Synthesis of amido-ureas and the nature of caracasanamide, the hypotensive principle of Verbesina caracasana

Abstract

Syntheses of the (E)-1 and (Z)-2 forms of 1-(3-methylbut-2-enyl)-3-{4-[3-(3,4-dimethoxyphenyl)-prop-2-enamido]butyl}urea, proposed structures for the natural hypotensive caracasanamide, have been carried out. The compounds were found not to be identical with the natural products, the structures of which have now been revised from containing a urea to containing a corresponding guan-idine segment. Using aminoiminomethanesulfonic acid or 3-methylbut-2-enylcyanamide as reagents, the synthesis can be diverted to caracasanamide 15(R = H) through an amine intermediate.