Showing papers on "Glucal published in 1999"
TL;DR: The AB-ring fragment of ciguatoxin was synthesized in ten steps from tri-O-benzyl-d -glucal based on a highly diastereoselective ring-closing metathesis and subsequent cross-metathesis as discussed by the authors.
48 citations
TL;DR: In this paper, polymer-supported electrophilic reagents are prepared which efficiently add to carbohydrate-derived glycals under very mild conditions, and 2-deoxy-2-halo-pyranosyl acetates or azides are generated in excellent yield.
38 citations
TL;DR: In this article, the reaction of D-glucal and its derivatives with the electrophilic N-F-fluorination reagents F-TEDA tetrafluoroborate and triflate was studied by means of 19F NMR spectroscopy.
31 citations
TL;DR: In this article, the asymmetric total synthesis of (−)-prosophylline from d -glucal via (2 S )-hydroxymethyl-dihydropyridone 6 by 17-step synthesis and 12% overall yield is presented.
30 citations
21 citations
21 citations
TL;DR: The treatment of D-glucal with a catalytic amount of Sm(OTf)3 or RuCl2(PPh3)3 in the presence of 1 equiv.
21 citations
TL;DR: The Pauson-Khand reaction on suitable 4-oxa-hept-1-en-6-ynes gives the cyclopentane-annulated pyranosides that can be efficiently and stereoselectivelly transformed into chiral, advanced, highly oxygenated intermediates for the synthesis of iridoid aglycones.
Abstract: The Pauson−Khand reaction on suitable 4-oxa-hept-1-en-6-ynes (1, 17) obtained from 3,4,6-tri-O-acetyl-d-glucal gives the cyclopentane-annulated pyranosides (2, 18) that can be efficiently and stere...
19 citations
TL;DR: In this article, the results showed that 2,3,4,6- tetra -O- acetyl -α-d -glucopyranosyl chloride (2) with EDTA, NTA, IDA, GLY, MAL, and NTA-IDA-GLY complexes can achieve 70-90% yields and 95% purity.
18 citations
TL;DR: In the presence of catalytic amount of Pd(dba)2 and P(o-tol)3, the reaction of 3,4,6- tri -O- acetyl-2-bromo -d - glucal with ethylene proceeded smoothly to afford the conjugated dieno-pyranoside in high yield as mentioned in this paper.
18 citations
TL;DR: In this article, Lewis acid mediated reactions of vinyl ethers with ArSCl adducts of benzyl protected D-glucal followed by quenching of the five-membered sulfonium salt intermediates with external nucleophiles, H2O, MeOH, and n-Bu4NBH4, lead to a highly stereoselective formation of β-Cglucopyranosides with different functional groups in the lateral chain.
TL;DR: X-ray crystallography and 1H NMR spectroscopy indicate that the conformations of both rings A and B and the relative orientation of the rings in the C-linked disaccharide 1,3,4,6-tetra-O-acetyl-2-C-(4, 6-di-Oacetyl)-2,3-dideoxy-α-D-erythro-hex-hex 2-enopyranosyl) in solution are virtually identical to the crystalline structure as mentioned in this paper.
TL;DR: In this article, the treatment of D-glucal with a catalytic amount of Sm(OTf)3 or RuCl2(PPh3)3 in the presence of 1 equiv. of H2O afforded optically active furan diol in good yield under mild conditions.
Abstract: The treatment of D-glucal with a catalytic amount of Sm(OTf)3 or RuCl2(PPh3)3 in the presence of 1 equiv. of H2O afforded optically active furan diol in good yield under mild conditions.
Patent•
02 Nov 1999
TL;DR: In this article, the problem of obtaining a new compound having inhibitory activity against selection, useful as a therapeutic agent for inflammatory diseases, by introducing a methylene chain to between an aromatic ring and a saccharide part and providing a distance between the saccharides part and a carboxylic acid on the aromatic ring was solved.
Abstract: PROBLEM TO BE SOLVED: To obtain a new compound having inhibitory activity against selection, useful as a therapeutic agent for inflammatory diseases, by introducing a methylene chain to between an aromatic ring and a saccharide part and providing a distance between the saccharide part and a carboxylic acid on the aromatic ring and orientation with the degree of freedom. SOLUTION: This compound is shown by formula I [Ar is an aryl ring or a heteroaryl ring; R is H, a 1-6C alkyl or the like; (n) is 1-5; Sugar is an (unsaturated) saturated monosaccharide composed of L-series or D-series of formula II, formula III (R is H or a hydroxyl-protecting group; R is H, methyl or the like; (p) is 1-3) or the like], its salt, its ester or other derivatives such as 1-C-(3'-carboxybenzyl)-6-deoxy-L-glucal. The compound of formula I is obtained by reacting a glucal of formula IV (R is a hydroxyl-protecting group; R to R are each a 1-6C alkyl; R is H or CH2 OR ) made into a stannous compound with a substituted benzyl halide of formula V (R is H, a protecting carboxy or the like) in the presence of a palladium-containing complex catalyst.
TL;DR: In this article, the reaction of D-glucal and its derivatives with the electrophilic N-F-fluorination reagents F-TEDA tetrafluoroborate and triflate was studied by means of 19F NMR spectroscopy.
Abstract: The reaction of D-glucal and its derivatives with the electrophilic N-F-fluorination reagents F-TEDA tetrafluoroborate and triflate was studied by means of 19F NMR spectroscopy. In all cases mixtures of 2-deoxy-2-fluoro-D-gluco- and -D-mannopyranose derivatives were formed, the ratio of which was dependent on the nature of the O-protecting groups. Concerning the products arising from the direct addition of reagents across the double bond, the D-gluco-configured compounds (13-20) generally showed higher hydrolysis rates than their D-manno-counterparts (21-28). Product separation was only achieved when single anomers (e.g., 2,4-dinitrophenyl glycosides 29e/37e and disaccharidic fluorides 35d/43d) or per-O-acetates (e.g. 29f/37f) were formed.
TL;DR: In this article, the results showed that 2,3,4,6- tetra -O- acetyl -α-d -glucopyranosyl chloride (2) with EDTA, NTA, IDA, GLY, MAL, and NTA-IDA-GLY complexes can achieve 70-90% yields and 95% purity.
Abstract: Reactions of 2,3,4,6- tetra -O- acetyl -α- d -glucopyranosyl bromide (3) with chromium(II)L complexes (L = EDTA, NTA, IDA, GLY, MAL) in neutral (5 3,4,6- tri -O- acetyl-1,5-anhydro-2-deoxy- d -arabino- hex-1-enitol (13) in 70–90% yields and >95% purity. Complexes of Cr(II) with L = EDTA, NTA were similarly efficient with 2,3,4,6- tetra -O- acetyl -α- d -glucopyranosyl chloride (2) in furnishing glucal 13, while with L = IDA, GLY, MAL hydrolysis of 2 could not be suppressed. Under the same conditions [CrII(EDTA)]2− also efficiently gave the corresponding glycals 14–19 from 2,3,4,6- tetra -O- benzoyl - ( 4 ) and 2,3,4,6- tetra -O- pivaloyl -α- d -glucopyranosyl bromide (5), per-O-acetylated α- d -galactopyranosyl chloride (6) and bromide (7), α- d -mannopyranosyl chloride (8), α- d -xylopyranosyl chloride (9), and bromide (10), β- d -arabinopyranosyl bromide (11), and α- l -rhamnopyranosyl chloride (12).
TL;DR: In this paper, Lewis acid mediated reactions of vinyl ethers with ArSCl adducts of benzyl protected D-glucal followed by quenching of the five-membered sulfonium salt intermediates with external nucleophiles, H2O, MeOH, and n-Bu4NBH4, lead to a highly stereoselective formation of β-Cglucopyranosides with different functional groups in the lateral chain.
Abstract: Lewis acid mediated reactions of vinyl ethers with ArSCl adducts of benzyl protected D-glucal followed by quenching of the five-membered sulfonium salt intermediates with external nucleophiles, H2O, MeOH, and n-Bu4NBH4, lead to a highly stereoselective formation of β-C-glucopyranosides with different functional groups in the lateral chain.
TL;DR: In this article, the asymmetric total synthesis of (−)-prosophylline from d -glucal via (2 S )-hydroxymethyl-dihydropyridone 6 by 17-step synthesis and 12% overall yield is presented.
Abstract: The asymmetric total synthesis of (−)-prosophylline from d -glucal via (2 S )-hydroxymethyl-dihydropyridone 6 by a 17-step synthesis and 12% overall yield is presented.