Copper-catalyzed ultrasound-expedited N-arylation of sulfoximines using diaryliodonium salts

Article abstract of DOI:10.1002/adsc.201100808

An ultrasound-accelerated route for an expeditious N-arylation of NH-sulfoximines is described that involves the use of diaryliodonium salts in aqueous polyethylene glycol-400 and copper(I) bromide as catalyst at room temperature. The high yields of the p

Full text of DOI:10.1002/adsc.201100808

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DOI: 10.1002/adsc.201100808
Copper-Catalyzed Ultrasound-Expedited N-Arylation of
Sulfoximines using Diaryliodonium Salts
Buchireddy Vaddula,a John Leazer,a and Rajender S. Varmaa,*
a
Sustainable Technology Division, National Risk Management Research Laboratory, U.S. Environmental Protection
Agency, 26 West Martin Luther King Drive, MS 443, Cincinnati, OH 45268, USA
Fax : (+1)-513-569-7677; phone: (+1)-513-487-2701; e-mail: Varma.Rajender@epa.gov
Received: October 18, 2011; Revised: January 18, 2012; Published online: April 16, 2012
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.201100808.
Abstract: An ultrasound-accelerated route for an
expeditious N-arylation of NH-sulfoximines is de-
scribed that involves the use of diaryliodonium salts
in aqueous polyethylene glycol-400 and copper(I)
bromide as catalyst at room temperature. The high
yields of the products and simple work-up are the
highlights of the protocol.
tioselective a-arylation of aldehydes.[12] They are also
À
useful substrates in Cu-catalyzed C N cross-coupling
reactions[13] and in the reaction with inorganic ions.[14]
The idea of employing diaryliodonium salts for N-ary-
lation takes root from their ability to form Cu
ACHTUNGTRENN(UNG III) in-
termediates with Cu(I) catalysts.[15]
Earlier, the N-arylation of sulfoximines was carried
out using aryl halides, arylboronic acids, with metal
catalysts [e.g., as PdACHTUNGETRNNU(G OAc)2, CuO, FeCl3, CuI, Cu2O]
À
Keywords: N-arylation; C N cross-coupling; iodo-
nium salts; PEG-400; polyethylene glycol 400; sul-
foximines
in solvents such as DMF, DMSO, toluene and dioxane
requiring the presence of ligands and extended heat-
ing.[16] Our efforts for a rapid and facile N-arylation
of sulfoximines yielded the desired products in high
yields within short duration using an alternative
energy source, ultrasonication. Ultrasound in organic
À
The C N cross-coupling reactions are crucial organic reactions is known to provide specific activation on
transformations that play a vital role in the construc- the basis of acoustic cavitation (i.e., quick formation,
tion of many important organic intermediates and growth and collapse of bubbles in liquid). The high
biologically active compounds and are often metal- local energy associated with the rapid collapse of bub-
catalyzed.[1] More often, these reactions are copper- bles increases the reaction speed and output;[17] the
and palladium-catalyzed and involve the use of aryl employment of high intensity ultrasound reduced the
halides.[2] The N-substituted sulfoximines and their time dramatically in these reactions.
derivatives have been utilized as reagents in organic
The initial attempts for the N-arylation reaction in-
synthesis.[3] They are important chiral ligands, useful volved the reaction of equimolar quantities of sulfoxi-
in the construction of pseudopeptides and biologically mine 1a and diphenyliodonium triflate 2a in aqueous
active molecules, and act as chiral auxillaries.[4]
polyethylene glycol-400 (aq. PEG-400) in the pres-
Diaryliodonium salts, an important class of trivalent ence of CuI (10 mol%) as a catalyst. The use of aque-
iodine reagents with two carbon ligands, are well ous PEG-400 as a benign reaction medium[18] takes
known for their potential applications in photochem- root from earlier reported successful organic transfor-
istry, organic chemistry and medicinal chemistry.[5] mations.[19] The reaction afforded 50% yield after 4 h
They are non-toxic, non-explosive, readily available, of stirring at room temperature and never reached
and found to be stable towards heat and oxygen and completion even after raising the temperature up to
are widely used in a variety of organic transforma- 1008C and continuing overnight. The addition of
tions.[6] Recently, several improved methods have a base, Cs2CO3, did not ameliorate the progress of the
been reported for the simple preparation of different reaction.
diaryliodonium salts from the corresponding arenes in
In an effort to expedite the process, stoichiometric
one step.[7] Diaryliodonium salts have been employed quantities of the catalyst were unsuccessfully em-
in the synthesis of aryl ethers,[8] aryl esters,[9] diaryl- ployed. Catalyst screening was then performed under
ACHTUNGTRENNUNG
amines,[10] a-arylations by rearrangement,[11] and enan- identical conditions. Various catalysts such as CuBr,
986
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Adv. Synth. Catal. 2012, 354, 986 – 990

Copper-Catalyzed Ultrasouns-Expedited N-Arylation of Sulfoximines using Diaryliodonium Salts
À
Table 1. Catalyst screening for the C N coupling reaction.
Entry
Catalyst
Yield [%][a]
1
2
3
4
5
6
7
no catalyst
CuBr
CuCl
0
Figure 1. The iodobenzene separates from the reaction mix-
ture upon completion of the reaction.
60
40
20
15
18
0
Cu
Cu(SO4)2
Cu(OAc)2
FeCl3
A
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
methyl-S-phenylsulfoximine with diphenyliodonium
triflate.
The generality and the scope of the protocol was
further explored using other sulfoximines 1b, c and io-
donium salts 2a–d (Table 2). The reaction of sulfoxi-
mine 1a with other iodonium salts 2b–d progressed
[a]
Yields obtained at room temperature stirring.
CuCl, CuACHTUNGTRENNUNG(OTf)2, CuACHTUNTREGN(GNUN SO4)2, FeCl3, CuACTHNUGTREN(NUGN OAc)2 were smoothly (83–92%). The sulfoximine 1b reacted with
evaluated (Table 1). The reactions performed in the iodonium salts 2a and 2b resulting in high product
absence of a catalyst has not shown any desired prod- yields (89–94%). Sulfoximine 1c reacted more readily
uct formation whereas copper(I) bromide demonstrat- (1–2 min) with iodonium salts 2a–c affording the
ed an edge over the other catalysts in terms of the products in good yields (87–95%). Sulfoximine 1d,
yield.
however, did not readily participate in the reaction
The reaction was also explored in benign reaction with iodonium salts 2a and 2c thus resulting in the
solvents such as water, PEG-400 and other combina- products in moderate yields (60% and 65%, respec-
tions of water and PEG-400; but a 1:1 mixture of tively). A significant amount of the sulfoximine 1d re-
water and PEG-400 proved to be effective. In order mained unreacted in these reactions even after con-
to improve the overall reaction yields, ultrasonication tinuous sonication (15 min). The unreacted sulfoxi-
was explored as an alternate energy source. The N- mine 1d was successfully isolated via silica gel column
phenylation of sulfoximine 1a with iodonium salt 2a chromatography. The steric bulk of the S,S-diphenyl-
afforded the product 3a in 88% yield in 5 min (pulse sulfoximine 1d may explain the lack of reactivity. A
À
program: 20 sec pulse with 10 sec pause). A 5 mol% plausible mechanism for the C N cross-coupling may
loading of the catalyst was found to be optimal under be attributed to the formation of a Cu
(III) com-
sonication. The reaction was explored with different plex.[15]
À
pulse programs in order to avoid the elevated temper-
In summary, an efficient and facile C N cross-cou-
atures that arise due to continuous sonication. A soni- pling protocol for the rapid synthesis of N-arylsulfoxi-
cation cycle with 20 seconds pulse followed by 10 sec- mines has been developed. The reaction is conducted
onds pause was found to be suitable (Scheme 1).
in aqueous PEG-400 using ultrasound as an energy
It was observed that upon completion of the reac- source, thus eliminating the need for hazardous, ex-
tion, a layer of iodoarene separates from the reaction pensive and toxic solvents, ligands and harsh condi-
mixture. The iodoarene can thus be recycled/reused tions. The use of various substrates and mild reaction
for regeneration of iodonium salts. Figure 1 shows the conditions bodes well for the generality of this proto-
separation of iodobenzene from the reaction of S- col.
Experimental Section
General Procedure for the N-Arylation of
Sulfoximines
A 10-mL beaker was charged with sulfoximine 1 (1 mmol)
and diaryliodonium salt 2 (1 mmol), CuBr (5 mol%, 7.2 mg)
and a presaturated solution of aqueous PEG-400 (1:1, v/v,
2 mL). This mixture was subjected to sonication on Vibra-
À
Scheme 1. CuBr-catalyzed C N cross-coupling of sulfoxi-
mines using ultrasonication.
Adv. Synth. Catal. 2012, 354, 986 – 990
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asc.wiley-vch.de
987

Buchireddy Vaddula et al.
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Table 2. Various products synthesized by the optimized N-arylation protocol.
[a]
Product yields after purification by flash chromatography.
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Adv. Synth. Catal. 2012, 354, 986 – 990

Copper-Catalyzed Ultrasouns-Expedited N-Arylation of Sulfoximines using Diaryliodonium Salts
Cell apparatus with a probe (frequency: 20 kHz, amplitude:
30%, cycle: 20 seconds pulse followed by 10 seconds pause)
for 2–10 min at room temperature. The reaction mixture
was then diluted with water and extracted into ethyl acetate.
The ethyl acetate layer was washed with water and dried
over anhydrous sodium sulfate. The crude residue was
passed over a silica gel column (EtOAc:hexane) to provde
the pure product in 60–95% yield.
Raabe, Org. Lett. 2007, 9, 2155–2158; c) M. Reggelin,
S. Slavik, P. Bu¨hle, Org. Lett. 2008, 10, 4081–4084; d) C.
Bolm, D. Kaufmann, M. Zehnder, M. Neuburger, Tet-
rahedron Lett. 1996, 37, 3985–3988; e) M. Reggelin, B.
Junker, T. Heinrich, S. Slavik, P. Bꢁhle, J. Am. Chem.
Soc. 2006, 128, 4023–4034; f) M. Reggelin, C. Zur, Syn-
thesis 2000, 2000, 1,64.
[4] a) S. J. Shetty, G. D. Patel, B. B. Lohray, V. B. Lohray,
G. Chakrabarti, A. Chatterjee, M. R. Jain, P. R. Patel,
(Cadila Healthcare Limited), Patent WO 2007077574
(A2), 2007; b) J. Sedelmeier, C. Bolm, J. Org. Chem.
2007, 72, 8859–8862; c) H. Okamura, C. Bolm, Chem.
Lett. 2004, 33, 482–487; d) P. Rꢂmy, M. Langner, C.
Bolm, Org. Lett. 2006, 8, 1209–1211; e) S. J. Park, H.
Buschmann, C. Bolm, Bioorg. Med. Chem. Lett. 2011,
21, 4888–4890; f) R. Bentley, Chem. Soc. Rev. 2005, 34,
609–624; g) E. B. Benetskiy, C. Bolm, Tetrahedron:
Asymmetry 2011, 22, 373–378.
N-Phenyl-S-methyl-S-phenyl sulfoximine (3a): 1H NMR
(300 MHz, CDCl3): d=7.95–7.88 (m, 2H), 7.52–7.42 (m,
3H), 7.08–7.02 (m, 2H), 6.96–6.93 (m, 2H), 6.83–6.78 (m,
1H), 3.17 (s, 3H); 13C NMR (75 MHz, CDCl3): d=144.95,
139.42, 133.17, 129.50, 128.97, 128.61, 123.31, 121.69, 46.00.
Acknowledgements
This project was supported in part by an appointment to the
Research Participation Program for the U.S. Environmental
Protection Agency, Office of Research and Development, ad-
ministered by the Oak Ridge Institute for Science and Educa-
tion through an interagency agreement between the U.S. De-
partment of Energy and the EPA.
[5] a) J. L. Dektar, N. P. Hacker, J. Org. Chem. 1990, 55,
639–647; b) G. F. Koser, in: The Chemistry of Function-
al Groups, Supplement D, (Eds.: S. Patai, Z. Rappo-
port), John Wiley & Sons, New York, 1983; c) R. A.
Wiley, M. A. Salter, J. Med. Chem. 1966, 9, 228–231;
d) E. A. Merritt, B. Olofsson, Angew. Chem. 2009, 121,
9214–9234; Angew. Chem. Int. Ed. 2009, 48, 9052–9070.
[6] a) R. B. Sandin, Chem. Rev. 1943, 32, 249–276; b) F. M.
Beringer, R. A. Falk, M. Karniol, I. Lillien, G. Masullo,
M. Mausner, E. Sommer, J. Am. Chem. Soc. 1959, 81,
342–351; c) H. E. Bachofner, F. M. Beringer, L. Meites,
J. Am. Chem. Soc. 1958, 80, 4274–4278; d) F. M. Be-
ringer, H. E. Bachofner, R. A. Falk, M. Leff, J. Am.
Chem. Soc. 1958, 80, 4279–4281.
[7] a) M. Bielawski, D. Aili, B. Olofsson, J. Org. Chem.
2008, 73, 4602–4607; b) M. Zhu, N. Jalalian, B. Olofs-
son, Synlett 2008, 592–596; c) E. A. Merritt, J. Malmg-
ren, F. J. Klinke, B. Olofsson, Synlett 2009, 2277–2280;
d) V. W. Pike, F. Butt, A. Shah, D. A. Widdowson, J.
Chem. Soc. Perkin Trans. 1 1999, 245–248; e) A. Shah,
V. W. Pike, D. A. Widdowson, J. Chem. Soc. Perkin
Trans. 1 1997, 2463–2466.
[8] a) N. Jalalian, E. E. Ishikawa, L. F. Silva, B. Olofsson,
Org. Lett. 2011, 13, 1552–1555; b) A. Krief, W.
Dumont, M. Robert, Synlett 2006, 484–486.
[9] a) T. B. Petersen, R. Khan, B. Olofsson, Org. Lett.
2011, 13, 3462–3465; b) Z. Chen, Y. Jin, P. J. Stang, J.
Org. Chem. 1987, 52, 4117–4118.
[10] M. A. Carroll, R. A. Wood, Tetrahedron 2007, 63,
11349–11354.
[11] P.-O. Norrby, T. B. Petersen, M. Bielawski, B. Olofsson,
Chem. Eur. J. 2010, 16, 8251–8254.
References
[1] a) J. Chan, K. D. Baucom, J. A. Murry, J. Am. Chem.
Soc. 2007, 129, 14106–14107; b) G. Pelletier, D. A.
Powell, Org. Lett. 2006, 8, 6031–6034; c) M. H. S. A.
Hamid, C. L. Allen, G. W. Lamb, A. C. Maxwell, H. C.
Maytum, A. J. A. Watson, J. M. J. Williams, J. Am.
Chem. Soc. 2009, 131, 1766–1774; d) L. Benati, G. Ben-
civenni, R. Leardini, D. Nanni, M. Minozzi, P. Spagno-
lo, R. Scialpi, G. Zanardi, Org. Lett. 2006, 8, 2499–
2502; e) T. Hu, C. Li, Org. Lett. 2005, 7, 2035–2038;
f) S. V. Ley, A. W. Thomas, Angew. Chem. 2003, 115,
5558–5607; Angew. Chem. Int. Ed. 2003, 42, 5400–5449;
g) K. Kunz, U. Scholz, D. Ganzer, Synlett 2003, 2003,
2428,2439; h) I. P. Beletskaya, A. V. Cheprakov, Coord.
Chem. Rev. 2004, 248, 2337–2364; i) J.-P. Corbet, G.
Mignani, Chem. Rev. 2006, 106, 2651–2710; j) J. F. Hart-
wig, Synlett 2006, 2006, 1283,1294.
[2] a) J. F. Hartwig, Angew. Chem. 1998, 110, 2154–2177;
Angew. Chem. Int. Ed. 1998, 37, 2046–2067; b) A. R.
Muci, S. L. Buchwald, Top. Curr. Chem. 2002, 219, 131–
209; c) K. W. Anderson, R. E. Tundel, T. Ikawa, R. A.
Altman, S. L. Buchwald, Angew. Chem. 2006, 118,
6673–6677; Angew. Chem. Int. Ed. 2006, 45, 6523–6527;
d) T. Ikawa, T. E. Barder, M. R. Biscoe, S. L. Buchwald,
J. Am. Chem. Soc. 2007, 129, 13001–13007; e) J. C. An-
tilla, A. Klapars, S. L. Buchwald, J. Am. Chem. Soc.
2002, 124, 11684–11688; f) J. C. Antilla, J. M. Baskin,
T. E. Barder, S. L. Buchwald, J. Org. Chem. 2004, 69,
5578–5587; g) H.-J. Cristau, P. P. Cellier, J.-F. Spindler,
M. Taillefer, Chem. Eur. J. 2004, 10, 5607–5622;
h) R. A. Altman, E. D. Koval, S. L. Buchwald, J. Org.
Chem. 2007, 72, 6190–6199; i) X. Lv, W. Bao, J. Org.
Chem. 2007, 72, 3863–3867.
[12] A. E. Allen, D. W. C. MacMillan, J. Am. Chem. Soc.
2011, 133, 4260–4263.
[13] a) H.-Y. Niu, C. Xia, G.-R. Qu, Q. Zhang, Y. Jiang, R.-
Z. Mao, D.-Y. Li, H.-M. Guo, Org. Biomol. Chem.
2011, 9, 5039–5042; b) S.-K. Kang, S.-H. Lee, D. Lee,
Synlett 2000, 1022,1024.
[14] a) M. A. Carroll, J. Nairne, G. Smith, D. A. Widdows-
on, J. Fluorine Chem. 2007, 128, 127–132; b) J. J. Lubin-
kowski, M. Gomez, J. L. Calderon, W. E. McEwen, J.
Org. Chem. 1978, 43, 2432–2435.
[3] a) C. R. Johnson, Acc. Chem. Res. 1973, 6, 341–347;
b) A. Adrien, H.-J. Gais, F. Kçhler, J. Runsink, G.
[15] R. J. Phipps, N. P. Grimster, M. J. Gaunt, J. Am. Chem.
Soc. 2008, 130, 8172–8174.
Adv. Synth. Catal. 2012, 354, 986 – 990
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
989

Buchireddy Vaddula et al.
COMMUNICATIONS
[16] a) N. Yongpruksa, N. L. Calkins, M. Harmata, Chem.
Commun. 2011, 47, 7665–7667; b) A. Correa, C. Bolm,
Adv. Synth. Catal. 2008, 350, 391–394; c) A. Correa, C.
Bolm, Adv. Synth. Catal. 2007, 349, 2673–2676; d) C.
Moessner, C. Bolm, Org. Lett. 2005, 7, 2667–2669; e) Y.
Macꢂ, B. Pꢂgot, R. Guillot, C. Bournaud, M. Toffano,
G. Vo-Thanh, E. Magnier, Tetrahedron 2011, 67, 7575–
7580; f) M. Frings, I. Atodiresei, Y. Wang, J. Runsink,
G. Raabe, C. Bolm, Chem. Eur. J. 2010, 16, 4577–4587;
g) P.-F. Larsson, A. Correa, M. Carril, P.-O. Norrby, C.
Bolm, Angew. Chem. 2009, 121, 5801–5803; Angew.
Chem. Int. Ed. 2009, 48, 5691–5693; h) Z.-J. Liu, J.-P.
Vors, E. R. F. Gesing, C. Bolm, Green Chem. 2011, 13,
42–45; i) M. Langner, P. Rꢂmy, C. Bolm, Chem. Eur. J.
2005, 11, 6254–6265; j) G. Y. Cho, P. Rꢂmy, J. Jansson,
C. Moessner, C. Bolm, Org. Lett. 2004, 6, 3293–3296.
[17] K. S. Suslick, Science 1990, 247, 1439–1445.
[18] J. Chen, S. K. Spear, J. G. Huddleston, R. D. Rogers,
Green Chem. 2005, 7, 64–82.
[19] a) D. Kumar, V. B. Reddy, R. S. Varma, Tetrahedron
Lett. 2009, 50, 2065–2068; b) D. Kumar, V. B. Reddy,
Synthesis 2010, 1687–1691; c) D. Kumar, V. B. Reddy,
B. G. Mishra, R. K. Rana, M. N. Nadagouda, R. S.
Varma, Tetrahedron 2007, 63, 3093–3097.
990
asc.wiley-vch.de
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 986 – 990