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.
提供了两种合成天然维里酸的方法,这是一种具有两个蒽酰胺单元的不寻常的三次N-甲基化肽。第一种方法基于肽偶联策略,经过六个步骤以20%的总产率得到光学活性的天然产物。一种更经济的方法只需四个步骤,通过利用Ugi四组分反应(Ugi-4CR)作为关键转化,可以得到类似活性的消旋体。易得到一小批维里酸类似物库,提供首批SAR洞察。评估了天然产物及其衍生物对革兰氏阴性细菌Aliivibrio fischeri的生物活性。