名称:
Preparation of Anhydro-Thiohexopyranosides and -Thiohexofuranosides with D-fructo-, L-sorbo-, L-psico- and L-tagato-Configuration Starting from L-Sorbose
摘要:
Methyl alpha- L-sorbopyranoside is transformed into the bicyclic thiosugar methyl 1,5-anhydro-3,4-di-O-mesyl-1-thio-beta-D-fructopyranoside in two steps, whereas the corresponding 3-O-benzoate is obtained from methyl 1,3-O-benzylidene-alpha-L-sorbopyranoside in three steps. 2,3-O-Isopropylidenesorbofuranosides, on the other hand, can be transformed into 6-S-thioacetates by use of the thio-Mitsunobu reaction. These are suitable precursors for the preparation of 1,6-anhydro-1-thiosorbofuranosides. Also, methyl 1-S-acetyl-1-thio-L-sorbofuranosides with mesylate leaving groups are available by the thio-Mitsunobu reaction. They yield 1,4-anhydro-1-thio-beta-L-tagatofuranosides, 1,3-anhydro-alpha-L-psicofuranosides and 1,6-anhydro-1-thio-alpha-L-sorbofuranosides depending on the configuration of the starting compound. Attempts to prepare azido-thio-sugars by displacement of mesylate groups with alkali metal azides failed.