Preparation of bacteriopetroporphyrins by partial synthesis from the Chlorobium chlorophylls

Abstract

Chemical degradation of the natural bacteriochlorophyll d homologous mixture to give the corresponding bacteriopetroporphyrin methyl esters is described. 1 H NMR spectroscopy of the nickel(II) complexes is used to establish that the pigments are identical with those isolated from immature Messel oil shale. Similar degradative transformations of the bacteriochlorophyll c homologues (and also of the bacteriochlorophyll e mixture) to give «bacteriopetroporphurins c» (which have not yet been observed in oil shales) are reported, and the proton NMR signatures of their nickel(II) complexes are obtained and assigned