Glycosidic juvenogens: Derivatives bearing alpha,beta-unsaturated ester functionalities

Wimmer, Zdeněk; Pechová, L.; Sile, L.; Šaman, David; Jedlička, Pavel; Wimmerová, Martina; Kolehmainen, E.
BIOORGANIC AND MEDICAL CHEMISTRY 15 [22]: 7126-7137, 2007

Keywords: Pyrrhocoris apterus; juvenogen; insect juvenile hormone analog
Abstract: A series of the protected alkyl glycosides 5a/5b-12a/12b was synthesized from the parent isomeric alcohols (insect juvenile hormone bioanalogs; juvenoids), 4-[4'-(2"-hydroxycyclohexyl)methylphenoxy]-3-methyl-but-2-enoic acid ethyl ester (Ia/1b-4a/4b; racemic structures) and (1a-4a; enantiopure structures). Cadmium carbonate was used as a promoter of this Koenigs-Knorr reaction. and the products were obtained in 82 92% yields. Deprotection of the carbohydrate functionality of 5a/5b-12a/12b was carefully, performed using ethanolysis in the presence of zinc acetate, due to the presence of another ester functionality in the aglycone part of the molecule of protected alkyl glycosides. Resulting alkyl glycosides 13a/13b-20a/20b (diastereoisomeric mixtures) and 13a20a (enantiopure compounds), biochemically activated hormonogenic compounds juvenogens), were obtained in 82-93/() yields. Finally, chiral HPLC separation of the diastereoisoineric mixtures of alkyl glycosides was applied to get sufficient quantities of the respective enantiomers 13b-20b of the alkyl glycosides for their structure elucidation and C-13 chemical shift assignment by H-1 and C-13 NMR spectroscopy. Partial introductory entomological screening tests of the target alkyl glycosides 13a/13b-20a/20b were performed on the red firebug (Pyrrhocoris apterus). The results of this biological testing clearly demonstrated the time-extended effect of several juvenogens on P. apterus due to their biochemical activation, i.e., hydrolysis of the juvenogen molecule, which results in liberation of the biologically active juvenoid in the insect organism.
DOI:
IEB authors: Zdeněk Wimmer