Transition metal complexes as bifunctional carriers of polar organometallics: Their application to large molecule modifications and to hydrocarbon activation

Modifications of the meso-octaethylporphyrinogen have been successful using a bifunctional approach in the application of organometallic methodologies. The homologation of meso-octaethylporphyrinogen to meso-octaethyltris(pyrrole)monopyridine and to meso-octaethylbis(pyrrole)bispyridine were carried out by reacting carbon monoxide with Zr-C and Zr-H functionalities respectively, supported by the auxiliary ligand meso-octaethylporphyrinogen, [Et(8)N(4)H(8)]. Such an homologation of a pyrrole to a pyridine ring within the porphyrinogen skeleton was achieved with high selectivity, controlled regiochemistry, good yield and on multiple gram quantities. A novel mode of electrophilic activation of aliphatic C-H bonds, assisted by zirconium(IV) in conjunction with an excess of MH [M = Li, Na, K], allows the metalation and then functionalization of the meso-octaethylporphyrinogen periphery. Reaction of sigma bond metathesis allowed the isomerization of zirconium-alkyl functionalities and the activation of aliphatic hydrocarbons.