ChemInform Abstract: HYDROGENOLYSIS OF THE BENZYLIDENE ACETALS OF THIOGLYCOSIDES WITH THE LITHIUM ALUMINUM HYDRIDE‐ALUMINUM CHLORIDE REAGENT. SYNTHESIS OF PARTIALLY BENZYLATED THIOGLYCOSIDE DERIVATIVES

Lipták, András; Jodál, I.; Harangi, János; Nánási, Pál

doi:10.1002/chin.198348299

Cited by 13 publications

(20 citation statements)

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“…In addition, we assumed that the activation of the STaz moiety over the O-pentenyl moiety would be possible in the presence of MeOTf. [60] To perform these studies we chose a number of suitable glycosyl acceptors, S-ethyl glycosides 69, [44] 72, [61] 75, [62] and 77; [63] S-phenyl glycosides 79 [64] and 81; [65] and Opentenyl glycosides 83 [66] and 85 [67] (Table 5). All glycosylations summarized in Table 5 afforded the intended disaccharide products in good yields.…”

Section: Resultsmentioning

confidence: 99%

S‐Thiazolinyl (STaz) Glycosides as Versatile Building Blocks for Convergent Selective, Chemoselective, and Orthogonal Oligosaccharide Synthesis

Pornsuriyasak

Demchenko

2006

Chemistry A European J

103

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In the aim of developing new procedures for efficient oligosaccharide assembly, a range of S-thiazolinyl (STaz) glycosides have been synthesized. These novel derivatives were evaluated against a variety of reaction conditions and were shown to be capable of being chemoselectively activated in the armed-disarmed fashion. Moreover, the S-thiazolinyl moiety exhibited a remarkable propensity for selective activation over other common leaving groups. Conversely, a variety of leaving groups could be selectively activated over the STaz moiety, which, in turn, allowed STaz/S-ethyl and STaz/S-phenyl orthogonal approaches. To demonstrate versatility of novel STaz derivatives, a number of oligosaccharide targets have been synthesized in a convergent selective, orthogonal, and chemoselective fashion.

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Section: Resultsmentioning

confidence: 99%

S‐Thiazolinyl (STaz) Glycosides as Versatile Building Blocks for Convergent Selective, Chemoselective, and Orthogonal Oligosaccharide Synthesis

Pornsuriyasak

Demchenko

2006

Chemistry A European J

103

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“…The first five steps involve the transformation of maltose into thioglycoside 5 to differentiate the hydroxyl functions and to activate the anomeric center. The sequence involved peracetylation, thioglycosylation using thiophenol and tin tetrachloride in 1,2-dichloroethane (DCE), 9 hydrolysis of acetyl groups, selective protection of 4 0 -O and 6 0 -O positions with benzaldehyde in the presence of zinc dichloride, 10 and permethylation of the remaining free hydroxyl functions in basic conditions (Scheme 2). Compound 5 was then transformed into disaccharide 6 by the selective reduction of the benzyl acetal with sodium cyanoborohydride under acidic conditions.…”

Section: Indirect Methodsmentioning

confidence: 99%

Indirect and direct approaches in the synthesis of a new mono-6-O-benzyl methylated γ-cyclodextrin as chiral selector for enantioselective gas chromatography

Chaise

Cardinaël

Tisse

et al. 2008

Tetrahedron: Asymmetry

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“…Disaccharidic acceptor 1e was prepared by coupling donor 2c (18) with acceptor 2d (18) followed by in situ removal of the C-4Ј trimethylsilyl group. The disaccharides 1h and 1i were obtained by coupling donor 2e (19) with acceptor 2f (18) and donor 2a (18) with acceptor 2g (20), respectively, using the same promoters as for the synthesis of compounds 3, to give intermediate 1f and 1g, followed by removal of benzyl groups. According to international nomenclature the position of the methyl-esterified carboxyl is numbered starting from the reducing end of the molecule.…”

Section: Methodsmentioning

confidence: 99%

Performance of Selected Microbial Pectinases on Synthetic Monomethyl-esterified Di- and Trigalacturonates

Kester¹,

Magaud²,

Roy³

et al. 1999

Journal of Biological Chemistry

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Two monomethyl esters of ␣-(1-4)-linked D-galacturonic dimers and three monomethyl esters of ␣-(1-4)-linked D-galacturonic acid trimers were synthesized chemically and further used as substrates in order to establish the substrate specificity of six different endopolygalacturonases from Aspergillus niger, one exopolygalacturonase from Aspergillus tubingensis, and four selected Erwinia chrysanthemi pectinases; exopolygalacturonan hydrolase X (PehX), exopolygalacturonate lyase X (PelX), exopectate lyase W (PelW), and oligogalacturonan lyase (Ogl). All A. niger endopolygalacturonases (PGs) were unable to hydrolyze the two monomethyldigalacturonates and 2-methyltrigalacturonate, whereas 1-methyltrigalacturonate was only cleaved by PGI, PGII, and PGB albeit at an extremely low rate. The hydrolysis of 3-methyltrigalacturonate into 2-methyldigalacturonate and galacturonate by all endopolygalacturonases demonstrates that these enzymes can accommodate a methylgalacturonate at subsite ؊2. The A. tubingensis exopolygalacturonase hydrolyzed the monomethyl-esterified digalacturonates and trigalacturonates although at lower rates than for the corresponding oligogalacturonates. 1-Methyltrigalacturonate was hydrolyzed at the same rate as trigalacturonate which demonstrates that the presence of a methyl ester at the third galacturonic acid from the nonreducing end does not have any effect on the performance of exopolygalacturonase. Of the four E. chrysanthemi pectinases, Ogl was the only enzyme able to cleave digalacturonate, whereas all four enzymes cleaved trigalacturonate. Ogl does not cleave monomethyl-esterified digalacturonate and trigalacturonate in case the second galacturonic acid residue from the reducing end is methyl-esterified. PehX did not hydrolyze any of the monomethyl-esterified trigalacturonates. The two lyases, PelX and PelW, were both only able to cleave 1-methyltrigalacturonate into ⌬4,5-unsaturated 1-methyldigalacturonate and galacturonate.Fungi from the genus Aspergillus and bacteria from the genus Erwinia produce a wide spectrum of enzymes involved in pectin degradation. Pectin is a heteropolysaccharide with smooth regions of ␣-1-4-linked D-galacturonic acid residues of which approximately 70% of the carboxylic groups are methylesterified. Besides these homogalacturonan parts, the polysaccharide also contains highly branched regions with L-rhamnose and D-galacturonate as the alternating constituents of the backbone structure in which rhamnose can be found to be highly substituted with galactose or long branched arabinose side chains and in which the D-galacturonate moieties can be methyl-esterified, O-acetylated, or substituted with xylose (1). Aspergillus niger was shown to harbor an endopolygalacturonase (PG) 1 gene family consisting of 7 members (2). The PG encoding genes have been cloned and sequenced, and six of them have been overexpressed individually (3-6).2 The enzymes have been characterized biochemically using polygalacturonate, pectins with different degree of methyl esterification, and oligog...

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ChemInform Abstract: HYDROGENOLYSIS OF THE BENZYLIDENE ACETALS OF THIOGLYCOSIDES WITH THE LITHIUM ALUMINUM HYDRIDE‐ALUMINUM CHLORIDE REAGENT. SYNTHESIS OF PARTIALLY BENZYLATED THIOGLYCOSIDE DERIVATIVES

Abstract: Synthesis of Partially Benzylated Thioglycoside Derivatives.

Cited by 13 publications

References 0 publications

S‐Thiazolinyl (STaz) Glycosides as Versatile Building Blocks for Convergent Selective, Chemoselective, and Orthogonal Oligosaccharide Synthesis

S‐Thiazolinyl (STaz) Glycosides as Versatile Building Blocks for Convergent Selective, Chemoselective, and Orthogonal Oligosaccharide Synthesis

Indirect and direct approaches in the synthesis of a new mono-6-O-benzyl methylated γ-cyclodextrin as chiral selector for enantioselective gas chromatography

Performance of Selected Microbial Pectinases on Synthetic Monomethyl-esterified Di- and Trigalacturonates

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