Two Unusual Methylidenecyclopropane Glucosides from Metaxya rostrata C.Presl

Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-β-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(β-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-β-D-glucopyranosylcaffeic acid (3) and (E)-4-O-β-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl. The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.