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1.
《Carbohydrate research》1986,148(2):209-219
Epoxidation of trans- and cis-1,3,4-trideoxy-5,6-O-isopropylidene-d-glycero-hex-3-enulose (2) by alkaline hydrogen peroxide gave a mixture of 3,4-anhydro-1-deoxy-5,6-O-isopropylidene-d-arabino- and -d-xylo-hexulose that was resolved by chromatography. Epoxidation of 2 with 3-chloroperbenzoic acid gave (1S)-1-acetoxy-1,2-anhydro-3,4-O-isopropylidene-d-erythrose hydrate and (1R)-1-acetoxy-1,2-anhydro-3,4-O-isopropylidene-d-threose hydrate. Reduction of 2 followed by epoxidation and oxidation gave the corresponding epoxides with the d-ribo and d-lyxo configurations. Structures and configurations of the above compounds were established on the basis of their analytical and spectroscopic data, and by chemical transformations. 相似文献
2.
Juan A. Galbis Pérez P. Areces Bravo F. Rebolledo Vicente J.I. Fernandez Garcia-Hierro J. Fuentes Mota 《Carbohydrate research》1984,126(1):91-100
The reaction of 1-aryl-(1,2-dideoxy-d-glycero-β-l-gluco-heptofurano)[1,2-d]imidazolidine-2-thiones with benzyl chloride and an equivalent amount of sodium hydrogencarbonate yields 1-aryl-2-(benzylthio)-(1,2-dideoxy-d-glycero-β-l-gluco-heptofurano)[1,2-d]-2-imidazolines (2). If the reaction is carried out in the absence of sodium hydrogencarbonate, the 1-aryl-2-(benzylthio)-4-(d-galacto-pentitol-1-yl)imidazoles are obtained. These compounds are also obtained by acid-catalyzed isomerization of compounds 2. 相似文献
3.
Acid-catalysed condensation of methyl β-d-glycero-l-manno-heptopyranoside with cyclohexanone yielded an approximately 3:1 mixture of the 2,3:6,7- and 2,3:4,7-di-O-cyclohexylideneheptosides (1 and 2), which could be separated either as their benzoates (3 and 4) or as their methyl ethers (5 and 6). The latter compounds afforded the 4- and 6-methyl ethers (7 and 8) of d-glycero-l-manno-heptitol. 相似文献
4.
《Carbohydrate research》1987,166(2):211-217
6-O-Benzyl-7,8-dideoxy-1,2:3,4-di-O-isopropylidene-l-glycero-α-d-galacto-oct-7-ynopyranose reacted with tributyltin hydride to afford (Z-6-O-benzyl-7,8-dideoxy-1,2:3,4-di-O-isopropylidene-8-(tributylstannyl)-l-glycero-α-d-galacto-oct-7-enopyranose, which was subsequently isomerized to the E-olefin 4. Replacement of the tributyltin moietey with lithium in 4 afforded the vinyl anion which reacted with 3-O-benzyl-1,2-O-isopropylidene-α-d-xylo-pentodialdo-1,4-furanose, furnishing 3-O-benzyl-6-C-[(E)-6-O-benzyl-7-deoxy-1,2:3,4-di-O-isopropylidene-l-glycero-α-d-galacto-heptopyranos-7-ylidene] -60-deoxy-1,2-O-isopropylidene-α-d-gluco- (6) and -β-l-ido-furanose (7) in yields of ∼70 or ∼87% (depending on the temperature of the reaction). The configurations of the new chiral centers in 6 and 7 were determined by their conversion into 3-O-benzyl-1,2-O-isopropylidene-α-d-gluco- and -β-l-ido-furanose, respectively. Oxidation of 6 and 7 gave the same enone, 3-O-benzyl-6-C-[(E)-6-O-benzyl-7-deoxy-1,2:3,4-di-O-isopropylidene-l-glycero-α-d-galacto- heoptopyranos-7-ylidene]-6-deoxy-1,2-O-isopropylidene-α-d-xylo-hexofuranos-5-ulose. 相似文献
5.
Oxidative dimerization of 7,8-dideoxy-1,2:3,4-di-O-isopropylidene-d-glycero-α-d-galacto-oct-7-ynopyranoside (1) gave a high yield of the diyne 2, readily reduced by lithium aluminum hydride to the trans,trans-diene (4). The structures of 2 and 4 were established spectroscopically and by degradation of 4 to d-glycero-d-galacto-heptitol (perscitol). A mixture of the alkyne 1 and its 7-epimer 10 was readily oxidized by dimethyl sulfoxide-acetic anhydride to the 6-ketone 11, and the 8-alkene analog was similarly prepared from the alkenes derived from 1 and 10. Likewise, oxidation of 6,7-dideoxy-1,2-O-isopropylidene-α-d-gluco(and β-L-ido)-hept-6-enopyranose gave the corresponding 5-ketone. The acetylenic ketone 11 gave a crystalline oxime and (2,4-dinitrophenyl)hydrazone, the latter being accompanied by the product of attack of the reagent at the acetylene terminus (C-8). Previous work had shown that formyl-methylenetriphenylphosphorane did not convert 1,2:3,4-di-O-isopropylidene-6-aldehydo-α-d-galacto-hexodialdo-1,5-pyranose into the corresponding C8 unsaturated aldehyde, although the latter was obtainable via1 and 10 by an ethynylation-hydroboration sequence. The Wittig route with formylmethylenetriphenylphosphorane is shown to be satisfactory for obtaining C7 unsaturated aldehydes from 3-O-benzyl-1,2-O-isopropylidene-5-aldehydo-α-d-xylo-pentodialdo-1,4-furanose (22) and the 3-epimer of 22, respectively. These reactions provide convenient access to higher-carbon sugars and chiral dienes for synthesis of optically pure products of cyclo-addition reactions. 相似文献
6.
F.J. Lopez Aparicio M. Plaza Lopez-Espinosa R. Robles Diaz 《Carbohydrate research》1984,132(2):233-240
Photo-oxygenation of 3-hydroxymethyl-5-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-2-methylfuran, 5-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-3-(1-hydroxyethyl)-2-methylfuran (8a), and 2-methyl-5-(1,2,3,4-tetra-O-acetyl-d-arabino-tetritol-1-yl)-3-furoic acid (8b) yielded the corresponding endo-peroxides, which were transformed into 4-hydroxymethyl-6-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-3-methylpyridazine, 6-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-4-(1-hydroxyethyl)-3-methylpyridazine, and 6-(d-arabino-tetritol-1-yl)-3-methylpyridazine by treatment with hydrazine. The γ-di-ketones (Z)-1-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-3-(1-hydroxyethyl)pent-2-ene-1,4-dione and d-arabino-6,7,8,9-tetraacetoxy-4-methoxynonane-2,5-dione can be obtained by reduction of the endo-peroxides 9a and 9b (derived from 8a and 8b, respectively) with dimethyl sulphide. The C → O rearrangement reported for C-glycosyl endo-peroxides was also observed for 9a. 相似文献
7.
D-manno-3-Heptulose (5) was synthesized by dimethyl sulfoxide-phosphorus pentaoxide oxidation of 1,2:3,4:6,7-tri-O-isopropylidene-D-glycero-D-manno-heptitol (3, prepared from volemitol), followed by hydrolysis. D-ido-3-Heptulose (8) was synthesized similarly by oxidation of 1,2:4,5:6,7-tri-O-isopropylidene-D-glycero-l-galacto-heptitol (7, prepared from D-glycero-l-galacto-heptitol, 6). Another tri-O-isopropylidene derivative (11), having a free primary hydroxyl group, was produced in larger amount than 7, and 11 yielded D-glycero-l-galacto-heptose (14). Compound 8 was also synthesized by way of 1,2:4,5.6,7-tri-O-isopropylidene-D-glycero-l-gulo-heptitol (15). The production of 15 from D-glycero-l-gulo-heptitol (13) was accompanied by a larger amount of 2,3:4,5:6,7-tri-O-isopropylidene-D-glycero-D-ido-heptitol (17) which, upon oxidation followed by hydrolysis, yielded D-glycero-D-ido-heptose (18). One of the two tri-O-isopropylidene derivatives obtained by acetonation of perseitol, 2,3:4,5:6,7-tri-O-isopropylidene-D-glycero-D-galacto-heptitol (19), yielded D-glycero-D-galacto-heptose (20). 相似文献
8.
《Carbohydrate research》1993,246(1):75-88
A stereocontrolled, facile total synthesis of ganglioside GD3 is described as an example of a proposed systematic approach to the preparation of gangliosides containing an α-sialyl-(2 → 8)-sialic acid unit α-glycosidically linked to O-3 of a d-galactose reesidue in their oligosaccharide chains. Glycosylation of 2-(trimethylsilyl)ethyl 6-O-benzoyl-, 3-O-benzoyl-, or 3-O-benzyl-β-d-galactopyranosides, or 2-(trimethylsilyl)ethyl 2,3,6,2′,6′-penta-O-benzyl-β-lactoside (7), with methyl [phenyl 5-acetamido-8-O-(5-acetamido-4,7,8,9- tetra-O-acetyl-3,5-dideoxy-d-glycero-α-d-galacto-2-nonulopyranosyl-ono-1′,9-lactone)-4,7-di-O-acetyl-3,5-dideoxy-2-thio- d-glycero-d-galacto-2-nonulopyranosid]onate (3), using N-iodosuccinimide-trifluoromethanesulfonic acid as a promoter, gave the corresponding α glycosides 8 (32%), 13 (33%), 14 (48%), and 17 (31%), respectively. The glycyl donor 3 was prepared from O-(5-acetamido-3,5-dideoxy-d-glycero-α-d-galacto-2-nonulopyranosylonic acid)-(2 → 8)-5-acetamido-3,5-dideoxy-d-glycero- d-galacto-2-nonulopyranosonic acid by treatment with Amberlite IR-120 (H+) in methanol, O-acetylation, and subsequent replacement of the anomeric acetoxy group with phenylthio. Compound 8 was converted into the methyl β-thioglycoside via O-benzoylation, replacement of the 2-(trimethylsilyl)ethyl group by acetyl, and introduction of the methylthio group by reaction with methylthiotrimethylsilane. Compound 17 was converted, via O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, and reaction with trichloroacetonitrile, into the α-trichloroacetimidate, which was coupled with (2S,3R,4E)-2-azido-3O-benzoyl-4-octadecene-1,3-diol to give the β-glycoside. This glycoside was easily transformed, via selective reduction of the azido group, condensation with octadecanoic acid, O-deacylation, and hydrolysis of the methyl ester and lactone functions, into ganglioside GD3. 相似文献
9.
Boris A. Dmitriev Anatoly Ya. Chernyak Oleg S. Chizhov Nikolay K. Kochetkov 《Carbohydrate research》1976,47(1):25-34
Acid-catalyzed acetonation of d-glycero-d-galacto-heptose yields solely the 1,2:3,4:6,7-tri-O-isopropylidene pyranoid derivative, whereas d-glycero-l-gluco- and d-glycero-l-manno-heptose react in the furanose form to give 1,2:5,6-(major) and 1,2:6,7-di-O-isopropylidene-d-glycero-l-gluco-heptose (minor), and 2,3:5,6-(major) and 2,3:6,7-di-O-isopropylidene-d-glycero-l-manno-heptose (minor), respectively. 相似文献
10.
The 3,4-O- and 1,2:3,4-di-O-isopropylidene derivatives (7 and 8) of l-dendroketose [4-C-(hydroxymethyl)-l-glycero-pentulose] (1) have been synthesized stereo-specifically from 4-C-(hydroxymethyl)-1,2:3,4-di-O-isopropylidene-l-erythro-pentitol (2). 相似文献
11.
Eric Westerlund 《Carbohydrate research》1981,91(1):21-30
When kept at 105° for 2.5 h, weakly alkaline, syrupy d-erythrose was readily converted into a mixture containing mainly d-glycero-tetrulose, the previously unknown β-d-altro-l-glycero-3-octulofuranose (2), and α-d-gluco-l-glycero-3-octulopyranose, which were isolated as the corresponding acetates. Treatment of 2 with Dowex 50 (H+) resin yielded 3,8-anhydro-β-d-altro-l-glycero-octulopyranose, identified as its acetate. Previous discrepancies in the [α]d values for d-erythrose appear partly to originate in the self-aldol reaction. The dimerisation of d-erythrose 4-phosphate is also described. 相似文献
12.
d-erythro-2,3-Hexodiulosono-1,4-lactone 2-arylhydrazones (2) were prepared by condensation of dehydro-d-arabino-ascorbic acid with the desired arylhydrazine. Reaction of 2 with hydroxylamine gave the 2-arylhydrazone 3-oximes (3). On boiling with acetic anhydride, 3 gave 2-aryl-4-(2,3-di-O-acetyl-d-erythro-glycerol-1-yl)-1,2,3-triazole-5-carboxylic acid 5,11-lactone (5), whereas the unacetylated triazole derivatives were obtained upon reaction of 3 with bromine in water. On treatment of 5 with hydrazine hydrate, 2-aryl-4-(d-erythro-glycerol-1-yl)-1,2,3-triazole-5-carboxylic acid 5-hydrazides (6) were obtained. Acetylation of 6 gave the hexaacetyl derivatives. Similarly, treatment of 5 with liquid ammonia gave the triazolecarboxamides (12). Vigorous acetylation of 12 with boiling acetic anhydride gave tetraacetates, whereas acetylation with acetic anhydride-pyridine gave triacetates. Periodate oxidation of 6 gave the 2-aryl-4-formyl-1,2,3-triazole-5-carboxylic acid 5-hydrazides (8), and, on reduction, 8 gave the 2-aryl-4-(hydroxymethyl)-1,2,3-triazole-5-carboxylic acid 5-hydrazides, characterized as acetates. Similarly, periodate oxidation of 12 gave the triazolealdehyde (15), and reduction of 15 gave the hydroxymethyl derivatives (16). Acetylation of 16 gave the mono- and di-acetates, and, on reaction with o-phenylenediamine, 15 afforded the triazoleimidazole. Controlled reaction of 3 with sodium hydroxide, followed by neutralization, gave 3-(d-erythro-glycerol-1-yl)-4,5-isoxazolinedione 4-arylhydrazones. Reaction of 3 with HBr-HOAc gave 5-O-acetyl-6-bromo-6-deoxy-d-erythro-2,3-hexodiulosono-1,4-lactone 2-arylhydrazone 3-oximes (21). Compounds 21 were converted into 4-(2-O-acetyl-3-bromo-3-deoxy-d-erythro-glycerol-1-yl)-2-aryl-1,2,3-triazole-5-carboxylic acid 5,11-lactone on treatment with acetic anhydride. 相似文献
13.
Methyl 2,3-anhydro-4,6-O-benzylidene-3-C-nitro-β-d-allopyranoside (1), as well as its β-d-manno (2) and α- d-manno (3) isomers, reacted with dimethylamine to give the same, crystalline 3-(dimethylamino) adduct (4) of 1,5-anhydro-4,6-O-benzylidene-2-deoxy-2-(dimethylamino)-d-erythro-hex-1-en-3-ulose (5). The enulose 5 was obtained from 4 by the action of silica gel. Similarly, the β-d-gulo (6) and α-d-talo (7) stereoisomers of 1–3 afforded a 3-(dimethylamino) adduct (8) of the d-threo isomer (9) of 5. Reaction of dimethylamine with 5,6-anhydro-1,2-O-isopropylidene-6-C-nitro-α-d-glucofuranose (10) yielded a mixture of two diastereoisomeric (possibly anometic at C-6) 5-deoxy-5-(dimethylamino)-1,2-O-isopropylideric-α-d-hexodialdo-1,4:6,3-difuranoses (11). The β-glycoside 1 and the α-glycoside 3 reacted with methylmagnesium iodide to produce methyl 4,6-O-benzylidene-3-deoxy-3-C-methyl-3-(N-hydroxy-N-methylamino)-β- and -α-d-hexopyranosides (12) and (13), respectively; both products had the 1,2-trans configuration, but their configurations at the quaternary center C-3 have not been determined. 相似文献
14.
2,6-Anhydro-1-deoxy-1-diazo-D-glycero-L-manno-heptitol (2) decomposes in 0.01M methanolic sodium methoxide with a half-life of approx. 18 min. Decomposition in aqueous solution is too rapid for spectrophotometric measurement. Seven products could be identified in methanolic and aqueous reaction mixtures. 2,6-Anhydro-1-deoxy-D-galacto-hept-1-enitol (6), 2,7-anhydro-1-deoxy-β-D-galacto-heptulopyranose (10), and 4-O-vinyl-D-lyxose (12) are products of rapid intramolecular reactions. The major portion consists of the direct solvolysis products 2,6-anhydro-1-O-methyl-D-glycero-L-manno-heptitol (3) and 2,6-anhydro-D-glycero-L-manno-heptitol (5). 相似文献
15.
Photoamidation of 3-O-acetyl-1,2:5,6-di-O-isopropylidene-α-d-erythro-hex-3-enofuranose (1) afforded 3-O-acetyl-4-C-carbamoyl-1,2:5,6-di-O-isopropylidene-α-d-gulofuranose (2) and 3-O-acetyl-3-C-carbamoyl-1,2:5,6-di-O-isopropylidene-d-α-allofuranose (3) in 65 and 26% yields, respectively (based on consumed1). Treatment of2 with 5% hydrochloric acid in methanol yielded the spiro lactone5, which was deacetylated to yield7. Reduction of5 with sodium borohydride afforded 4-C-(hydroxymethyl)-1,2-O-isopropylidene-α-d-gulofuranose (9) in 79% yield. Oxidation of9 with sodium metaperiodate afforded a dialdose that was reduced with sodium borohydride to give 4-C-(hydroxymethyl)-1,2-O-isopropylidene-α-d-erythro-pentofuranose (11) in 88% yield. Treatment of the acetate12, derived from11, with trifluoroacetic acid, followed by acetylation, afforded the branched-chain sugar acetate14. Condensation of the glycosyl halide derived from14 withN6-benzoyl-N6, 9-bis-(trimethylsilyl)adenine yielded an equimolar anomeric mixture of protected nucleosides15 and16 in 40% yield. Treatment of the latter compounds with sodium methoxide in methanol afforded 9-[4-C-(hydroxymethyl)-β-d-erythro-pentofuranosyl]-adenine (17) and the α-d anomer18. The structure of3 was determined by correlation with the known 5,3′-hemiacetal of 3-C-(hydroxymethyl)-1,2-O-isopropylidene-α,α′-d-ribo-pentodialdose (25). 相似文献
16.
Irradiation of a solution of 2-acetoxy-3,4,6-tri-O-acetyl-D-glucal (1) in 1:200 acetone-2-propanol with a high-pressure mercury-lamp gave 4,5,6,8-tetra-O-acetyl-3,7-anhydro-1-deoxy-2-C-methyl-D-glycero-D-gulo-octitol (2) (51.2%), -D-glycero-D-ido-octitol (3) (16.2%), and-D-glycero-D- galacto-octitol (4) (21.0%). The irradiation of 1 in 1:1 acetone-2-propanol gave 5,6,8-tri-O-acetyl-3,7-anhydro-1-deoxy-4-C-(1-hydroxy-1-methylethyl)-2-C-methyl-D-glycero-D-(gluco or manno, etc.)-octitol 2,4,41-orthoacetate (17%) and a 2:1:1 mixture of 2, 3, and 4 (64%). Moreover, the irradiation of 1 in 1:9 acetone-tert-butyl alcohol gave 2 (15%), 3 (9%), 4 (7%), and (4S)-4,5,6,8-tetra-O-acetyl-2,4:3,7-dianhydro-1-deoxy-2-C-methyl-D-gluco-octos-4-ulose (14%). 相似文献
17.
Anti-Markovnikov hydration of the olefinic bond of 5,6-dideoxy-1,2-O-isopropylidene-3-O-p-tolylsulfonyl-α- d-xylo-hex-5-enofuranose (4) and methyl 5,6-dideoxy-2,3-di-O-p-tolylsulfonyl-α-l-arabino-hex-5-enofuranoside (11) by the addition of iodine trifluoroacetate, followed by hydrogenation in the presence of a Raney nickel catalyst in ethanol containing triethylamine, afforded 5-deoxy-1,2-O-ísopropylidene-3-O-p-tolylsulfonyl-α-d-xylo-hexofuranose (6) and methyl 5-deoxy-2,3-di-O-p-tolylsulfonyl-α-d-arabino-hexofuranoside (14), respectively. 5-deoxy-d-xylo-hexose and 5-deoxy-l-arabino-hexose were prepared from 6 and 14, respectively, by photolytic O-detosylation and acid hydrolysis. Syntheses of 9-(5-deoxy-β-d-xylo-hexofuranosyl)-adenine and 9-(5-deoxy-α-l-arabino-hexofuranosyl)adenine are also described. Application of the sodium naphthalene procedure, for O-detosylation, to 11 is reported in connection with an alternative synthetic route to methyl 5-deoxy-α-l-arabino- hexofuranoside. 相似文献
18.
R S Tipson 《Carbohydrate research》1974,35(1):1-2
Addition of ethyl isocyanoacetate in strongly basic medium to the glycosuloses 1,2:5,6-di-O-isopropylidene-α-d-ribo-hexofuranos-3-ulose (1) and 1,2-O-isopropylidene-5-O-trityl-d-erythro-pentos-3-ulose (2) gave the unsaturated derivatives (E)- and (Z)-3-deoxy-3-C-ethoxycarbonyl(formylamino)methylene-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (3 and 4), and (E)-3-deoxy-3-C-ethoxycarbonyl(formylamino)methylene-1,2-O-isopropylidene-5-O-trityl-α-d-ribofuranose (5). In weakly basic medium, ethyl isocyanoacetate and 1 gave 3-C-ethoxycarbonyl(formylamino)methyl-1,2:5,6-di-O-isopropylidene-α-d-allofuranose (12) in good yield. The oxidation of 3 and 4 with osmium tetraoxide to 3-C-ethoxalyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (17), and its subsequent reduction to 3-C-(R)-1′,2′-dihydroxyethyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (18) and its (S) epimer (19) and to 3-C-(R)-ethoxycarbonyl(hydroxy)methyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (21) and its (S) epimer (22) are described. Hydride reductions of 12 yielded the corresponding 3-C-(1-formylamino-2-hydroxyethyl), 3-C-(2-hydroxy-1-methylaminoethyl), and 3-C-(R)-ethoxycarbonyl(methylamino)methyl derivatives (13, 14 and 16). Catalytic reduction of 3 and 4 yielded the 3-deoxy-3-C-(R)-ethoxycarbonyl-(formylamino)methyl derivative 6 and its 3-C-(S) epimer. Further reduction of 6 gave 3-deoxy-3-C-(R)-(1-formylamino-2-hydroxyethyl)-1,2:5,6-di-O-isopropylidene-α-d-allofuranose (23) which was deformylated with hydrazine acetate to 3-C-(R)-(1-amino-2-hydroxyethyl)-3-deoxy-1,2:5,6-di-O-isopropylidene-α-d-allofuranose (24). The configurations of the branched-chains in 16, 21, and 22 were determined by o.r.d. 相似文献
19.
Derek Horton 《Carbohydrate research》1978,67(2):357-370
Addition of phenyl azide to 3,5-di-O-acetyl-6,7-dideoxy-1,2-O-isopropylidene-β-l-idio-hept-6-ynofuranose (1) and subsequent saponification gave a 4-substituted 1-phenyl-1,2,3-triazole derivative (3) whose optical rotatory dispersion (o.r.d.) curve was positive. The α-d-gluco analog (5) of 1 similarly gave the 5-epimer (7) of 3; its o.r.d. curve was negative. Both 3 and 7 were degraded to the known 1-phenyl-1,2,3-triazole-4-carboxaldehyde. Similarly, addition of 2,4,6-trimethylbenzonitrile N-oxide to 1 or 5 gave the corresponding, crystalline 3-mesitylisoxazoles as single products; 13C-n.m.r. spectroscopy was used to establish the orientation of addition. Related 3-mesitylisoxazoles (11 and 13) were obtained from 1,2:3,4-di-O-isopropylidene-d-glycero-α-d-galacto-oct-7-ynopyranose (10) and its l-glycero 6-epimer (12), respectively; 11 showed the expected, large levorotation, and the 6-epimer 13 was also levorotatory. Benzonitrile (N-phenyl)imine, prepared in situ from 1-(α-chlorobenzylidene)-2-phenylhydrazine and base, did not react with 10 (or its 6-epimer 12), but did react with the 6-keto analog to give a 5-substituted 1,3-diphenyl-1,2-diazole. 相似文献
20.
Treatment of 2,3,6-trideoxy-1,4-di-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-l-lyxo-hexopyranose (1) with benzyl 2,3-dideoxy-d-glycero-pentopyranoside and p-toluenesulfonic acid gave a mixture of benzyl 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3- (trifluoroacetamido)-l-lyxo-hexopyranoside (49%) and benzyl 2,3-dideoxy-4-O-[2,3,6-trideoxy-4-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-α-l-lyxo-hexopyranosyl]-d-glycero-pentopyranoside (4, 20 %). The structure of the disaccharide 4 was confirmed by a detailed, mass-spectrometric analysis in three modes, namely, negative- and positive-ion, chemical ionization, and electron impact. Similar treatment of the bis(p-nitrobenzoate) 1 with ethyl 2,3-dideoxy-d-glycero-pentopyranoside gave the ethyl glycoside and the desired disaccharide, showing that the transglycosylation is not restricted to benzyl glycosides. Removal of the p-nitrobenzoyl and the benzyl groups from 4 gave the disaccharide 2,3-dideoxy-4-O-(2,3,6-trideoxy-3-trifluoroacetamido-α-l-lyxo-hexopyranosyl)-d-glycero-pentopyranose. 相似文献