A R T I C L E S
Zdilla and Abu-Omar
by 14.7 g (75 mmol) of pentafluorobenzaldehyde. The reaction mixture
was heated at 60 °C open to atmosphere to afford a gradual color change
to brown. Once all solvent had evaporated, the mixture was heated for
an additional 4 h and then cooled at room temperature for 12 h. The
solid was dissolved in 100 mL of CH2Cl2 and filtered to remove
alumina; 8.52 g (37.5 mmol) of solid 2,3-dichloro-5,6-dicyano-1,4-
benzoquinone was added slowly (to avoid overboiling) with stirring to
afford a color change to black. This solution was stirred for 8 h and
separated on a silica column with 1:1 CH2Cl2:hexanes as eluant. The
location of product corrole on the column is apparent by its red
fluorescence under long-wave UV light. The solvent was removed from
the product-containing fraction in vacuo, and the product was separated
on a second column of alumina with CH2Cl2:hexanes as eluant. A 1:2
mixture was used to elute the initial fractions; a 1:1 mixture was then
substituted until the product began eluting, and a 2:1 mixture was used
to encourage elution of the remainder of the product. The solvent was
removed in vacuo, and the solid was recrystallized from CH2Cl2 and
hexanes to give 0.59 g of H3(tpfc) (0.72 mmol, 4.0%) as purple-gray
crystals.
complex 2 at HAT reactions, such as the “third oxidant” 4
suggested above for the aziridination reaction. Recently the
groups of Borovik and Holland have reported on HAT from
putative Fe(IV) imido intermediates.29
Conclusion
The manganese(V) tosylimide with a corrole auxiliary ligand
has been synthesized and spectroscopically characterized. The
reaction of (tpfc)MnIII(EtOAc) and ArIdNTs proceeds rapidly
on stopped-flow time scale, and the experimental rate law is in
agreement with a mechanism that involves iodoimine adduct
formation, (tpfc)MnIII(ArIdNTs), in route to the manganese-
(V) imido product, (tpfc)MnVdNTs. While (tpfc)Mn serves as
an effective catalyst for aziridination of styrene substrates
without requiring excess olefin, the imido complex (tpfc)MnVd
NTs is not the active intermediate. Labeling experiments
demonstrate unambiguously that the active group transfer
catalyst is an adduct of Mn(V), (tpfc)MnV(NTs)(ArIdNTs).
Mn(tpfc)EtOAc‚EtOAc (1) was prepared according to a modified
procedure of Gross et al.18a Before chromatographic separation, the dried
reaction mixture was heated gently under vacuum for 30 min to remove
all traces of DMF. The crystalline material obtained after chromatog-
raphy is suitable for use as a reagent or catalyst but can be further
purified by recrystallization from ethyl acetate/heptane (82% recovery).
UV-vis (C6H6): λmax [nm] (log ꢀ) ) 400 (4.64), 409 (4.67), 422 (4.60),
450 (4.28), 478 (4.21), 504 (4.02), 593 (4.16), 611 (4.16). Anal. Calcd
for C41H16F15MnN4O2‚C4H8O2: C, 52.75; H, 2.26; N, 5.47. Found: C,
52.71; H, 2.26; N, 5.53. MS (MALDI) m/z: 847.73 (theory ) 848.426
for Mn(tpfc)).
Experimental Section
General. All operations were carried out under inert atmosphere
using standard glovebox and Schlenk line techniques30 except where
otherwise noted. Benzene, toluene, and n-pentane were distilled from
sodium benzophenone ketyl; acetonitrile and pyrrole were distilled from
CaH2; CH2Cl2 was obtained from an Anhydrous Engineering solvent
purification system. Solvents were degassed and stored over activated
4-Å molecular sieves in a glovebox for 24 h prior to use. NMR solvents
were purchased from Cambridge Isotope Laboratories. Those used for
aziridination kinetics and for observation of 2 were stored over activated
4-Å molecular sieves for 24 h prior to use. TstBuNH2 was purchased
from Oakwood Products, Inc. Olefins were purchased from Aldrich
(X-styrene (XdH, 4-CF3, 4-Cl, 3-Cl), R-methylstyrene, cis- and trans-
stilbene, and trans-â-methylstyrene) and TCI (cis-â-methyl styrene).
All purchased chemicals were used as obtained from the manufacturers
unless specified otherwise.
2-(tert-Butylsulfonyl)(p-(tert-butylbenzene)sulfonyliminoiodo)-
benzene (ArINTstBu) was prepared according to a modified procedure
for the preparation of ArINTs.15 To a stirred yellow solution of ArI-
15
(OAc)2 (3.00 g, 6.74 mmol) in MeOH (50 mL), a solution of KOH
(1.5 g, 27 mmol) in MeOH (50 mL) was added, followed immediately
by a solution of TstBuNH2 (1.45 g, 6.80 mmol) in MeOH (50 mL) under
atmospheric conditions. The resulting cream-colored suspension was
stirred for 4 h, poured into 1 L of ice, and chilled at 4 °C for 10 h. The
mixture was filtered to give 0.922 g of cream-colored solid, and the
filtrate was saved. The residue was washed with 8 mL of C6H6 for 30
min and filtered to give 0.421 g of ArINTstBu. The initial filtrate was
evaporated in vacuo by 20 mL and chilled at 4 °C for 10 h to give
more cream-colored solid, which was filtered and washed with benzene
to give 0.559 g of more ArINTstBu. Total yield: 0.980 g, 28%. 1H NMR
UV-vis spectra were recorded on a Shimadzu UV-2501PC scanning
spectrophotometer. NMR spectra were obtained on Inova/Varian 300
MHz spectrometers. Gas chromatography was carried out on an Agilent
Technologies 6890N Network GC System with a J&W Scientific DB-5
capilary column. Oven temperature was ramped from 70 to 150 °C at
25 °C/min, then from 150 to 230 at 15 °Ì/min in constant flow mode
at 2.5 mL/min. Kinetics were performed using an Applied Photophysics
SX.18MV stopped-flow analyzer. Data were fit to theoretical curves
using KaleidaGraph.
(CD3CN) δ: 1.23 (s, 9H, Ts-tBu), 1.38 (s, 9H, SO2 Bu), 7.37 (dd, 2H,
t
Ts-m-H), 7.67 (m, 2H, Ar-H 3- and 4-position), 7.11 (dd, 2H, Ts-o-
H), 7.80 (ddd, 1H, Ar-H ortho to I), 7.89 (ddd, 1H, Ar-H ortho to
S). MS (ESI) m/z: 535.73 (theory ) 535.454 for [ArINHTstBu]+).
Synthesis: 2-(tert-Butylsulfonyl)iodobenzene (ArI) and 2-(tert-
butylsulfonyl)(p-toluenesulfonyliminoiodo)benzene (ArINTs) were
prepared according to the method of Macikenas et al.15
p-Toluenesulfonyliminoiodobenzene (PhINTs) was prepared ac-
cording to the method of Heuss et al.31
General Procedure for Catalytic Aziridination. To a stirred
suspension of ArINTs (580 mg, 1.18 mmol) in benzene (24 mL), a
green solution of 1 (10 mg, 0.0098 mmol) in benzene (1 mL) was added
to afford a color change to red-brown. Neat styrene (67.5 µL, 0.59
mmol) was added, and the reaction was stirred for 24 h. The reaction
mixture was opened to air, and the solvent was removed in vacuo. The
residue was separated on a silica column to isolate aziridine.
5,10,15-Tris(pentafluorophenyl)corrole ((tpfc)H3). A facile syn-
thesis of H3(tpfc) has been described by Gross et al.32 We have been
unable to reproduce the yields described and have therefore adopted
the following revised protocol to maximize product yield: to 15 g of
Brockmann I alumina with enough dry CH2Cl2 to cover the alumina,
5.04 g (75 mmol) of pyrrole was added with slow stirring, followed
N-(p-Tolylsulfonyl)-2-phenylaziridine. Aziridine was prepared as
describe above. Separation was achieved using 1:6 diethyl ether:benzene
as eluant. The fractions were collected in 1 mL increments and spotted
onto TLC plates. TLC analysis shows aziridine in a spot at Rf ) 0.69.
Quantitative isolation of aziridine was unsuccessful due to overlapping
of the aziridine and ArI (Rf ) 0.56) bands from the silica column. The
resulting azirdine solid was dissolved in a few drops of diethyl ether
and chilled to -20 °C. After 24 h, the supernatant was decanted to
give 103 mg of tan crystals (67%). 1H NMR (CDCl3) δ: 2.40 (d, 1H,
(29) HAT from a putative [FeIVdNR]: (a) Lucas, R. L.; Powell, D. R.; Borovik,
A. S. J. Am. Chem. Soc. 2005, 127, 11596. (b) Eckert, N. A.; Vaddadi, S.;
Stoian, S.; Lachicotte, R. J.; Cundari, T. R.; Holland, P. L. Angew. Chem.
Int. Ed. 2006, 45, 6868.
(30) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-SensitiVe
Compounds, 2nd ed.; Wiley: New York, 1986; 326 pp.
(31) Heuss, B. D.; Mayer, M. F.; Dennis, S.; Hossain, M. Inorg. Chim. Acta
2003, 342, 301.
(32) Gross, Z.; Galili, N.; Simkhovich, L.; Saltsman, I; Botoshansky, M.; Bla¨ser,
D.; Boese, R.; Goldberg, I. Org. Lett. 1999, 1 (4), 599.
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16978 J. AM. CHEM. SOC. VOL. 128, NO. 51, 2006