Diene(tricarbonyl)iron complexes linked to spirooxazolones for the synthesis of cyclopropyldihydroxyphenylalanine

Complexed cyclopropyl-3,4-dihydroxyphenylalanine (∇ DOPA) were synthesized by diazomethane cyclopropanation of the appropriate diene(tricarbonyl)iron complexes linked to azlactones. Opening of the oxazolone ring by treatment with MeOH and DMAP gave the corresponding methyl esters. Introduction of the Boc group, cleavage of the carbamate with hydrazine provided Boc-protected cyclopropylogs of dl-dihydroxyphenylalanine.