J. Org. Chem.
1983,48, 3277-3281
3277
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 MnII'TPPX Complexes with Phase-Transfer Catalysis Craig L. Hill,* John A. Smegal, and Timothy J. Henly Department of Chemistry, University of California, Berkeley, California 94720
Received December 9 , 1982
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 M n m W P X 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 incotporated into the alkane, NaX, X = N3-, NCO-, I-, Br-, or C1-, 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 tran@ferof X- 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, ibdosylbenzene, 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.
The activation of hydrocarbon C-H bonds has been an explosively expanding field in the last few years. There are two general types of complexes that facilitate the stoichiometric activation of hydrocarbon C-H bonds under mild conditions in the liquid phase.' The first type are low-valent, highly polarizable, electron-rich species such as Ir(1) c0mplexes~9~ and the second type are high-valent electron-poor species such as Co(II1) carboxylate^.^ The latter complexes also function as catalysts for the oxidation of organic substrates by dioxygen. However, the main role of the cobalt ions in these processes is to catalyze the decomposition of peroxide intermediates.6 The specific involvement of the cobalt ion in C-H activation in these systems remains to be established. Recently, metalloporphyrin complexes of Fe6, Cr', and Mn6l0 have been shown to catalyze the transfer of reduced oxygen to hydrocarbon substrates, with the MnmTPPXiodosylbenzenesystem+" (TPP = tetraphenylporphyrin) being the most effective at catalyzing the functionalization of alkanes. The MnmTPPX-iodosylbenzene system, X = C1, Br, I, N3,results in the catalytic production of alcohol products, ROH, and the stoichiometric production of RX products from alkane, RH9J0 (eq 1 and 2). The stoiRH RH + PhI=O
-+
+ P h I = O MnTPP + MnTPPX
ROH
+ PhI
(1)
RX MnTPPOH + PhI (2) chiometric oxidant iodosylbenzene is converted in high yield to the deoxygenated product iodobenzene in nearly all cases. In these systems, several high-valent Mn complexes derived from the oxidation of the Mn(II1) reactant complex by iodosylbenzene, as well as long-lived freely diffusing alkyl radicals, have been shown to be intermed i a t e ~ . ~The J ~ yield of RX products is limited in this system by the amount of X available-the 1 equiv present as the axial ligand on the starting MnmTPPX catalyst. We previously demonstrated that if a second liquid phase of *Present Address: Department of Chemistry, Emory University, Atlanta, GA 30322.
aqueous NaN3is introduced, the RX prgduct, alkyl azide, can be produced catalytically based on the Mn complex.12 We report here that alkanes can be catalytically functionalized to produce alkyl azides, chlorides, bromides, iodides, or alcohols using systems with two liquid phases where the organic phase contains the alkane substrate and the MnmTPPX catalyst and the aqueous phase contains the sodium salt of the function to be incorporated, X. In these systems the MnTPP moiety functions in a threefold capacity: it facilitates the cleavage of the C-H bonds, it activates X- for transfer to alkyl radical intermediates, and (1)Review on alkane activation by metal complexes: (a) Sheldon, R. A.; Kochi, J. K. 'Metal-Catalyzed Oxidations of Organic Compounds"; Academic Press: New York, 1981;pp 206-211. (b) Shilov, A. E. Pure Appl. Chem.1978,50,725-733.(c) Shilov, A. E.; Shteinman, A. k Coord. Chem. Reu. 1977,24,97-143. (d) Webster, D.E. Adv. Organomet. Chem. 1977,15,147-188. (e) Parshall, G. W. Acc. Chem. Res. 1975,8,113-117. (2) (a) Bergman, R. G.; Janowicz, A. H. J. Am. Chem. SOC. 1982,104, 352-354. (b) Crabtree, R. H.; Mellea, M. F.; Mihelcic, J. M.; Quirk, J. M. Ibid. 1982,104,107-113. (3)(a) Haggin, J. Chem. Eng. News 1983,61 (7),9-12. (b) Dagani, R. Ibid, 1982,60 (3),59-63 and work cited therein. (4)Jones, S. R.; Mellor, J. M. J. Chem. SOC.,Perkin Trans. 2 1977, 511-517 and references cited therein. (5)(a) Parshall, G. W. "Homogeneous Catalysis"; Wiley: New York, 1980;Chapter 10. (b) Parshall, G. W. J. Mol. Catal. 1978,4,243-270. (6)(a) Shannon, P.; Bruice, T. C. J. Am. Chem. SOC. 1981, 103, 4580-4582. (b) Mansuy, D.; Bartoli, J.-F.; Chottard, J.-C.; Lange, M. Angew, Chem., Int. Ed. Engl. 1980,IS,909-910. (c) Groves, J. T.; Kruper, W. J.; Nemo, T. E.; Meyers, R. S. J. Mol. Catal. 1980,7, 169-177. (d) Chang, C. K.; Kuo, M.-S.; J. Am. Chem. SOC. 1979,101,3413-3415. (e) Groves, J. T.; Nemo, T. E.; Myers, R. S. Ibid. 1979, 101, 1032-1033. (7)Groves, J. T.; Kruper, Jr., W. J. J. Am. Chem. SOC. 1979,101, 7613-7615. (8)(a) Peree-Fauvet, M.; Gaudemer, A. J. Chem. SOC.,Chem. Commun. 1981,874-875. (b) Tabushi, I.; Yazaki, A. J.Am. Chem. SOC.,1981, 103,7371-7373. (c) Tabashi, I.; Koga, N. Zbid. 1979,101,6456-6458. (d) Tabushi, I.; Koga, N. Tetrahedren Lett. 1979,3681-3684. (e) Tabushi, I.; Koga, N. Zbid. 1978,5017-5020. (9)(a) Hill, C. L.; Schardt, B. C. J. Am. Chem. SOC.1980, 102, 6374-6375. (b) Groves, J. T.; Kruper, Jr., W. J.; Haushalter, R. C. Ibid. 1980,102,6375-6377. (10)Smegal, J. A.; Hill, C. L. J.Am. Chem. SOC. 1983,105,3515-3521. (11)Abbreviation: TPP is the 5,10,15,20-tetra~henvl~or~hinato di. . . - _- -
anion 'ligand. (12)Hill, C. L.;Smegal, J. A. N o w . J. Chim. 1982,6,287-289.
0022-3263/83/1948-3277$01.50/00 1983 American Chemical Society
3278 J. Org. Chem., Vol. 48, No. 19, 1983
Hill, Smegal, and Henly
Table I. Catalytic Functionalization of Cyclohexane Using Iodosylbenzene as the Oxidant" no. 1
2 3 4 5
6 7 8 9 10
11 12
13 14 15 16 17 18 19
catalyst (MnIIITPPX')
X - in H,O
,
Mn TPPN MnTPP( OAc) MnTPPCl MnTPPCl MnTPPCl MnTPPCl MnTPP( OAc) MnTPPN, MnTPP( OAc) MnTPP( OAc) MnTPP( OAc) MnTPP( OAc) MnTPPBr MnTPPI MnTPP( NCO) FeTPPCl FeTPPN, CrTPPN, VOTPP
N3N, N3c1-e Cl-f c1-g
c1-
c1FOAcCNNO,Br-
I-
product yieldsC RX
55 53 54 18 5 9 17 13 h h h
4 57 25 7 6 7
RX' h
c-C,H,,O
ROH
0.4
21 20 20 30 28 4 29 27 47 46 9 11 22
d d
