Alkyl-, aryl-, and acyl-metal(III) complexes of aetioporphyrin I

Abstract

Reaction of pyridinobromocobalt(III) aetioporphyrin I with a variety of alkyl- and aryl-magnesium bromides gives the corresponding alkyl- and aryl-cobalt(III) derivatives. In an alternative synthesis, the cobalt(I) derivative of aetioporphyrin I reacts with alkyl or acyl halides to give the alkyl- or acyl-cobalt(III) compounds. The latter approach has also been used for the preparation of hydroxyalkylcobalt(III) porphin derivatives which are shown to yield aliphatic carbonyl derivatives on photolysis. The porphin ring exhibits a profound shielding effect on the protons of the alkyl-, aryl-, and acyl-cobalt groups and a maximum effect on the protons of the second carbon atom of the chain. p-Tolyl- and ethyl-iron(III) derivatives of aetioporphyrin I are also described.