93173-18-3Relevant academic research and scientific papers
On the regioselective acylation of 1,6-anhydro-β-D- and L-hexopyranoses catalysed by lipases: Structural bass and synthetic applications
Boissière-Junot, Nathalie,Tellier, Charles,Rabiller, Claude
, p. 99 - 115 (2007/10/03)
With the aim of providing new methods for the regioselective protection at the 2,3 and 4 positions of monosaccharides, we have studied the acetylation of a class of rigid sugars: the 1,6-anhydro-β-D- and L-hexopyranoses (hexopyranosanes D-1 to D-5 and L-1 to L-5), using vinyl acetate as an acyl donor and two common lipases,Candida rugosa and Pseudomonas cepacia, as catalysts. Our results indicate that the relative orientation of the hydroxyls governs the regioselectivity of acetylation. In the D-series, when the 3-OH is in the axial position, acetylation occurs mainly at the 4-axial OH, while the 2-axial OH is preferred when the 4-OH is equatorial. Conversely, when the 3-OH is equatorial, a strong selectivity affects the equatorial 2-OH. Compounds of the L-series were shown to be poor substrates for the lipase Pseudomonas cepacia except for L-galactosane for which the 2-monoacetyl ester was obtained in good yield. An attempt to rationalize the results by means of molecular modelling is also made to account for the catalytic activity of the Candida rugosa lipase on hexopyranosanes 1-3.
ENZYME-CATALYZED PARTIAL DEACETYLATION OF 1,6-ANHYDRO-2,3,4-TRI-O-ACETYL-β-D-GLUCOPYRANOSE
Zemek, Jiri,Kucar, Stefan,Anderle, Dusan
, p. 2347 - 2352 (2007/10/02)
Various esterases, lipases, and proteases with esterolytic activity were investigated for their power to catalyse deacetylation of 1,6-anhydro-2,3,4-tri-O-acetyl-β-D-glucopyranose.Out of these, chymotrypsin, esterase ex liver, lipase ex pancreas, and lipase ex wheat-germ have been found to be selective catalysts of deacetylation; chymotrypsin and wheat-germ lipase preferably removed the acetyl at C(3), whereas liver esterase and pancreas lipase the acetyl at C(4).Compared to chemical catalysis, whether by methanolic hydrogen chloride or hydrazine hydrate, the locoselectivity of the enzyme-catalysed deacetylation appear to be much better.
PARTIAL HYDROLYSIS OF ACYL 1,6-ANHYDRO-β-D-GLUCOPYRANOSE
Kucar, Stefan,Zamocky, Juraj,Zemek, Juraj,Anderle, Dusan,Matulova, Maria
, p. 1780 - 1787 (2007/10/02)
Partial hydrolysis of per-O-acetyl- and per-O-benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose with methanolic hydrogen chloride and hydrazine hydrate was investigated.The acyl group at C(3) is of substantial influence on the course of hydrolysis.The esterified hydroxyl group at C(3) was found to be most stable on acid hydrolysis with methanolic hydrogen chloride when compared with that at C(2), or C(4); on the other hand, this ester group is the most labile upon hydrolysis with hydrazine hydrate.Selectivity of the respective ester groups towardshydrolysis made it possible to prepare all variations of acetyl and benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose.
