Catalytic sulfoxidation and epoxidation with a Mn(III) triazacorrole: evidence for a "third oxidant" in high-valent porphyrinoid oxidations.
The reaction between (TBP)8(Cz)Mn(III) (1) and the oxygen atom donors iodosylbenzene (PhIO) or p-cyanodimethylaniline-N-oxide (CDMANO) leads to the manganese(V)-oxo complex (TBP)8(Cz)Mn(V)O (2), which has been isolated and characterized previously. Under catalytic conditions with 1 as added catalyst and PhIO as oxidant, both sulfoxidation of PhSMe and epoxidation of cis-stilbene is observed, whereas with CDMANO no sulfoxidation takes place, suggesting that 2 is not the active oxidant. Examination of the independent reactivity of isolated 2 toward PhSMe and cis-stilbene supports this conclusion. A mechanism which relies on a novel type of oxidant involving Lewis acid activation of PhIO by the Mn(V)-oxo complex 2 accounts for these observations and is confirmed by 18O-labeling experiments.
Wang
Sheena Hailin
SH
Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Mandimutsira
Beaven S
BS
Todd
Ryan
R
Ramdhanie
Bobby
B
Fox
Joseph P
JP
Goldberg
David P
DP
D004852:Epoxy Compounds / Q000138:chemical synthesis*; D008345:Manganese / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry*; D010084:Oxidation-Reduction; D010103:Oxygen Isotopes; D011166:Porphyrins / Q000737:chemistry*; D013454:Sulfoxides / Q000138:chemical synthesis*
D004852:Epoxy Compounds; D008665:Metalloporphyrins; D010103:Oxygen Isotopes; D011166:Porphyrins; D013454:Sulfoxides; C431863:corrole; D008345:Manganese