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51.
A highly sensitive method for the quantitative determination of 2,6-dimethy-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-[2-(N-benzyl-N-methyl-amino)]-ethyl ester 5-methyl ester hydrochloride (YC-93) in plasma is described. After extraction, YC-93 was oxidized to pyridine analogue with nitrous acid and detected by electron capture gas chromatography. The sensitivity was 2–3 ng/ml, which is suficient to determine plasma concentrations of YC-93 after oral administration of clinical doses to humans. 相似文献
52.
Mukai C Inagaki F Yoshida T Yoshitani K Hara Y Kitagaki S 《The Journal of organic chemistry》2005,70(18):7159-7171
[reaction: see text] Rhodium(I)-catalyzed PKR of allenynes was found to be applicable for constructing azabicyclo[5.3.0]decadienone as well as oxabicyclo[5.3.0]decadienone frameworks. In addition, a reliable procedure for constructing a 10-monosubstituted bicyclo[5.3.0]deca-1,7-dien-9-one ring system by the rhodium(I)-catalyzed PKR of allenynes was developed under the condition of 10 atm of CO. Investigation of the rhodium(I)-catalyzed cycloisomerization of 4-phenylsulfonylnona-2,3-dien-8-ynes under nitrogen atmosphere gave the corresponding cyclohexene derivatives, whereas the C1-homologated allenynes produced cycloheptene derivatives and/or bicyclo[5.2.0]nonene skeletons depending on the substitution pattern at the allenic terminus. Thus, proper choice of the starting allenynes and reaction conditions led to the selective formation of 2-phenylsulfonylbicyclo[5.3.0]deca-1,7-dien-9-ones (Pauson-Khand-type product), 3-alkylidene-1-phenylsulfonyl-2-vinylcycloheptene derivatives, and bicyclo[5.2.0]nonene frameworks. 相似文献
53.
A convergent synthesis of the A-F ring segment of yessotoxin and adriatoxin was achieved via the intramolecular allylation of an α-chloroacetoxy ether and subsequent ring-closing metathesis. 相似文献
54.
Shoichi Katsuta Hirokazu Wakabayashi Mariko Tamaru Yoshihiro Kudo Yasuyuki Takeda 《Journal of solution chemistry》2007,36(4):531-547
Equilibria concerning picrates of tetraalkylammonium ions (Me4N+, Et4N+, Pr4N+, Bu4N+, Bu3MeN+) in a dichloromethane−water system have been investigated at 25 ∘C. The 1:1 ion-pair formation constants (K
IP,o
o) in dichloromethane at infinite dilution were conductometrically determined. The distribution constants (K
D
o) of the ion pairs and the free cations between the solvents were determined by a batch-extraction method. The K
IP,o
o value varies in the cation sequence, Bu4N+ ≈ Pr4N+ ≈ Et4N+ < Bu3MeN+ < < Me4N+; this trend is explained by the electrostatic cation−anion interaction taking into account the structures of the ion pairs
determined by density functional theory calculations. For the ion pairs of the symmetric R4N+ cations, there is a linear positive relationship between log10
K
D
o and the number of methylene groups in the cation (N
CH
2). The ion pair of asymmetric Bu3MeN+ has a higher distribution constant than that expected from the above log10
K
D
o
versus
N
CH
2 relationship. These cation dependencies of log10
K
D
o for the ion pairs are explained theoretically by using the Hildebrand-Scatchard equation. For all the cations, the log10
K
D
o value of the free cation increases linearly with N
CH
2; the variation of log10
K
D
o is discussed by decomposing the distribution constant into the Born-type electrostatic contribution and the non-Born one,
and attributed to the latter that is governed by the differences in the molar volumes of the cations. The cation dependencies
of the ion-pair extractability and ion pairing in water are also discussed.
An erratum to this article can be found at 相似文献
55.
Igarashi S Inami H Hara H Fujii M Koutoku H Oritani H Mase T 《Chemical & pharmaceutical bulletin》2000,48(3):382-388
In a search for novel nonsteroidal inhibitors of human prostatic 5alpha-reductase, we found a new series of indole derivatives that showed potent inhibitory activities for the human enzyme. Among them, 4-[(1-benzyl-1H-indol-5-yl)oxyl-3-chlorobenzoic acid (2d, YM-32906) showed more potent inhibitory activity than finasteride with an IC50 value of 0.44 nM. 3-Chloro-4-[[1-(4-phenoxybenzyl)-1H-indol-5-yl]oxy]benzoic acid (2m) showed inhibitory activities for both human and rat prostatic 5alpha-reductase with IC50 values of 2.1 and 73 nM, respectively. The synthesis and structure-activity relationships of these indole derivatives are presented. 相似文献
56.
Yoshinori Tominaga Mayumi Hara Harumasa Honkawa Akira Hosomi 《Journal of heterocyclic chemistry》1990,27(5):1245-1248
N-Bis(methylthio)methylene-p-toluenesulfonamide ( 1 ) reacted with active methylene compounds such as malononitrile ( 2a ) and, cyanoacetamide ( 2b ) to give the corresponding 3-methylthio-3-p-toluenesulfonylami-nopropenenitrile derivatives 3a,b which were found to be convenient starting materials for the synthesis of 3,5-diaminopyrazole derivatives. Reaction of 3a and 3b with hydrazines gave the corresponding 3,5-diaminopyrazoles 4a-e , key intermediates for the synthesis of 3-aminopyrazolo[3,4-d]pyrimidine derivatives 5a-d . 相似文献
57.
We use the lace expansion to study the standard self-avoiding walk in thed-dimensional hypercubic lattice, ford5. We prove that the numberc
n ofn-step self-avoiding walks satisfiesc
n
~A
n
, where is the connective constant (i.e. =1), and that the mean square displacement is asymptotically linear in the number of steps (i.e.v=1/2). A bound is obtained forc
n(x), the number ofn-step self-avoiding walks ending atx. The correlation length is shown to diverge asymptotically like (––Z)1/2. The critical two-point function is shown to decay at least as fast as x–2, and its Fourier transform is shown to be asymptotic to a multiple ofk
–2 ask0 (i.e. =0). We also prove that the scaling limit is Gaussian, in the sense of convergence in distribution to Brownian motion. The infinite self-avoiding walk is constructed. In this paper we prove these results assuming convergence of the lace expansion. The convergence of the lace expansion is proved in a companion paper.Supported by the Nishina Memorial Foundation and NSF grant PHY-8896163.Supported by NSERC grant A9351 相似文献
58.
Simultaneous analysis of tea catechins, caffeine, gallic acid, theanine and ascorbic acid by micellar electrokinetic capillary chromatography 总被引:4,自引:0,他引:4
A micellar electrokinetic capillary chromatography (MEKC) method for the simultaneous analysis of five tea catechins, theanine, caffeine, gallic acid and ascorbic acid has been developed. The catechins are (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate. p-Nitrophenol serves as both reference and internal standard. All the components are separated within 13 min with a 57 cm uncoated fused-silica column. On-column detection was carried out at 200 nm. This method has been used to measure these compounds in fresh tea leaves and tea liquor. The limit of detection for all analytes ranged from 1 to 20 microg/ml. 相似文献
59.
[reaction: see text] We describe an efficient synthesis of di-branched heptasaccharide 1 having phytoalexin elicitor activity in soybeans by one-pot glycosylation. The synthesis involves chemo- and regioselective sequential six-step glycosylations using seven independent building blocks and sequential removal of acyl- and benzyl ether-type protecting groups. The coupling of seven building blocks requires only four chemoselective activitable leaving groups of glycosyl donors. Both the glycosylation and deprotection reactions can be achieved utilizing a parallel manual synthesizer. 相似文献
60.
A new preparative sequence from 2,3-polymethylene-2-cyclopentenone 5 to 2,6-polymethylenebromobenzenes 3 (n = 6, 7, 10) and 2,6-polymethylenephenyllithiums 6 has been found. The reaction of 6 with various electrophiles produces a number of new compounds to disclose the unique reactivity of the aryl C-Li moiety surrounded by the polymethylene chain. Photolysis of 3a and 3b provides transannular products 8, 10 and 11, all arising from the proximity between the aromatic bromine and the aliphatic hydrogen intraannularly opposed to be removed as HBr. Spectrometric study gives quantitative data of the dependence of the molecular geometry upon the chain length and the aromatic substituents. The energy barriers ΔGc≠ of the conformational flipping are 17·4 kcal/mol (Tc 76·5°) for [6]metacyclophane (7a), 11·5 kcal/mol (Tc ?28°) for [7]metacyclophane (7b), ·8 kcal/mol for [10]metacyclophane (7c). The lower-energy process of the aliphatic chain in [6]metacyclophane derivatives is the pseudorotation with substituent-dependent barrier ΔGc≠ 11·1 kcal/mol (Tc ?31·5°) for 7a, 12·4 kcal/mol (Tc ?4·5°) for 3a and 12·7 kcal/mol (Tc 1·0°) for 12a. The rather large rotational barrier is attributed to the compressed structure of each system. The benzene ring distortion of the cyclophanes is deduced from the bathochromic shift of the B-band and the diamagnetic shift of the benzene proton signals in the PMR. 相似文献