Novel 1,4-dihydropyridine calcium antagonists. II. Synthesis and antihypertensive activity of 3-[4-(substituted amino)phenylalkyl]ester derivatives

Novel 1,4-dihydropyridine derivatives bearing 3-[4-(substituted amino)phenylalkyl]ester side chains were prepared and tested for their antihypertensive activity in spontaneously hypertensive rats. Most compounds showed a more potent antihypertensive effect and a longer duration of action than nicardipine. The derivatives with a benzhydrylpiperazinyl and a benzhydrylpiperidinyl group were distinctive. 2-[4-(4-Benzhydryl-1-piperazinyl)phenyl]ethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylate (4e), its 4-(4-cyano-2-pyridyl) analogue (4f), its 3-[4-(4-benzhydryl-1-piperazinyl)phenyl]propyl ester analogue (4h), its 2-[4-(4-benzhydryl-1-piperidinyl)phenyl]ethyl ester analogue (4j), and its 2-[4-(1-benzhydryl-4-piperidinyl)phenyl]ethyl ester analogue (4k) were selected as candidates for further pharmacological investigations.     

Aspirin prodrugs: synthesis and hydrolysis of 2-benzyloxy-2-methyl-4H-1,3-benzodioxin-4-ones

Aspirin is widely used for its analgesic, antiinflammatory and antipyretic properties. Among its disadvantages are the relatively narrow therapeutic margin, its irritancy towards the gastric mucosa, and occasionally patient hypersensitivity towards aspirin. As part of our effort to develop prodrugs without these liabilities eleven new title compounds have been isolated and characterized. These 'superaspirin' candidates were subjected to non-enzymatic hydrolysis for a first rapid screening in vitro. Only 2-(2,6-dimethoxybenzyloxy)-2-methyl-4H-1,3-benzodioxin-4-one (4c) was observed to act as an exclusive aspirin prodrug, while 2-(2-methoxybenzyloxy)-2-methyl-4H-1,3-benzodioxin-4-one (4b) and 2-(2-ethoxybenzyloxy)-2-methyl-4H-1,3- benzodioxin-4-one (4d) were shown to release both aspirin 6 and salicylic acid 7. Subsequently, these three candidates were further characterized by investigation of the pH profile of their hydrolysis rates.     

Novel benzamides as selective and potent gastrokinetic agents. IV. Synthesis and structure-activity relationships of 2-substituted 4-amino-N-[(4-benzyl-2-morpholinyl)methyl]-5-chlorobenzamides.

A new series of 2-substituted 4-amino-N-[(4-benzyl-2-morpholinyl)methyl]-5-chlorobenzamides (4-39) including a few 4-fluorobenzyl analogues were prepared and evaluated for their gastrokinetic activity by determining their effects on the gastric emptying activity of phenol red semisolid meal in rats. The C-2 substituent comprises alkoxy and variously substituted alkoxy groups. Among the derivatives, 4-amino-N-[(4-benzyl-2-morpholinyl)methyl]-2-(n-butoxy)-5-chlorobenza mide (5), its 4-fluorobenzyl (6), and 3-methyl-2-butenyloxy analogues (22) were superior to cisapride and essentially equipotent to the 2-ethoxy analogue (1b, AS-4370 as its citrate) in gastrokinetic activity. These compounds, like AS-4370, had no dopamine D2 receptor antagonistic activity.     

Stability and reactivity of all-metal aromatic and antiaromatic systems in light of the principles of maximum hardness and minimum polarizability

It is demonstrated that among various possible isomers of all-metal aromatic compounds such as Al(4)(2-) and their complexes the most stable isomer with the minimum energy is the hardest and the least polarizable. A similar situation is observed for different isomers of all-metal antiaromatic compounds such as Al(4)(4-) and their complexes. It is shown that linear Al(4)(4-) is energetically more stable than its cyclic isomer. The reaction energies associated with the complexation processes highlight the stability of those complexes. The difference in energy, hardness, and polarizability between a cyclic molecule and its linear counterpart convincingly shows that an aromatic molecule exhibits negative changes in energy and polarizability but positive changes in hardness as expected from the principles of minimum energy, minimum polarizability, and maximum hardness. Although the aromaticity of Al(4)(2-) is unequivocally established through this study, the antiaromaticity picture in the case of Al(4)(4-) is shown to be poorly understood;however, the present analysis sheds light on this controversy.     

D2-symmetric dirhodium catalyst derived from a 1,2,2-triarylcyclopropanecarboxylate ligand: design, synthesis and application

Dirhodium tetrakis-(R)-(1-(4-bromophenyl)-2,2-diphenylcyclopropanecarboxylate) (Rh(2)(R-BTPCP)(4)) was found to be an effective chiral catalyst for enantioselective reactions of aryl- and styryldiazoacetates. Highly enantioselective cyclopropanations, tandem cyclopropanation/Cope rearrangements and a combined C-H functionalization/Cope rearrangement were achieved using Rh(2)(R-BTPCP)(4) as catalyst. The advantages of Rh(2)(R-BTPCP)(4) include its ease of synthesis, its tolerance to the size of the ester group in the styryldiazoacetates, and its compatibility with dichloromethane as solvent. Computational studies suggest that the catalyst adopts a D(2)-symmetric arrangement, but when the carbenoid binds to the catalyst, two of the p-bromophenyl groups on the ligands rotate outward to make room for the carbenoid and the approach of the substrate to the carbenoid.     

A new unusual natural pigment from Selaginella sinensis and its noticeable physicochemical properties

A new unusual pigment with a novel carbon framework named selaginellin (1) was isolated from the acetone extract of Selaginella sinensis, and its methoxy derivative (1a) was synthesized. Both selaginellin 1 and 1a are racemic compounds. The structure of selaginellin 1 was established as (R,S)-4-[(4'-hydroxy-4-(hydroxymethyl)-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene]-2,5-cyclohexadien-1-one and 1a as (R,S)-4-[(4'-methoxy-4-(methoxymethyl)-3-((4-methoxyphenyl)ethynyl)biphenyl-2-yl)(4-methoxyphenyl)methylene]-2,5-cyclohexadien-1-one by the analysis of one- and two-dimensional NMR data, HR-ESIMS, EI-MS, IR, UV, CD, and single-crystal X-ray experiments, and the mechanism of their color change according to different pH values and fluorescent properties was studied.     

Synthetic sulfated glucuronosyl paragloboside (SGPG) and its use for the detection of autoimmune peripheral neuropathies

The sulfated glucuronosyl paragloboside SO₄-3-GlcA(β1-3)Gal-(β1-4)GlcNAc(β1-3)Gal-(β1-4)Glcβ(1-1′)Cer (SGPG) is a specific constituent of the peripheral nervous system involved in human dysimmune neuropathies. Although it is highly immunogenic in human pathology, it is not a major constituent of peripheral nerve in humans. Pure SGPG is very difficult to obtain from natural sources, but is needed for the design of efficient and reproducible immunoassays. We describe a new chemical synthesis of this important glycolipid with a stearic tail, including its complete characterization by mass spectrometry and its use in the detection of autoimmune neuropathies.     

Synthetic studies of carbapenem and penem antibiotics. II. Synthesis of 3-acetyl-2-azetidinones by (2 + 2) cycloaddition of diketene and Schiff bases.

It was found that (2 + 2) cycloaddition reaction of diketene with Schiff bases was effectively promoted by imidazole as a catalyst to afford 3-acetyl-2-azetidinone derivatives 4. As an application of this new method, a practical asymmetric synthesis of 4 and its conversion into (3S,4S)-4-carboxy-1-(di-p-anisylmethyl)-3-[(R)-1-hydroxyethyl]-2- azetidinone, which is a key intermediate for the synthesis of carbapenem and penem antibiotics, were accomplished.     

Synthesis and Analysis of the Sterically Constrained L-Glutamine Analogues (3S,4R)-3,4-Dimethyl-l-glutamine and (3S,4R)-3,4-Dimethyl-l-Pyroglutamic Acid

The nonproteinogenic amino acids (3S,4R)-3,4-Dimethyl-l-pyroglutamic acid and (3S,4R)-3,4-dimethyl-l-glutamine -- found in the cyclic depsipeptides callipeltin B, callipeltin A, and papuamide A -- were synthesized from a common intermediate derived from l-pyroglutamic acid. The diastereoselective introduction of the methyl groups was accomplished by cuprate addition and enolate alkylation, followed by a kinetic epimerization of the C-4 methyl substituent. (3S,4R)-3,4-dimethyl-l-glutamine shows a conformational restriction of its side chain which may be related to its biological function in the natural products where it is found.     

Regioselective oxidative coupling of 4-hydroxystilbenes: synthesis of resveratrol and epsilon-viniferin (E)-dehydrodimers

Treatment of 5-[2-(4-hydroxyphenyl)vinyl]benzene-1,3-diol (resveratrol) with an equimolar amount of silver(I) acetate in dry MeOH at 50 degrees C for 1 h followed by chromatographic purification with a short silica gel column allowed the isolation of its (E)-dehydrodimer, 5-[5-[2-(3,5-dihydroxyphenyl)vinyl]-2-(4-hydroxyphenyl)-2,3-dihydrobenzofuran-3-yl]benzene-1,3-diol, as a racemic mixture in high yield. The present method was applicable to the oxidative dimerization of 4-hydroxystilbenes such as trans-styrylphenol and 5-[6-hydroxy-2-(4-hydroxyphenyl)-4-[2-(4-hydroxyphenyl)vinyl]-2,3-dihydrobenzofuran-3-yl]benzene-1,3-diol (epsilon-viniferin) leading to the corresponding 2-(4-hydroxyphenyl)-2,3-dihydrobenzofurans possessing various types of biological activities.     

Isoindole derivatives from 2-isonicotinoyl-acetophenone with ammonia and its derivatives

2-Isonicotinoylacetophenone (1) reacts with aqueous ammonia in the presence of acid to produce the deep blue 3-(4-pyridyl)-1-[3-(4-pyridyl)-1H -1-isoindolylidenemethyl]-2H-isoindole which changed to the deep bluish green adduct showing the wavelength maximum at 744 nm by treating with methyl iodide. From the reaction of 1 and glycine or its methyl ester the red 3,3′-di-(4-pyridyl)-1,1′-vinylenebis(2H-2-isoindoleacetic acid) or its derivative were obtained respectively.     

Synthesis of the optical isomers of 4-[1-(4-tert-butylphenyl)-2-oxo- pyrrolidine-4-yl]methyloxybenzoic acid (S-2) and their biological evaluation as antilipidemic agent

The enantiomers of (+/-)-4-[1-(4-tert-butylphenyl)-2-oxo-pyrrolidine- 4-yl]methyloxybenzoic acid (S-2), a new antilipidemic agent having dual action on the plasma triglyceride (TG) and cholesterol (Cho) lowering effects, were prepared via separation by Chiralcel OJ column chromatography of their methyl ester and also by the same method as the described racemate's synthesis from optically active 1-(4-tert-butylphenyl)-2-oxo-pyrrolidine-4-carboxylic acid respectively. These optically active carboxylic acids were prepared by the resolution of diastereomeric N-[(S)-(-)-[4-methyl-(alpha-methyl)benzyl]]-1-(4-tert-butylphenyl)-2-oxo - pyrrolidine-4-carboxyamide using silica gel column chromatography, followed by deamination with N2O4. The absolute configurations for the enantiomers of S-2 were indirectly determined using X-ray analysis of the 4-bromo-2-fluorobenzamide of the (+)-4-[1-(4-tert-butylphenyl)-2- oxo-pyrrolidine-4-yl]-methyloxybenzoic acid. S-2 and its enantiomers showed an essentially equipotent activity on the fatty acid- and sterol-biosynthesis inhibition in vitro. On the other hand, in the in vivo activity, (S)-(+)-4-[1-(4-tert-butylphenyl)-2-oxo-pyrrolidine- 4-yl]methyloxybenzoic acid (S-2E) was superior in the lowering abilities of the plasma TG and phospholipid(PL) and was chosen as a candidate for a novel antilipidemic agent. The difference in the in vivo activity among S-2 and its enantiomers was explained from the pharmacokinetics after administration p.o.     

Tunable supramolecular synthons and versatile, water-soluble building blocks for crystal engineering:

It is shown that the water-soluble dicarboxylic cationic acid [(eta5-C5H4COOH)2Co(III)]+ (1) is an extremely versatile building block for the construction of organometallic crystalline edifices. Removal of one proton from 1 leads to formation of the neutral zwitterion [(eta5-C5H4COOH)(eta5-C5H4COO)Co(III)] (2), while further deprotonation leads to formation of the dicarboxylate monoanion [(eta5-C5H4COO)2Co(III)]- (3). Compounds 1. 2 and 3 possess different hydrogen-bonding capacity and participate in a variety of hydrogen-bonding networks. The cationic form 1 has been characterised as its [PF6]- and Cl- salts 1-[PF6] and 1-Cl.H2O, as well as in its co-crystal with urea, 1-Cl.3(NH2)2CO, and with the zwitterionic form 2, [(eta5-CH4COOH)(eta5-C5H4COO)Co(III)][(eta5-C5H4COOH)2Co(III)]+[PF6]-, 2.1-[PF6]. The neutral zwitterion 2 behaves as a supramolecular crown ether: it encapsulates the alkali cations K+, Rb+ and Cs+ as well as the ammonium cation NH4+ in cages sustained by O-H...O and C-H...O hydrogen bonds to form co-crystalline salts of the type 2(2)-M[PF6] (M = K, Rb, Cs) and 2(2)-[NH4][PF6]. The deprotonated acid 3 has been characterised as its Cs+ salt, Cs+-3.3H2O.     

新型含噻吩基8-羟基喹啉锌配合物的合成及光电性能简

设计合成了含噻吩基的新型配体(E)-2-[2-(3-噻吩基)乙烯基]-8-羟基喹啉(4)及相应的锌配合物5,产物结构经核磁共振、红外光谱和元素分析进行表征. 利用X射线单晶衍射仪测定了中间体(E)-2-[2-(3-噻吩基)乙烯基]-8-乙酰氧基喹啉(3)和配体4的单晶结构,结果表明中间体3晶体分子间并无明显的氢键作用,分子间呈交错堆叠;配体4分子之间由硫氢氧键弱作用相互排列形成网状结构. 通过核磁滴定及紫外和荧光滴定模拟了配体4在溶液中与金属锌的配位过程. 固体荧光寿命研究结果表明,配合物5的荧光寿命为18.8 ms. 通过电致发光器件研究发现,配合物5作为发光层具有良好的电致发光性能,同时具有较好的电子传输能力.     

Indoprofen类似物的合成和表征

以邻硝基苯甲醛为超始原料，合成2-溴甲基-3-喹啉酸乙酯中间体，其分别与 苯胺、2-氯代苯胺、3-氯代苯胺、2-甲基苯胺和3-甲基苯胺发生Williamson反应， Williamson反应产物经闭环反应，得到新化合物2，3-二氢-1-氧代-2-苯基-1H-吡 咯并[3，4-b]喹啉（4a），2，3-二氢-1-氧代-2-（2-氯代苯基）-1H-吡咯并[3， 4-b]喹啉（4b），2，3-二氢-1-氧代-2-（3-氯代苯基）-1H-吡咯并[3,4-b]喹啉（ 4c），2，3-二氢-1-氧代-2-（2-甲基苯基）-1H-吡咯并[3，4-b]喹啉（4d）和2， 3-二氢-1-氧代-2-（3-甲基苯基）-1H-吡咯并[3，4-b]喹啉（4e）。12个新化合物 由元素分析、红外光谱、核磁共振氢谱、质谱予以证实。     

雪松烷二醇硼酸酯的合成及其不对称同系化反应

报道了手性试剂雪松烷二醇硼酸酯(3)的合成及其和二氯甲基锂进行不对称同系化反应,生成α-氯代硼酸酯4R和4S,其R/S的比率在25:1以上,并且有手性助剂容易回收的特点。通过对同系化产物4cR的单晶X衍射分析,发现其分子中的1,3-二氧杂-2-硼杂环戊烷为非平面结构,文中就这一结构特点进行了初步讨论,解释了雪松烷二醇硼酸酯容易水解的原因。     

Novel 1,4-dihydropyridine calcium antagonists. I. Synthesis and hypotensive activity of 4-(substituted pyridyl)-1,4-dihydropyridine derivatives

A series of 4-(substituted pyridyl)-1,4-dihydropyridine derivatives were synthesized and their hypotensive effects examined. Several compounds, 2-(N-benzyl-N-methylamino)ethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitro-2-pyridyl)-3,5-pyridinedicarboxylate (2b), its 4-(4-nitro-2-pyridyl) analogue (2g), 4-(3-trifluoromethyl-2-pyridyl) analogue (2c), 4-(2-trifluoromethyl-3-pyridyl) analogue (3e), 4-(4-cyano-2-pyridyl) analogue (2e), 4-(2-cyano-3-pyridyl) analogue (3d), and 4-(6-bromo-2-pyridyl) analogue (2i), were found to have a hypotensive activity parallel to that of nicardipine; 2c and 3e, in particular, had approximately twice the duration of nicardipine, and 2e had the most potent hypotensive activity of all the derivatives synthesized.     

Synthetic cephalosporins. VI. Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxy-1-methyl) ethoxyiminoacetamido]- 3-(3-hydroxy-4-pyridon-1-yl)methyl-3-cephem-4-carboxylic acid and related compounds

Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxy-1-methyl)ethoxyimin oacetamido]- 3-(3-hydroxy-4-pyridon-1-yl)-3-cephem-4-carboxylic acid (12) and its related compounds are described. Compound 12 exhibited excellent antibacterial activity against gram-negative bacteria, and its anti-pseudomonal activity was ten to fifteen times greater than that of ceftazidime.     

Gas phase analogs of stable sodium-tin Zintl ions: anion photoelectron spectroscopy and electronic structure

Mass spectrometry and photoelectron spectroscopy together with first principles theoretical calculations have been used to study the electronic and geometric properties of the following sodium-tin, cluster anion/neutral cluster combinations, (Na(n)Sn(4))(-)/(Na(n)Sn(4)), n = 0-4 and (NaSn(m))(-)/(NaSn(m)), m = 4-7. These synergistic studies found that specific Zintl anions, which are known to occur in condensed Zintl phases, also exist as stable moieties within free clusters. In particular, the cluster anion, (Na(3)Sn(4))(-) is very stable and is characterized as (Na(+))(3)(Sn(4))(-4); its moiety, (Sn(4))(-4) is a classic example of a Zintl anion. In addition, the cluster anion, (NaSn(5))(-) was the most abundant species to be observed in our mass spectrum, and it is characterized as Na(+)(Sn(5))(2-). Its moiety, (Sn(5))(2-) is also known to be present as a Zintl anion in condensed phases.     

Stabilisation of tetravalent cerium in perchloric acid medium and measurement of the stability constants of its fluoride complexes using ion selective potentiometry

The stability constants of the fluoride complexes of cerium(IV) in 1 M (HClO(4), NaClO(4)) medium have been measured potentiometrically using a fluoride ion-selective electrode. Quantitative oxidation of cerium to its tetravalent state and its stabilisation in the perchlorate medium were accomplished by oxidation with AgO followed by quick addition of a known amount of fluoride ion. This procedure ensures stability of the oxidation state and prevents hydrolysis and polymerisation of Ce(IV). Logarithms of the average values of beta(1), beta(2), beta(3) and beta(4) were estimated to be 7.57+/-0.04, 14.50+/-0.03, 20.13+/-0.37 and 24.14+/-0.10 respectively.