Metalloporphyrin as Effective Catalysts for the Aerial Oxidation of Bisnaphthols to Spirodienones

Porphyrins are cyclic ligands composed of four pyrrole units connected through CH bridges. Porphyrines and Metalloporphyrins are found in important biological systems, for example porphyrin is the basic building block of hemoglobin and myoglobin (an oxygen molecules carrier in blood) called heme. The Metal cation of heme is Fe2+ to which oxygen molecule is attached. Porphyrins and metalloporphyrins are also used as effective catalysts in a number of chemical and photochemical process (such as PDT).1 Porphyrins and metalloporphyrins2 have been prepared in our laboratory by refluxing pyrrole and benzaldehyde in the presence of concentrated HCl and N-hydroxyphthalimide in dimethylformamide. NMR data confirm the structure of these compounds. The synthesized metalloporphyrins were then used as effective catalysts for the aerial oxidation of bisnaphthols to spirodienones Scheme 1. The latter compounds are obtained in two diasteromeric forms which are easily characterized by their NMR spectral data. Reaction times, yields and melting points of all products are shown in Table 1.