Pyridinium hydrobromide perbromide: A versatile catalyst for aziridination of olefins using chloramine-T

Article abstract of DOI:10.1021/ol9900966

Formula presented Pyridinium hydrobromide perbromide (PyHBr3) catalyzes effectively the aziridination of electron-deficient as well as electron-rich olefins using Chloramine-T (N-chloro-N-sodio-p-toluenesulfonamide) as a nitrogen source to afford the corr

Full text of DOI:10.1021/ol9900966

ORGANIC
LETTERS
1999
Vol. 1, No. 5
705-707
Pyridinium Hydrobromide Perbromide:
A Versatile Catalyst for Aziridination of
Olefins Using Chloramine-T
Sayyed Iliyas Ali, Milind D. Nikalje, and A. Sudalai*
DiVision of Process DeVelopment, National Chemical Laboratory, Pune-411008, India
sudalai@dalton.ncl.res.in
Received May 20, 1999
ABSTRACT
Pyridinium hydrobromide perbromide (Py‚HBr3) catalyzes effectively the aziridination of electron-deficient as well as electron-rich olefins
using Chloramine-T (N-chloro-N-sodio-p-toluenesulfonamide) as a nitrogen source to afford the corresponding aziridines in moderate to good
yields.
The aziridine ring is a versatile building block for organic
synthesis, not only because the ring opening of aziridines
provides a convenient entry to the stereoselective preparation
of functionalized amino compounds but also because the
exocyclic N-substituent modulates the properties and reactiv-
ity of the three-membered ring.1 Many biologically active
compounds such as amino acids, â-lactam antibiotics, and
alkaloids have been derived from aziridines.2 The preparation
of aziridines is generally achieved by several noncatalytic
methods.3 On the other hand, there exists two pathways for
the catalytic preparation of aziridines: (i) transfer of a nitrene
onto olefins catalyzed mostly by Cu,4a Mn,4b,c and Rh salts;4
(ii) transfer of a carbenoid species onto imines by Rh,5a Re,5b
Fe complexes,5c BF3OEt2,5d etc. Although the formation of
aziridines from the addition of thermally or photochemicaly
generated nitrenes to olefins is a well-known method, its
utility is limited by (i) the formation of low yields due to
competing C-H abstraction and insertion processes and (ii)
the expense and inconvenience of PhIdNTs as a nitrene
source.
Chloramine-T trihydrate6 (TsNClNa‚3H2O), a commer-
cially available oxidant, finds wide synthetic applications in
aminochalcogenation7 and aminohydroxylation8 of alkenes
(5) (a) Mohan, J. M.; Uphade, B. S.; Choudhary, V. R.; Ravindranathan,
T.; Sudalai, A. Chem. Commun. 1997, 1429. (b) Zhu, Z.; Espenson, J. H.
J. Org. Chem. 1995, 60, 7090. (c) Haynes, J. S.; Sams, J. R.; Thompson,
R. C. S. Can. J. Chem. 1981, 59, 669. (d) Zhu, Z.; Espenson, J. H. J. Am.
Chem. Soc. 1996, 118, 9901. (c) Casarrubios, L.; Perez, J. A. J. Org. Chem.
1996, 61, 8358.
(6) Bremner, D. H. In Synthetic Reagents; Pizey, J. S., Ed.; Ellis Horwood
Ltd.: Chichester, 1985; Vol. 6, pp 9-59.
(7) Barton, D. H. R.; Britten-Kelly, M. R.; Ferreira, D. J. Chem. Soc.,
Perkin Trans. 1 1978, 1090.
(8) (a) Li, G.; Chang, H. T.; Sharpless, K. B. Angew. Chem., Int. Ed.
Engl. 1996, 35, 451.(b) Sharpless, K. B.; Chong, A. O.; Oshima, K. J. Org.
Chem. 1976, 41, 177. (c) Rubin, A. E.; Sharpless, K. B. Angew. Chem.,
Int. Ed. Engl. 1997, 36, 2637. (d) Rudolph, J.; Sennhenn, P. C.; Sharpless,
K. B. Angew. Chem., Int. Ed. Engl. 1996, 35, 2810. (e) Li, G.; Angert, H.
H.; Sharpless, K. B. Angew. Chem., Int. Ed. Engl. 1996, 35, 2813. (f) Reddy,
K. L.; Sharpless, K. B. J. Am. Chem. Soc. 1998, 120, 1207. (e) Reddy, K.
L.; Dress, K. R.; Sharpless, K. B. Tetrahedron Lett. 1998, 39, 3667.
(1) Pearson, W. H.; Lian, B. W.; Bergmeier, S. C. In ComprehensiVe
Heterocyclic Chemistry II; Padwa, A., Ed.; Pergamon Press: New York,
1996; Vol 1A, pp 1-60.
(2) Tanner, D. Angew. Chem., Int. Ed. Engl. 1994, 33, 599.
(3) Deyrup, J. A. In The Chemistry of Heterocyclic Compounds; Hassner,
A., Ed.; Wiley: New York, 1983; Vol. 42, Part 1, Chapter 1.
(4) (a) Evans, D. A.; Faul, M. M.; Bilodeau, M. T. J. Am. Chem. Soc.
1994, 116, 2742. (b) Li, Z.; Conser, K. R.; Jacobsen, E. N. J. Am. Chem.
Soc. 1993, 115, 5326. (c) Minakata, S.; Ando, T.; Nishimura, M.; Ryu, I.;
Komatsu, M.; Angew. Chem., Int. Ed. Engl. 1998, 37, 3392. (d) Muller, P.;
Baud, C.; Jacquier, Y. Tetrahedron 1996, 52, 1543. (e) Nageli, I.; Baud,
C.; Bernardinelli, G.; Jacquier, Y.; Moran, M.; Muller, P. HelV. Chim. Acta
1997, 80, 1087. (f) Knight, J. G.; Muldownery, M. P. Synlett 1995, 949.
10.1021/ol9900966 CCC: $18.00 © 1999 American Chemical Society
Published on Web 07/30/1999

Table 1. Py‚HBr3-Catalyzed Aziridination of a Variety of Olefins Using Anhydrous Chloramine-Ta
and allylic amination via a selenium diimide intermediate.9
It has recently been shown to aziridinate alkenes with Cu(I)
triflate,10 phenyltri methylammonium tribromide,11 or iodine12
as catalyst. However, these procedures have drawbacks such
as (i) significant amounts of allylic amination products are
often observed for activated substrates such as cyclohexene,
(ii) electron-deficient olefins such as R,â-unsaturated ketones,
aldehydes, esters, etc. have failed to undergo aziridination,
and (iii) sometimes a large excess of olefin is required to
obtain reasonable yields of aziridines. In this paper, we report
the aziridination of a variety of alkenes utilizing anhydrous
Chloramine-T as nitrogen source and pyridinium hydro-
bromide perbromide (Py‚HBr3) as a new catalyst (Scheme
1).
Scheme 1a
a(i) Pyridinium hydrobromide perbromide (Py‚HBr3) (10 mol %),
anhydrous Chloramine-T (1.1 equiv), dry MeCN, 25 °C, 12 h.
(9) (a) Sharpless, K. B.; Hori, T.; Truesdale, L. K.; Dietrich, C. O. J.
Am. Chem. Soc. 1976, 98, 269. (b) Sharpless, K. B.; Hori, T. J. Org. Chem.
1976, 41, 177.
(10) Albone, D. P.; Aujla, P. S.; Taylor, P. C. J. Org. Chem. 1998, 63,
9569.
(11) Jeong, J. U.; Tao, B.; Sagasser, I.; Henninges, H.; Sharpless, K. B.
J. Am. Chem. Soc. 1998, 120, 6844.
(12) Ando, T.; Minakata, D. S.; Ryu, I.; Komatsu, M. Tetrahedron 1998,
54, 13485.
Under standard conditions (1 equiv of olefin, 1.1 equiv
of anhydrous Chloramine-T, 10 mol % of Py‚HBr3, MeCN,
25 °C, 12 h), the catalyzed aziridination proceeds in good
yields with both electron-deficient and electron-rich olefins.
706
Org. Lett., Vol. 1, No. 5, 1999

13
The influence of the amount of Py‚HBr3 as catalyst was
nucleophilic opening with Chloroamine-T followed by its
cyclization to give the aziridine.11 We have also prepared
two new chiral perbromides from (-)-hydroquinidine-4-
chlorobenzoate (DHQD-CLB) and (-)-sparteine by follow-
ing a procedure similar to that employed for the preparation
of Py‚HBr3.13 When styrene was subjected to aziridination
in the presence of these chiral perbromides, a low optical
induction was realized in the aziridinated products (2% ee
in each case).14,15
In conclusion, Py‚HBr3 is a versatile catalyst in aziridi-
nating a variety of olefins; in particular, it is quite active in
catalyzing the aziridination of electron-deficient olefins which
is complementary to the existing methods.11
evaluated using styrene as a representative case. It is observed
that no aziridinated product was formed when 1 mol % of
Py‚HBr3 was employed. Increasing the catalyst to either 5
or 10 mol % has resulted in the formation of aziridines in
65 and 70% yields, respectively. However, further increase
of catalyst (50 mol % to stoichiometric amount) had a
deleterious effect on improving the yield of aziridine. Also,
when PPh3Br2 was employed as catalyst, aziridination of
styrene still proceeded although in lowered yield (30%).
To gauge the scope and the generality of the reaction,
various olefins were subjected to Py‚HBr3-catalyzed aziri-
dination using anhydrous Chloramine-T as the nitrogen
source at 25 °C (Table 1, ref 15). For instance, when styrene,
cyclohexene, and cyclooctene were employed, the corre-
sponding aziridines were obtained in good yields whereas
terminal aliphatic olefins such as 1-hexene, 1-dodecene, and
a variety of allylic alcohols gave only a moderate yield of
aziridinated products. Substrates such as allyl bromide and
dihydropyran also underwent reaction, affording good yields
of aziridines, and no allylic amination was found in any of
the cases studied. It is remarkable that when a conjugated
diene such as 1,3-butadiene is subjected to aziridination, one
of the double bonds is selectively aziridinated in high yields.
Further, sensitive functional groups such as acetals and enol
ethers are not affected during aziridination. A novel feature
of the Py‚HBr3-catalytic system is the unexpected reactivity
shown by a variety of electron-deficient olefins affording
good yields of the aziridinated products. This reactivity
pattern could be explained on the basis of the fact
that Py‚HBr3, being more electrophilic in nature than
PhNMe3‚Br3, dissociates in the presence of olefins to give
Py‚Br2 which in turn reacts with olefins to form bromonium
ion as the key intermediate. This bromonium ion undergoes
Acknowledgment. M.D.N. thanks CSIR, New Delhi, for
SRF, and S.I.A. thanks the Director, NCL, for allowing the
experiments to be carried out.
Supporting Information Available: Text and figures
giving spectral data for the compounds described in this
paper. This material is available free of charge via the Internet
at http://pubs.acs.org.
OL9900966
(14) Alonso, D. A.; Andersson, P. G. J. Org. Chem. 1998, 63, 9459.
(15) Typical Experimental Procedure for Aziridination. To a mixture
of mesityl oxide (0.490 g, 5 mmol) and anyhydrous Chloramine-T (1.248
g, 5.5 mmol) in dry MeCN (25 mL) was added pyridinium hydrobromide
perbromide (0.160 g, 0.5 mmol) at 25 °C. The pale yellow colored solution
was stirred vigorously at 25 °C. The progress of the reaction was monitored
by TLC. After completion of the reaction, the reaction mixture was
concentrated under reduced pressure to give the crude product which was
purified by column chromatography (silica gel, 20% EtOAc-petroleum
ether as eluant). N-(p-Toluenesulfonyl)-2-acetyl-3,3′- dimethylaziridine:
yield, 0.801 g; viscous liquid; IR (CHCl3, cm-1) 3398, 3139, 3023, 2964,
2927, 1717, 1699, 1451, 1401, 1325, 1217, 1157, 1091, 1048; 1H NMR
(200 MHz, CDCl3) δ 7.85 (2H, d, J ) 8.2 Hz), 7.35 (2H, d, J ) 8.2 Hz),
3.50 (1H, s), 2.45 (3H, s), 1.95 (3H, s), 1.80 (3H, s), 1.30 (3H, s); 13C
NMR (200 MHz, CDCl3) δ 20.85, 21.37, 21.71, 28.39, 53.08, 55.03, 127.23,
129.49, 137.33, 144.13, 201.63; MS m/z (% rel intensity) 267 (M+, 2), 224
(6), 155 (14), 139 (6), 113 (15), 112 (100), 91 (73), 84 (21), 71 (32), 70
(87), 65 (47), 55 (9). Anal. Calcd for C13H17NSO3: C, 58.40; H, 6.40; N,
5.23; S, 11.99. Found: C, 58.41; H, 6.42; N, 5.25; S, 11.99.
(13) Fieser; Fieser, L. F. Experiments in Organic Chemistry, 3rd ed.; D.
C. Heath & Company: Boston, 1957; p 65.
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