4201-66-5Relevant academic research and scientific papers
Acid-catalysed isomerization of the tetraisopropyldisiloxane-1,3-diyl group. Simultaneous protection of two secondary alcoholic functions.
Verdegaal,Jansse,de Rooij,van Boom
, p. 1571 - 1574 (1980)
The reaction of 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane with ribonucleosides or sugar derivatives affords products containing one silyl-protected primary and secondary hydroxy function. Treatment of these products with MSA in DMF gives products having two silylated secondary hydroxy functions.
A novel enzymatic method for the synthesis of methyl 6-O-acetyl-α-D-glucopyranoside using a fermented solid containing lipases produced by Burkholderia contaminans LTEB11
Villalobos, Maribel Cordero,Gon?alves, Alan Guilherme,Noseda, Miguel Daniel,Mitchell, David Alexander,Krieger, Nadia
, p. 86 - 93 (2018)
Chemical methods for the regioselective modification of carbohydrates require several steps that involve the addition and removal of protective groups. Enzymatic methods are promising since they can give high selectivity in a single step. We developed a new method for acetylation of methyl-α-D-glucopyranoside with vinyl acetate, the reaction being catalyzed by a fermented solid containing lipases from Burkholderia contaminans LTEB11. The main product of the synthesis, methyl 6-O-acetyl-α-D-glucopyranoside (6-OAc-α-MetGlc), was identified by NMR and quantified by HPLC. The conversion of methyl-α-D-glucopyranoside to 6-OAc-α-MetGlc was evaluated at laboratory scale (4 mL) in different solvent systems. The conversion increased with increasing hydrophobicity of the solvent, with the highest conversion, 65% in 72 h, being obtained in the solvent-free system. This system was scaled up to a 1-L reaction medium. A conversion of 76% in 72 h was obtained, with a calculated yield of 1.05 g (4.43 mmol) of 6-OAc-α-MetGlc. This is the largest amount of 6-OAc-α-MetGlc (in moles) produced by enzymatic catalysis that has been reported in the literature to date. These results suggest that the fermented solid produced by B. contaminans LTEB11, which is a low-cost biocatalyst, could potentially be used for the industrial production of esters of α-D-glucose.
Selective Acetylation of the Primary Hydroxyl Group in Methyl D-Hexopyranosides with a Mixture of Acetic Anhydride and Acetic Acid
Tsvetkov,Yashunsky,Nifantiev
, p. 99 - 102 (2021/04/05)
Abstract—: 6-O-Acetylated derivatives of D-hexopyranosides are valuable intermediates in synthetic carbohydrate chemistry. We have developed a new simple procedure for selective acetylation of the primary hydroxyl group in methyl D-hexopyranosides consisting in treatment with a mixture of acetic anhydride and acetic acid at 50°C. As a result, corresponding 6-acetates were formed in 40–50% yield.
Regioselective acetylation of carbohydrates and diols catalyzed by tetramethyl-ammonium hydroxide in water
Lu, Yuchao,Wei, Peng,Pei, Yuxin,Xu, Hengfu,Xin, Xiaoting,Pei, Zhichao
, p. 4510 - 4514 (2014/12/10)
A novel method for an efficient regioselective acetylation of carbohydrates and diols in aqueous solution is described. Treatment of substrates with 1-acetylimidazole, and tetramethyl-ammonium hydroxide (TMAH) in water under mild conditions gave highly regioselective acetylation for primary hydroxyl groups. This discovery provides an eco-friendly way for selective acetylation of non-protected glycosides and diols in water, avoiding the use of toxic organic solvents and the necessity of pre-protection of secondary hydroxyl groups. This journal is
Carbohydrate esterases of family 2 are 6-O-deacetylases
Topakas, Evangelos,Kyriakopoulos, Sarantos,Biely, Peter,Hirsch, Jan,Vafiadi, Christina,Christakopoulos, Paul
experimental part, p. 543 - 548 (2011/01/03)
Three acetyl esterases (AcEs) from the saprophytic bacteria Cellvibrio japonicus and Clostridium thermocellum, members of the carbohydrate esterase (CE) family 2, were tested for their activity against a series of model substrates including partially acet
Directing-protecting groups for carbohydrates. Design, conformational study, synthesis and application to regioselective functionalization
Moitessier, Nicolas,Englebienne, Pablo,Chapleur, Yves
, p. 6839 - 6853 (2007/10/03)
A novel concept of regioselective transformation of secondary hydroxyl groups in carbohydrates is presented. First, the relative reactivity of the free hydroxyl groups of onoprotected d-glucose derivatives was assessed using acetylation as a model reactio
Esterase-catalysed regioselective 6-deacylation of hexopyranose per-acetates, acid-catalysed rearrangement to the 4-deprotected products and conversions of these into hexose 4- and 6-sulfates
Horrobin, Tina,Tran, Chuong Hao,Crout, David
, p. 1069 - 1080 (2007/10/03)
The esterase from Rhodosporidium toruloides has been used to catalyse the hydrolysis of a series of per-acetylated α-D-hexopyranoses and α-D-hexopyranosides. Per-acetylated glucose 4, mannose 6, N-acetylgalactosamine 8, galactose 10, methyl α-D-glucoside 12, methyl α-D-mannoside 14 and methyl α-D-galactoside 16 have been selectively cleaved at the C-6 position by the esterase to give the 6-OH derivatives 5, 7, 9, 11, 13, 15 and 17. Acid-catalysed rearrangement of acetates 5, 7, 13, 15, 11, 17 and 9 with 4→6 acetyl migration gives the corresponding 4-deprotected derivatives 22-28, respectively. Hydrolyses of β-D-glucose pentaacetate 20 and α-D-lactose octaacetate 21 have been attempted, but no hydrolyses have been observed. 1,2,3,6-TetraacyIated α-D-hexopyranoses 3 and 22, derivatives of N-acetylglucosamine and glucose respectively, and 2,3,6-triacetylated α-D-hexopyranosides 24 and 25, derivatives of glucose and mannose, respectively, have been hydrolysed by the esterase to the corresponding 4,6-dihydroxy acetates 29, 18, 30 and 31. Acylation of methyl α-D-glucopyranoside 32 catalysed by the esterase provides the C-6 monoacetate 33 and the C-3 monoacetate 34 in 4 and 5% yield, respectively. The sodium salts of N-acetylglucosamine, glucose, N-acetylgalactosamine, galactose and mannose 6-sulfates 38-42, respectively, are prepared in two steps from the 6-deacetylated hexopyranoses 2, 5, 9, 11 and 7, respectively. The sodium salts of N-acetylglucosamine, glucose and mannose 4-sulfates 43-45, respectively, are prepared in two steps from the 4-deacetylated precursors 3, 22 and 26 which are obtained via acid catalysed 4→6 acyl migration of compounds 2, 5 and 7.
Regioselective deacetylation of fully acetylated mono- and di-saccharides with hydrazine hydrate
Khan, Riaz,Konowicz, Paul A.,Gardossi, Lucia,Matulova, Maria,De Gennaro, Sergio
, p. 293 - 298 (2007/10/03)
Selective deacetylation reactions of the peracetylated reducing disaccharides (1), (5), (9), (15), β-D-glucopyranose (17) and 2-acetamido-2-deoxy-β-D-glucopyranose (19), with 1-2 equiv. of hydrazine hydrate in acetonitrile, gave predominantly the corresponding heptaacetates (2), (6), (10), (16), the tetraacetate (18) and the triacetate (20), with the free hydroxy group at C1. Reaction of (1) with 1-2 equiv. of hydrassine hydrate in N,N-dimethylformamide also afforded the heptaacetate (2), but in lower yield. When reactions of (1), (5) and (9) were performed with 2-5 equiv. of hydrazine hydrate, deacetylation also occurred at other positions to afford the corresponding hexaacetates (3), (7), (11) and (12), with hydroxy groups at C 1,2 or C 1,3, and the pentaacetates (4), (8) and (13), with hydroxy groups at C 1,2,3. Maltose octaacetate (9). in addition, yielded the tetraacetate (14) in which the free hydroxy groups were located at C1,2,2′,3. Compound (15) on treatment with 2-5 equiv. of hydrazine hydrate afforded an intractable mixture. The reaction of methyl 2,3,4,6-tetra-O-acetyl-α-D-glucopyranoside (21) with 2-5 equiv. of hydrazine hydrate gave the 3,4,6-triacetate (22), a mixture of the 2,6- and the 3,6-diacetates (23) and (24), respectively, the 4,6-diacetate (25), and the 6-acetate (26).
Dispiroketals in Synthesis (Part 8): Regioselective Protection of D-Glucopyranose Substrates.
Entwistle, David A.,Hughes, Andrew B.,Ley, Steven V.,Visentin, Giuseppina
, p. 777 - 780 (2007/10/02)
A new process for the efficient regioselective formation of 1,8,13,16-tetraoxadispirohexadecanes (dispiroketals) of various D-glucopyranosyl substrates by the chiral recognition of enantiomeric trans 1,2-diol relationships is described.This was achieved using the novel enantiomerically pure 2,2'-disubstituted 3,3',4,4'-tetrahydro-6,6'-bi-2H-pyrans 1,2 and 11.New conditions for the removal of dispiroketal protecting groups are presented.
Dispiroketals in Synthesis (Part 17): Regioselective Protection of D-Glucopyranoside, D-Galactopyranoside and D-mannopyranoside Substrates
Edwards, Paul J.,Entwistle, David A.,Genicot, Christophe,Ley, Steven V.,Visentin, Giuseppina
, p. 2609 - 2632 (2007/10/02)
Chiral recognition of enantiomeric trans-1,2-diol relationships leading to regioselective formation of 1,8,13,16-tetraoxadispirohexadecanes (dispiroketals) of various D-glucopyranoside, D-galactopyranoside and D-mannopyranoside substrates is desc
