C O M M U N I C A T I O N S
Table 1. Substrates in Reactions with Cp*Ir Catalystsg
chemistry, contrary to the usual expectation from radical H atom
abstraction. The mechanism can only be speculative until compu-
tational work15 is completed, but an oxene-like insertion into the
C-H bond is possible. Since the source of the O incorporated is
water, this reaction may also be useful for isotope incorporation
into organic molecules.
General Procedure for C-H Oxidation. In 4 mL of degassed
1:1 tBuOH/H2O, 1 g of CAN, 50 µL of cis-decalin, and 7.5 mg of
3 were added sequentially. The reaction was stirred under nitrogen
for 12 h. Additional DCM and water were then added, and the
organic layer was collected. The aqueous layer was extracted with
DCM (2×). The combined organic solution was washed twice with
water and once with brine and then dried over sodium sulfate. The
product was isolated by column chromatography with 15% AcOEt
in hexane. The eluent was monitored by GC-MS. The products
were identified by comparing the GC-MS with that of the authentic
samples.14
Acknowledgment. This material is based upon work supported
as part of the Center for Catalytic Hydrocarbon Functionalization,
an Energy Frontier Research Center funded by the U.S. Department
of Energy, Office of Science, Office of Basic Energy Sciences under
Award Number DE-SC-0001298 (R.H.C. and M.Z.) and the DOE
catalysis program DE-FG02-84ER13297 (N.D.S.).
Supporting Information Available: Synthetic details for the
complexes and screening of different solvents and primary oxidants.
This material is available free of charge via the Internet at http://
pubs.acs.org.
a 50 µL of substrates were used. b Yield obtained by NMR with
1,3,5-trimethoxybenzene as the internal standard unless stated otherwise.
The yield is based on total starting material, yield based on converted
starting material in parentheses. c Estimated from GC-MS. d D2O as
solvent, yield obtained by NMR with L-leucine as the internal standard.
e 82% unreacted starting material recovered. f 3:1 AcOMe/H2O as
solvent. g Reactions were run at room temperature (21 °C) under
nitrogen or argon in 1:1 tBuOH/H2O solvent unless stated otherwise.
References
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THF was converted to lactone (entries 10-12). No product was
seen in pyrrolidine oxidation (entry 14). No other products were
detected in >1% for cis-decalin, >3% for cyclooctene and ethyl-
benzene, and >8% for thf.
Alternative terminal oxidants, including pyridine N-oxides,
iodosobenzene, iodosobenzene diacetate, oxone, and mCPBA, were
far less efficient for catalytic epoxidation and C-H oxidation (see
Supporting Information (SI)). Various other solvents, mostly
miscible with water, proved less satisfactory (see SI).
This work shows that Cp*Ir complexes can catalyze both alkane
C-H oxidation and alkene epoxidation with a simple 1e primary
oxidant, Ce(IV). Moreover, the C-H hydroxylation of alkanes
proceeds with a remarkably high degree of retention of stereo-
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