3-Amino-1-[2-(2-ethoxyethoxy)ethoxy ] benzo[∫]quinazoline

The structure of an anomalous product, isolated as a companion substance during the catalytic dehydrogenation of 1,3-diamino-5,6-dihydrobenzo[?] quinazoline, has been elucidated with the aid of chemical and spectral evidence, including mass spectrometric data. The mass spectrometric fragmentation pattern of the compound is in good agreement with the assigned structure.     

Catalyst‐free one‐pot regioselective synthesis of benzo[d]imidazo[2,1‐b]thiazoles by heating or grinding

Eco‐friendly, efficient, and simple one‐pot catalyst‐free new procedures have been reported for the synthesis of benzo[d]imidazo[2,1‐b]thiazoles by condensation of phenylglyoxal, cyclic enolizable carbonyl compounds, and 2‐aminobenzothiazole at 80°C or by grinding the components at room temperature in glycerol. Cyclic enolizable carbonyl compounds employed in the protocol include dimedone, cyclohexa‐1,3‐dione, cyclopenta‐1,3‐dione, 5‐methylcyclohexa‐1,3‐dione, and 4‐hydroxy‐6‐methyl‐2‐pyrone. All the reactions were complete in ~30 min. The structures of all the products were confirmed by spectral data. The structures of compounds IVl and IVe have also been confirmed by X‐ray crystallographic studies. This protocol offers advantages such as short reaction time, easy workup, high yields and an environmentally benign methodology.     

Nanomagnetically modified thioglycolic acid (γ‐Fe2O3@SiO2‐SCH2CO2H): Efficient and reusable green catalyst for the one‐pot domino synthesis of spiro[benzo[a]benzo[6,7]chromeno[2,3‐c]phenazine] and benzo[a]benzo[6,7]chromeno[2,3‐c]phenazines

Superparamagnetic nanoparticles of modified thioglycolic acid (γ‐Fe₂O₃@SiO₂‐SCH₂CO₂H) represent a new, efficient and green catalyst for the one‐pot synthesis of novel spiro[benzo[a ]benzo[6,7]chromeno[2,3‐c ]phenazine] derivatives via domino Knoevenagel–Michael–cyclization reaction of 2‐hydroxynaphthalene‐1,4‐dione, benzene‐1,2‐diamines, ninhydrin and isatin. This novel magnetic organocatalyst was easily isolated from the reaction mixture by magnetic decantation using an external magnet and reused at least six times without significant loss in its activity. The catalyst was fully characterized using various techniques. This procedure was also applied successfully for the synthesis of benzo[a ]benzo[6,7]chromeno[2,3‐c ]phenazines.     

2,2′‐Bi[benzo[b]thiophene]: an unexpected isolation of the benzo[b]thiophene dimer

The crystal structure of 2,2′‐bi[benzo[b]thiophene], C₁₆H₁₀S₂, at 173 K has triclinic (P) symmetry. It is of interest with respect to its apparent mode of synthesis, as it is a by‐product of a Stille cross‐coupling reaction in which it was not explictly detected by spectroscopic methods. It was upon crystal structure analysis of a specimen isolated from the mother liquor that this reaction was determined to give rise to the title compound, which is a dimer arising from the starting material. Two independent half‐molecules of this dimer comprise the asymmetric unit, and the full molecules are generated via inversion centers. Both molecules in the unit cell exhibit ring disorder, and they are essentially identical because of their rigidity and planarity.     

Syntheses of 4-(benzo[b]furan-2 or 3-yl)- and 4-(benzo[b]-thiophen-3-yl)piperidines with 5-HT2 antagonist activity

The syntheses of 4-(benzo[b]furan-3-yl)piperidines, 4-(benzo[b]furan-2-yl)piperidines and 4-(benzo[b]thiophen-3-yl)piperidines with 5-HT₂ antagonist activity are described. Reaction of 1-acetyl-4-(2,4-difluorobenzo-yl)piperidine 2 with methyl glycolate gave methyl 6-fluoro-3-(1-acetylpiperidin-4-yl)benzo[b]furan-2-carboxylate 3 , which was converted to 2-[2-[4-(benzo[b]furan-3-yi)piperidin-1-yl]ethyl-5,6,7,8-tetrahydro-1,2,4-triazolo-[4,3-a]pyridin-3(2H)-one hydrochloride 9 . Analogous benzo[b]furans 17a-d and benzo[b]thiophenes 10a,b and 18a were prepared by a similar method. Cyclization of 4-fluoro-2-(4-pyridinylmethoxy)acetophenones 20a,b afforded 4-(benzo[b]furan-2-yl)pyridines 21a,b , which were converted to 2-[2-[4-(benzo[b]furan-2-yl)-piperidin-1-yl]ethyl-5,6,7,8-tetrahydro-1,2,4-triazolo[4,3-a]pyridin-3(2H)-one hydrochlorides 24a,b. Among them, benzo[b]furans 9 and 17a,d and benzo[b]thiophenes 10 and 18a showed potent 5-HT₂ antagonist activity in vitro.     

An efficient synthesis of new benzo[1′,2′:6,7]quinolino[2,3‐d]‐pyrimidine derivatives via three‐component microwave‐assisted reaction

A series of benzo[1′,2′:6,7]quinolino[2,3‐d]pyrimidine derivatives were synthesized via condensation of an aromatic aldehyde, 2‐hydroxy naphthalene‐1,4‐dione and 2,6‐diaminopyrimidin‐4‐one in mixed solvent of acetic acid and glycol (3:1,V:V) under microwave irradiation. This one‐pot protocol has the advantage of good yield (86‐91%), simple workup procedure and rapid reaction time (4‐8min).     

Synthesis of new benzo[h]‐ and benzo[f]chromeno[2,3‐b]‐pyridine‐5‐ones

A number of new benzo[h]‐ and benzo[f]chromeno[2,3‐b] pyridine‐5‐ones derivatives were synthesized from benzo[h]‐ and benzo[f]‐chromone‐carbonitriles and amino‐benzo[h]‐ and benzo[f]chromone‐carbaldehydes. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:2–7, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20152     

A new approach to the synthesis of 2β- and 3β-hydroxygibberellins

The first examples of the use of hydroxyl inversion reactions to prepare the gibberellin plant hormones are described. Treatment of 2- and 3-mesylates with caesium acetate gave, after hydrolysis, good yields of the required 2β- and 3β-hydroxygibberellins. Alternatively inversion of the 2-mesylate and hydrolysis of the 7-methyl ester may be achieved in one-pot by treatment of (2) with potassium superoxide.     

Synthesis and photovoltaic properties of thieno[3,4‐b]pyrazine or dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2‐d]imidazole‐containing conjugated polymers

Novel conjugated polymers composed of benzo[1,2‐b:4,5‐b′]dithiophene and thieno[3,4‐b]pyrazine or dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2‐d]imidazole units are synthesized by Stille polycondensation. The resulting polymers display a longer wavelength absorption and well‐defined redox activities. The effective intramolecular charge‐transfer and energy levels of all polymers are elucidated by computational calculations. Bulk‐heterojunction solar cells based on these polymers as p‐type semiconductors and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) as an n‐type semiconductor are fabricated, and their photovoltaic performances are for the first time evaluated. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1067–1075     

A new approach to the synthesis of benzofuro[3,2‐b]quinolines,benzothieno[3,2‐b]quinolines and indolo[3,2‐b]quinolines

Treatment of 2‐hydroxy‐, 2‐mercapto‐, and 2‐ethoxycarbonylamino‐benzonitriles 12 with 2‐fluoro‐ or 2‐nitrophenacylbromides 13 under alkaline conditions provided the corresponding benzofuran, benzothiophene, and indole intermediates 10 , respectivelly. Nucleophilic cyclization of these compounds led to the corresponding tetracyclic quinolinones 7a, 7b , and 3. Denitrocyclization reaction of compounds 10 (R = NO₂) was found especially useful. Compounds 7a, 7b , and 3 were converted to their chloro derivatives 14a‐c , which were reduced with hydrogen and a catalyst to the corresponding compounds 8a, 8b , and 2. The presented pathway represents a new method of preparation of quindoline 2 and its O and S analogs 8. Chloro derivatives 14 are reactive enough to provide the corresponding methoxy derivatives 15 and dimethylamino derivatives 16. Methylation of compounds 7a and 7b with iodomethane providing mixtures of major N‐methyl derivatives 17 and minor O‐methyl derivatives 15 were also studied.     

2-Amino-3-(benzimidazol-2-yl)benzo[b]furans

The corresponding 2-amino-3-(benzimidazol-2-yl)benzo[b]furans were obtained by reaction of 2,3,5-trimethyl-1,4-benzoquinone with 2-cyanomethylbenzimidazoles. It is shown that new benzo[b]furo[2′,3′∶4,5]pyrimido[1,6-a]benzimidazole polynuclear heterocyclic systems (bases and quaternary salts) are formed in the reaction of these products with acylating agents. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 164–166, February, 1980.     

A facile synthesis of pyrrolo[3,2‐d]pyrimidines from 6‐azidouracils and ylide phosphoranes

A series of the title compounds, 9‐deazaxanthines, was regioselectively prepared in reasonable yields as major products from the reactions of 6‐azidouracils 1a,b with stabilized ester‐ 2a,b or keto‐ 2c ylide phosphoranes and a moderated phosphorus ylide 3 , instead of the expected triazoles. Side products were also observed wherein pyrimido[5,4‐g]pteridine‐2,4,5,7‐tetrone ( 15 ) and other fused ring systems or acyclic‐substituted uracil derivatives were isolated. A comparative study on the reactivity of 1a in analogy to 1b toward phosphoranes is also described. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:357–365, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10048     

Convenient synthesis of substituted benzo[e][1,2,4]- or [d][1,2,6]oxadiazepines,benzo[f][1,3,5]triazocines from N-aryliminoesters

We report herein a short and efficient synthesis of benz[e][1,2,4]- or [d][1,2,6]oxadiazepines and benzo[f][1,3,5]triazocines from easily prepared N-aryl iminoesters. The strategy involves a bis-nucleophile reagent (hydroxylamine or guanidine) that promotes a one-step ring closure from the starting functionalized iminoesters.     

Synthesis and in vitro antiproliferative activity of new substituted benzo[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidines

The synthesis of new planar benzo[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidine derivatives, carrying different side groups in the 2 position, is described. The novel substituted pyrimidines were obtained by reaction of the key intermediate 3‐dimethylamino methylen‐7‐methoxy‐2,3‐dihydrobenzo[3′,2′:5,6]thiopyran‐4(4H)‐one, characterized by a reactive group adjacent to the C?O function, with the suitable binucleophile amidines in a basic medium. All the new compounds were evaluated for the antiproliferative ability by an in vitro assay on two human tumour cell lines (HL‐60 and HeLa), and the 2‐phenyl substituted derivative showed the capacity to inhibit cell growth on HL‐60. Linear flow dichroism measurements indicated the inability to form a molecular complex with DNA.     

A new route for the synthesis of isomeric benzo[b]furoindoles

A new synthesis of 1H-benzo[b]furo[3,2-f]- and 1H-benzo[b]furo[2,3-e]indoles was described. The corresponding ring-fused isatins, synthesized by the Sandmeyer reaction, were utilized as initial compounds. The reduction of the last to the unsubstituted benzo[b]furoindoles depends both on the nature of the substituent, and on the reaction conditions. Georgian Technical University, Tbilisi 380075. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1419–1423, October, 1999.