Abstract
Gigartinine and gongrine, both isolated from the red alga, Gymnogongrus flabelliformis, were confirmed by synthesis to be L-α-amino-δ-(guanylureido)-n-valeric acid and γ-(guanylureido) butyric acid, respectively. DL-Gigartinine was synthesized from α-chloro-δ-amino-n-valeric acid through esterification, phosgenation, condensation with guanidine, hydrolysis, and Rf values in paper chromatography agreed well with those fo natural L-gigartinine. Another guanylureido compound identical with natural gongrine was obtained from γ-amino-butyric acid through phosgenation followed by condensation with guanidine.
