Stereoselective synthesis of cis-4,7-disubstituted 4,7-dihydroxy-4,7-dihydro[2.2]paracyclophanes

The nucleophilic addition of butyllithium, phenyllithium, methyllithium, and triallylborane to [2.2]paracyclophane-4,7-quinone (1) proceeded regio- and stereospecifically to give the corresponding cis-4,7-disubstituted 4,7-dihydroxy-4,7-dihydro[2.2]paracyclophanes 2—5 with the endo orientation of the hydroxy groups. The structures of quinone 1 and diols 2, 4, and 5 were established by X-ray diffraction analysis.     

Facile Regioselective On-Water Synthesis of 4,7-Dihydropyrazolo[1,5-a]Pyrimidines and 4,7-Dihydro[1,2,4]Triazolo[1,5-a]Pyrimidines

Chemistry of Heterocyclic Compounds - Efficient and regioselective on-water synthesis of variously substituted 5-amino-4,7-dihydropyrazolo[1,5-a]pyrimidine-6-carbonitriles and...     

Synthesis of 4,7-diaminopyridazino[4,5-c]furoxan

4,7-Diaminopyridazino[4,5-c]furoxan was synthesized by intramolecular cyclization of 3-cyanofuroxan-4-carbamidrazone obtained from 3,4-dicyanofuroxan and hydrazine.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1559–1560, August, 1995.     

Reactions of 4,7-dibromo[1,2,5]thiadiazolo[3,4-d]pyridazine with alcohols

Russian Chemical Bulletin - The reaction of 4,7-dibromo[1,2,5]thiadiazolo[3,4-d]pyridazine with alcohols and sodium alkoxides was evaluated under various conditions. Depending on the reaction...     

A synthesis of 6-functionalized 4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidines

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.     

Synthesis of pyrrolo[2,3-b]azepine-4,7-dione derivatives

The Dieckmann reaction has been successfully applied for the first time in the synthesis of pvrrolo[2,3-b)]azepines.     

4,7-二噻吩-[2,1,3]苯并硒二唑的合成及其光电性能

苯并硫二唑经溴代,还原和闭环反应制得4,7-二溴[2,1,3]苯并硒二唑(3);以Pd(PPh3)2Cl2为催化剂,3与2-三丁基锡噻吩(4)经斯蒂尔偶联反应合成了4,7-二噻吩-[2,1,3]苯并硒二唑(5)。5为新化合物,其结构和性能经1H NMR,13C NMR,UV-Vis,荧光光谱法和循环伏安法表征。结果表明:5具有应用于光伏材料的带隙(12.2 e V);有较宽的吸收波长(260 nm~487 nm),在红光区域发射较强的荧光(620 nm);有可逆的氧化还原曲线,电化学性质稳定。     

The synthesis of [15]annulenone 4,7:10,13-dioxides and aromatic 4,7:10,13-dioxido[15]annulenium cations : Novel 14]gp ‘odd’ annulene systems

2,15 - Dimethoxycarbonyl - [15]annulenone 4,7:10,13 - dioxide (14) has been prepared by the condensation of cis -α,β -bis(5 - formyl - 2 - furyl)ethy]ene (13) with dimethyl acetonedicarboxylate. Treatment of 14 with conc H₂SO₄ led to 4,7:10,13-dioxido[15]annulenone 2,15-dicarboxylic acid anhydride (17), which was subsequently converted to the corresponding dicarboxylic acid (18) by dilute KOH. Decarboxylation of 18 gave rise to two isomeric [15]annulenone 4,7:10,13 - dioxides, i.e., the tri-cis isomer (7) and the mono - trans - di - cis isomer (8).Regarding to the ring current effects, the proton chemical shifts of these [15]annulenones were compared with those of a reference model, 4,7:10,13 - dioxido - cyclopentadecaheptaene (2.4.6.8.10.12.14) (3). Both of the parent [15]annulenones (7 and 8) have been interpreted as nondiatropic, while the anhydride (17) has been shown to be diatropic, sustaining an induced diamagnetic ring current. The enforced planarity and symmetrical geometry of the anhydride have been discussed. As expected, when 7, 8, 14, 17 and 18 were dissolved in CF₃COOH or conc H₂SO₄, completely delocalized [15]annulenium cations were produced, all of which proved to be diatropic. Three possible geometrical isomers of these 14π cations were established experimentally.     

Studies on dihydropyridine derivatives-I: 4,7-dihydroisoxazolo[5,4-b]pyridines

Reactions of 5-aminoisoxazoles with α,β-unsaturated ketones in t-butanol on heating afforded 4,7-dihydroisoxazolo [5,4-b]pyridines. However, when the reactions were carried out at 20° using ethylene glycol as the solvent, the kinetically controlled amino adducts were obtained in excellent yields. The amino adducts were converted into the thermodynamically controlled 4,7-dihydroisoxazolo[5,4-b]pyridines by heating. Tentative mechanisms for the reactions are also presented.     

Synthesis and tautomerism of 5,7-diaryl-4,7(6,7)-dihydrotetrazolo[1,5a]pyrimidines

5,7-Diaryl-4,7(6,7)-dihydrotetrazolo[1,5-a]pyrimidines were synthesized by the cyclocondensation of 5-aminotetrazole with chalcones. The tautomerism of the compounds obtained is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1489–1493, November, 1988.     

Multi-component reaction to access a library of polyfunctionally substituted 4,7-dihydropyrazolo[3,4-b]pyridines

A practical approach to polyfunctionally substituted 4,7-dihydropyrazolo[3,4-b]pyridine derivatives from heteroaryl hydrazine, 3-aryl-3-oxopropanenitriles and aldehydes have been described in the report. The present catalyst-free protocol involves the intermediacy of 5-aminopyrazole and α-cyanochalcone, which undergoes in situ Michael addition to afford title compounds in moderate to good yields. All the steps were conducted concomitantly to render the procedure as practical and straightforward as possible. The expeditious synthetic protocol experiment takes less than one hour and shows broad substrate scope.     

Vanillin esters of aromatic carboxylic acids in the synthesis of benzo[a]acridine and benzo[b][4,7]phenanthroline derivatives

By condensation of vanillin esters of substituted benzoic acids with 2-naphthylamine and 6-quinolylamines and also with cyclic β-diketones (1,3-cyclohexanedione and dimedone) 2-methoxy-4-(11-oxo-7,8,9,10,11,12-hexahydrobenzo[a]acridin-12-yl)-and 2-methoxy-4-(11-oxo-7,8,9,10,11,12-hexahydrobenzo[b][4,7]-phenanthrolin-12-yl)phenyl benzoates were prepared.