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Synthesis and Conformational and Biological Aspects of Carbasugars

“…299 This approach has been recently reviewed. 300 Vogel and co-workers 83,301 also reported the synthesis of carbaxylopyranosides [(+)-84 and (-)-84] with D-and L-xylose configurations, from (+)-665 and (-)-665, respectively (Scheme 98). Compound (+)-665 was conveniently converted to 666, which, upon base treatment, as previously reported by the authors, 302 underwent oxa-bridge opening, leading, after protecting group manipulations, to 667.…”

Naphthyl Thio‐ and Carba‐xylopyranosides for Exploration of the Active Site of β‐1,4‐Galactosyltransferase 7 (β4GalT7)

“…However, the active compound d ‐ 11 shows the same sign, that is, (−), of the specific rotation as the previously published active compound 6 . Also, previous studies of l ‐xylosides, and analogues thereof, have shown that they do not act as substrates for β4GalT7 . We thus propose that the carbasugars with d ‐configuration are the actual substrates for β4GalT7.…”

“…Remarkably, the authors propose that the l ‐xylo‐derivative 6 shows a much higher antithrombotic activity compared to the d ‐xylo‐enantiomer 5 and that only the compound with l ‐xylo conformation functioned as substrate for β4GalT7 when assayed with enzyme extracts from chicken embryo. This is in stark contrast to other investigations where l ‐enantiomers of xylosides rarely act as substrates for β4GalT7 …”

“…As part of our ongoing investigation to explore the active site of β4GalT7, we present the xyloside analogues 2‐naphthyl 5‐thio‐ and 2‐naphthyl 1,5‐dithio‐β‐ d ‐xylopyranoside 9 and 10 , respectively, as well as the 2‐naphthyl 5a‐carba‐β‐xylopyranoside 11 in both the d and l configuration (Figure ). Because the activity of previously published thio and carba analogues (Figure ) was tested with partially purified enzyme extracts from chicken embryos,, we judged it mandatory to confirm the activity of 9 , 10 , d ‐ 11 , and l ‐ 11 in a β4GalT7 assay by using purified enzyme. The xylosides 7 and 8 (Figure ) were also included in our enzyme study for comparison reasons.…”

Chemistry of xylopyranosides

“…xylopyranosides can be synthesized using several different routes of which (+)-conduritol F derivatives are common precursors. Vogel and co-workers initiated their synthesis of 5a-carbaβ-D-xylopyranoside 100 from the Diels-Alder adduct 97, which was converted to the conduritol F derivative 98 in several steps (Scheme 22) 347. Performing a Mitsunobu reaction with 98 and 4-ethylumbelliferone generated 99 with the desired stereochemistry after which hydrogenation and desilylation yielded 100.…”