首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
In exploring the structural features which determine the antitumor activity of 2,4,6-tris-[(hydroxymethyl)methylamino]-1,3,5-triazine (trimelamol, 1), we have synthesized analogues in which the methyl groups have been replaced by the electron-withdrawing substituents 2,2,2-trifluoroethyl (5), propargyl (13), and cyanomethyl (15) via the respective tris(alkylamino)triazines 3, 12, and 14. Three mono[(hydroxymethyl)amino]triazines (4, 7, and 10) were also prepared. All the new tris(hydroxymethyl) derivatives showed cytotoxicities toward a variety of experimental rodent and human ovarian tumor cell lines similar to those shown by 1, the cyanomethyl analogue (15) having the most favorable profile. Mono(hydroxymethyl) derivatives (4 and 7) were ca. one-third as toxic. The new tris(hydroxymethyl) analogues were more stable to aqueous hydrolysis than was 1. Half-life (pH 7.5) values were, for 1, 120 min, for 5, 690 min, for 13, 450 min, and for 15, 275 min, but at pH 2.0, 15 (t1/2 350 min) was the most stable. This cyanomethyl analogue was also the most water-soluble, being comparable to 1 whereas 5 and 13 were poorly soluble.  相似文献   

2.
A simple synthesis of disaccharide oxazolines has been developed. Condensation of methyl 2-acetamido-4,6-O-benzylidene-2-deoxy-alpha-D-glucopyranoside with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide, followed by removal of the 4,6-O-benzylidene group from the resulting disaccharide derivative, gave crystalline methyl 2-acetamido-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-alpha-D-glucpyranoside which, on acetolysis with acetic anhydride-acetic acid-sulfuric acid, provided 2-methyl-[4,6-di-O-acetyl-1,2-dideoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-alpha-D-glucopyrano]-[2',1':4,5]-2-oxazoline (7). Synthesis of the related alpha-D-mannopyranosyl compound was similarly accomplished. The glycosylating capability of 7 was employed for the synthesis of 6-(benzyloxycarbonylamino)hexyl-2-acetamido-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-beta-D-glucopyranoside (18). An alternative synthesis of compound 18 is also described.  相似文献   

3.
Chemical synthesis of the branched pentasaccharide 6'-alpha-maltosyl-maltotriose (15) is reported, based on the use of one synthon as a glycosyl acceptor and another synthon as a glycosyl donor. The synthon used as glycosyl acceptor was phenyl 2,3,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside (7) and was synthesized from D-glucose with phenyl 2,3-di-O-acetyl-4,6-O-benzylidene-1-thio-beta-D-glucopyranoside and phenyl 2,3-di-O-benzyl-4,6-O-benzylidene-1-thio-beta-D-glucopyranoside as key intermediates. The synthon used as glycosyl donor was O-(2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-O-(2,3,6-tri-O -benzyl - alpha-D-glucopyranosyl)-(1-->6)-O-[(2,3,4,6-tetra-O-benzyl-alpha-D- glucopyranosyl)-(1-->4)]-2,3-di-O-benzyl-alpha,beta-D-glucopyranosyl trichloroacetimidate (12) and was synthesized from phenyl O-2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-O-(2,3,6-tri-O- benzyl- alpha-D-glucopyranosyl)-(1-->6)-O-[(2,3,4,6-tetra-O-acetyl-alpha-D- glucopyranosyl)-(1-->4)]-2,3-di-O-acetyl-1-thio-beta-D-glucopyranoside with O-(2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-O-(2,3,6-tri-O - benzyl-alpha-D-glucopyranosyl)-(1-->4)]-2,3-di-O-benzyl-D-glucopyranose as an intermediate. Condensation of compounds 7 and 12 followed by removal of the phenylthio group and debenzylation provided the branched pentasaccharide 15. Alternatively, the branched pentasaccharide was produced from amylopectin by consecutive alpha- and beta-amylase treatments and purified by chromatography. The identity of the products obtained by chemical synthesis and enzymatic hydrolysis is documented by 1H and 13C NMR spectra.  相似文献   

4.
Ethyl 2,3,4,6-tetra-O-acetyl-1-thio-alpha-D-glucopyranoside has been prepared in a good yield by anomerization of the corresponding beta-thioglucoside with tin(IV) chloride and transformed, in three steps, into ethyl 2-O-benzoyl-4,6-O-benzylidene-1-thio-alpha-D-glucopyranoside (18). Chloroacetylation of 18, followed by treatment of the product with chlorine gave crystalline 2-O-benzoyl-4,6-O-benzylidene-3-O-chloroacetyl-beta-D-glucopyranosyl chloride (20). This was coupled with methanol in the presence of silver carbonate-silver perchlorate and the product was O-dechloroacetylated to afford methyl 2-O-benzoyl-4,6-O-benzylidene-beta-D-glucopyranoside (22). Silver triflate-promoted glucosylation of 18 with 20 gave a beta-(1-->3)-linked disaccharide derivative, reaction of which with chlorine yielded crystalline O-(2-O-benzoyl-4,6-O-benzylidene-3-O-chloroacetyl-beta-D-glucopyranosyl) - (1-->3)-2-O-benzoyl-4,6-O-benzylidene-beta-D-glucopyranosyl chloride (24). Likewise, condensation of 22 with 20 gave a beta-(1-->3)-linked disaccharide glycoside, which was partially deprotected to give methyl O-(2-O-benzoyl-4,6-O-benzylidene-beta-D-glucopyranosyl)-(1-->3)-2-O-benz oyl- 4,6-O-benzylidene-beta-D-glucopyranoside (26). The methyl beta-glycosides of a homologous series of (1-->3)-linked beta-D-gluco-oligosaccharides from the tri- to the octa-saccharide have been synthesized in a blockwise manner by using 22 and 26 as the glycosyl acceptors, 24 as the disaccharide donor, and silver triflate as the promoter.  相似文献   

5.
Pradimicin L, a new congener of pradimicin A having the D-glucosyl-D-thomosamine moiety at the C-5 position, was isolated from Actinomadura verrucosospora subsp. neohibisca subsp. nov. The structure of pradimicin L was deduced to be N-[[(5S,6S)-5-O-[4,6-dideoxy-4-(methylamino)-3-O-(beta-D-glucopyranosyl) - beta-D-galactopyranosyl]-5,6,8,13-tetrahydro-1,5,6,9,14-pentahydroxy-11- methoxy-3-methyl-8,13-dioxobenzo[a]naphthacene-2-yl]carbonyl ]-D-alanine by MS and NMR spectrometry and degradation studies. Pradimicin FL which has the D-serine moiety instead of D-alanine was produced by directed biosynthesis in D-serine-supplemented medium. Pradimicins L and FL have a broad spectrum of in vitro antifungal activity. Pradimicin L was equiactive to pradimicin A and pradimicin FL was more active than pradimicin L.  相似文献   

6.
In continuation of our previous work on eosinophilia inhibitors, we synthesized an additional series of inhibitors, which consisted of 5-amino-1-[(methylamino)thiocarbonyl]-1H-1,2,4-triazole derivatives and a newly developed series of 1,2,4-triazolo[1,5-a]-1,3,5-triazine derivatives. We evaluated their inhibitory activity on the airway eosinophilia model, which was induced by the intravenous (iv) injection of Sephadex particles. In the 1,2,4-triazole series with various substituents at the 3 position of the triazole ring such as 2-furyl, pyridyl, and phenoxy, none of derivatives had comparable activity to the previously reported compound GCC-AP0341, 5-amino-3-(4-chlorophenyl)-1-[(methylamino)thiocarbonyl]-1H-1,2, 4-triazole. In the triazolo[1,5-a]triazine series, 2-(4-chlorophenyl)-6-methyl-1,2,4-triazolo[1,5-a]-1,3, 5-triazine-7(6H)-thione (3h) was highly potent, and when given orally it had an ID50 value of 0.3 mg/kg, which is comparable to that of GCC-AP0341. The fact that the structure-activity relationship of these two series was quite similar suggests that a common substructure, such as the 1,2,4-triazole ring with a substituted phenyl ring at the 3 position and a thiocarbonyl moiety at the 1 position, could contribute to the activity. Our selected compound 3h was less active than GCC-AP0341 in the antigen-induced hyper-responsiveness model in guinea pigs; however, we plan to carry out further studies on eosinophil functions, especially on their activation, using our two compounds, 3h and GCC-AP0341.  相似文献   

7.
The objective of this study was to assess the effectiveness of alkaline hydrolysis as an alternative ex situ technology for remediating groundwater contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Treatment in both batch reactor and continuous stirred tank reactor (CSTR) was investigated. RDX reactivity was strongly dependent on the reaction pH investigated (11–13). The batch system achieved pseudo-first-order RDX reaction rates in the range of (0.8–27.7)×10?3?min?1, corresponding to half-life periods of 17.9?to?0.5?h, respectively. In the CSTR system operated at the initial RDX concentration of 4.5×10?3?mM, 99% RDX removal was achieved with the hydraulic retention time of 2?days and the reaction pH of 11.9. Formate and nitrite were produced as the major hydrolysates in the CSTR system, indicating a simultaneous reaction mechanism involving RDX ring cleavage and elimination of the ring nitrogen. The net OH? demand used only for RDX removal in the CSTR was found to be 1.5, 390, and 130?M OH?/M RDXremoved at pH values of 11.9, 11.5, and 11.0, respectively. A conceptual cost analysis indicated that the expense of alkaline treatment may be comparable to the expense of granular activated carbon treatment for long treatment periods (30?years or more), due to the potentially lower annual operational cost of alkali treatment.  相似文献   

8.
The reduction kinetics of two explosives, 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), by Fe(II) was investigated in aqueous systems. A dilute ferrous iron solution effectively reduces these nitroaromatic (NAC) and nitramine (NAM) compounds between pH 6.75 and 9.2. Observed reaction rates are first order in monohydroxl and dihydroxyl ferrous iron [FeOH+ or Fe(OH)20], and NAC/NAM concentrations. The reaction does not require the presence of a mediating surface. Intrinsic rate constants for TNT and RDX reduction by monohydroxyl ferrous iron are 2.00(±0.17)E+09 and 2.04(±0.24)E+06?M?2?s?1, respectively. The reduction half-lives at neutral pH were on the order of minutes for TNT and hours for RDX, yielding rates faster than any known natural process or current bioremediation technique. The use of a mobile reductant, such as hydroxyl-complexed Fe(II) or other aqueous Fe(II) complexes, for NAC/NAMs could be an effective remediation technique at contaminated sites.  相似文献   

9.
1,3,5-Triazacycloheptanes were synthesized and examined for reversal of the multidrug resistance dependent on P-glycoprotein. Most of these compounds increased the intracellular uptake of vinblastine in multidrug-resistant mouse leukemia P388/ADR cells without influence upon the vinblastine accumulation in P388/S cells. The efficacy of 1,5-dibenzyl-1,3,5-triazacycloheptanes in increasing the vinblastine accumulation was in the order of 2,4-dithioxo (5) > 2-oxo-4-thioxo (4) approximately 4-(methylthio)-2-oxo (6) > 2,4-dioxo (2). The efficacy was further increased when the benzyl group was converted to a chlorobenzyl group. Among these compounds, 6c [1,5-bis(4-chlorobenzyl)-1,5,6,7-terahydro-4-(methylthio)-2H-1,3,5 - triazepin-2-one] potentiated the in vitro cell growth-inhibitory effect of vinblastine, adriamycin, and mitomycin C on P388/ADR cells and prolonged the life span of P388/ADR-bearing mice in combined therapy with vinblastine more than vinblastine alone.  相似文献   

10.
A series of 6-substituted amino analogs of 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl) purines (F-ddN) has been synthesized and characterized with the objective of finding compounds which might be superior to existing drugs for the treatment of HIV in the central nervous system. These compounds are intended to be more lipophilic than the currently approved anti-HIV drugs for better blood-brain barrier penetration. Subsequent adenosine deaminase (ADA)-catalyzed hydrolysis of these prodrugs in the brain is expected to produce the anti-HIV agent, 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl)hypoxanthine (F-ddI). The new compounds, synthesized from the corresponding 6-chloro analog, include F-ddN which contain methylamino, ethylamino, dimethylamino, hydroxylamino, methoxyamino, benzyloxyamino, hydrazino, and nitro substituents in the 6-position. The 6-nitro analog was isolated as an unexpected product during the preparation of the 6-chloro derivative. Among the analogs with anti-HIV activity, the ethylamino and dimethylamino compounds are ca. 100 times more lipophilic than ddI or F-ddI. As expected, 2'-fluoro substitution protects the compounds from acid-catalyzed glycosylic cleavage. Only the hydroxylamino and nitro analogs underwent any nonenzymatic hydrolysis at pH 1.0 or 7.4. This reaction, however, results in hydrolysis of the group in the 6-position rather than glycosylic bond cleavage. ADA catalyzes the hydrolysis of the 6-substituents at rates which vary from slightly slower (NO2, 1.7x) to much slower (NHEt, 5000x) than F-ddA. The 6-dimethylamino analog is the only compound which possesses anti-HIV activity (ED50 18 microM) without ADA hydrolysis. With the exception of the two inactive alkoxyamino compounds, the other prodrugs exhibited cellular protection in the HIV-1/PHA-PBM system with IC50 potencies of 7-40 microM.  相似文献   

11.
The conversion of aflatoxin B1 into its epoxide was evaluated in vitro by two different approaches based on HPLC analysis: the quantitative estimation of the tris(OH)AFB1 addition product resulting from the indirect reaction of AFB1-epoxide with tris buffer (hydroxymethyl) aminomethane and on the other hand by the quantification of the formation of the glutathione conjugate (AFB1-SG). The tris(OH)AFB1 is more sensitive than AFB1-SG in fluorescence detection. The AFB1-SG obtained (5.42 +/- 0.42 microgram) is weakly less than the quantity of tris(OH)AFB1 (6.00 +/- 0.72) obtained in the same experimental conditions.  相似文献   

12.
The enantiomerically pure synthesis of [(2'S, 3'S)-bis(hydroxymethyl)pyrrolidin-1-yl] thymine 17 and -adenine 20 was achieved via construction of the base on the 1-amino-pyrrolidine 15, and their anti-HSV-1 and -2, and anti-HIV-1 activities were evaluated.  相似文献   

13.
The triazine antifolates, cycloguanil and 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-[(2,4,5-trichlorophenoxy)propy loxy]-1,3,5-triazine hydrobromide (WR99210), and their parent biguanide compounds, proguanil and N-[3-(2,4,5-trichlorophenoxy)propyloxy]-n-(1-methylethyl)-imido dicarbonimidic-diamine hydrochloride (PS-15), were tested in combination with a series of antimalarial drugs for synergism against Plasmodium falciparum growing in erythrocytic culture. Four synergistic combinations were found: cycloguanil dapsone, WR99210-dapsone, proguanil-atovaquone, and PS-15-atovaquone. Cycloguanil-dapsone or WR99210-dapsone had a profound suppressive effect on the concentration of dTTP in parasites while that of dATP increased. Depletion of dTTP is consistent with cycloguanil or WR99210 inhibiting dihydrofolate reductase and dapsone inhibiting dihydropteroate synthase. For the combinations proguanil-atovaquone and PS-15-atovaquone, the levels of nucleoside triphosphates (NTPs) and dNTPs were generally suppressed, suggesting that inhibition is not through nucleotide pathways but probably through another metabolic mechanism(s). Combinations of two synergistic pairs of antimalarial drugs, (proguanil-atovaquone)-(cycloguanil-dapsone) and (PS-15-atovaquone)-(WR99210-dapsone), were tested, and it was found that NTPs and dNTPs decreased much more than for a single synergistic combination. Dual synergistic combinations could play an important role in the therapy of multidrug-resistant malaria, just as combination chemotherapy is used to treat cancer.  相似文献   

14.
Radioligands that specifically target dopamine uptake sites can provide a means of determining dopamine fiber loss at intrastriatal mesencephalic grafts in Parkinsonian patients, using Positron Emission Tomography (PET). The BTCP derivative, 1-[1-(2-benzo(b)thiophenyl)cyclohexyl]-4-(2-hydroxyethyl)-piperazine, shows in vitro high affinity and selectivity for the dopamine transporter. To evaluate the potential of such a compound as a potential dopaminergic PET tracer the positron-emitting analogues, 1-[1-(2-benzo(b)thiophenyl)cyclohexyl]-4-(2-[18F]fluoroethyl)-piperazine and 1-[1-(2-benzo(b)thiophenyl)cyclohexyl]-4-[11C]methylpiperazine, were synthesized. Radiofluorination was carried out by the reaction of 1-[1-(2-benzo(b)thiophenyl)cyclohexyl]-4-(2-chloroethyl)-piperazine with cyclotron-produced n.c.a. 18F-(half life 109.9 min) obtained by the (p,n) reaction on 18O-enriched water. Labelling with carbon-11 (half life 20.4 min) was achieved by 11C methylation of 1-[1-(2-benzo(b)thiophenyl)cyclohexyl]-piperazine with [11C]methyl iodide. After intravenous administration to rats these two compounds enter the brain, but despite their high in vitro affinity they display a high non specific binding in vivo which greatly limits their use as PET radioligands.  相似文献   

15.
We found a potent aromatase inhibitor through the screening of agents for estrogen-dependent breast cancer. SEF19 (2-(imidazol-1-yl)-4,6-dimorphorino-1,3,5-triazine) decreased 50% of human placental aromatase activity in vitro at the concentration of 5.3 nM. In order to clarify the selectivity of SEF19 for enzyme inhibition, we determined the effect of SEF19 on the activities of four steroidogenic cytochrome P450 enzymes in porcine adrenal gland, P450SCC(side-chain cleavage of cholesterol), P450(11 beta) (11 beta-hydroxylase), P450(17 alpha)(17 alpha-hydroxylase/C17,20 lyase) and P450C21 (21-hydroxylase). SEF19 failed to inhibit the activities of porcine adrenal P450SCC, P450(17 alpha) and P450C21 up to the concentration of 100 microM and showed some inhibition on P450(11 beta) activity at 100 microM, while SEF19 completely nullified the aromatase activity at 1 microM. We also determined the potency of SEF19 for the suppression of aromatase activity in vivo. SEF19 suppressed dose-dependently the uterine hypertrophy of immature rats caused by administration of androstenedione (30 mg/kg, s.c.). The ED50 of SEF19 for the suppression of uterine hypertrophy was 0.8 mumol/kg. These results suggest that SEF19 may serve as a potent and selective agent for the treatment of estrogen-dependent breast cancer.  相似文献   

16.
The drug tamoxifen shows evidence of genotoxicity and induces liver tumours in rats. Covalent DNA adducts have been detected in the liver of rats treated with tamoxifen and these arise, at least in part, from its metabolite alpha-hydroxytamoxifen. This probably undergoes conjugation in the liver tissue to give an ester, which alkylates DNA. We have prepared alpha-acetoxytamoxifen as a model for this reactive intermediate and studied its reaction with DNA in vitro. The products of this reaction were chromatographically identical to DNA adducts found in the liver of rats treated with tamoxifen. We have isolated three of these products as the nucleosides TG1, TG2 and TA1 and identified them by ultraviolet, mass and proton magnetic resonance spectroscopy. TG1 and TG2 were tamoxifen-deoxyguanosine adducts in which the alpha-position of tamoxifen was linked to the amino group of guanine; TG1, (E)-4-[4-[2-(dimethylamino)ethoxy]phenyl]-3,4-diphenyl-2-(9beta-de oxyribofuranosyl-6-oxopurin-2-ylamino)-3-butene; TG2, (Z) isomer of TG1. In TG2, the tamoxifen group had undergone trans-cis isomerization. The minor product TA1 was a tamoxifen-deoxyadenosine adduct, where linkage was through the amino group of adenine: (E)-4-[4-[2-(dimethylamino) ethoxy]phenyl]-3,4-diphenyl-2-(9beta-deoxyribofuranosylpurin -6-ylamino)-3-butene. These three adducts accounted for >90% of the reaction products (approximately 67% TG1, 18% TG2 and 7% TA1); trace products included other stereoisomers of these and dinucleotide adducts which resisted enzymatic digestion.  相似文献   

17.
The gustatory responses of the Mongolian gerbil were tested with a large number of monosaccharides. Electrophysiological methods were used to record from the chorda tympani nerve. Methyl glycosides which have structural features in common with sucrose are the most effective monosaccharides for eliciting a neural response. Among the monosaccharides tested, efficacy appears to be highest in D-pyranosides having equatorial substituents at the C-2 and C-4 positions and axial substituents at the C-1 position. A C-5 hydroxymethyl group is not required. Similarities in the structural requirements for taste response in the fly and gerbil are discussed.  相似文献   

18.
The role of endogenous androgens in enhancing the body's protein anabolic capacity has been controversial. To examine this question we chose to study whole-body protein and glucose kinetics in a group of 21 young, postpubertal females (16.3 +/- 0.6 yr), 8 of whom had clinical and laboratory evidence of ovarian hyperandrogenism (OH) (BMI = 37.8 +/- 1.3 kg/m2). We used L-[1-13C]leucine and [6,6,2H2]glucose tracer infusions before and after suppression of their endogenous androgens with estrogen/progesterone supplementation in the form of Triphasil for 4 weeks. Their baseline data were also compared with those of similar aged girls, 7 obese (OB) (BMI = 36.4 +/- 1.5) and 6 lean (LN) (BMI = 20.9 +/- 0.7) who were normally menstruating and had no evidence of androgen excess. Despite comparable glucose concentrations, both OH and OB groups had significant hyperinsulinemia (OH > OB), both basally and after iv glucose stimulation, as compared to LN controls (basal insulin: OH, 252 +/- 52 pmol/L; OB, 145 +/- 41; LN, 60 +/- 9, P = 0.009 OH vs. LN; peak insulin: OH, 2052 +/- 417; OB, 1109 +/- 127, LN, 480 +/- 120, P = 0.0009 OH vs. LN). The rate of appearance (Ra) of glucose, a measure of glucose production, was greater in the LN controls than in the OH or OB groups (OH, 2.0 +/- 0.1 mg/kg.fat free mass.min; OB, 1.9 +/- 0.1; LN, 3.3 +/- 0.1, P < 0.004 vs. LN). Calculated total rates of whole-body protein breakdown (leucine Ra), oxidation, and protein synthesis (nonoxidative leucine disposal) were substantially higher in the OH and OB groups as compared with LN controls (P < 0.04 vs. LN); however, when data are expressed on a per kilogram of fat free mass basis, the OH group had higher rates of proteolysis than the OB and LN, with indistinguishable rates between the latter two groups. None of the above-mentioned parameters changed after 1 month of administration of Triphasil, despite marked improvement in circulating testosterone and free testosterone concentrations after treatment (testosterone, -50%, P = 0.003; free testosterone, -70%, P = 0.02). We conclude that obesity in young postpubertal females is associated with insulin resistance for both peripheral carbohydrate and protein metabolism, and that patients with the OH syndrome have even greater insulin resistance as compared with simple obesity, regardless of treatment for the androgen excess. Carefully designed studies targeting interventions to improve both the hyperandrogenic and hyperinsulinemic state may prove useful even in the early juvenile stages of this disease.  相似文献   

19.
Condensation of 5-thio-D-glucopyranose pentaacetate with 4-cyanobenzenethiol, in the presence of trimethylsilyl triflate, gave 4-cyanophenyl 2,3,4,6-tetra-O-acetyl-1,5-dithio-alpha-D-glucopyranoside 7 and 3,4,6-tri-O-acetyl-2,5-anhydro-5-thio-D-mannose bis(4-cyanophenyl) dithioacetal 9 in a 2:3 ratio. The latter is probably formed from the 4-cyanophenyl 2,3,4,6-tetra-O-acetyl-1,5-dithio-beta-D-glucopyranoside 6 via a transannular participation of the ring sulfur atom. When 2,3,4,6-tetra-O-acetyl-5-thio-alpha-D-glucopyranosyl bromide was used as donor and the reaction was carried out in the presence of potassium carbonate, 6, 7, 4-cyano-2-(2,3,4,6-tetra-O-acetyl-5-thio-alpha-D-glucopyranosyl)phenyl and 4-cyano-2-(2,3,4,6-tetra-O-acetyl-5-thio-beta-D-glucopyranosyl)phenyl 1,5-dithio-beta-D-glucopyranoside (14 and 16) were formed in a 23:4:2:1 ratio. The mechanism of formation of 14 and 16 is discussed. Condensation of 2,3,4,-tri-O-acetyl-6-deoxy-5-thio-alpha-D-glucopyranosyl bromide with 4-cyanobenzenethiol in the presence of potassium carbonate gave 4-cyanophenyl 2,3,4-tri-acetyl-6-deoxy-1,5-dithio-alpha- and beta-D-glucopyranoside (29 and 30) as well as 4-cyano-2-(2,3,4-tri-O-acetyl-6-deoxy-5-thio-alpha-D-glucopyranosyl)phen yl 2,3,4-tri-O-acetyl-6-deoxy-1,5-dithio-beta-D-glucopyranoside in a ratio of approximately 1:8:1. Compound 30 could be obtained in a higher overall yield using 2 as starting material and converting it via its 4-cyanophenyl 2,3,4-tri-O-acetyl-6-O-methanesulfonyl-1,5-dithio-beta-D-glucopyranoside derivative into the 4-cyanophenyl 2,3,4-tri-O-acetyl-6-deoxy-6-iodo-1,5-dithio-beta-D-glucopyranoside 33 which gave 30 on reduction with sodium borohydride-nickel(II) chloride. Treatment of 33 with silver acetate gave 4-cyanophenyl 2,3,4-tri-O-acetyl-6-deoxy-1,5-dithio-beta-D-xylo-hex-5-enopyranoside 35. The compounds obtained on deacetylation of 6, 9, 14, 30 and 35 showed a stronger oral antithrombotic effect in rats as compared to beciparcil, used as reference.  相似文献   

20.
2-hydroxy-5-tert-butyl benzylalcohol and 2,6-bis(hydroxymethyl)-4-tert-butylphenol were identified as contact allergens in a phenolic resin used as a tackifier in the ink of a marking pen, which, after being used directly on the skin, caused an acute contact dermatitis on the hand of a 13-year-old boy. The patient also reacted to 4-tert-butylphenol-formaldehyde resin (BPF resin) 1% pet. included in the European standard series.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号