Die Konstitution des Loroglossins. 163. Mitt. über organische Naturstoffe

The Constitution of Loroglossine Loroglossine, a characteristic constituent of orchids, is shown to be bis[4‐(β‐ D ‐glucopyranosyloxy)‐benzyl]‐(2 R , 3 S )‐2‐isobutyl‐tartrate (1) . Base catalysed hydrolysis and esterification with diazomethane gave 1 mol‐equiv. of dimethyl (+)‐2‐isobutyl‐erythro‐tartrate ((+)‐ 3 ) and 2 mol‐equiv. of a glucoside which after acetylation formed 4 identical with a synthetic sample. The structure of (+)‐ 3 follows from the synthesis of (±)‐ 3 by osmium tetroxide oxidation of isobutyl‐maleic acid anhydride and subsequent esterification. The absolute configuration of (+)‐ 3 was based on Horeau experiments and NMR. data of the diastereomeric mixture of its esters 15 and 16 and pure 15 with ( S )‐(+)‐ and ( R )‐(−)‐α‐phenyl‐butyric acid, respectively.