The syntheses of the imidazole alkaloid casimiroedine (7), a natural product isolated from the seeds of the Mexican fruit "Zapote blanco," and its hydrolysis product casimidine (6) have been accomplished. The key step in the synthesis of casimiroedine (7) involves the formation of the peptide linkage between irans-cinnamic acid and casimidine. The unambiguous synthesis of 7 established the stereochemistry of the cinnamoyl moiety as trans. This assignment was corroborated by the synthesis of cis-casimiroedine ( 8) and spectral evidence. Chemical investigations conducted on the seeds of the fruit of the tree Casimiroa edulis La Llave et Lejarza have shown them to contain a variety of constituents. 2-4 The principal constituent, the alkaloid casimiroedine (7), was found to be the cinnamic acid amide of casimidine ( 6).6 Degradation studies6 on casimidine confirmed the presence of A-methylhistamine and a carbohydrate fragment. An X-ray analysis7•8 firmly established the structure of the carbohydrate as /S-D-glucose and of casimidine as 4-[2-(methylamino)ethyl]-l-(/3-D-glucopyranosyl)imidazole. These studies provided the basic structure of casimiroedine (7) and left one question unanswered, whether casimiroedine was the cisor trans-cinnamic acid amide of 6. This final question has now been resolved by the total synthesis of casimiroedine.113 Results and DiscussionChemical Synthesis. The chloromercury derivative9 (2) of 4-(2-chloroethyl)imidazole hydrochloride10•11 (1) (Scheme I) was glycosylated with 2,3,4,6-tetra-O-acetyl--D-glucosyl bromide12 (3) to provide 4 as a thick syrup.(1) (a) This investigation was supported in part by Research Contract No. C72-3710 with the
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