Oxidative C-H/N-H Functionalization Mediated by Ruthenium Phthalocyanines

Abstract

Metallophthalocyanines constitute a large family of metal compounds which have attracted broad interest in various areas including synthetic chemistry and catalysis. We are interested in the design and synthesis of novel types of metallophthalocyanines, particularly those of ruthenium bearing reactive N- or P-ligands (such as ketimido/amido/imido or phosphido/phosphinidene), along with exploration of their reactivity and/or catalytic properties in C–H, N–H, or P–H functionalization reactions, including C-H functionalization reminiscent of that mediated by metalloporphyrins. Previously we synthesized primary and secondary phosphine complexes of ruthenium(II) phthalocyanines which underwent P-H functionalization with alkenes, and also prepared diaryl ketimido ruthenium(IV) phthalocyanines which represent rare examples of high-valent ruthenium phthalocyanines and exhibit significant differences in reactivity compared with their porphyrin counterparts/analogues. In this study, we focused on the use of ruthenium phthalocyanine complexes for activation or functionalization of C-H and/or N-H bonds of organic substrates, with synthesis and spectroscopic and X-ray crystallographic characterization of a series of new ruthenium phthalocyanine complexes bearing N-ligands (such as alkyl amines and alkyl imines) and examination of their catalytic properties, together with generation of reactive species such as a phthalocyanine-supported high-valent ruthenium dialkyl ketimido complex, which contributes a unique example of dialkyl ketimido metallophthalocyanines as well as a rare example of dialkyl ketimido ruthenium complexes. Efforts were also directed toward exploration of an approach to reactive phthalocyanine-supported ruthenium amido complexes, in view of the involvement of metal amido active intermediates in metal-mediated C-H functionalization with N-compounds including amines.