SYNTHESIS AND BIOLOGICAL EVALUATION OF A BACKBONE-MODIFIED PHYTOALEXIN ELICITOR

Two suitably protected building blocks (11 and 33) for the preparation of amide-linked heptaglucoside mimetic 2, an analogue of the naturall y occurring phytoalexin elicitor 1a, were readily accessible by glycal chemistry. Sequential elongation of terminal glucuronide 21 with lami naribiosyl hemiaminal 33 and anomeric amine 11 by EDC/HOBt-catalyzed c ondensation and two-step conversion of the C6-OTr moiety into the corr esponding carboxylate function afforded homogeneous carbopeptoid 2 in high overall yield. It was found that replacement of the acetal linkag es by the more rigid amide bonds destroys the phytoalexin-elicitor act ivity.