Synthesis and some properties of 4-phosphorylated derivatives of 5-mercapto-1,3-oxazoles

Various approaches to the synthesis of new derivatives of diethyl 5-mercapto-2-R-1,3-oxazole-4-ylphosphonates were considered. The behavior of these compounds in the presence of mineral acids and alkalis resulting in the synthesis of previously unknown 5-mercapto-2-R-1,3-oxazole-4-ylphosphonic acids was studied.     

Synthesis and mesomorphic properties of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

A series of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoate liquid crystals have been synthesized. Their phase transition temperatures have been measured by optical polarizing microscopy and confirmed by DSC. The results show that a highly fluorinated terminal chain impairs mesomorphic properties.     

Synthesis and mesomorphic properties of n-alkyl 4-[4-(4-n-octyloxybenzyloxy-2,3,5,6-tetrafluorophenyl)ethynyl]benzoates

A new series of n-alkyl 4-[4-(4-n-octyloxybenzyloxy-2,3,5,6-tetrafluorophenyl)ethynyl)benzoates have been prepared. Polarizing microscopic textural observation shows that they are liquid crystals with nematic phase.     

Synthesis and mesomorphic properties of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

A series of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoate liquid crystals have been synthesized. Their phase transition temperatures have been measured by optical polarizing microscopy and confirmed by DSC. The results show that a highly fluorinated terminal chain impairs mesomorphic properties.     

Synthesis and mesomorphic properties of the homologous series of 4'-bromophenyl 4'-[(4-n-alkoxy-2,3,5,6 tetrafluorophenyl)ethynyl]benzoates

A homologous series of 4'-bromophenyl 4'-[(4-n-alkoxy-2,3,5,6-tetrafluoro-phenyl)ethynyl]benzoates has been synthesized. The transition temperatures were studied by polarizing optical microscopy. The compounds exhibit nematic and smectic A phases.     

Synthesis and anti-HBV activity of S-substituted 7-mercapto-4-methylcoumarin analogs

Twelve S-substituted 7-mercapto-4-methylcoumarin analogs were synthesized and evaluated for the inhibition to HBV in HepG2 2.2.1.5 cell. Among them, ten compounds exhibited potent inhibition to HBsAg and/or HBeAg with the IC50 values of sub μmol/L level. The ICso of anti-HBsAg activities of 5c and 5j reached 0.01 μmol/L respectively which were 16 fold more potent than that of 3TC. Compounds 3, 5e, 5g, 5h and 5i showed admirable inhibitory activity to both HBsAg and HBeAg. The bioassay results indicated the S-substituted 7-mercapto-4-methylcoumarin analogs merit attention as novel anti-HBV agents.     

Synthesis and mesomorphic properties of 4-n-alkoxy 4'-[4-((4-n-alkoxy-2,3,5,6-tetrafluoro-phenyl)ethynyl)benzyloxy]benzoates

Two series of tolane-based liquid crystals have been prepared that incorporate a tetrafluorophenyl moiety and a flexible methyl ether bond into the core structure. The mesomorphic properties have been studied by polarizing microscopic textural observation and DSC measurements. By comparison with their non-fluorinated analogues, the effect of tetrafluorophenylene on mesomorphic behaviour has been discussed in this paper.     

2,3,5,6-四氟苯甲醇的合成

经氟代、水解脱羧、酯化、还原等步骤合成了杀虫剂四氟苯菊酯的重要中间体2,3,5,6-四氟苯甲醇, 改进了氟代反应的无水操作和反应条件, 产物四氟对苯二甲腈纯度高达98.3%, 通过加入水参与反应改进了水解反应, 使水解和脱羧由两步反应变为一步, 且产物为只脱一个羧基的2,3,5,6-四氟苯甲酸, 收率可以高达92.5%, 用相对价廉的NaBH₄/I₂体系还原2,3,5,6-四氟苯甲酸甲酯以52.3%的收率得到了目标产物, 总收率29.6%.     

Synthesis and some properties of 4-alkyl-5-cyano-6-mercapto-3,4-dihydropyridin-2(1H)-ones

Condensation of propionic (or acetic) aldehyde, cyanothioacetamide, Meldrum's acid, andN-methylmorpholine occursvia the intermediate formation of the corresponding Michael adducts and yields 4-alkyl-5-cyano-6-mercapto-3,4-dihydropyridin-2(1H)-ones. The oxidation of the reaction products with DMSO and their alkylation were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2016–2019, November, 1997.     

Synthesis and Diels-Alder Reactivity of 2,3,5,6-Tetramethylidenenorbornane

Pd-catalyzed double carbomethoxylation of the Diels-Alder adduct of cyclo-pentadiene and maleic anhydride yielded the methyl norbornane-2,3-endo-5, 6-exo-tetracarboxylate ( 4 ) which was transformed in three steps into 2,3,5,6-tetramethyl-idenenorbornane ( 1 ). The cycloaddition of tetracyanoethylene (TCNE) to 1 giving the corresponding monoadduct 7 was 364 times faster (toluene, 25°) than the addition of TCNE to 7 yielding the bis-adduct 9 . Similar reactivity trends were observed for the additions of TCNE to the less reactive 2,3,5,6-tetramethylidene-7-oxanorbornane ( 2 ). The following second order rate constants (toluene, 25°) and activation parameters were obtained for: 1 + TCNE → 7 : k₁ = (255 + 5) 10^?4 mol^?1 · s^?1, ΔH≠ = (12.2 ± 0.5) kcal/mol, ΔS≠ = (?24.8 ± 1.6) eu.; 7 + TCNE → 9 , k₂ = (0.7 ± 0.02) 10^?4 mol^?1 · s^?1, ΔH≠ = (14.1 ± 1.0) kcal/mol, ΔS≠ = ( ?30 ± 3.5) eu.; 2 + TCNE → 8 : k₁ = (1.5 ± 0.03) 10^?4 mol^?1 · s^?1, ΔH≠ = (14.8 ± 0.7) kcal/mol, ΔS≠ = (?26.4 ± 2.3) eu.; 8 + TCNE → 10 ; k₂ = (0.004 ± 0.0002) 10^?4 mol^?1 · s^?1, ΔH≠ = (17 ± 1.5) kcal/mol, ΔS≠ = (?30 ± 4) eu. The possible origins of the relatively large rate ratios k₁/k₂ are discussed briefly.     

Synthesis and mesomorphic properties of 1-(4′-ethyl biphenylyl) 2-(4-alkoxy-2,3,5,6-tetrafluorophenyl) acetylenes

A series of l-(4′-ethylbiphenylyl) 2-(4-alkoxy-2,3,5,6-tetrafluorophenyl)acetylenes and their nonfluorinated analogues have been prepared. The polarizing microscope observation shows that the fluorinated target compounds exhibit enantiotropic nematic phases, whereas the nonfluorinated analogues show complicated DSC results. The effect of structure modification of the core on mesogenic phases was discussed by comparing the data of fluorinated target compounds with those of corresponding nonfluorinated analogues.     

Reactions of Polyhalopyridines. 16. Synthesis and Reactions of 2,3,5,6-Tetrafluoro-4-perfluoroalkylthiopyridines

Identical reaction products, viz. 2,3,5,6-tetrafluoro-4-perfluoroalkylthiopyridines 3a-c, were obtained on thermal decomposition of Xe(II) bisperfluoroalkylcarboxylates in the presence of mercaptotetrafluoropyridine and bis(2,3,5,6-tetrafluoro-4-pyridyl) disulfide. Compounds 3a-c readily interact with N-, O-, and S-containing nucleophiles, though with the first two types of reactant only with substitution of fluorine atoms in position 2 of the pyridine ring. In the latter case products are obtained both with retention of the perfluoroalkylthio group on interaction with sodium N,N-dimethyldithiocarbamate, and with total fission of that group in the case of alkali metal methanethiolate and toluenethiolate.     

Synthesis and mesomorphic behaviour of 4''''-methoxyphenyl 4"-[(4-n-alkoxy-2,3,5,6-tetrafluorophenyl) ethynyl] benzylethers

A novel homologous series of 4'-methyoxyphenyl 4"-[(4-n-alkoxy-2,3,5,6-tetrafluoro-phenyl]benzyl ethers have been prepared via Pd-catalysed Heck reactions. Polarizing microscopic textural observation shows that these compounds exhibit enantiotropic nematic phases.     

The synthesis and mesomorphic properties of 4-n-alkoxyphenyl 4-[(4-n-alkoxy-2,3,5,6-tetrafluorophenyl)ethyl]benzoates

4-n-Alkoxyphenyl4-[(4-n-alkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]benzoates (compound A) are synthesised by a convenient method. These compounds exhibit only enantiotropic nematic phases and have very high clearing points. These compounds (As) can be transformed into corresponding ethane derivatives, via hydrogenation using a palladium catalyst (Pd/C), which exhibit monotropic nematic phases. The effect of the ethylene bridge (–CH₂CH₂–) on the mesomorphic behaviour is discussed.     

4-巯基-4-脱氧-4'-去甲表鬼臼毒素的立体控制合成

4-巯基-4-脱氧-4'-去甲表鬼臼毒素是合成4位硫取代的4'-去甲表鬼臼毒素的关键中间体,由4'-去甲表鬼臼毒素与硫化氢在BF~3·Et~2O存在下立体控制制备,也可通过以NH~3/CH~CN选择性 地水解4-乙酰硫基-4-脱氧-4'-去甲表鬼臼毒素而制备.     

Mesomorphic properties of 4-(polyfluoroalkoxycarbonyl)phenyl 4-(4-n-heptoxy-2,3,5,6-tetrafluorophenyl)benzoates

A series of 4-(polyfluoroalkoxycarbonyl)phenyl 4-(4-n-heptoxy-2,3,5,6-tetrafluorophenyl)benzoates were synthesized and observed using DSC and optical polarizing microscopy. The results show that they are not mesogens. Their mesomorphic properties were compared with similar compounds containing no aromatic fluorine substituents.     

Synthesis and alkylation of 2-mercapto-4-quinazolone and the fungicidal activities of the compounds obtained

A convenient method of obtaining 2-mercapto-4-quinazolone has been developed and the alkylation of its ambidentate anions has been studied. It has been found that they exhibit a dual reactivity in alkylation reactions. It has been shown that alkylated 2-mercapto-4-quinazolones possess a moderate fungicidal activity.