On the Novel Free Porphyrins Corallistin B, C, D, and E: Isolation from the demosponge Corallistes sp. of the Coral Sea and Reactivity of Their Nickel 55 (II) Complexes toward Formylating Reagents

Reported here are the novel free porphyrins corallistin B, C, D, and E, isolated as methyl esters 2a , 3a , 4a , and 5a , respectively, from the sponge Corallistes sp. (Lithistida) collected at the basis of the south New Caledonian coral reef. A protocol is also established for formylation of their Ni II complexes, which show a different reactivity pattern toward DMF/POCl3 from metal complexes of deuteroporphyrins. Together with corallistin A, Previously isolated as the methyl ester 1a , and the known deuteroporphyrin IX (isolated as 6a ) also present in the sponge, the new corallistins, which may be thought to derive from protoporphyrin via heme, account for an amazing 60% of the EtOh extract from the sponge.