Glucosylenamines as glycosyl acceptors: synthesis of gentiobiosylenamines.

The preparation of 2,3,4-tri-O-benzyl- (3), 2,3,4-tri-O-acetyl- (4), and 2,3,4-tri-O-benzoyl-N-(2,2-diethoxycarbonylvinyl)-6-O-trityl-beta- D-glucopyranosylamine (5) is described. The reaction of 3-5 with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide yields 2,3,4-tri-O-benzyl- (9), 2,3,4-tri-O-acetyl- (10), and 2,3,4-tri-O-benzoyl-N-(2,2-diethoxycarbonylvinyl)-6-O-(2,3,4,6-tet ra-O- acetyl-beta-D-glucopyranosyl)-beta-D-glucopyranosylamine (11), respectively. 2,3,4-Tri-O-benzyl- (6), 2,3,4-tri-O-acetyl- (7), and 2,3,4-tri-O- benzoyl-N-(2,2-diethoxycarbonylvinyl)-beta-D-glucopyranosylamine (8) are also described.     

Novobiocin-related compounds: synthesis of 3-benzoylamino-2-oxo-2H-1-benzopyran-7-yl D-glycopyranosides by the trichloroacetimidate methodology

A general stereoselective method for the synthesis of 4-deoxynovobiocin-related glycosides is described. 3-Benzoylamino-2H-1-benzopyran-7-yl 2,3,4,6-tetra-O-acetyl-D-glycopyranosides of glucose, galactose and mannose were synthesised from appropriate O-glycosyltrichloroacetimidates and N-(7-hydroxy-2-oxo-2H-1-benzopyran-3-yl)benzamides in boiling methylene chloride in the presence of boron trifluoride etherate. Heating of these products in a mixture of triethylamine and methanol gave the corresponding deprotected 3-benzoylamino-2-oxo-2H-1-benzopyran-7-yl beta-D-glycopyranosides.     

Acetylated methyl glucopyranuronate trichloroacetimidate as a glycosyl donor for efficient synthesis of disaccharides

Allyl (methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyl uronate)-(1-->3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-beta-D-glucopyranoside (4) and benzyl (methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyl uronate)-(1-->3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-beta-D-glucopyranoside (5) have been efficiently synthesized by coupling allyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-beta-D-glucopyranoside (2) or benzyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-beta-D-glucopyranoside (3) with methyl (2,3,4-tri-O-acetyl-1-O-trichloroacetimidoyl)-alpha-D-glucopyranuronate (1), respectively, using trimethylsilyl triflate as promoter.     

Geranyl flavonoids from the leaves of Artocarpus altilis

Five geranyl dihydrochalcones, 1-(2,4-dihydroxyphenyl)-3-{4-hydroxy-6,6,9-trimethyl-6a,7,8,10a-tetrahydro-6H-dibenzo[b,d]pyran-5-yl}-1-propanone (2), 1-(2,4-dihydroxyphenyl)-3-[3,4-dihydro-3,8-dihydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (4), 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(3,4-epoxy-4-methyl-1-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (5), 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(4-hydroxy-4-methyl-2-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (8), and 2-[6-hydroxy-3,7-dimethylocta-2(E),7-dienyl]-2',3,4,4'-tetrahydroxydihydrochalcone (9), along with four known geranyl flavonoids (1, 3, 6, 7), were isolated from the leaves of Artocarpus altilis. Their structures were established by spectroscopic means and by comparison with the literature values. Compounds 2, 4, and 9 exhibited moderate cytotoxicity against SPC-A-1, SW-480, and SMMC-7721 human cancer cells.     

Homoisoflavonoids and xanthones from the tubers of wild and in vitro regenerated Ledebouria graminifolia and cytotoxic activities of some of the homoisoflavonoids

Eleven homoisoflavonoids and two xanthones were isolated and characterized from the bulbs of Ledebouria graminifolia. Five of the homoisoflavonoids are new compounds and were identified as: 5-hydroxy-7-methoxy-3-(4'-hydroxybenzyl)-4-chromanone, 5-hydroxy-6,7-dimethoxy-3-(4'-hydroxybenzyl)-4-chromanone, 5,7,8-trimethoxy-3-(4'-hydroxybenzyl)-4-chromanone, 5-hydroxy-3',4',7-trimethoxyspiro[2H-1-benzopyran-7'-bicyclo[4.2.0]octa-trien]-4-one, 5,7-dihydroxy-3',4'-dimethoxyspiro[2H-1-benzopyran-7'-bicyclo[4.2.0]octa-trien]-4-one. Structures were elucidated by extensive 1D, and 2D NMR spectroscopy and HRMS. A method for tissue culture was developed and the bulbs of mature plants were found to contain all the compounds isolated from the wild specimens of L. graminifolia.     

Three isoflavanones with cannabinoid-like moieties from Desmodium canum

Three further derivatives of 5,7,2',4'-tetrahydroxy-6-methyl isoflavanone have been isolated from the root extract of Desmodium canum and assigned the structures 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(1a,2,3,3a,8b,8c-hexahydro-6-hydroxy-1,1,3a-trimethyl-1H-4-oxabenzo[f]cyclobut[c,d]inden-7-yl)-4H-1-benzopyran-4-one (1) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(6a,7,8,10a-tetrahydro-3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl)-4H-1-benzopyran-4-one (2) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl) 4H-1-benzopyran-4-one (3). The three compounds and the previously isolated chromene 4 all derive from the geranylated precursor 5 by a series of cannabinoid-like oxidative rearrangements.     

New coumarins from the umbels of Seseli sibiricum

Three new coumarins, seselinal, sesibiricol and sibirinol, and 12 known coumarins have been isolated from the umbels of Seseli sibiricum. The new coumarins have been characterized as 5, 7-dimethoxy-8-(2-methyl-2-formylpropyl)-2H-1-benzopyran-2-one, 5-(3-methylbut-2-enyloxy)-7-methoxy-8-(2-hydroxy-3-methylbut-3-enyl)-2H-1-benzopyran-2-one and 5,7-dimethoxy-8-(2-hydroxy-3-methylbut-3-enyl)-2H-1-benzopyran-2-one,respectively. The known ones were identified as sesibiricin, isosibiricin, osthol, coumurrayin, sesebrin, sesebrinol, sibiricin, imperatorin, bergapten, xanthotoxin, isopimpinellin and mexoticin.     

Two New Isoprenylated Stilbenes from Artocarpus chama

Two new stllbenes with two Isoprenoid groups, namely artostllbenes A （compound 1） and B （compound 2）, were Isolated from the stems of Arfocarpus chama Buch.-Ham. by repeated column chromatography. The＆ structures were elucldated as （E）-4-[2-（7-meth-xy-2-2-d-methy-6-（3-methy-but-2-eny-）-2H-1-benz-pyran-5-y-）v-ny-]benzene-1- 2-dlol （compound 1） and （Z）-4-[2-（7-meth-xy-2-2-dimethy--6-（3-methy-but-2-eny-）-2H-1-benz-pyran-5-y-）v-ny-]ben- zene-l,2-dlol （compound 2） by spectroscopic methods, mainly by 1D-, 2D-NMR and MS spectra. Compounds 1 and 2 are two cls- and trans-lsomers and compound 2 is the flrst cis-stllbene isolated from Moraceous plants.     

New efficient electrochemical synthesis of 1,5-dithioxylopyranosides in the presence of a sacrificial anode

Electroreduction of the disulfide derivative RSSR (5, R= [bond]C(6)H(4)[bond]CO[bond]C(6)H(4)[bond]CN) on a mercury pool or a carbon gauze electrode in the presence of 2,3,4-tri-O-acetyl-5-thio-D-xylopyranosyl bromide (1), using a sacrificial zinc anode gave an alpha,beta anomeric mixture of [4-(4-cyanobenzoylphenyl)] 2,3,4-tri-O-acetyl-1,5-dithio-D-xylopyranoside (6) in 40-70% yield, according to the experimental conditions used (nature of solvent, electrolyte salt, and temperature). High selectivity favouring the alpha anomer of 6 is observed starting from the alpha anomer of 1. Mechanistic aspects are discussed.     

Synthesis of beta-D-GlcA-(1----3)-beta-D-Gal disaccharides with 4- and 6-sulfate groups and 4,6-disulfate groups.

The sodium salts of the 6-sulfate 7, the 4-sulfate 10, and the 4,6-disulfate 12 of benzyl 3-O-(beta-D-glucopyranosyl uronate)-beta-D-galactopyranoside (5) have been synthesized. Methyl (2,3,4-tri-O-acetyl-1-bromo-1-deoxy-alpha-d-glucopyran)uronate (1) was coupled with benzyl 2-O-benzoyl-4,6-O-benzylidene-beta-D-galactopyranoside (2) to yield 3. The benzylidene acetal of 3 was hydrolyzed to give benzyl 2-O-benzoyl-3-O-[methyl (2,3,4-tri-O-acetyl-beta-D-glucopyranosyl)uronate]-beta-D-galactopyra noside (4). Compound 4 was utilized as a key intermediate to prepare the sulfated disaccharides 7,10, and 12. Direct sulfation of 4 with sulfur trioxide-trimethylamine for 2 days yielded the 6-sulfate 6. The 4,6-disulfate 11 was accessible by running the reaction under the same conditions for 14 days. The 4-sulfate 9 was obtained after protecting the 6-OH group of 4 by reaction with benzoyl imidazole to give the 6-benzoate 8, followed by sulfation under vigorous conditions. Treatment of the protected compounds 4, 6, 9, and 11 with aqueous sodium hydroxide in tetrahydrofuran gave the unprotected 5, 7, 10, and 12, respectively.     

Synthesis of 5 alpha-androstane-3 alpha,17 beta-diol 3- and 17-glucuronides

The glucuronidation of 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol) was carried out by three different methods: The Koenigs-Knorr reaction using methyl-2,3,4-tri-O-acetyl-1 alpha-bromo-1-deoxy-beta-D-glucuronate, by employing methyl-2,3,4-tri-O-acetyl-1-O-(trichloroacetimidoyl)-alpha-D-gl ucopyranuronate (imidate procedure), and by the reaction of 2,3,4-tri-O-acetyl-alpha-D-glucopyranuronate catalyzed by trimethylsilyl trifluoromethanesulfonate (triflate method). The Koenigs-Knorr method gave the beta-anomers of both the 3- and 17-glucuronides. The imidate procedure also resulted in the beta-anomers of the 3- and 17-glucuronides, but in lower yield. The triflate method, however, yielded only the alpha-anomers of the 3- and 17-glucuronides. The structural assignments of these compounds were made from NMR spectral data obtained with a 500 mHz instrument.     

Coumarins from the Malagasy Cedrelopsis rakotozafyi Cheek and Lescot (Rutaceae)

A phytochemical analysis of the bark of the Malagasy Cedrelopsis rakotozafyi Cheek and Lescot (Rutaceae) yielded the novel 8-hydroxy-7-methoxy-6-(2R-hydroxy-3-methylbut-3-enoxy)-2H-1-benzopyran-2-one, and 7-hydroxy-6-(2R-hydroxy-3-methylbut-3-enoxy)-2H-1-benzopyran-2-one, 5,6,7-trimethoxy-2H-1-benzopyran-2-one, scoparone, scopoletin, lupeol and β-amyrin. The placement of Cedrelopsis within the Rutaceae is supported phytochemically by the typically Rutaceous coumarins isolated.     

New class of quaternary ammonium salts, derivatives of methyl D-glucopyranosides

Reactions of two aromatic and two aliphatic amines with methyl 6-O-p-toluenesulfonyl-alpha-D-glucopyranoside or methyl 6-O-p-toluenesulfonyl-beta-D-glucopyranoside were performed on a micro-scale. The synthesis and preparative isolation methods have been developed for quaternary N-(methyl 2,3,4-tri-O-acetyl-6-deoxy-alpha- and -beta-D-glucopyranoside-6-yl)ammonium salts derived from three amines: trimethylamine, 2-methylpyridine, and pyridine. The reaction products were examined with 1H, 13C NMR spectroscopy. N-(Methyl 2,3,4-tri-O-acetyl-6-deoxy-beta-d-glucopyranoside-6-yl)trimethylammonium tosylate was additionally analyzed with X-ray crystallography.     

X-Ray diffraction and high resolution NMR analysis of methyl D-glucopyranuronate derivatives

X-Ray diffraction and high resolution 1H and 13C NMR spectral data for methyl 2,3,4,-tri-O-acetyl-alpha-D-glucopyranuronate and methyl (allyl 2,3,4-tri-O-acetyl- beta-D-glucopyranosid)uronate are presented. Both compounds adopt the 4C1 conformation.     

Synthesis of beta-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->2)-[beta-L-Xylp-(1-->4)]-alpha-L-Rhap-(1-->3)-alpha-L-Rhap,the repeating unit of the O-antigen produced by Pseudomonas solanacearum ICMP 7942

An efficient synthesis of beta-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->2)-[beta-L-Xylp-(1-->4)]-alpha-L-Rhap-(1-->3)-alpha-L-Rhap, the repeating unit of the O-antigen produced by Pseudomonas solanacearum ICMP 7942 and its isomer beta-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->4)-[beta-L-Xylp-(1-->2)]-alpha-L-Rhap-(1-->3)-alpha-L-Rhap was achieved via sequential assembly of the building blocks, allyl 2,3-O-isopropylidene-alpha-L-rhamnopyranoside (2), allyl 3,4-O-isopropylidene-alpha-L-rhamnopyranoside (3), allyl 2,4-di-O-benzoyl-alpha-L-rhamnopyranoside (6), 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl trichloroacetimidate (7), and 2,3,4-tri-O-benzoyl-beta-L-xylopyranosyl trichloroacetimidate (12). The process was carried out in a regio- and stereoselective manner using glycosyl trichloroacetimidates as donors and unprotected or partially protected rhamnopyranosides as acceptors in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf).     

迷果芹根化学成分的研究

利用普通硅胶柱色谱技术和多种现代波谱技术,从迷果芹(Sphallerocarpus gracilis)的根中分离并鉴定了11个化合物,通过波谱学方法鉴定为:falcarinol(1)、(3R,8S)-falcarindiol(2)、diplaniol(3)、5-hydroxy-8-methoxy-2H-1-benzopyran-2-one(4)、esculetin(5)、东莨菪内酯(6)、xanthalin(7)、isoimperatorin(8)、胡萝卜苷(9)、β-谷甾醇(10)和豆甾醇(11),其中化合物1～6为首次从该植物中分离得到。     

Synthesis of p-nitrobenzyl and p-nitrophenyl 1-thioglycopyranosides.

Reaction of 2,3,4-trio-O-acetyl-alpha-L-fucopyranosyl bromide (1) with thiourea (2), followed by reductive cleavage of the product, gave 2,3,4-tri-O-acetyl-1-thio-beta-L-fucopyranose (4). Reaction of 4 with p-nitrobenzyl bromide followed by O-deacylation yielded p-nitrobenzyl 1-thio-beta-L-fucopyranoside (6). Similar reaction conditions were used for the synthesis of p-nitrobenzyl 1-thio-beta-D-fucopyranoside (11) and 1-thio-alpha-D-mannopyranoside (16). A facile preparation of O-acylated p-nitrophenyl 1-thioglycopyranosides was achieved by condensing the appropriate glycosyl halide with sodium p-nitrobenzenethioxide in N,N-dimethylformamide.     

Geranylated phenolic constituents from the fruits of Artocarpus nobilis

Chemical investigation of the combined dichloromethane and ethyl acetate extracts of the fruits of Artocarpus nobilis, furnished four new geranylated phenolic constituents, 2,4,4'-trihydroxy-3-[(2E)-5-methoxy-3,7-dimethylocta-2,6-dienyl]chalcone (4), 1-(3,4-dihydro-3,5-dihydroxy-2-methyl-2-(3-methyl-2-butenyl)-2H-1-benzopyran-6-yl-3-(4-hydroxyphenyl)-2(E)-propen-1-one (5), 8-geranyl-3',4',7-trihydroxyflavone (8), 3'-geranyl-4',5,7-trihydroxyflavanone (9), together with known related compounds, xanthoangelol (1), xanthoangelol B (2), 3-geranyl-2,3',4,4'-tetrahydroxychalcone (3), lespeol (6), 8-geranyl-4',7-dihydroxyflavanone (7), and isonymphaeol-B (10). Compounds 3, 8 and 10 showed strong antioxidant activity against DPPH radical by spectrophotometric method.     

Regioselective sulfonylation of 6,1',6'-tri-O-tritylsucrose through dibutylstannylation: synthesis of 4'-O-sulfonyl derivatives of sucrose

3-O-Mesyl-1,6-di-O-trityl-beta-D-fructofuranosyl-(2-->1)-6-O-trityl-alpha-D-glucopyranoside (3) was synthesized via stannylation of 6,1',6'-tri-O-tritylsucrose with dibutyltin oxide in benzene, followed by treatment of the crude product with methanesulfonyl chloride in the presence of triethylamine in dichloromethane at 0 degrees C. A similar treatment of the tri-tritylsucrose in toluene, instead of benzene, yielded 4-O-mesyl-1,6-di-O-trityl-beta-D-fructofuranosyl-(2-->1)-6-O-trityl-alpha-D-glucopyranoside (4) as the major product. The X-ray crystal structure of the corresponding acetyl derivative, 3-O-acetyl-4-O-mesyl-1,6-di-O-trityl-beta-D-fructofuranosyl-(2-->1)-2,3,4-tri-O-acetyl-6-O-trityl-alpha-D-glucopyranoside (5), confirms the position and stereochemistry of the methanesulfonyl group at C-4 of the fructofuranosyl ring.     

Iridoid glucosides and flavones from the aerial parts of Avicennia marina

Two new iridoid glucosides, namely, 2'-O-[(2E,4E)-5-phenylpenta-2,4-dienoyl]mussaenosidic acid (1; mussaenosidic acid = [1S-(1alpha,4aalpha,7alpha,7aalpha)]-1-(beta-D-glucopyranosyloxy)-1,4a,5,6,7,7a-hexahydro-7-hydroxy-7-methylcyclopenta[c]pyran-4-carboxylic acid) and 2'-O-(4-methoxycinnamoyl)mussaenosidic acid (2), were isolated from the aerial parts of the mangrove plant Avicennia marina. Beside that, one known iridoid glucoside, 2'-O-coumaroylmussaenosidic acid (3) and four known flavones (flavone = 2-phenyl-4H-1-benzopyran-4-one) including 4',5-dihydroxy-3',7-dimethoxyflavone (4), 4',5-dihydroxy-3',5',7-trimethoxyflavone (5), 4',5,7-trihydroxyflavone (6), and 3',4',5-trihydroxy-7-methoxyflavone (7) were also isolated and identified. The structures of these compounds were elucidated by NMR spectroscopy and by low- and high-resolution mass spectrometry. The chemotaxonomic significance of these findings was discussed. In addition, each isolated compound was evaluated for the ability of alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity.