Making Fe(BPBP)-catalyzed C-H and C[double bond, length as m-dash]C oxidations more affordable.
The limited availability of catalytic reaction components may represent a major hurdle for the practical application of many catalytic procedures in organic synthesis. In this work, we demonstrate that the mixture of isomeric iron complexes [Fe(OTf)2(mix-BPBP)] (mix-1), composed of Λ-α-[Fe(OTf)2(S,S-BPBP)] (S,S-1), Δ-α-[Fe(OTf)2(R,R-BPBP)] (R,R-1) and Δ/Λ-β-[Fe(OTf)2(R,S-BPBP)] (R,S-1), is a practical catalyst for the preparative oxidation of various aliphatic compounds including model hydrocarbons and optically pure natural products using hydrogen peroxide as an oxidant. Among the species present in mix-1, S,S-1 and R,R-1 are catalytically active, act independently and represent ca. 75% of mix-1. The remaining 25% of mix-1 is represented by mesomeric R,S-1 which nominally plays a spectator role in both C-H and C[double bond, length as m-dash]C bond oxidation reactions. Overall, this mixture of iron complexes displays the same catalytic profile as its enantiopure components that have been previously used separately in sp(3) C-H oxidations. In contrast to them, mix-1 is readily available on a multi-gram scale via two high yielding steps from crude dl/meso-2,2'-bipyrrolidine. Next to its use in C-H oxidation, mix-1 is active in chemospecific epoxidation reactions, which has allowed us to develop a practical catalytic protocol for the synthesis of epoxides.
Organic Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. r.j.m.kleingebbink@uu.nl.
Vital A
VA
Yazerski
Peter
P
Spannring
David
D
Gatineau
Charlotte H M
CH
Woerde
Sara M
SM
Wieclawska
Martin
M
Lutz
Henk
H
Kleijn
Robertus J M Klein
RJ
Gebbink
D001688:Biological Products / Q000737:chemistry*; D002384:Catalysis; D004852:Epoxy Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*
D001688:Biological Products; D004852:Epoxy Compounds; D005296:Ferrous Compounds; D006838:Hydrocarbons; D011725:Pyridines; D011759:Pyrrolidines; D006861:Hydrogen Peroxide