Alkaloids of Alchornea javanensis (Euphorbiaceae): The isolation of Hexahydroimidazo[1,2-a]pyrimidines and guanidines

Abstract

Alchornea jawanensis (Bl.) Muel1.-Arg. (family Euphorbiaceae) has been found to contain both hexahydroimidazo[l,2-a]pyrimidine and guanidine alkaloids. Alchornine has been shown to be (1), and alchornidine is either (6) or (7). Hydrolysis of alchornidine with ethanolic potassium hydroxide affords 2,2-dimethylacrylic acid and alchornine, but hydrolysis of alchornidine with dilute acetic acid gives isoalchornine (8), which can be converted into alchornine in high yield by reaction with alkali. One guanidine alkaloid, now shown to be N1,Nl-diisopentenylguanidine (14), was incorrectly formulated as N1,N2-diisopentenylguanidine in a preliminary communication. Another guanidine has been shown to be Nl,N2,N3-triisopentenylguanidine by synthesis of its hexahydro derivative, Nl,X 2,N 3-triisopentylguanidine. 2,2-Dimathylacrylamide has also been isolated from extracts of A. javanensis.