Tropolone Analogues of the Amino Acid Mimosine

Abstract

The synthesis of DL-α-amino-β-(4-hydroxy-5-oxocyclohepta-1,3,6-trienyl)propanoic acid (2) and the corresponding 6-hydroxy isomer (3), tropolone analogues of the wool-growth inhibiting amino acid mimosine (1),is described. Both isomers were obtained in a single sequence, commencing with the cycloaddition of dichloroketene to (β, β-diethoxyethyl)cyclopentadiene, and were readily separated at an intermediate stage via the copper complexes.