Microtropins A-I: 6 '-O-(2 '' S,3 '' R)-2 ''-Ethyl-2 '',3 ''-dihydroxybutyrates of aliphatic alcohol beta-D-glucopyranosides from the branches of Microtropis japonica

摘要

From the branches of Microtropis japonica (Celastraceae), nine aliphatic glucosides, named microtropins A-I, were isolated. The 6-position of glucose was esterified with (2S,3R)-2-ethyl-2,3-dihydroxybutyric acid. Microtropins A-D contained a rare natured product nitrile functional group in their aglycones. The absolute structures of the (25,3R)-2-ethyl-2,3-dihydroxybutyric acid moiety and aglycone of microtropin A were determined by an X-ray crystallographic method