Synthesis and characterisation of the C30-de-ethylaetioporphyrin present in petroleum

Abstract

The four de-ethyl analogues of the relatively ubiquitous and biogenetically significant petroporphyrin aetioporphyrin III (3a–d) have been synthesized utilising the ac-biladiene route. A reversed-phase HPLC method of separating a mixture of the four synthetic isomers was developed, and comparisons with the C₃₀-de-ethylaetioporphyrins occurring in Gilsonite and Serpiano shale revealed them to be identical with the synthetic C-ring isomer (3c). This significant result indicates that the C₃₀-aetioporphyrin present in petroleum results from degradative maturation processes on chlorophyll-a itself.