Catalytic Asymmetric Epoxidations with Chiral Iron Porphyrins

Article abstract of DOI:10.1021/ja00356a016

Iron porphyrins have been modified to include optically active functionalities at the meso positions.Asymmetric epoxidations of prochiral olefins with these chiral iron porphyrins and iodosyl compounds have been investigated.Thus, 5α,10β,15α,20β-tetrakis(o-(R)-hydratropamidophenyl)porphyrin (H2T(α,β,α,β-Hyd)PP) and 5α,10β,15α,20β-tetrakis(o<(S)-2'-carboxymethyl-1,1'-binaphthyl-2-carboxamido>phenyl)porphyrin (H2T(α,β,α,β-Binap)PP) were synthesized by the condensation of optically active acid chlorides with 5α,10β,15α,20β-tetrakis(o-aminophenyl)porphyrin.Subsequent insertion of iron into H2T(α,β,α,β-Hyd)PP and H2T(α,β,α,β-Binap)PP gave FeT(α,β,α,β-Hyd)PPCl and FeT(α,β,α,β-Binap)PPCl, respectively.Emploing FeT(α,β,α,β-Hyd)PPCl iodosylbenzene, styrene was oxidized to (R)-(+)-styrene oxide in 31percent ee.Similarly, FeT(α,β,α,β-Binap)PPCl and iodosylmesitylene gave (R)-(+)-styrene oxide in 48percent ee.Various substituted styrenes and aliphatic olefins were epoxidized with enantiomeric excesses varying between 0percent for 1-methylcyclohexene oxide and 51percent for p-chlorostyrene oxide.