title: The multicomponent approach to N-methyl peptides: total synthesis of antibacterial (-)-viridic acid and analogues.
abstract: Two syntheses of natural viridic acid, an unusual triply N-methylated peptide with two anthranilate units, are presented. The first one is based on peptide-coupling strategies and affords the optically active natural product in 20% overall yield over six steps. A more economical approach with only four steps leads to the similarly active racemate by utilizing a Ugi four-component reaction (Ugi-4CR) as the key transformation. A small library of viridic acid analogues is readily available to provide first SAR insight. The biological activities of the natural product and its derivatives against the Gram-negative bacterium Aliivibrio fischeri were evaluated.
authors.affiliation: Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120 Halle (Saale), Germany, Tel: +49 345 5582 1301, Address for correspondence).
authors.forename: Ricardo A W
authors.initials: RA
authors.lastname: Neves Filho
authors.forename: Sebastian
authors.initials: S
authors.lastname: Stark
authors.forename: Bernhard
authors.initials: B
authors.lastname: Westermann
authors.forename: Ludger A
authors.initials: LA
authors.lastname: Wessjohann