Synthesis of Vinyl Sulfoxide‐Modified Pent‐2‐enofuranosides and Hex‐2‐enopyranosides and Preliminary Studies of Their Reactivity
Vinyl sulfoxide-modified pent-2-enofuranosides and hex-2-enopyranosides have been synthesized by using a controlled oxidation of C-3-deoxy-C-3-thioaryl furanosides and pyranosides, respectively, followed by mesylation of the C-2-hydroxyl group and elimination. In the furanose system, both diastereomers were formed in almost equal ratio, whereas the pyranose ring imposed diastereoselectivity of oxidation of the sulfur atom to produce only Ss isomers in good overall yields. Vinyl sulfoxide-modified 2-enofuranosides were treated with NaCH2NO2 to obtain C-2 branched chain sugars. Furanosyl sulfoxides yielded products that were similar to the adducts obtained by treatment of the corresponding sulfones with nitromethane. The sulfinyl group in thepyranosides influenced the diastereoselectivity of addition to produce adducts that differed from the products obtained from the corresponding vinyl sulfones under similar reaction conditions.