Polymer-supported ruthenium porphyrins: Versatile and robust epoxidation catalysts with unusual selectivity

Abstract

Carbonyl ruthenium(II) 5,10,15-tris(4-R-phenyl)-20-(4- hydroxyphenyl)porphyrins (R = Cl, Me) covalently attached to Merrifield's peptide resin were prepared. The catalyst with R = Cl was found to efficiently catalyze Cl 2pyNO epoxidation of a wide variety of alkenes, including aromatic and aliphatic terminal alkenes, cis- and trans-stilbene, cyclohexene and cyclooctene, α,β-unsaturated ketones, conjugated enyne, glycal, and protected α-amino alkene. Unusual selectivities were observed for the epoxidations of 1,5-cyclooctadiene, cis-1-phenyl-3-penten-1-yne (9), 3,4,6-tri-O-acetyl-D-glucal (11), and 2-(Boc-amino)-1-phenylbut-3-ene (13), which feature a complete bisepoxide selectivity (1,5-cyclooctadiene), unprecedentedly high cis:trans ratio (9), and complete diastereoselectivity (11 and 13). The new heterogenized metalloporphyrin epoxidation catalysts are of high stability and reusability.