Catalytic aziridination of olefins and amidation of thioanisole by a non-heme iron complex

Article abstract of DOI:10.1039/b404561k

A non-heme iron complex catalyses the aziridination of various olefins and the amidation of thioanisole in good yields at the expense of an aryl iodinane.

Full text of DOI:10.1039/b404561k

Catalytic aziridination of olefins and amidation of thioanisole by a
non-heme iron complex†
Frédéric Avenier and Jean-Marc Latour*
DRDC/PMB, UMR 5155 CEA-CNRS-UJF, 17 Rue des Martyrs, CEA-Grenoble, 38054 Grenoble Cedex 9,
France. E-mail: Jean-Marc.Latour@cea.fr; Fax: 33 438 78 34 62; 33 438 78 44 07
Received (in Cambridge, UK) 29th March 2004, Accepted 30th April 2004
First published as an Advance Article on the web 3rd June 2004
A non-heme iron complex catalyses the aziridination of various
olefins and the amidation of thioanisole in good yields at the
expense of an aryl iodinane.
an exchangeable hydrogen was confirmed by positive ESI-MS
which showed the shift of the pattern of the dication by 0.5 unit
(Fig. 2c) in the presence of D O. In addition, preliminary magnetic
2
susceptibility and Mössbauer analyses confirmed the ferric nature
of the two iron ions.
Biomimetic oxygen transfer has been thoroughly investigated over
the past three decades both from heme and non-heme systems.1
Consequently, the mechanism of the reaction has been largely
deciphered and points to the occurrence of high-valent oxo-iron
,2
2+
When 2 was prepared from 1 eq. ArINTs, it was unable to react
2+
with styrene. On the other hand, when 1 was treated with 20 eq.
PhINTs, 22 formed rapidly, as judged from the 480 nm
chromophore, and addition of 1000 eq. styrene caused a decrease of
the intensity of the chromophore (Fig. 3) over 2 h. NMR analysis of
the resulting solution showed the formation of the tosylaziridine of
styrene in 88% yield (with respect to PhINTs).
+
3
intermediates. In the early 80s, Mansuy et al. reported that heme
complexes were able to catalyse tosylamine transfer to olefins from
4
aryl iodinanes. It was shown later that manganese and ruthenium
5
6
porphyrins, as well as non-porphyrinic complexes of ruthenium
and copper7 were similarly active. Very recently, Que et al.
,8
Aziridination of styrene, cyclooctene and 1-hexene was studied
7
reported that a non-heme iron complex mediated the stoichiometric
in conditions used recently by Halfen et al. for copper complexes:
9
intramolecular insertion of a tosylamine group in the ligand. In the
course of our continuous study of biomimetic diiron com-
plexes,1
0,11
we reported that the mixed-valent complex of the
12
unsymmetrical hexadentate phenol ligand (HL, Scheme 1, X = H)
is able to mediate the hydroxylation of the dangling benzyl group
1
3
from oxygen donors such as mCPBA or ArIO (ArIO = o-tert-
butylsulfone iodosyl benzene). In this communication, we show
2
+
that the analogous complex 1(CH
3
OH) obtained from the
2
,6-dichlorobenzyl ligand (HLA, Scheme 1, X = Cl) is able to react
1
3
2+
with the tosylamine iodinane ArINTs to produce an adduct 2
which catalyses the aziridination of various olefins in the presence
of an excess of aryliodinane.
The synthesis and structural characterisation of complex
3 3
(CH OH) was
OH)2+ were described earlier. When 1(CH
11
2+
1
reacted with ArINTs in acetonitrile a new chromophore developed
at 480 nm (Fig. 1) with an isosbestic point at ca. 610 nm.14 This
species was fully formed after addition of 1 eq. ArINTs and was
moderately stable in these conditions. ESI-MS analyses of the
corresponding solution in the negative mode (Fig. 2a) revealed a
complex pattern of peaks for a monoanion at m/z = 1397. In the
positive mode another pattern was observed at m/z = 549 for a
dication (Fig. 2b). These peculiar isotopic distributions reflect the
presence of different numbers of chlorine atoms in the two charged
species. From comparison with theoretical isotopic distributions
Fig. 1 UV-visible titration of 1(CH
3
OH) 2+ in acetonitrile by ArINTs. Insert:
titration curve.
(
Figure S1†), the dication and the monoanion could be assigned the
2
+
2+
respective formulas: Fe
2
2
(LA)(mpdp)(NHTs) ,
4 3 4 3
(LA)(mpdp)(NHTs) (ClO ) } , {2(ClO ) } . Complex 2 is
2
and {Fe-
2 2
2+
2
therefore a diferric complex of the TsNH group. The presence of
Scheme 1 (S = acetonitrile.)
†
Electronic supplementary information (ESI) available: Fig. S1 illustrates
Fig. 2 ESI-MS spectra of 22+ (a) in the negative mode with a zoom on the
the theoretical isotopic patterns for the respective formulae. See http://
www.rsc.org/suppdata/cc/b4/b404561k/
molecular peak in the insert, (b) in the positive mode and (c) as (b) in the
presence of D O.
2
1
544
C h e m . C o m m u n . , 2 0 0 4 , 1 5 4 4 – 1 5 4 5
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4

transfer upon oxidation. A high-valent metal imino species Ru =
6
NTs was proposed to be the active species, as in the case of
metalloporphyrins.3 In the present system, the tosylamidoiron(III
)
–5
complex inactive in stoichiometric tosylamine transfer appears a
precursor of the catalytic species (Fig. 3) in presence of excess
ArINTs. Therefore, all available evidence suggests that the present
non-heme iron system behaves as the above ruthenium com-
plexes.16 Therefore, it is reasonable to envisage that the actual
aziridination and sulfamidation catalyst is a high-valent iron-imino
species formed upon oxidation of 22 by excess ArINTs.
To summarize, we have reported the first tosylamine transfer
catalysed by a non-heme iron complex. This reaction applies
efficiently to the aziridination of olefins and amidation of
thioethers. Its scope and mechanism are presently being investi-
gated and isolation of putative intermediates is being actively
pursued.
+
Fig. 3 UV-visible monitoring of the reaction of 22+ with styrene in
acetonitrile. Spectra were recorded 0, 1, 10, 15, 30, 60 min. after styrene
addition.
Notes and references
1
2
3
B. Meunier, Chem. Rev., 1992, 92, 1411.
L. Que Jr., J. Chem. Soc., Dalton Trans., 1997, 3933.
D. Mansuy, P. Battioni and J. P. Mahy, J. Am. Chem. Soc., 1982, 104,
catalyst (0.05), PhINTs (1), olefin (2000). The yields of aziridine
(isolated after crystallisation) with respect to the iodinane are given
4
487.
in the Table and compared to the copper systems used by Halfen et
4 J. T. Groves and T. Takahashi, J. Am. Chem. Soc., 1983, 105, 2073.
5 S. M. Au, J. S. Huang, W. Y. Yu, W. H. Fung and C. M. Che, J. Am.
Chem. Soc., 1999, 121, 9120.
6
7
8
9
7
8
al. and Dodd et al. It can be seen (entry 1) that our system is less
active toward styrene than the copper systems, although it exhibits
notable activity (entry 2) even at a low catalyst/reagent ratio of 1%.
Also worth noting is the fact that the present system works equally
well (entry 3) when the reagent consists of a mixture of PhIO and
S. M. Au, J. S. Huang, C. M. Che and W. Y. Yu, J. Org. Chem., 2000,
5, 7858.
6
J. A. Halfen, J. M. Uhan, D. C. Fox, M. P. Mehn and L. Que Jr., Inorg.
Chem., 2000, 39, 4913.
P. Dauban, L. Saniere, A. Tarrade and R. H. Dodd, J. Am. Chem. Soc.,
2
TsNH . In the latter case, no product from oxygen transfer was
found indicating a far stronger tosylamine transfer ability of the
system. In the case of less active olefins such as cyclooctene (entry
2
001, 123, 7707.
M. P. Jensen, M. P. Mehn and L. Que Jr, Angew. Chem. Int. Ed., 2003,
42, 4357.
4) and 1-hexene (entry 5), the present system appears more efficient
than the copper-based ones. This is also the case in the amination of
thioanisole (entry 6). Indeed, a yield of 96% of Ph(Me)SNTs
10 W. Kanda, W. Moneta, M. Bardet, E. Bernard, N. Debaecker, J. Laugier,
A. Bousseksou, S. Chardon-Noblat and J. M. Latour, Angew. Chem., Int.
Ed. Engl., 1995, 34, 588.
11 S. Chardon-Noblat, O. Horner, B. Chabut, F. Avenier, N. Debaecker, P.
Jones, J. Pécaut, L. Dubois, C. Jeandey, J. L. Oddou, A. Deronzier and
J. M. Latour, Inorg. Chem., 2004, 43, 1638.
(
2
isolated product) is obtained after 4 h while 63% is reached after
4 h with a copper catalyst.
1
5
The present observations that a tosylamido Fe(III) species
catalyse tosylamine transfer in the presence of an excess tosylami-
noiodinane is reminiscent of the behaviour of non-porphyrinic
1
1
1
2 F. Avenier, L. Dubois and J. M. Latour, New J. Chem., 2004, DOI:
1
0.1039/402403f.
1
6
ruthenium complexes. Indeed, a bistosylamidoruthenium(III
)
3 D. Macikenas, E. Skrzypczak and J. Protasiewicz, J. Am. Chem. Soc.,
1999, 121, 7164.
complex was isolated and shown to become active in the amine
11
4 1(CH
obtained by addition of 1.5 eq. of ArINTs (17.5 mg) to an acetonitrile
solution of 1(CH OH)(ClO (40 mg in 200 mL), 2 min stirring,
of the volume and careful precipitation with diethyl
3 4 2 4 2
OH)(ClO ) was prepared as already described. 2(ClO ) was
13
Table 1 Catalytic tosylamine transfer to olefins and thioanisolea
3
4 2
)
1
concentration to
4
Entry
Substrate
Reaction
Time (h)
Amine yield (%)
ether (all operations performed in a glove box under argon). In a typical
catalytic experiment, 120 mg (0.03 mmol) of tosyliminoiodobenzene
PhINTs were suspended in 2 mL acetonitrile with 1 mL of styrene. 16.9
Halfen
This work
3 4 2
mg of 1(CH OH)(ClO ) in solution in 100 mL acetonitrile were then
1
2
3
4
5
6
a
Styrene
Styrene
Styrene
Cyclooctene
1-Hexene
3
16
18
24
24
4
80–96
69
46
42
50
51
96
added. The reaction mixture was vigorously stirred for 3 h, filtered on
alumina which was then washed with acetonitrile and ethyl acetate (10
mL each). After evaporation of the combined fractions, the resulting oil
was treated with hexane to precipitate a white solid which was
recrystallised in hexane/diethyl ether at 220 °C. All other substrates
were treated similarly.
b
b
c
99
75
c
25–35
25–30
63
d
Thioanisole
b
15 J. A. Halfen, J. K. Hallman, J. A. Schultz and J. P. Emerson,
Organomet., 1999, 18, 5435.
16 S. M. Au, S. B. Zhang, W. H. Fung, W. Y. Yu, C. M. Che and K. K.
Cheung, Chem. Commun., 1998, 2677.
Conditions: catalyst/reagent/substrate = 0.05/1/2000 catalyst/reagent/
substrate = 0.01/1/2000 c reagent = PhIO+TsNH
substrate = 1/20/20, reaction time 24 h
8
d
2
catalyst/reagent/
15
C h e m . C o m m u n . , 2 0 0 4 , 1 5 4 4 – 1 5 4 5
1545