Catalytic Replacement of Unactivated Alkane Carbon-Hydrogen Bonds with Carbon-X Bonds (X = Nitrogen, Oxygen, Chlorine, Bromine, or Iodine). Coupling of Intermolecular Hydrocarbon Activation by MnIIITPPX Complexes with Phase-Transfer Catalysis

Article abstract of DOI:10.1021/jo00167a023

A simple system has been devised to facilitate the first processes for the catalytic replacement of unactivated alkane C-H bonds with C-X bonds, X = nitrogen and iodine.The system also enables alkane C-H bonds to be replaced by C-X bonds, X = chlorine, bromine, and oxygen.The system is composed of two liquid phases and the oxidant iodosylbenzene (iodosobenzene).The alkane substrate, the Mn^IIITPPX catalyst, and the organic solvent (dichloromethane, chlorobenzene, or other aromatic hydrocarbon) constitute one phase, a saturated aqueous solution of the sodium salt of the anion to be incorporated into the alkane, NaX, X = N3(1-), NCO(1-), I(1-), Br(1-), or Cl(1-), constitutes the second phase, and the sparingly soluble oxidant iodosylbenzene constitutes a third phase.When the two liquid phases and the oxidant iodosylbenzene are stirred under an inert atmosphere, both RX and ROH products are produced catalytically based on MnTPP and in reasonable yield based on iodosylbenzene.The MnTPP moiety functions as a catalyst for C-H bond cleavage and for phase transfer of X(1-) from the aqueous phase to the organic phase where the functionalization chemistry takes place.The oxidant hypochlorite can be used in place of, but is less effective than, iodosylbenzene, and the oxidants hydrogen peroxide, periodate, and persulfate are ineffective.Product distributions obtained from the oxidation of cyclohexane, isobutane, 2,3-dimethylbutane, and tert-butylbenzene are most consistent with a product-determining step that involves transfer of X from manganese to a free alkyl radical intermediate.