Isolation of (E)-9,10-dihydroxy-2-decenoic acid from royal jelly and determination of the absolute configuration by chemical synthesis

(E)-9,10-Dihydroxy-2-decenoic acid 1 was isolated as a new compound from royal jelly. The planar structure was deduced by spectroscopic analyses, whereas the absolute configuration was established by chemical synthesis of both enantiomers of 1. The natural product was revealed to be ca. 3.5:1 mixture of (R)- and (S)-acids by comparison of 1 with authentic samples.

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(R)-4-(Hept-6-enyl)-2,2-dimethyl-1,3-dioxolaneC12H22O2[α]D23=-17.9 (c 1.21, CHCl3)Absolute configuration: (R)Source of chirality: (4R)-4-(2-hydroxyethyl)2,2-dimethyl-1,3-dioxolane

(E)-tert-Butyl 8-((R)-2,2-dimethyl-1,3-dioxolan-4-yl)oct-2-enoateC17H30O4[α]D23=-10.4 (c 1.39, CHCl3)Absolute configuration: (R)Source of chirality: (4R)-4-(2-hydroxyethyl)2,2-dimethyl-1,3-dioxolane

(2E,9R)-9,10-Dihydroxy-2-decenoic acidC10H18O4[α]D25=+11.9 (c 0.51, MeOH)Absolute configuration: (R)Source of chirality: (4R)-4-(2-hydroxyethyl)2,2-dimethyl-1,3-dioxolane