Rapid microwave-promoted solvent-free synthesis of hypervalent iodine reagents

Article abstract of DOI:10.3184/030823409X396427

Hypervalent hydroxy(sulfonyloxy)iodoarenes, hydroxy(phosphoryloxy) iodoarenes and bis(trifluoroactoxy)iodobenzene have been synthesised by a fast and convenient solvent-free ligand exchange reaction from the (diacetoxyiodo)arene under microwave irradiation, providing a simple method for the synthesis of these hypervalent iodine reagents in good yield and in a short time.

Full text of DOI:10.3184/030823409X396427

30 RESEARCH PAPER
JANUARY, 30–31
JOURNAL OF CHEMICAL RESEARCH 2009
Rapid microwave-promoted solvent-free synthesis of hypervalent
iodine reagents
Zhongshi Zhoua* and Xuehan Heb
aCollege of Biological and Environmental Sciences, Zhejiang Shuren University, Hangzhou 310015, P.R. China
bZhejiang Institute of Geology and Mineral Resource Laboratory, Hangzhou 310007, P.R. China
Hypervalent hydroxy(sulfonyloxy)iodoarenes, hydroxy(phosphoryloxy)iodoarenes and bis(trifluoroactoxy)iodo-
benzene have been synthesised by a fast and convenient solvent-free ligand exchange reaction from the
(diacetoxyiodo)arene under microwave irradiation, providing a simple method for the synthesis of these hypervalent
iodine reagents in good yield and in a short time.
Keywords: hypervalent iodine reagent, microwave irradiation
Hypervalent iodine reagents have found wide application in
organic chemistry and are frequently used in synthesis.1-3
Because hypervalent iodine reagents are nonmetallic oxidising
reagents, they avoid the issues of toxicity of many transition
metals that are commonly involved in such processes.
Therefore, they have a high potential for the improvement
of known reactions not only from an environmental and
pharmaceutical point of view, but also as interesting
reagents for the development of completely new synthetic
transformations. Since many hypervalent iodine reagents
have a low solubility in the most ecologically harmful
organic solvents and usually need a substantial volume for
their reactions, the development of solvent-free reactions
is a big step forward and should lead to an increased use of
this chemistry. Solvent-free reactions have many advantages
including reduced pollution, lower costs and the simplicity
of the processes involved.4 Here we would like to report a
fast and convenient solvent-free reaction for the synthesis
of hypervalent iodine reagents under microwave irradiation
ꢀ6FKHPHꢁ ꢂꢃꢄꢁ 7Rꢁ WKHꢁ EHVWꢁ RIꢁ RXUꢁ NQRZOHGJHꢁ WKLVꢁ LVꢁ WKHꢁ ¿UVWꢁ
report of a rapid synthesis of hypervalent iodine reagents
under microwave irradiation.
OH
OR
microwave
Ar
I(OAc)
ROH
Ar
I
2
1
2
3
Scheme 1
at comparable reaction temperature. Recently interest has
been focused on the use of microwave-irradiated procedures
in water as a medium or under solvent-free condition for
RUJDQLFꢁV\QWKHVLVꢁGXHꢁWRꢁWKHLUꢁHI¿FLHQWꢁDQGꢁHQYLURQPHQWDOO\ꢁ
benign conditions.7,8 In this paper, only iodine (III) reagents
have been considered for these reactions because some iodine
(V) compounds are known to be shock and pressure sensitive.9
The iodine (III) reagents described here have been safely used
on a millimolar scale.
In our initial investigations, we used (diacetoxyiodo)benzene
1a(Ar=Ph)asarepresentative,hypervalentiodinereagentsince
it is commercially available and can also easily be prepared.10
Ligand exchange reactions on this compound are known
and have been used frequently to prepare other hypervalent
iodine reagents.11 We found that when 1a was mixed with
an equivalent amount of p-toluenesulfonic acid monohydrate
2a and then heated in a glass tube in a microwave oven for
only 20 seconds, the ligand exchange reaction was completed
Microwave-assisted organic synthesis is a new and quickly
growing area in synthetic organic chemistry.5,6 This technique
is based on the empirical observation that some organic
reactions proceed much faster and with higher yields under
microwave irradiation compared to conventional heating. In
many cases reactions that normally require many hours at
UHÀX[ꢁWHPSHUDWXUHꢁXQGHUꢁFODVVLFDOꢁFRQGLWLRQVꢁFDQꢁEHꢁFRPSOHWHGꢁ
within several minutes or seconds in a microwave oven, even
and
a yield of 98% [hydroxyl(tosyloxy)iodo]benzene
3a (Koser's reagent) was obtained. This is usually prepared in
an organic solvent such as CH2Cl2 or CH3CN.12 This result
prompted us to investigate further the solvent-free reactions of
(diacetoxyiodo)arenes 1 with sulfonic acids, dialkyl phosphates
Table 1 The results of the synthesis of hypervalent iodine reagents
Entry
1: Ar
2: R
Product 3
Yield/%a
98
1
2
3
4
5
6
7
Ph
1a
1a
p-Me-C6H4SO2
3a
3b
3c
3d
3e
3f
2a
MeSO2
93
2b
1a
1a
1a
1a
(1R)-10-camphory- sulfonyl
94
2c
(PhO)2PO
91
2d
(PhCH2O)2PO
90
2e
CF3CO
2f
71
4-Cl-C6H4
2a
3g
97
1b
1b
2-Toluene
1c
8
9
2d
2a
3h
3i
94
95
aIsolated yield
* Correspondent. E-mail: zhoushan@hz.zj.cn

JOURNAL OF CHEMICAL RESEARCH 2009 31
[Hydroxy[(bis(phenyloxy)phosphoryl)oxy]iodo]benzene (3d): M.p.
101–103°C (Lit.16 102–105°C); 1H NMR (400 MHz, CDCl3),
G: 7.05–7.09 (m, 6H), 7.20–7.28 (m, 6H), 7.39–7.42 (m, 1H), 7.89 (d,
J = 4.4 Hz, 2H); IR (KBr), Q/cm-1: 3399, 3058, 1743, 1295, 1192.
DQGꢁ WULÀXRURDFHWLFꢁ DFLGꢁ 2 under microwave irradiation. We
found that these similar reactions were usually completed in
20 seconds to afford the corresponding hypervalent iodine
reagents in good to excellent yields (Table 1).
[Hydroxy[(bis(benzoyloxy)phosphoryl)oxy]iodo]benzene (3e): Oil16
;
It can be seen in Table 1 that, except for the reaction of
WULÀXRURDFHWLFꢁDFLGꢁ2f with (diacetoxyiodo)benzene 1a which
JDYHꢁ >ELVꢀWULÀXRURDFWR[\ꢃLRGR@EHQ]HQHꢁ 3f in yield of 71%,
all the reactions gave provided products in excess of 90%
yields. Compared to sulfonic acids, the yields of diphenyl
phosphate 3d and dibenzyl phosphate 3f produced in the
reactions were somewhat lower. All formed hypervalent iodine
reagents were characterised by 1H NMR, IR, MS spectra and
melting points, which were consistent with the literature data.
In summary, a rapid and convenient method for the
formation of hypervalent iodine reagents is afforded by the
microwave-promoted solvent-free ligand exchange reaction. It
is simple, fast and gives good to excellent yields in synthesis
of hypervalent iodine reagents.
1H NMR (400 MHz, DMSO-d6), G: 4.74 (d, J = 5.6 Hz, 4H), 7.27–4.34
(m, 10H), 7.49–7.52 (m, 2H), 7.56–7.58 (m, 1H), 8.12 (d, J = 5.6 Hz,
2H); IR (KBr), Q/cm-1: 3369, 3061, 2951, 1268, 1215, 1024.
>%LVꢀWULÀXRURDFWR[\ꢁLRGR@EHQ]HQH (3f): M.p. 119–122°C (Lit.17
122–125°C).; 1H NMR (400 MHz, CDCl3), G: 7.17–7.22 (m, 2H),
7.74–7.76 (m, 1H), 8.16 (d, J ꢁꢅꢄꢆꢁ+]ꢇꢁꢈ+ꢃꢉꢁ,5ꢁꢀ¿OPꢃꢇꢁQ/cm-1: 3420,
1791, 1681, 1471, 1438, 1208, 1142.
[Hydroxy(tosyloxy)iodo]-4-Cl-benzene (3g): M.p. 157–159°C
(Lit.18 159–161°C); 1H NMR (400 MHz, CDCl3), G: 2.33 (s, 3H),
7.08–7.13 (m, 4H), 7.58–7.62 (m, 2H), 7.85 (d, J = 4.0 Hz, 2H);
,5ꢁꢀ¿OPꢃꢇꢁQ/cm-1: 3045, 1570, 1454, 1240, 1093, 798.
[Hydroxy[(bis(phenyloxy)phosphoryl)oxy]iodo]-4-Cl-benzene
(3h): M.p. 95–97°C; 1H NMR (400 MHz, CDCl3), G: 7.05–7.11 (m,
6H), 7.16 (d, J = 6.8 Hz, 2H), 7.21–7.26 (m, 4H), 7.73 (d, J = 6.4 Hz,
ꢈ+ꢃꢉꢁ,5ꢁꢀ¿OPꢃꢇꢁQ/cm-1: 3392, 3063, 1268, 1207, 1109, 1084; EI-MS
(m/z): 504 (M+, 100); HRMS: Calcd for C18H15ClIO5P = 503.9391,
found M+ = 503.9378.
Experimental
[Hydroxy(tosyloxy)iodo]-2-toluene (3i): M.p. 107–109°C (Lit.18
108–110°C); 1H NMR (400 MHz, CDCl3), G: 2.27 (s, 3H), 2.43 (s,
3H), 6.92–7.40 (m, 7H), 7.92 (d, J = 6.8 Hz, 1H); Q/cm-1: 3386, 3045,
1567, 1247, 1207, 1115, 1008.
Melting points were determined on a digital m.p. apparatus and were
not corrected. IR spectra were recorded on a FT-170 SX instrument,
1H NMR spectra were measured on a VARIAN-400 spectrometer,
and mass spectra were determined on MS-EI instrument (FINNIGAN
Trace DSQ) mass spectrometer. Microwave irradiation was carried
out with an LWMC-201 domestic microwave oven at full power
(650 W). (Diacetoxyiodo)arenes 1 were prepared according to the
literature procedures.10,13 All acids 2 are commercially available.
Received 18 September 2008; accepted 25 November 2008
Paper 08/0177 doi: 10.3184/030823409X396427
Published online: 23 January 2009
A typical procedure for synthesis of hypervalent iodine reagents
(Diacetoxyiodo)benzene 1a (200 mg, 0.62 mmol, 1.0 equiv) and
p-toluenesulfonicacidmonohydrate2a(118mg, 0.62mmol, 1.0equiv)
were mixed in a 10 ml glass tube. The mixture tube was placed inside
in an alumina bath and irradiated for 20 seconds in a microwave oven
at full power (650 W).After cooling, the solid residue was washed with
ethyl ether (5 ml) and dried under high vacuum to afford [hydroxyl
(tosyloxy)iodo]benzene 3a (238 mg, 98% yield).
References
1
2
3
4
P.J. Stang and V.V. Zhdankin, Chem. Rev., 1996, 96, 1123.
V.V. Zhdankin and P.J. Stang, Chem. Rev., 2002, 102, 2523.
T. Okuyama, Acc. Chem. Res., 2002, 35, 12.
M. Eissen, J.O. Metzger, E. Schmidt and U. Schneidewind, Angew. Chem.,
Int. Ed. Engl., 2002, 41, 414.
5
6
7
8
9
S. Caddick, Tetrahedron, 1995, 51, 10403.
S.A. Galema, Chem. Soc. Rev., 1997, 26, 223.
S. Deshayes, M. Liagre and A. Loupy, Tetrahedron, 1999, 55, 10851.
R.K. Arvela and N.E. Leadbeater, J. Org. Chem., 2005, 70, 1786.
J.B. Plumb and D.J. Harper, Chem. Eng. News, 1990, 68, 3.
[Hydroxy(tosyloxy)iodo]benzene (3a): M.p. 133–135°C (Lit.12
135–138°C); 1H NMR (400 MHz, DMSO-d6), G: 2.35 (s, 3H), 7.14 (d,
J = 6.4 Hz, 2H), 7.41–7.45 (m, 2H), 7.52–7.54 (m, 1H), 7.57 (d,
J = 6.4 Hz, 2H), 8.12 (d, J = 6.4 Hz, 2H); IR (KBr), Q/cm-1: 3045,
1574, 1464, 1444, 1240, 1207.
10 J.G. Sharefkin and H. Saltzman, Org. Synth., 1963, 43, 62.
11 G.F. Koser and R.H. Wettach, J. Org. Chem., 1980, 45, 1542.
12 G.F. Koser, R.H. Wettach, J.M. Troup and B.A. Frenz, J. Org. Chem.,
1976, 41, 3609.
13 A. Mckillop and D. Kemp, Tetrahedron, 1989, 45, 3299.
14 J.S. Loday and G.F. Koser, J. Org. Chem., 1988, 53, 210.
15 J.M. Goff, M.W. Justic and G.F. Koser, Tetrahedron Lett., 2001, 42, 5597.
16 G.F. Koser, J.S. Lodaya, D.G. Ray and P.B. Kokil, J. Am. Chem. Soc,
1988, 110, 2987.
[Hydroxy[(methysulfonyl)oxy]iodo]benzene (3b): M.p.118–120°C
(Lit.14 120–122°C); 1H NMR (400 MHz, DMSO-d6), G: 2.39 (s, 3H),
7.56–7.67 (m, 3H), 8.18–8.32 (m, 2H); IR (KBr), Q/cm-1: 3050, 1570,
1468, 1437, 1318, 1230, 1190, 1057.
[Hydroxy[((1R)-10-camphorylsulfonyl)oxy]iodo]benzene (3c): M.p.
116–118°C (Lit.15 118–120°C); 1H NMR (400 MHz, DMSO-d6), G:
0.79 (s, 3H), 0.98 (s, 3H), 1.32–1.37 (m, 1H), 1.56–1.62 (m, 1H),
1.88 (d, J = 14.8 Hz, 1H), 1.90–1.96 (m, 1H), 2.03–2.05 (m, 1H),
2.31–2.39 (m, 2H), 2.77 (d, J = 12.0 Hz, 1H), 3.30 (d, J = 12.0 Hz,
1H), 7.45-7.56 (m, 3H), 8.17 (d, J = 6.8 Hz, 2H); IR (KBr), Q/cm-1:
3048, 1735, 1450, 1300, 1250, 1150.
17 J.G. Sharefkin and H. Saltzman, Organic Synthesis; Wiley: New York,
1973; Collect. Vol. V, p 660.
18 C.S. Carman and G.F. Koser, J. Org. Chem., 1983, 48, 2534.