Communications
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an analogous dihydroxylating agent in the enzyme mecha-
nism.
We have thus designed a ligand that gives rise to iron
complexes that approximate the 2-His-1-carboxylate environ-
ment of the Rieske dioxygenases. Even though less than one
turnover of olefin oxidation is achieved, the activation of
H2O2 by the triflate complex leads to the cis-dihydroxylation
of double bonds. Label incorporation from H218O implicates a
high-valent iron-oxo species as the oxidant for this novel
reaction.
Experimental Section
HL1:
A
mixture of Kempꢀs acid chloroanhydride[7] (970 mg,
3.75 mmol), di-(2-pyridyl)methylamine[8] (842.8 mg, 2.86 mmol), and
DMAP (4-dimethylaminopyridine, 37 mg) in freshly distilled pyridine
(12 mL) was heated under argon to 908C and stirred for 2 days. Upon
cooling to room temperature, the solvent was removed in vacuo,
leaving a dark solid. Water (10 mL) was added to this solid, and the
product was extracted into ethyl acetate (3 25 mL). This crude
yellow product obtained from the extraction was purified with
chromatography on a silica gel column with an ethyl acetate/methanol
gradient to obtain a white solid (1.35 g, 89% yield), which was
[9] Single-crystal structure and refinement data for 1-Cl:
C23H24ClFeN3O4, Mw = 497.75, monoclinic, space group P21/n,
a = 10.8970(6), b = 13.3325(7), c = 15.0564(8) , a = 90.000(1),
b = 95.9000(1), g = 90.000(1)8, V= 2175.9(2) 3, Z = 4, 1calcd
=
1.519 MgmÀ3, MoKa radiation (l = 0.71073 , m = 0.852 mmÀ1),
T= 173(2) K. total of 4946 (Rint = 0.0388) independent
A
reflections with 2q < 27.498 were collected. The resulting param-
eters were refined to converge at R1 = 0.0379 (I > 2q) for 292
parameters on 4946 independent reflections (wR2 = 0.0926).
Max./min. residual electron density 0.501/À0.281 eÀ3; GOF =
1.006. Further experimental details are provided in the Support-
ing Information. CCDC-613027 contains the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data
1
characterized by Hand 13C NMR spectroscopy (see the Supporting
Information). Minor impurities included monoacylated and acyclic
diacylated products. ESIMS (CH3CN): m/z 408 ([HL1+H]+).
1-Cl: A solution of HL1 (168.9 mg, 0.44 mmol) and Et3N
(41.9 mg, 0.44 mmol) in CH3CN (2 mL) was added dropwise to a
stirred solution of FeCl2 (52.6 mg, 0.44 mmol) in CH3CN (2 mL) in an
anaerobic glove box. Overnight stirring at room temperature afforded
a yellow solid, which was recrystallized from MeOH/Et2O (112 mg,
51% yield). Further recrystallization in CH3CN at À208C resulted in
the overnight formation of yellow blocks suitable for X-ray crystallo-
graphic studies. UV/Vis (CH3CN), lmax (e [mÀ1 cmÀ1]): 264 (5800), 310
(1600), 450 nm onset. ESIMS (CH3OH): m/z 869 ([Fe(L1)2+H]+), 498
([Fe(L1)(Cl)+H]+), 462 ([Fe(L1)]+), 408 ([HL1+H]+). Elemental
analysis (%) calcd for C23H24ClFeN3O4: C 55.50, H4.86, N 8.44, Cl
7.12; found: C 55.68, H5.14, N 8.76, Cl 6.87.
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Chem. Soc. 2002, 124, 3026; b) K. Chen, M. Costas, L. Que, Jr.,
Dalton Trans. 2002, 672.
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Chem. Int. Ed. 1999, 38, 2227; b) K. Chen, L. Que, Jr., J. Am.
Chem. Soc. 2001, 123, 6327; c) M. Klopstra, G. Roelfes, R. Hage,
R. M. Kellogg, B. L. Feringa, Eur. J. Inorg. Chem. 2004, 846.
[12] D. Quiꢁonero, K. Morokuma, D. G. Musaev, R. Mas-Ballestꢂ, L.
Que, Jr., J. Am. Chem. Soc. 2005, 127, 6548.
1-OTf: Ag(OTf) (67.8 mg, 0.264 mmol) in CH3CN (1.5 mL) was
added to a yellow suspension of 1-Cl (131.2 mg, 0.264 mmol) in
CH3CN (2.5 mL) in an anaerobic glove box. After stirring at room
temperature overnight, the reaction suspension was concentrated to
[13] M. D. Wolfe, J. D. Lipscomb, J. Biol. Chem. 2003, 278, 829.
produce
a brown-green dark solid. UV/Vis (CH3CN), lmax
(e [mÀ1 cmÀ1]): 260 (9100), 356 nm (sh, 3000). ESIMS (CH3OH; see
Figure S4 in the Supporting Information): m/z 869 ([Fe(L1)2+H]+),
612 ([Fe(L1)(OTf)+H]+), 462 ([Fe(L1)]+), 408 ([HL1+H]+).
Received: August 25, 2006
Revised: October 2, 2006
Published online: November 10, 2006
Keywords: dihydroxylation · dioxygenases · enzyme models ·
.
epoxidation · oxidation
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Stiefel, J. S. Valentine), University Science Books, Sausalito,
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ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2006, 45, 7975 –7978