Selective functionalisation of saturated C–H bonds with metalloporphyrin catalysts

Abstract

The recent surge of interest in metal-catalysed C-H bond functionalisation reactions reflects the importance of such reactions in biomimetic studies and organic synthesis. This critical review focuses on metalloporphyrin-catalysed saturated C-H bond functionalisation reported since the year 2000, including C-O, C-N and C-C bond formation via hydroxylation, amination and carbenoid insertion, respectively, together with a brief description of previous achievements in this area. Among the metalloporphyrin-catalysed reactions highlighted herein are the hydroxylation of steroids, cycloalkanes and benzylic hydrocarbons; intermolecular amination of steroids, cycloalkanes and benzylic or allylic hydrocarbons; intramolecular amination of sulfamate esters and organic azides; intermolecular carbenoid insertion into benzylic, allylic or alkane C-H bonds; and intramolecular carbenoid C-H insertion of tosylhydrazones. These metalloporphyrin-catalysed saturated C-H bond functionalisation reactions feature high regio-, diastereo- or enantioselectivity and/or high product turnover numbers. Mechanistic studies suggest the involvement of metal-oxo, -imido (or nitrene), and -carbene porphyrin complexes in the reactions. The reactivity of such metal-ligand multiple bonded species towards saturated C-H bonds, including mechanistic studies through both experimental and theoretical means, is also discussed (244 references).

Porphyrins as Catalysts in Scalable Organic Reactions

“…This cytochrome family of enzymes play a key role in aerobic oxidation reactions in biological systems under mild conditions, such as highly selective hydroxylation of alkanes (C-O bond formation via saturated C-H bond functionalization) (Scheme 2) [28,29]. Metalloporphyrins with ruthenium, iron, manganese, among other metals, constitute the family of catalysts which are efficient to mediate C-H oxidations with high selectivity and good yields [30].…”

Chemical Synthesis and Medicinal Applications of Glycoporphyrins

“…While catalytic applications have no direct relevance for biomedical uses such studies do indicate the degree to which porphyrin-conjugates can be fine-tuned and modified for a specific purpose, such as substrate or receptor binding. The catalytic ability of metalloporphyrins is well known [402][403][404] and use of glycoporphyrins might result in either water soluble catalysis and/or enhance catalyst selectivity. Such studies can also be of relevance for understanding natural porphyrin based oxidations.…”

Metalloporphyrin Symmetry in Chiral Recognition and Enantioselective Catalysis

“…This second part focuses on asymmetric catalysis using metalloporphyrins (metals: Fe, Ru, Mn) as catalysts conducted by our group. There are excellent and recent reviews devoted to this topic [29,30].…”