Selective sulfonylation and acylation of methyl and benzyl glycopyranosides of D-xylose and D-glucose

Tetraisopropyldisiloxane-1,3-diyl as a versatile protecting group for pentopyranosides

“…3 The reactivity order for methyl β-D-xylopyranoside has been previously established to be HO-4 > HO-3 > HO-2. 24 The results from this study support these observations since methyl α-D-xylopyranoside forms the 2,3-cyclic product and methyl β-D-xylopyranoside forms the 3,4-cyclic product. See Table 1 for comparison of different cyclic protection groups on D-xylopyranosides.…”

Total synthesis of astrosterioside A, an anti-inflammatory asterosaponin

“…7 To enhance the efficiency in the assembly of the glycan, a regio-selective glycosylation of disaccharide diol 8 was explored (Scheme 3). 26,27 Thus, coupling of the xylopyranoside 2,4-diol 8 (1.5 equiv.) with thiogalacoside 17 28 under the action of TMSOTf (0.1 equiv.)…”

Chemistry of xylopyranosides

“…xylopyranosides (Table 8). 266 The order of reactivity of the α-anomer was determined to be O2 > O4 > O3, whereas the order for the corresponding β-anomer was O4 > O3 > O2. This trend had been indicated previously.…”

“…Tosylation of methyl and benzyl α-D-xylopyranoside using TsCl in dry pyridine showed the same selectivity as for the mesylation, where the 2-O-tosyl was the major product for monotosylation and 2,4-di-O-tosyl was formed as the major product when using 2 equivalents of TsCl. 266,[268][269] The reaction with methyl β-D-xylopyranoside was on the other hand much less regioselective and 2,4-, 4-, and 2,3-O-tosylated products were isolated in 34%, 31%, and 20% yield, respectively, when sulfonated with 2 equivalents of TsCl. 269 Alternatively, tosyl protective groups can be introduced by reaction with Bu2SnO in combination with TsCl.…”