Syntheses of partially pivaloylated d-glucopyranoses: new substrates for the esterase from rabbit serum

Pivaloylated glucoconjugates with heterocyclic oximes

“…Pivaloylation of β-d-glucopyranose in pyridine with a 10-fold molar excess of pivaloyl chloride produced penta-Opivaloyl-β-d-glucopyranose [7] which was, after isolation and purification, treated with HBr (33% in glacial acetic acid) to give the starting tetra-O-pivaloyl-α-d-glucopyranosyl bromide (1) [2,7]. Heterocyclic oxime 3 is commercially available while oximes 2 and 4 were prepared following the previously reported procedure [12][13][14].…”

“…The pivaloyl group has been used as an useful protecting group in the synthesis of acylated monosaccharides [1][2][3][4] and disaccharides [1,2]. It can be introduced selectively to produce various partially pivaloylated saccharides, its position in a molecule is easily detectable by 1 H NMR, and it can be removed totally or selectively by esterases from mammalian sera [2,[4][5][6].…”

“…It can be introduced selectively to produce various partially pivaloylated saccharides, its position in a molecule is easily detectable by 1 H NMR, and it can be removed totally or selectively by esterases from mammalian sera [2,[4][5][6]. Furthermore, the pivaloyl group has been used in carbohydrate chemistry because of its advantageous stereodirecting properties in glycosylation reactions.…”

Methyl 4-O-pivaloyl-β-D-xylopyranoside

“…The introduction and/or removal of protecting groups represent some of the most challenging transformations in sugar chemistry. In our previous work we described the synthesis and the hydrolysis of several series of acylated monosaccharides, acyl being acetyl, pivaloyl or a combination of both (Ljevaković et al, 1992;Tomić et al, 1993;Ljevaković et al, 1995;Petrović et al, 1997). Selective acylations and deacylations can be achieved with enzymes as regio-and chemoselective catalysts.…”

“…Selective acylations and deacylations can be achieved with enzymes as regio-and chemoselective catalysts. We demonstrated that mammalian sera, which are a rich source of different enzymes, contain esterases specific for acylated monosaccharides and can be used for the selective hydrolysis of O-acyl derivatives of different monosaccharides (Tomić et al, 1993;Ljevaković et al, 1995;Petrović et al, 1997).…”