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1.
The reaction of 4-aryl-2-hydrazino-3-nitro-6-R-quinolines with NaNO2 in AcOH gives the corresponding tetrazolo[1,5-a]quinolines. In contrast to tetrazolo[1,5-c]pyrimidines they cannot be converted to 6-R-4-phenyl[1,2,5]oxadiazolo[3,4-b]quinoline-3-oxides by heating in THF, toluene, or AcOH. Total energy quantum-chemical calculations using the MINDO/3 and MNDO methods show that [1,2,5]oxadiazolo[3,4-b]quinoline-3-oxides are significantly higher in energy (230-280 kcal/mol) than the mentioned tetrazolo[1,5-a]quinolines and hence their formation is unlikely.  相似文献   

2.
Azide-tetrazole equilibrium in azidopyrimidines bearing trifluoromethyl group on the example of 2-azidopyrimidines has been studied. The latter were synthesized via nitrosation of 2-hydrazino-4-trifluoromethylpyrimidine and reaction of NaN3 with 4-trifluoromethyl-2- chloro-6-(4-chlorophenyl)pyrimidine. The tautomeric equilibrium 5-trifluoro methyl tetrazolo[1,5-a]pyrimidine ? 2-azido-4-trifluoromethylpyrimidine was observed in the absence of solvent and in DMSO-d6 solution, whereas in CDCl3 only an azide form exists. For 2-azido- 4-trifluoromethyl-6-(4-chlorophenyl)pyrimidine, only an azide isomer was detected in CDCl3 solution, and in DMSO-d6 solution it is in equilibrium with 5-(trifluoromethyl)-7-(4-chlorophenyl) tetrazolo[1,5-a]pyrimidine (the tautomer ratio is 99 : 1). Thermodynamic and kinetic parameters of 5-trifluoromethyltetrazolo[1,5-a]pyrimidine ? 2-azido-4-trifluoromethylpyri midine tautomeric rearrangement in DMSO-d6 for 5-trifluoromethyltetrazolo[1,5-a]pyrimidine were determined using the exchange spectroscopy (EXSY) technique.  相似文献   

3.
Pyrido[2,3-d]pyrimidines are synthesized in a two-step procedure from amides and tetrazolo[1,5-a]pyridine-8-carbonyl chloride. Reaction of the crude imides with triphenylphosphine effects an intramolecular aza-Wittig reaction to afford a variety of substituted pyrido[2,3-d]pyrimidines in good to moderate yields (30-76%).  相似文献   

4.
An easy and efficient route for the synthesis of some tetrazolo[1,5-a]-, pyrazolo[1,5-a]- and pyrimido[1,6-a] pyrimidine derivatives was described through the reaction of sodium salts of formyl ketones with 5-aminotetrazole, 5-aminopyrazole derivatives and 6-aminothiouracil, respectively. The antimicrobial screening of some derivatives of the prepared compounds has been achieved, and it exhibited a moderate activity against the tested microorganisms.  相似文献   

5.
A combinatorial synthetic route yielding imidazo[1,5-a]quinoxalines and pyrazolo[1,5-a]quinoxalines is described. The use of 2-fluoroaniline and 1H-imidazole-4-carboxylic acid, respectively, 1H-pyrazole-3-carboxylic acid in the Ugi-reaction (U-4CR) followed by a nucleophilic aromatic substitution (SNAr) affords the imidazo- as well as the pyrazolo-[1,5-a]quinoxaline moiety in good yield and high diversity.  相似文献   

6.
A series of novel tetrazolo[1,5-a]thiopyrano[3,4-d]pyrimidine derivatives were synthesized by reaction of aryl aldehyde, 2H-thiopyran-3,5(4H,6H)-dione, and 5-aminotetrazole under solvent-free conditions. The features of this procedure are mild reaction conditions, high yields, and operational simplicity.  相似文献   

7.
Microwave assisted efficient Hantzsch reaction via four-component coupling reactions of tetrazolo[1,5-α]quinoline-4-carbal-dehyde, dimedone/cyclohexane-1,3-dione,ethyl/methyl acetoacetate and ammonium acetate was described as the preparation of tetrazolo[1,5-α]quinoline based 1,4-dihydropyridines,acridine-1,8-diones and polyhydroquinolines.The process presented here is simple,rapid,environmentally welcoming and high yielding.All the derivatives were subjected to an in vitro antimicrobial screening against a representative panel of bacteria and fungi and results worth further investigations.  相似文献   

8.
Attempted cyclization of (4-(hydroxymethyl)-8-nitro-4H-benzo[b]tetrazolo[1,5-d][1,4]oxazin-4-yl)methyl 4-methylbenzenesulfonate 2 did not give the expected spirooxetane product 1, but instead provided 9-nitro-5H-spiro[benzo[b]tetrazolo[1,5-d][1,4]oxazepine-4,2′-oxirane] 3via an unusual ring-expansion process. The structure of compound 3 was confirmed by single-crystal X-ray crystallography. The spiroepoxide (oxirane) in compound 3 could be ring-opened with a variety of nucleophiles to give products of potential interest to medicinal chemists.  相似文献   

9.
The reaction of 7-chloro-4-(2-cyano-2-hydroxyvinyl)tetrazolo[1,5-a]quinoxaline 2a with o-aminophenol gave 7-chloro-4-(b-hydroxyphenylcarbamoylmethylene)4,5-dihydrotetrazolo[1,5-a]quinoxaline 4 , while the reaction of compound 2a with o-aminophenol hydrochloride afforded 4-[2-(2-benzoxazolyl)-2-hydroxyvinyl]-7-chlorotetrazolo[1,5-a]quinoxaline 5 , whose acetylation provided 4-[2-acetoxy-2-(2-benzoxazolyl)vinyl]-7-chlorotetrazolo[1,5-a]quinoxaline 6 . The behavior in a deuteriodimethyl sulfoxide or deuteriotrifluoroacetic acid solution is described for compounds 4–6 .  相似文献   

10.
A diversity-oriented method for the synthesis of novel poly-substituted pyrazolo[1,5-a]quinolines has been developed on the basis of an SNAr/Knoevenagel cyclization cascade reaction or an SNAr/Dieckmann–Thorpe cyclization cascade reaction. The methods provide a variety of poly-substituted pyrazolo[1,5-a]quinolines bearing an amino, alkyl or aryl substituent at the 5-position. In addition, a diversity-oriented method for the synthesis of 2-substituted pyrazolo[1,5-a]quinolines from a readily available 2-[[(trifluoromethyl)sulfonyl]oxy]pyrazolo[1,5-a]quinoline has also been disclosed.  相似文献   

11.
The reaction of 4-hydrazino-7-phenylpyrazolo[1,5-a]-1,3,5-triazine ( 4 ) with nitrous acid gave 8-phenyltetrazolo[1,5-e]pyrazolo[1,5-a]-1,3,5-triazine ( 5b ), which was determined by pmr and ir spectra to be in equilibrium with 4-azido-7-phenylpyrazolo[1,5-a]-1,3,5-triazine ( 5a ). The equilibrium between the tetrazolo ( 5b ) and azido ( 5a ) forms was studied by pmr and an attempt was made to determine if substituents in the pyrazole nucleus could sufficiently stabilize the tricyclic tetrazolo form ( 5b ) over the bicyclic azido form ( 5a ). Thermal degradation of 5 (a ? b) in an aprotic solvent gave 4-amino-7-phenylpyrazolo[1,5-a]-1,3,5-triazine ( 7 ), indicating the probability of a nitrene mechanism involved in the decomposition. Heating 5 in aqueous base gave both 7 and the “hydroxy” analog, 7-phenylpyrazolo[1,5-a]-1,3,5-triazin-4(3H)one ( 6 ), further substantiating the existence of a nitrene intermediate with a competing nucleophilic displacement of the azido group by a hydroxyl group. Cyclization of 4 with diethoxymethylacetate (DEMA) gave 8-phenyl-s-triazolo[4,3-e]pyrazolo[1,5-a]-1,3,5-triazine ( 8 ), which underwent thermal rearrangement to 8-phenyl-s-triazolo[2,3-e]pyrazolo[1,5-a]-1,3,5-triazine ( 9 ). Acid catalyzed ring opening of 9 with formic acid gave 3-N-formamido-5-phenyl-2(2-s-triazolyl)pyrazole ( 10 ). The failure of 10 to recyclize to 9 with the resultant loss of water, supported the theory that the rearrangement of 8 to 9 might occur simply as a concerted, thermally induced “anhydrous” rearrangement rather than via a covalently hydrated intermediate or a Dimroth type mechanism (in the base catalyzed rearrangement).  相似文献   

12.

Abstract  

A series of new tetrazolo[1,5-a]quinoline-4-carbonitrile derivatives were synthesized for the first time via tetrazolo[1,5-a]quinoline derivatives. Elemental analysis, IR, 1H NMR, 13C NMR, and mass spectral data were used to elucidate the structures of all newly synthesized compounds. In vitro antimicrobial activities of synthesized compounds were investigated against Gram-positive Bacillus subtilis, Gram-negative Escherichia coli, and two fungi, Candida albicans and Aspergillus niger, in comparison with standard drugs. Some of the tested compounds showed significant antimicrobial activity.  相似文献   

13.
《Mendeleev Communications》2022,32(3):393-394
Efficient syntheses of new heterocyclic systems comprising pyrimido[1',2':1,5]pyrazolo[3,4-c]-2,7-naphthyridine, pyrazolo[3,4-c][1,2,4]triazolo[3,4-a]-2,7-naphthyridine and pyrazolo[3,4-c]tetrazolo[5,1-a]-2,7-naphthyridine cores were performed in two simple steps. In the first step, pyrazole ring was fused at the 2-chloro-3-cyanopyridine moiety by treatment with hydrazine. In the second step, pyrimidine part was fused at the thus formed 3-aminopyrazole moiety by heterocyclization with acetylacetone.  相似文献   

14.
A convenient synthesis of a series of tetrazolo[1,5-a]-α-cycloalkanones 4a-d with the carbonyl group attached at the tetrazole carbon is described. The sequence entails the formation of an exocyclic olefin at the α-methylene position and subsequent ozonolysis. The reactions proceed under mild conditions, and the tetrazole moiety is well tolerated.  相似文献   

15.
The preparation of 1,2,4-triazolo[1,5-c]quinazolines 4a-d , 5 , 8a-d by cyclocondensation of 1a-c with carboxylic acids and carboxylic anhydrides, respectively, is described. By different pathways, the 5-thioxo-5,6-dihydro-1,2,4-triazolo[1,5-c]quinazolines 4a-d react with hydrazine hydrate or amines with the formation of 5-substituted 1,2,4-triazolo[1,5-c]quinazolines 9 and 10a-d . Cyclocondensation of 9 with carboxylic acids, carboxylic anhydrides, and nitrous acid, respectively, leads to the new anellated heterocycles bis-1,2,4-triazolo[4,3-a:1,5-c]quinazoline 13 and tetrazolo [1,5-a]-1,2,4-triazolo[1,5-c]quinazoline ( 14 ).  相似文献   

16.
Azido-Ugi reaction involving cyclic ketone, primary amine, isonitrile, and azide afforded substituted tetrazole derivatives 5. These intermediates were hydrolyzed to corresponding acid derivatives. EDAC/HOBt mediated amide bond formation of 5 gave fused tetrazolo[1,5-a][1,4]benzodiazepine 6 in high yield and good diversity.  相似文献   

17.
The condensation of 4,4,4-trifluoro-1-phenylbut-1-en-3-one with 2-aminobenzimidazole, 3-amino-1,2,4-triazole, and 5-aminotetrazole gives hydroxy-substituted tetrahydro derivatives of pyrimido[1,2-a]benzimidazole, and of 1,2,4-triazolo-, and tetrazolo[1,5-a]pyrimidine. Dehydration of them to the corresponding dihydroazolopyrimidines has been carried out. An X-ray structural investigation was carried out and the molecular structure of 5-hydroxy-7-phenyl-5-trifluoromethyl-4,5,5,7-tetrahydrotetrazolo[1,5-a]pyrimidine is discussed.  相似文献   

18.
Bismuth triflate has been found as a potential catalyst for an efficient and solvent-free synthesis of symmetrical 2,4,6-triarylpyridines in 86–93% yields. Moreover, catalytic reactivity of bismuth triflate toward tetrazolo[1,5-a]quinoline-4-carbaldehydes for the unexpected formation of their corresponding acetals has been exploited.  相似文献   

19.
20.
6-Unsubstituted 7-R-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines (R = H or Me) were synthesized via two pathways: (a) deacylation of the corresponding 5-acetyl Biginelli-like precursors in KOH/H2O and (b) reduction of the corresponding 1,2,4-triazolo[1,5-a]pyrimidines using LiAlH4. The products could be easily formylated at position 6, which is promising for the further synthesis of functionalized 6-substituted derivatives of 4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines. In contrast, 6-acetyl-7-(4-(N,N-dimethylaminophenyl))-5-methyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine undergoes a cascade process in KOH/H2O, leading to the formation of a 4,5,8,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazoline derivative.  相似文献   

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