Synthesis of Vulculic Acid from Nimbya alternantherae

Vulculic acid is a kind of phytotoxin separated from the metabolite of Nimbya alternantherae, which is a leaf spot fungus isolated from alligatorweed. This phytotoxin can result in plant withered and is a potential herbicide to alligatorweed. The synthesis of vulculic acid using the commercially available 3,4,5-trimethoxyphenylacetic acid as the starting material was described. The whole route involved five steps in 21% overall yield with methyl esterification, followed by Friedel-Crafts acylation, demethylation, selective methylation and hydrolysis reaction. This synthesis takes advantage of a selective methylation reaction using borax as the chelating agent. Synthesized Vulculic acid was dissolved in distilled water to detect its effect on alligatorweed leaf through the method of leaf-puncture-soak. The results show that synthetic Vulculic acid could cause leaf spot, same as the symptom by the native Vulculic acid, at the level of 50 mu g/mL after treating for 24 h. These results suggest that synthesized Vulculic acid should be good prospect for the application in the control of alligatorweed.