis, bioassay results, and structure-activity relationship of this series of novel pyridazinone derivatives.     

A novel approach to functionalised pyridazinone arrays

A series of 3,6-dichloro-1H-pyridazin-4-ones have been prepared via the cycloaddition of 3,6-dichlorotetrazine with alkynylboronates, and their employment as useful synthetic intermediates was highlighted through a selection of highly regioselective C-O, C-S and C-C bond forming reactions.     

Synthesis of adenosine-based fluorosides containing a novel heterocyclic ring system

A novel class of fluorescent adenosine derivatives (fluorosides) containing the previously unreported 8-(3H-[1,2,3]triazol-4-yl)-9H-purine heterocyclic ring system is reported, with Sonogashira cross-coupling and [3+2]-cycloaddition reactions being the key steps in the synthesis.