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1.
Abstract

Selective acetolysis of methyl 2, 3, 4, 6-tetra-O-benzyl-α-D-manno-pyranoside (2) allows for easy preparation of 1-acetates of 2, 3,4, 6-tetra-O-benzyl (5), 6-O-acetyl-2, 3, 4, tri-O-benzyl-(6), 4, 6-di-O-acetyl-2,3-di-O-benzyl-(7), 3, 4, 6-tri-O-acetyl-2-O-benzyl-(8), and 2, 4, 6-tri-O-acetyl-3-O-benzyl-D-mannopyranoside (9). 8 and 9 formed are separated by preparative HPLC in 30-60g scale. The time course of previously described acetolyses of 3, 4, 6-tri-O-benzyl- 1, 2-O-(1-methoxyethyidene)-β-D-mannopyranose (3), and methyl 2, 3-dt-O-benzyl-4, 6-O-benzylldene-α-D-mannopyranoside (4) giving 9, 1, 2, 6-tri-O-acetyl-3, 4-di-O-benzyl-(10), and 1, 2-di-O-acetyl-3, 4, 6-tri-O-benzyl-(11) α-D-mannopyranose as well 7 have been studied.  相似文献   

2.
Abstract

Fully protected 1-thioglycopyranosyl esters of N-acylamino acids (5, 6, and 7) were prepared by condensation of methyl 2, 3, 4-tri-O-acetyl-1-thio-β-d–glucopyranuronate (1), 2, 3, 4-tri-O-acetyl-1-thio-l–arabinopyranose (2), and 2, 3, 4-tri-O-acetyl-1-thio-D-arabinopyranose (3) with pentachlorophenyl esters of N-acylamino acids in the presence of imidazole. The 13C NMR chemical shifts of the starting 1-thio sugars and the 1-thiol ester products are reported.  相似文献   

3.
Nitrones 2a , 2b obtained from the aldehydes 1a , 1b , are used for the syntheses of the N-ethoxy iminium salts 4a and 4b . In the following procedure 4a and 4b react to several esters of phosphinic acids 6a - 6d .  相似文献   

4.
The use of precipitation followed by acetylation procedures and preparative TLC purification allowed a facile isolation of four carbohydrates from the methanol extract of Pinus halepensis seeds. The isolated oligosaccharides exhibited high degree of purity. They were identified as α-D-galactosyl-(1→1)-myo-inositol nonaacetate (1), α-D-glucosyl-(1→2)-β-D-fructosyl octaacetate (2), α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl undecaacetate (3), and α-D-galactosyl-(1→6)-α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl tetradecaacetate (4) and were isolated for the first time from this plant. The 1H and 13C NMR assignments for compounds 2, 3, and 4 were detailed herein for the first time.  相似文献   

5.
Abstract

N-Phenylmorpholine (1) reacted with chlorosulfonic acid to give the p-sulfonyl chloride (2), which was characterized as the sulfonamides (35). Benzothiazole (6) was converted into the sulfonyl chloride (7) by sequential treatment with hot chlorosulfonic acid and thionyl chloride. Reaction of (7) with amines afforded the derivatives (810); NMR spectral analysis of the dimethylamide (8) indicated that it was a mixture of the 4- and 7-isomers. Chlorosulfonation of 2-methylbenzothiazole (11) was achieved by heating with chlorosulfonic acid with or without thionyl chloride. The chloride (12) was converted into amides (1319). Study of the NMR spectra indicated that mixtures of the 5- and 6-isomers were formed. 2,4,5-Triphenyloxazole (20) reacted with chlorosulfonic acid to give either the mono-(21), bis (23) or bis-tris sulfonylchlorides (23, 34); these were converted into 14 sulfonamides. 2-(p-Nitrophenyl)-4,5-diphenyloxazole (41) reacted with hot chlorosulfonic acid to give the bis-sulfonyl chloride (42), characterized as the dimethylsulfonamide (43). Attempts to form the pure monosulfonyl chloride and to mono nitrate 2,4,5-triphenyloxazole (20) were unsuccessful.  相似文献   

6.
Abstract

3, 6-Di-O-methyl-d-glucose was prepared via 5-O-allyl-1, 2-O-isopropylidene-3-O-methyl-αd-glucofuranose and was converted into 2, 4-di-O-acetyl-3, 6-di-o-methyl-dD-glucopyranosy 1 chloride. Condensation of the chlorosugar with methanol or allyl 2, 3-O-isopropylidene-α-l-rhamnopyranoside gave the corresponding crystalline β-glycbsides. The allyl 4-O-(2,4-di-O-acetyl-3, 6-di-O-Tnethyl-β-dD-glucopyranosyl)-2, 3-O-isopropylidene-α-l-rhamnopyranoside was converted into the title compounds and into crystalline 2, 3-di-O-acetyl-4-O-(2, 4-di-O-benzyl-3, 6-di-O-methyl-β-d-glucopyranosyl)-l-rhamnopyranosyl chloride which should serve as an intermediate for the synthesis of the trisaccharide portion of the major glycolipid of Mycobacterium leprae.  相似文献   

7.
Abstract

Prolonged treatment of tetra-O-acetyl-1, 5-anhydro-hex-1-enitols (“tetra-O-acetyl-hydroxy-glycals”) 3 and 5 with BF3 in CH2Cl2 at RT lead to anomeric mixtures of the title compounds 2 and 4a, the α-anomer 4a dominating. Reaction of 5 gave the higher yields of 4a (71%) and 2 (12%), the results being accounted mechanistic grounds. The same reaction performed in an aromatic solvent, like toluene, gave rise to competing C-alkylation., The ortho and para-tolyl derivatives 6 and 7, also with enone structure, were isolated in a combined maximum yield of 40% from 5. β-Enone 2 was also prepared in moderate yield by thermolysis of β-d-glucopyranose pentaacetate (1). In this case no α-anomer 4a was detected.  相似文献   

8.
Abstract

Glycosylation of methyl 3-O-(2-acetamido-3, 6-di-O-benzyl-2-deoxy-β-D-glucopyranosyl)-2,4,6-tri-O-benzyl-β-D-galactopyranoside (2) with 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide (1), catalyzed by mercuric cyanide, afforded a trisaccharide derivative, which was not separated, but directly O-deacetylated to give methyl 3-O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-β-D-galactopyranosyl-β-D-giucopyranosyl)-2,4,6-tri-O-benzyl-β-D-galactopyranoside (8). Hydrogenolysls of the benzyl groups of 8 then furnished the title trisaccharide (9). A similar pflyccsylation of methyl 3-O-(2-acetamido-3-O-acetyl-2-deoxy-β-D-glucopyranosyl)-2,4,6-tri-O-benzyl- β-D-galactopyranoside (obtained by acetylation of 4, followed by hydrolysis of the benzylidene acetal group) with bromide 1 gave a tribenzyl trisaccharide, which, on catalytic hydrogenolysls, furnished the isomeric trisaccharide (12). Methylation of 4 and 2 with methyl iodide-silver oxide in 1:1 dichloro-methane-N, N-dimethylformamide gave the 3-O- and 4-O-monomethyl ethers (13) and (15), respectively. Hydrogenolysis of the benzyl groups of 13 and 15 then provided the title monomethylated disaechartdes (15) and (16), respectively. The structures of trisacchacides 9 and 12, and disaccharides 14 and 16 were all established by 13C MMR spectroscopy.  相似文献   

9.
R. S. Mali  S. G. Tilve 《合成通讯》2013,43(13):2041-2047
A convenient, two-step synthesis of 2-vinylindoles is described from the easily accessible (E)-ethyl-α-allyl-2-nitrocinnamates. Ethylcinnamates (1a and 1b) on reaction with triethylphosphite provide ethyl-2-allylindole-3carboxylates (2a and 2b ) along with minor amounts of their N-ethoxyderivatives (4a and 4b). Alkaline hydrolysis of 2a and 2b provide (E)-2-vinylindoles 3a and 3b in 60 and 67% yield respectively.  相似文献   

10.
A mixture of 1-methyl- and 2-methyl-1,4,4a,8a,-tetrahydro-endo-1,4-methano-naphthalene-5,8-diones ( 2 & 3 ) was chemically transformed into separable methyl substituted tricyclo[5.2.1.02,6]decadienones 7 , 8 & 9 . The structure of 8 & 9 were elucidated via Cope rearrangement of their corresponding allylic alcohols ( 10 & 11 ) to furnish 12 & 13 respectively.  相似文献   

11.
Abstract

The reaction of N-phenyliminoketenylidenetriphenylphosphorane [a] (1), with 2-benzylidene-1, 3-indandione (2), 1,2-diphenyl-3,4-pyrazolidenedione (3)and/or 5-benzylidene barbituric acid (4) has been investigated. When ylide 1 was allowed to react with compounds 2, 3 or 4 in THF at ambient temp. the corresponding new pyrano-phosphoranylidenes 5, 6 or 7 were obtained. The elemental microanalyses, IR, 1H NMR, 31P NMR and MS data agree with the structure of the cyclic iminophosphoranes by [4+2]-cycloaddition and exclude 4-membered ring structure by [2+2]-cycloaddition. When the Wittig reaction was carried on the pyrano-phosphoranes 5, 6 or 7 using p-nitrobenzaldehyde, the exocyclic olefins together with triphenylphosphine oxide were isolated.  相似文献   

12.
Abstract

The reactions of bromide, chloride, and iodide ions with 1,3,4, 6-tetra-O-acetyl-2-O-(trifluoromethylsulfonyl) -α-D-glucopyranose (2) and with 1, 3, 4, 6-tetra-O-acetyl-2-O-(trifluoromethylsulfonyl)-β-D-mannopyranose (3) gave good to excellent yields of the corresponding deoxyhalogeno sugars. In contrast, when the gluco triflate 2 and tetra-butylammonium fluoride were heated under reflux in benzene, only 5-(acetoxymethyl)-2-formylfuran (13) was formed. Reaction of the manno triflate 3 under similar conditions produced 1, 3,4, 6-tetra-O-acetyl-2-deoxy-2-fluoro-β-D-gluco-pyranose (17), 1. 3, 4. 6-tetra-O-acetyl-2-deoxy-β-D-erythro-hex-2-eno-pyranose (18), 4,6-di-O-acetyl-1, 5-anhydro-2-deoxy-D-erythro-hex-l-enitol-3-ulose (19), and 1, 2, 3, 4, 6-penta-O-acetyl-β-D-glucopyranose (20). The mechanisms of the reactions of The triflates 2 and 3 with fluoride ion are discussed.  相似文献   

13.
Abstract

Partial benzoylation of l-rhamnono-l,4-lactone (1) gave 2,5-di-O-benzoyl-l-rhamnono-1,4-lactone (2) as the main product. In similar conditions, d-mannono-l,4-lactone (3) gave preferentially 2,5,6-tri-O-benzoyl-d-mannono-l,4-lactone (4). 2,3,5,6-Tetra-O-benzoyl- (5) and 3,6-di-O-benzoyl-d-mannono-1,4-lactone (6) were isolated in low yield from the reaction mixture. The structures of the partially benzoylated compounds 2, 4 and 6 were assigned on the basis of spectroscopic data.  相似文献   

14.
Abstract

The syntheses of phospholes (7, [3+2]-cycloaddition), bicyclophosphaalkenes (17, [4+2]-cycloaddition), and phosphabenzenes (15, [4+2]-cycloaddition followed by an extrusion process) starting from the phosphaalkynes (4) are described. The 2–Dewar phosphabenzene 18, obtained from the cyclobutadiene 21 and 4 (R =tBu), is the starting material for the synthesis of the valency isomers 19, 20, 22, and 23.  相似文献   

15.
Abstract

A scheme of asymmetric synthesis of C-glycosyl α-glycines is described. Reductive hydrolysis of 2-deoxy-3,5-di-O-p-toluoyl-β D-erythropentofuranose 1-cyanide (4) in the presence of N,N-diphenylethylenediamine gave the imidazolidine 5, which was converted to 2,5-anhydro-3-deoxy-4,6-di-O-p-toluoyl-β-D-allose (3)by acid hydrolysis. The aldehyde (3), chiralamine, benzoic acid and t-butyl isocyanide four component condensation afforded in good yield two diastereomeric adducts (6a and 6b), which were separated by column chromatography and deblocked to furnish 2-deoxy-β-D-erythropentofuranosyl R and S-glycines (1a) and (1b).  相似文献   

16.
Abstract

Starting with methyl 2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (1), the isomeric methyl 2-amino-2-deoxy-α-D-glucopyranoside 3-, 4-, and 6-sulfates have each been prepared by sulfation of suitably blocked intermediates. Tritylation and acetylation of 1 followed by detritylation gave methyl 3,4-di-0-acetyl-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (3), having a free 6-hydroxyl group. Base catalyzed 0–4→0–6 acetyl migration provided the corresponding 3,6 di-O-acetyl derivative (4) posessing a free 4-hydroxyl group. Preparation of methyl 4,6-0-benzylidene-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (9) provided the intermediate bearing a free 3-hydroxyl group. 0-sulfation of 3, 4, and 9 was effected with the pyridine sulfur trioxide complex in dry pyridine.  相似文献   

17.
Abstract

The reaction of 1,2-benzo [a] phenazine-8, 9-dione 1 and/or 1,2,3-indantrione 2, with phosphonium ylides has been studied. When 1 was reacted with two molar amounts of methoxy-(3a) and/or ethoxycarbonylmethylenetriphenylphosphorane (3b), in THF, at the reflux temp, for 3 hrs, dimethyl (4a) and/or diethyl 1,2-dihydrobenzo a furo [3,2-h] phenazine-1,2-dicarboxylate (4b), along with triphenylphosphine oxide and triphenylphosphine were obtained. On the other hand, reaction of equimolar amounts of ylides 3 with the red trione 2 in THF at room temp., afforded colourless crys tals of 2′,4′-dihydroxyspiro [indan-2,3′ (2′H)-indeno [1,2-b] pyran]-1,3,5′(4′H)-trione diacetate (5a) or dipropionate (5b), together with triphenylphosphine oxide. Formation of 6-membered dihydro aromatic ring like 5, is considered as a new reaction of phos phoranes. The structure of the new compounds 4 and 5 was confirmed and the reaction mechanisms are discussed.  相似文献   

18.
The protection of the hydroxy group of p-cresol 1 by o-silylation gives derivatives 2 and 3 , the methyl group of which can be brominated by NBS. The phase transfer catalysis applied to 4 and 5 is a good way which permits the mild introduction of the allylthio group ( 6 and 7 ). Hydroboration applied to silylated compounds 8 and 9 , followed by methanolysis and hydrolysis leads to target acids 10 and 11 in a good yield.

La protection du groupement hydroxy du p-crésol 1 par o-silylation donne les dérivés 2 et 3 ce qui permet de bromer le substituant méthyle par le N-bromosuccinimide (NBS). La catalyse par transfert de phase (CTP) appliquée aux produits 4 et 5 est une bonne méthode pour introduire un groupement allylthio (composés 6 , 7 ). L'hydroboration des composés silylés 8 et 9 , suivie d'une méthanolyse et d'une hydrolyse permet d'accéder aux acides cibles 10 et 11 avec de bons rendements.  相似文献   

19.
Abstract

N-[2-S-(2-Acetamido-2,3-dideoxy-D-glucopyranose-3-y1)-2-thio-D-lactoyl]-L-alanyl-D-isoglutamine, in which the oxygen atom at C-3 of N-acetylmuramoic acid moiety in N-acetylmuramoyl-L-alanyl-D-isoglutamine (MDP) has been replaced by sulfur, was synthesized from allyl 2-acetamido-2-deoxy-β-D-glucopyranoside (1).

Treatment with sodium acetate of the 3-O-mesylate, derived from 1 by 4,6-O-isopropylidenation and subsequent mesylation, gave allyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-allopyranoside (4). When treated with potassium thioacetate, the 3-O-mesylate, derived from 4, afforded allyl 2-acetamido-3-S-acetyl-2-deoxy-4,6-0-isopropylidence-β-D-glucopyranoside (6). S-Deacetylation of 6, condensation with 2-L-chloropropanoic acid, and subsequent esterification, gave the 3-s[D-1(methoxycarbonyl)ethyl]-3-thio-glucopyranoside derivative (7). Coupling of the acid, derived from 7, with the methyl ester of L-alanyl-D-isoglutamine, and subsequent hydrolysis, yielded the title compound.  相似文献   

20.
Abstract

In order to elucidate further the relationship between the composition of the fatty acyl groups in the nonreducing-sugar subunit of bacterial lipid A and its biological activity, 3-O-[(3R)-3-(acyloxy)tetradecanoyl]-2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-4-O-phosphono-D-glucose [GLA-63(R, R) and GLA-64(R, R)], and 3-O-[(3R)-3-(acyloxy)tetradecanoyl]-2-deoxy-4-O-phosphono-2-tetradecanamido-D-glucose [GLA-67(R), GLA-68(R) and GLA-69(R)] have been synthesized. Benzyl 2-[(3R)-3-(benzyloxymethoxy)tetradecanamido]-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranoside (5) and benzyl 2-deoxy-4,6-O-isopropylidene-2-tetradecanamido-β-D-glucopyranoside (6) were each esterified with (3R)-3-dodecanoyloxytetradecanoic acid (1), (3R)-3-tetradecanoyloxytetradecanoic acid (2) or (3R)-3-hexadecanoyloxy-tetradecanoic acid (3), to give 7-11, which were then transformed, by the sequence of deisopropylidenation, 6-O-tritylation and 4-O-phosphorylation, into a series of desired compounds.  相似文献   

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