p-TSA-catalyzed one-pot synthesis of novel 7-aryl-6H-benzo[h][1,3]dioxolo[4,5-b]xanthene-5,6(7H)-diones in ethanol

A one-pot, three-component reaction of aromatic aldehydes, 2-hydroxy-1,4-naphthoquinone, and 3,4-methylenedioxyphenol has been reported for the synthesis of novel 7-aryl-6H-benzo[h][1,3]dioxolo[4,5-b]xanthene-5,6(7H)-diones using environmentally benevolent para-toluene sulfonic acid (p-TSA) as the catalyst. This methodology provides a mild and fast route to diverse pyran derivatives in moderate to good yields.     

A synthesis of 6-functionalized 7-unsubstituted- and 7-methyl[1,2,4]azolo[1,5-a]pyrimidine derivatives

6-Functionalized 7-R-4,7-dihydro[1,2,4]azolo[1,5-a]pyrimidines (R?=?H or Me) were synthesized by Biginelli-like reaction of formaldehyde or acetaldehyde, aminoazoles, and corresponding β-dicarbonyl precursor. Alkylation of the obtained compounds proceeds smoothly at position 4, while oxidation leads to 7-R-[1,2,4]azolo[1,5-a]pyrimidines formation. 6-Ethoxycarbonyl derivatives could be reduced to the corresponding alcohols by LiAlH₄ and hydrolyzed to the acids.     

Synthesis of 7-oxopyrrolo[3,2-B]pyridine-6-carboxylic acid derivatives as potential antimicrobial agents

A route for the synthesis of various derivatives of 7-oxopyrrolo[3,2-b]pyridine-6-carboxylic acid from 2-methyl-3-carbomethoxy-4-aminopyrrole is reported.     

Preparation and characterization of 6-substituted 1,8-diazabicyclo[5.4.0]undec-7-ene

The lithium 1,8-diazabicyclo[5.4.0]undec-6-ide ( 1 ) prepared from 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and n-butyllithium reacts with alkyl halides and carbonyl compounds such as benzophenone, acetophenone, and benzaldehyde to give 6-substituted DBU derivatives in good yields. The reaction behavior of 6-substi-tuted DBU was also investigated.     

Cyclic guanidines: Synthesis of 4,6,7,8-tetrahydro-1H-imidazo[1,2-a]pyrazolo[3,4-d]pyrimidin-7-ones and 1,4,6,7,8,9-hexahydropyrazolo[3′,4′:4,5]pyrimido[2,1-c] [1,2,4]triazin-7-ones

The synthesis of potential platelet aggregation inhibitors 4,6,7,8-tetrahydroimidazo[1,2-a]pyrazolo[3,4-d]-pyrimidin-7-ones and 1,4,6,7,8,9-hexahydropyrazolo[3′,4′:4,5]pyrimido[2,1-c] [1,2,4]triazin-7-ones derivatives is described starting from 4,6-dichloropyrazolo[3,4-d]pyrimidines.     

Synthesis of New [1,2,4]Triazolo[1,5‐a]pyrimidine Derivatives: Reactivity of 3‐Amino[1,2,4]triazole towards Enaminonitriles and Enaminones

A diversity of new 7 ‐substituted[1,2,4]triazolo[1,5‐a]pyrimidine and 6‐substituted[1,2,4]triazolo[1,5‐a]pyrimidine‐7‐amine derivatives has been synthesized via reaction of 3‐amino‐[1,2,4]triazole with enaminonitriles and enaminones. The regio orientation and the structure of the products were confirmed by spectral and analytical data and synthesis via an alternative route. The procedure proved to be simple, efficient, and high yielding, and diversities of [1,2,4]triazolo[1,5‐a]pyrimidines were obtained.     

Synthesis of 5H-Tetrazolo[1,5-d] [1,4]benzodiazepin-6(7H)ones

Syntheses of 5H-tetrazolo [1,5-d] [1,4 ]benzodiazepin-6(7H)ones 2a-d from 5-(o-aminophenyl)-tetrazoles 1a-d and bromoacetyl bromide are described. Compounds 2a-d are representatives of a novel tricyclic ring system. Several alternate methods for the synthesis of 2a-d were attempted without success. Spectral evidence for structural assignments 2a-d is presented. Chemical evidence for these assignments includes the transformation of 2a to 6-(2,2-dimethylhydrazino)-5H-tetrazolo[1,5-d] [1,4]benzodiazepine ( 19 ) via the thione analog of 2a ( 18 ).     

Syntheses and reactions of [1,3,4]thiadiazolo[3,2-a]pyrimidinone derivatives

5-Imino-6H-7-one, 7-amino-5-one and 5-isocyano-7-one derivatives of [1,3,4]thiadiazolo- and -[1,3]thiazolo-[3,2-a]pyrimidines were synthesized. 5-Isocyano-7-one derivatives were obtained by the reaction of the corresponding 5-imino-6H-7-ones with the Vilsmeier reagent in one step.     

Diastereodivergent Synthesis of Hexahydro-6H-benzo[c]chromen-6-one Derivatives Catalyzed by Modularly Designed Organocatalysts

The diastereodivergent synthesis of hexahydro-6H-benzo[c]chromen-6-one derivatives with good to high diastereoselectivities (up to 98:2 d.r.) and enantioselectivities (up to >99 % ee) has been achieved by using a domino Michael/Michael/hemiacetalization reaction between trans-2-hydroxy-β-nitrostyrenes and trans-7-oxo-5-heptenals followed by oxidation. With use of appropriate modularly designed organocatalysts (MDOs) that are self-assembled in situ from amino acid derivatives and cinchona alkaloid derivatives, two different diastereomers of the desired hexahydro-6H-benzo[c]chromen-6-ones are obtained from the same substrates.     

Synthesis and isomerization of epoxides derived from 7-phenylsulfonyl-and 7-methylsulfonyl-6-methylidenebicyclo[3.1.1]heptanes

Oxidation of exo-7-phenylsulfonyl-and exo-7-methylsulfonyl-6-methylidenebicyclo[3.1.1]heptanes with m-chloroperoxybenzoic acid gave the corresponding epoxy derivatives, anti-7-phenylsulfonyl-and anti-7-methylsulfonyl-endo-2′-oxaspiro[bicyclo[3.1.1]heptane-6,2′-cyclopropanes]. Treatment of the phenylsulfonyl-substituted epoxide with potassium tert-butoxide in THF led to the 1,3-cyclization product, 7-phenylsulfonyltricyclo[4.1.0.0^2,7]hept-1-ylmethanol. anti-7-Methylsulfonyl-endo-2′-oxaspiro[bicyclo[3.1.1]heptane-6,2′-cyclopropane] under analogous conditions underwent 1,6-cyclization, being converted into 6-hydroxy-3λ⁶-thiatricyclo[4.4.0.0^2,7]decane 3,3-dioxide.     

Straightforward Synthesis and Properties of Highly Fluorescent [5]‐ and [7]‐Helical Dispiroindeno[2,1‐c]fluorenes

This work presents a general approach for synthesis of substituted [5]‐helical dispiroindeno[2,1‐c]fluorenes based on Rh‐catalyzed intramolecular cyclotrimerization of triynes. This approach was further extended for the first synthesis of configurationally stable [7]‐helical dispiroindeno[2,1‐c]fluorenes. A series of variously substituted derivatives was prepared and their photophysical and electrochemical properties were evaluated. Their fluorescence emission maxima were in the region of 351–428 nm and quantum yields up to 88 % are the highest measured among the full‐carbon helical compounds.     

Synthesis of 1H,3H-imidazo[1,5-c]thiazole-5,7-[6H,7aH]-dione and 7,8-dihydro-5-H-imidazo[1,5-c][1,3]thiazine-1,3-[2H,8aH]-dione and derivatives

1H,3H-Imidazo[1,5-c]thiazole-5,7-[6H,7aH]-dione and the corresponding 7-thione derivatives as well as 7,8-dihydro-5H-imidazo[1,5-c][1,3]thiazine-1,3-[2H,8aH]-dione and the corresponding 3-thione derivatives were synthesized starting from L -cysteine and DL -homocysteine thiolactone, respectively. The second group of bicyclic compounds represents a new heterocyclic ring system. The structures of the compounds were confirmed by spectroscopic studies and elemental analyses.     

Studies with Heterocyclic β‐Enaminoniriles: A Simple Route for the Synthesis of Polyfunctionally Substituted Thiophene,Imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene and Thieno[3,2‐d]pyrimidine Derivatives

Reaction of 3,5‐diaminothiophene‐2‐carbonitrile derivatives 3a‐c with ethoxycarbonylmethyl isothiocyanate and/or N‐[bis(methylthio)methylene]glycine ethyl ester led to formation of 7‐substituted‐8‐amino‐5‐thioxo‐6H‐imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one derivatives 6a‐c and 7‐substituted‐8‐amino‐5‐(methylthio)imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one 7a‐c , respectively. Also, the synthetic potential of the β‐enaminonitrile moiety in 3a‐c has been explored; it proved to be a promising candiate for the synthesis of 1,6‐disubstituted‐2,4‐diamino‐7,8‐dihydro‐8‐oxopyrrolo[1,2‐a]thieno[2,3‐e]pyrimidine derivatives 10a‐f and pyrido[2′,3′:6,5]pyrimido[3,4‐a]benzimidazole derivatives 12a,b .     

Synthesis of benzofuro[3,2-b] quinolin-6(11H) one and derivatives

A new and efficient synthesis of benzof'uro[3,2-b]quinolin-6(11H) one ( 3 ) is reported, by treatment of 2- {[(phenoxy)acetyl]amino} benzoic acid ( 6a ) with polyphosphoric acid. An intermediate in the conversion of 3 to 6a , namely, 2-(3-benzofuranylamino)benzoic acid ( 7 ), was defined. An improved method for the synthesis of 6a is also described, which was used to prepare analogs ( 6b-n ) of 6a . In addition, an 11-alkoxy derivative ( 8 ) and 11-dialkylamino derivatives ( 10 and 11 ) of benzofuro [3,2-b]quinoline were prepared from 3 .     

Synthesis and antifungal activities of 3,5-diphenyl-7-amino-[1,3]-thiazolo[3,2-a]pyrimidine-6-nitrile derivatives

A series of novel 3,7-diphenyl-7-amino[1,3]-thiazolo[3,2-a]pyrimidine-6-nitrile derivatives 3 were synthesized by refluxing 2-amino-4-phenyl-1,3-thiazole 1 and arylidinemalononitrile 2 in propanol using NaOH as catalyst. Various synthesized products were characterized by ¹H NMR, mass spectrometry (MS), infrared (IR), and elemental analysis. Antifungal activities of the synthesized compounds were done by testing against Rhizoctonia solani and Drechslera orazae, two fungal pathogens causing diseases on rice crops.     

The synthesis of [1]benzothieno[2,3-c]quinolines, [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline,and [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline

Photocyclization of 3-chloro-N-phenylbenzo[b]thiophene-2-carboxamide 10 afforded [1]benzothieno[2,3-c]-quinolin-6(5H)-one 11 which was chlorinated to 6-chloro[1]benzothieno[2,3-c]quinoline 12 followed by dechlorination to give [1]benzothieno[2,3-c]quinoline 5 . A series of 6-substituted alkoxy and thioalkoxy[1]benzothieno[2,3-c]quinoline derivatives were prepared along with the N-methyl quaternary salt 13 of 5 . 6-Chloro[1]-benzothieno[2,3-c]quinoline 12 was converted into 6-hydrazino[1]benzothieno[2,3-c]quinoline 23 which upon treatment with formic acid yielded [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline 6 . Treatment of 23 with nitrous acid resulted in [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline 7 . Compounds 6 and 7 are novel heterocyclic ring systems.     

Novel synthesis of 5,11-dihydro-6H-pyrido[2,3-b]-[1,4]benzodiazepin-6-ones and related studies

5,11-Dihydro-6H-pyrido[2,3-6][1,4]benzodiazepin-6-one (1), a basic intermediate in the preparation of 11-α-aminoacetyl derivatives with important biological activities, has been obtained by a three-step synthesis starting from easily available isatoic anhydride and anhydro ornithine. Some model cyclisation reactions leading to 5-member ring derivatives 10 and 12 instead of 7-member ring analogues of 1 , are reported. Easy transformations of the tetrahydro congener of 1 , i.e., compound 4 into 19 , which actually represents a tetrahedral intermediate in the transformation of 5 into 4 , is noticed. Further rearrangement of 19 into spiro compound 20 , and return of the latter into 5 is described.     

Solid-phase synthesis of 2-alkylidene-6-alkyl-imidazo[2,1-b]thiazole-3,5[2H,6H]-dione derivatives

A solid-phase synthesis of 2-alkylidene-6-alkyl-imidazo[2,1-b]thiazole-3,5[2H,6H]-dione derivatives is reported. The desired products were obtained in good purities and yields.     

A general synthesis of alkyl 6-substituted-pyrazolo-[3,2-c] -s-triazolo-7-carboxylates

A general synthesis of alkyl 6-methyl- and 6-phenylpyrazolo[3,2-c]-s-triazolo-7-carboxylates by photochemical Wolf rearrangement of 6-methyl- and 6-phenyl-7-diazo-8-oxo-s-triazolo-[4,3-b]pyridazine in an alcohol is described.     

Mass spectrometric studies of 6-chloro-6H-dibenz[c,e] [1,2]oxaphosphorine-6-sulphide and its derivatives

The electron-impact induced fragmentation of 6-chloro-6H-dibenz[c,e] [1,2]oxaphosphorine-6-sulphide and its 6-ethoxy and 6-hydroxy derivatives has been studied and it has been found that formation of the dibenz[c,e] [1,2]oxaphosphorin system and elimination of HCP are common features. β-Hydrogen rearrangement, in the case of the ethoxy derivative, is comparable to ethers with a P? O? CH₂? CH₃ linkage.