Synthesis of heterocycles based on arylation products of unsaturated compounds: XVII. Arylation of 2-acetylfuran and synthesis of 3-R-6-(5-aryl-2-furyl)-7<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazines

Reaction of 2-acetylfuran with arenediazonium chlorides under Meerwein reaction conditions led to the formation of 5-aryl-2-acetylfurans. The bromination of these compounds gave 2-bromo-1-(5-aryl-2-furyl)-ethanones that reacted with 4-amino-4H-5-R-1,2,4-triazole-3-thiols to form 3-R-6-(5-aryl-2-furyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines.     

Synthesis and properties of 2-(2-furyl)-and 2-(2-Thienyl)-1,3-benzoxazoles

Condensation of o-aminophenol with furoyl and thenoyl chlorides in 1-methylpyrrolidin-2-one gave, respectively, 2-(2-furyl)- and 2-(2-thienyl)-1,3-benzoxazoles in which the furan and thiophene rings showed no acidophobic properties. Reactions of 2-(2-furyl)- and 2-(2-thienyl)-1,3-benzoxazoles with electrophilic reagents (acylation, bromination, nitration, and sulfonation) afforded products of hydrogen replacement in both hetaryl and benzene rings, depending on the conditions.     

Heterocyclic Syntheses on the Basis of Arylation Products of Unsaturated Compounds: X. 3-Aryl-2-chloropropanals as Reagents for the Synthesis of 2-Amino-1,3-thiazole Derivatives

Meerwein reaction of arenediazonium chlorides with acrolein gave 3-aryl-2-chloropropanals which were brought into cyclocondensation with thiourea. The resulting 2-amino-5-benzyl-1,3-thiazoles were acylated with carboxylic acid chlorides and phthalic anhydride to afford, respectively, 2-acylamino-5-benzyl-1,3-thiazoles and N-(5-benzyl-1,3-thiazol-2-yl)phthalimides.     

Nitrile oxide cycloaddition routes to 2-(isoxazolyl)-benzoates and 2-(1,2,4-oxadiazol-3-yl)benzoates

Cycloaddition of aromatic nitrile oxides to methyl o-vinylbenzoate produced methyl 2-(3-aryl-2-isoxazolin-5-yl)benzoates; the isoxazolines were converted to methyl 2-(3-arylisoxazol-5-yl)benzoates. Reaction of the nitrile oxide from o-methoxycarbonylbenzohydroximinoyl chloride ( 11 ) with phenylacetylene, styrenes, and aromatic nitriles resulted in methyl 2-(5-phenylisoxazol-3-yl)benzoate, methyl 2-(5-aryl-2-isoxazolin-3-yl)-benzoates ( 15 ), and methyl 2-(5-aryl-1,2,4-oxadiazol-3-yl)benzoates, respectively. The isoxazolines 15 were converted to the corresponding isoxazoles 16 .     

Diastereoselective Diels-Alder Reaction of 2-Thienyl and 2-Furyl Substituted 3-Propenethioamides with Electron Deficient Dienophiles

Summary. The hetero-Diels-Alder reaction of N-aryl-3-(2-thienyl)-2-propenethioamides with N-phenylmaleimide and maleimide yielded a mixture of endo- and exo-2-arylimino-4-(2-thienyl)tetrahydrothiopyran[2,3-c]pyrroles. Cycloaddition to diethyl fumarate required acylation and furnished a mixture of diastereoisomeric 5-(N-acetylphenylamino)-2,3-bis-(ethoxycarbonyl)-4-(2-thienyl)-3,4-dihydro-2H-thiopyrans. Reactions of 3-(2-furyl)-2-propenethioamides with N-arylmaleimides furnished the correspondent 2-arylimino-4-(2-furyl)tetrahydrothiopyran[2,3-c]pyrroles. In the cycloadditions of the heterodienes with N-arylmaleimides the endo-cycloadducts were formed as the major products.     

Studies on furan derivatives. V. A novel ethoxycarbonylmethylation of the 5-nitro-2-furan ring in the reaction of α-(2-furyl)-β-(5-nitro-2-furyl)ethynyl with N-ethoxycarbonylmethylpyridinium ylide

An unexpected product, 1-(4-ethoxycarbonylmethyl-5-nitro-2-furyl)-2-(2-furyl)-3-ethoxycarbonyl-indolizine was obtained by the reaction of α-(2-furyl)-β-(5-nitro-2-furyl)ethynyl with N-ethoxy-carbonylmethylpyridinium ylide in N,N-dimethylformamide, together with 1-(5-nitro-2-furyl)-2-(2-furyl)-3-ethoxycarbonylindolizine.     

An efficient synthesis of 2-(guaiazulen-1-yl)furan derivatives via intramolecular Wittig reactions

An efficient and mild synthesis of 2-(guaiazulen-1-yl)furans,starting from easily accessible 1-(3-aryl-2-cyanopropenoyl) guaiazulenes,tributylphosphine and acyl chlorides,is described.The strategy employs the intramolecular Wittig protocol as a key step to append the crticial furan ring,leading to the highly functional furans in good yields.     

On the Synthesis of 2-Acetyl-4-aryl-6H-1,3,4-thiadiazin-5-ones by Reaction of Nitrilimines with α-Mercapto Alkanoic Acids

Summary.  N′-Arylacetonitrilimines were generated from acetohydrazonyl chlorides and reacted with mercaptoalkanoic acids forming 4-aryl-5-oxo-3-thiahexanoic acids. These were cyclized by reaction with dicyclohexyl carbodiimide yielding 2-acetyl-4-aryl-6H-1,3,4-thiadiazin-5-ones. Received November 13, 2001. Accepted January 9, 2002     

Chemistry of acyl(imidoyl)ketenes. 7. Synthesis and thermolysis of 5-aryl-4-quinoxalinyl-2,3-dihydrofuran-2,3-diones

3-Aryl-Z-2-aroylmethylidene-1,2-dihydroquinoxalines react with oxalyl chloride to form 3-aryl-2-(2-aryl-4,5-dioxo-4,5-dihydro-3-furyl)quinoxalines, whose thermal decarbonylation generate 5-aryl-2-3(arylquinoxalin-2-yl)-4-aroyl-3-aroyloxy-1H-pyrido[1,2-a]quinoxalin-1-ones. The crystal and molecular structures of one of them (Ar = Ph) were established by X-ray diffraction analysis.     

An efficient synthesis of conjugated 5-aryl-1,3,4-oxadiazoles from 3-heteroarylacrylohydrazides and acid chlorides

New derivatives of 5-aryl-2-[2-(2-furyl)ethenyl]-1,3,4-oxadiazoles and 5-aryl-2-[2-(2-thienyl)ethenyl]-1,3,4-oxadiazoles are synthesized in a stepwise procedure through intermediate acyclic N′-arylcarbonyl-N-[2-(2-heteroaryl)acryloyl]hydrazines, starting from 3-(2-heteroaryl)acrylic acid hydrazides and acid chlorides. A facile one-pot methodology leading to the final 1,3,4-oxadiazoles is also described.     

Regioselective arylation of 3-bromopyridine

The addition of aryl Grignard reagents to the 1-phenoxycarbonyl salt of 3-bromopyridine affords 2-aryl-5-bromo-1-phenoxycarbonyl-1,2-dihydropyridines and 4-aryl-3-bromo-1-phenoxycarbonyl-1,4-dihydropyridines. The crude dihydropyridines were aromatized with o-chloranil in refluxing toluene to give 4- and 6-aryl-3-bromopyridines. The regioselectivity of this two-step process, 6- vs. 4-substitution, was examined and found to be dependent upon the structure of the Grignard reagent. Unhindered aryl Grignard reagents, e.g., phenyl and 2-naphthyl, gave mainly 6-aryl-3-bromopyridines (49-52%) along with 9% of the 4-substituted isomer and less than 4% of the 2-aryl-3-bromopyridine. Hindered aryl Grignard reagents, e.g., o-tolyl and 1-naphthyl, are less regioselective. When a catalytic amount of cuprous iodide is present during the Grignard reaction, nearly exclusive 1,4-addition results. The crude 4-aryl-3-bromo-1,4-dihydropyridines were aromatized with p-chloranil to provide 4-aryl-3-bromopyridines in good yield and high isomeric purity. The sequential use of the cuprous iodide-catalyzed Grignard reaction and the “normal” Grignard reaction provided a regiospeci-fic synthesis of 3-bromo-6-(p-methoxyphenyl)-4-phenylpyridine from 3-bromopyridine.     

Design and synthesis of novel quinoline derivatives bearing oxadiazole,isoxazoline, triazolothiadiazole,triazolothiadiazine, and piperazine moieties

A new series of 2,3-disubstituted quinoline derivatives were synthesized from 2-chloroquinoline-3-carbaldehyde. In the reaction sequence, acetanilide was cyclized to give 2-chloroquinoline-3-carbaldehyde 1 , which was transformed to 2-(4-phenylpiperazin-1-yl)quinolin-3-carbaldehyde 2 by reaction with 4-phenylpiperazine in DMF-containing anhydrous K₂CO₃; then, compound 2 was oxidized by iodine in methanol, and methyl 2-(4-phenylpiperazin-1-yl)quinoline-3-carboxylate 3 was synthesized. The key intermediate 4 , 4-amino-5-[2-(4-phenylpiperazin-1-yl)quinolin-3-yl]-4H-1,2,4-triazole-3-thiol, was prepared using the ester 3 by a series of step. Reaction of 5 with various aromatic carboxylic acids or phenacyl bromides yielded 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles 5a-c and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines 6a-c , respectively. Moreover, compound 2 condensed with o-phenylenediamine to give 2-[2-(4-phenylpiperazin-1-yl)quinolin-3-yl]-1H-benzimidazole 7 . Interaction of 7 and 2-chloromethyl-5-aryl-1,3,4-oxadiazoles in the presence of K₂CO₃ led to the title compounds 8a-c . Furthermore, 4,5-dihydroisoxazoline derivatives 9a-c were obtained by the reaction of readily accessible starting materials including 2-(4-phenylpiperazin-1-yl)quinolin-3-carbaldehyde 2 , 1-phenyl-2-(triphenylphosphoranylidene)ethanone and hydroximoyl chlorides under mild conditions in the presence of Et₃N. The hydrazone intermediates 10a-c were obtained by the condensation of 2 with aroylhydrazides in ethanol, then, refluxing in acetic anhydride yielded 3-acetyl-5-aryl-2-[2-(4-phenylpiperazin-1-yl)quinolin-3-yl]-2,3-dihydro-1,3,4-oxadiazoles 11a-c . Structures of these compounds were established by their elemental analysis, IR, ¹H NMR, and mass spectral data.     

Tetracarbonyl Systems: VII. Reactions of 1,3,4,6-Tetracarbonyl Compounds with o-Aminothiophenol in the Synthesis of Regioisomeric 3(2)-Aroylmethylene-1,4-benzothiazin-2(3)ones

In reaction of 1,6-diaryl-3,4-dihydroxy-2,4-hexadiene-1,6-diones with o-aminothiophenol (3Z)-3-aroylmethylene-3,4-dihydro-2H-1,4-benzothiazin-2-ones were obtained in a preparative yield. In solution of the latter compounds an enamine-imine tautomerism was observed. In reaction of ethyl esters or amides of 2-substituted 6-aryl-3,4-dihydroxy-6-oxo-2,4-hexadienoic acids with the o-aminothiophenol regioisomeric 2-aroylmethylene-2H-1,4-benzothiazin-3(4H)-ones were formed.     

Heterocyclic compounds from 3,3-dimercapto-1-aryl-2-propen-1-ones. Note 1. 4-Ary1-1,3-dihydro-2H-1,5-benzodiazepine-2-thiones

A series of new 4-aryl-1,3-dihydro-2H-1,5-benzodiazepine-2-thiones ( 3 ) has been synthesized by condensing the 3,3-dimercapto-1-aryl-2-propen-1-ones with o-phenylenediamine. The structure was established by the results of acid cleavage and by nmr spectra. The alkylation of compounds 3 gave 2-alkylthio-4-aryl-3H-1,5 benzodiazepines ( 10 ).     

Synthesis and interconversion of 6-aroyl-4-oxohexanoie acids and 5-aryl-2-furanpropionic acids. Antiinflammatory agents

A series of 6-aroyl-4-oxohexanoic acids ( 2 ) was prepared for intermediate use by acid-catalyzed solvolysis of substituted 3-(2-furyl)acrylophenones ( 1 ). This reaction occasionally gave 5-aryl-2-furanpropionic acids ( 3 ) instead of, or in addition to, the desired diketones ( 2 ). Equilibrium between 2 and 3 was observed in the case where Ar is m-nitrophenyl. A rationalization for the formation of 3 is offered, and published reports with which our results differ are discussed. Diketones ( 2 ) were cyclized to furans ( 3 ) and antiinflammatory screening data are reported for the latter.     

Reaction of 4-thioxo-1,3-benzothiazines with thiocarbohydrazine: Synthesis and reactivity of 1,3,4-triazolo[3,2-c]quinazoline derivatives

2-Aryl-4-thioxo-1,3-benzothiazines react with thiocarbohydrazide to give the new mesoionic compounds an-hydro 1-amino-5-aryl-2-mercapto-1,3,4-triazolo[3,2-c]quinazolin-4-ium hydroxides. These compounds react with methyl iodide, aldehydes and phenacyl bromides to give 1-amino-5-aryl-2-methylthio-1,3,4-triazolo-[3,2-c]quinazolin-4-ium iodides, 4-arylidenamino-3-(o-aroylamino)phenyl-1H-1,2,4-triazolin-5-thiones and 3-(o-aroylamino)phenyl-6-aryl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines, respectively. These latter compounds by sequential treatment with methyl trifluoromethanesulphonate and triethylamine lead to 3-(o-aroylamino)-phenyl-6-aryl-1-methyl-7-mercapto-1H-pyrazolo[5,1-c]-1,2,4-triazoles.     

Reaction of 1-Aryl-1H-1,2,3-Triazole-4-Carbonyl Chlorides/Isothiocyanates with 3-Amino-5-Methylisoxazole

Abstract

1-Aryl-1H-1,2,3-triazole-4-carbonyl chlorides were selected as starting materials for the Boulton–Katritzky rearrangement. When 3-amino-5-methylisoxazole was acylated by 1-aryl-1H-1,2,3-triazole-4-carbonyl chlorides, 1-aryl-5-methyl-N-(5-methylisoxazol-3-yl)-1H-1,2,3-triazole-4-carboxamides 5 were obtained and no further rearrangement occurred. On the other hand, when 1-aryl-1H-1,2,3-triazole-4-carbonyl chlorides were first converted into isothiocyanates by the reaction with KSCN and then were allowed to react with 3-amino-5-methylisoxazole 4 in one pot, intermediate thioureas were formed and spontaneously transformed in statu nascendi into 1,2,4-thiadiazole derivatives 6.

GRAPHICAL ABSTRACT      

Synthesis of heterocycles. Part VI. Synthesis and antimicrobial activity of some 4-amino-5-aryl-1,2,4-triazole-3-thiones and their derivatives

4-Amino-5-aryi-1,2,4-triazole-3-thiones I react with acid chlorides to yield 4-acylamino-5-aryl-1,2,4-triazole-3-thiones II. Compounds I also react with methylene iodide, chloroacetonitrile and methyl bromoacetate to give bis-(4-amino-5-aryl-1,2,4-triazol-3-ylthio)methanes III, 4-amino-5-aryl-3-cyanomethylthio-1,2,4-triazoles IV and 4-amino-5-aryl-3-carbomethoxymethylthio-1,2,4-triazoles V, respectively. Compounds V react with hydrazine hydrate to give the corresponding acid hydrazides VI which in turn condenses with acid chlorides and aldehydes to afford respectively 1-[(4-amino-5-aryl-1,2,4-triazol-3-ylthio)acetyl]-2-aroylhydrazines VII and aryl methylene (4-amino-5-aryl-1,2,4-triazol-3-ylthio)acethydrazones VIII. The antimicrobial activities of the above compounds were screened against different strains of bacteria and fungi.     

Synthesis of 2-phenyl-3-(2-furyl) — and 2-phenyl-3-[β-(2-furyl)vinyl]-1,2-dihydro-naphtho[1,2-d]-1,2,4-triazines

The corresponding 2-phenyl-3-(2-furyl)- and 2-phenyl-3-[-(2-furyl)vinyl]-1,2-dihydronaphtho-[1,2-d]-1,2,4-triazines were obtained by heating Schiff bases [prepared by reaction of 1-(phenyl-azo)-2-aminonaphthalene with furfural, -(2-furyl)acrolein, and their 5-bromo and 5-nitro derivatives] in glacial acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 158–160, February, 1973.     

1,2-Diacyl-1-arylhydrazines. 1. Derivatives of 2-hydroxy- and 2-halogenobenzoic acids

New 1,2-diacyl-1-arylhydrazines, containing a hydroxy group or a mobile halogen atom in the 1-acyl fragment, were obtained by the reaction of the arylhydrazones of acetyl and benzoyl chlorides with the salts of 2-hydroxy-, 2-acetoxy-, and 2-halogeno-3-nitrobenzoic acids. 1-(2-Hydroxybenzoyl)-1-aryl-2-acylhydrazines could not be converted into cyclic products. On heating in alkaline and acidic media elimination of the more hindered salicyloyl group and not dehydration occurred. When boiled in DMF in the presence of bases, 1-(2-halogeno-3-nitro-5-R-benzoyl)-1-aryl-2-acylhydrazines gave 2-aryl-5-R-7-nitroindazol-3-ones and not the expected 4,5-dihydrobenzo[f]-1,3,4-oxadiazepin-5-ones.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1424–1430, June, 1992.