m-Iodosylbenzoic acid, a tagged hypervalent iodine reagent for the iodo-functionalization of alkenes and alkynes

Article abstract of DOI:10.1016/j.tetlet.2007.12.120

An efficient and facile method for the iodo-functionalization of alkenes 5 and alkynes 6 by using recyclable m-iodosylbenzoic acid (2) was developed. The final products can be easily isolated without any chromatographic purification by simple treatment of the crude mixture with an anionic exchange resin. Unreacted m-iodosylbenzoic acid and reduced m-iodobenzoic acid are effectively recovered from the resin by acidification with hydrochloric acid.

Full text of DOI:10.1016/j.tetlet.2007.12.120

Available online at www.sciencedirect.com
Tetrahedron Letters 49 (2008) 1506–1509
m-Iodosylbenzoic acid, a tagged hypervalent iodine reagent
for the iodo-functionalization of alkenes and alkynes
a,
a
b,
*
*
Mekhman S. Yusubov , Roza Ya. Yusubova , Andreas Kirschning
Joo Yeon Park c, Ki-Whan Chi c,*
,
a The Siberian State Medical University, 2 Moskovsky Trakt, 634050 Tomsk, Russia and The Tomsk Polytechnic University,
30 Lenin Street, 634050 Tomsk, Russia
b Institut fu¨r Organische Chemie and Zentrum fu¨r Biomolekulare Wirkstoffe (BMWZ), Leibniz Universita¨t Hannover,
Schneiderberg 1B, D-30167 Hannover, Germany
c University of Ulsan, 680-749 Ulsan, Republic of Korea
Received 20 August 2007; revised 14 December 2007; accepted 21 December 2007
Available online 8 January 2008
Abstract
An efficient and facile method for the iodo-functionalization of alkenes 5 and alkynes 6 by using recyclable m-iodosylbenzoic acid (2)
was developed. The final products can be easily isolated without any chromatographic purification by simple treatment of the crude mix-
ture with an anionic exchange resin. Unreacted m-iodosylbenzoic acid and reduced m-iodobenzoic acid are effectively recovered from the
resin by acidification with hydrochloric acid.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Alkenes; Alkynes; Hypervalent iodine; Iodination; m-Iodosobenzoic acid; Scavenger
Iodo-functionalization of alkenes and alkynes has been
used as a pivotal transformation in organic synthesis.1a,b
In particular, hypervalent iodine compounds have been
successfully applied for iodination, iodo-functionalization,
and oxidation reactions due to their mild and selective oxi-
dizing characteristics.2a–f For example, Yusubov et al.2g
recently demonstrated an effective iodo-functionalization
of alkenes by using (dichloroiodo)benzene. Broader appli-
cation of hypervalent iodine compounds, however, has
been restricted due to the tedious purification and recovery
process necessary following reactions. To circumvent this
problem, several recyclable hypervalent iodine reagents
have been developed in the form of polymer-supported3a–y
or molecular species.4a–i Nevertheless, multi-step syntheses
and subsequent separation are required for the preparation
of these recyclable hypervalent reagents.
We have recently developed a straightforward approach
to simplify the work-up of iodine(III)-mediated reactions
by using 3-(dichloroiodo)benzoic acid4c (1) and m-iodosyl-
benzoic acid5a,b (2) as recyclable reagents (Fig. 1). A
detailed spectroscopic investigation of m-iodosylbenzoic
acid and its sodium salt by Katritzky et al. supported the
polymeric structure of these compounds.5a,c Both hyperva-
lent iodine reagents are prepared with ease and tagged with
a carboxylic acid group so that reduced iodine by-products
such as m-iodobenzoic acid (3) can be removed at the
end of the reaction by simple treatment with an anion
exchange resin (IRA 900; hydroxide form) or by the
HO
O
HO
Cl
I
I
I
O
O
HO
O
Cl
n
*
Corresponding authors.
E-mail address: andreas.kirschning@oci.uni-hannover.de (A. Kirsch-
2
1
3
Fig. 1.
ning).
0040-4039/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2007.12.120

M. S. Yusubov et al. / Tetrahedron Letters 49 (2008) 1506–1509
1507
Table 1
addition of NaHCO3. Moreover, these scavenged iodine
Iodohydroxylations and iodomethoxylations of alkenes 514,15
species could be easily recycled by simple acidification with
HCl followed by reoxidation. Using these tagged reagents,
we have shown that facile oxidation of primary and
secondary alcohols and iodination of arenes are possible
with a simplified purification step.5a,b
Based on this concept, we now report a simple and effi-
cient method for the methoxy and hydroxy iodination of
alkenes 5 and alkynes 6 by using m-iodosylbenzoic acid
(2) (Scheme 1).
R3
R4
R1
R2
5a-k
R3
I
1. I2, 2,CH3CN-H2O
R3
I
MeO
HO
R1
1. I2, 2, MeOH, r.t.
R4
(5:1), r.t.
R4
3 +
+ 3
R1
R2
2. IRA 900,
2. IRA 900,
R2
(HCO3- form)
(HCO3- form)
7a-k
8a,c,f-k
Alkene 5
Product 7/8
Yielda,b (%)
Thus, the treatment of 2 with alkenes 5a–j in the pres-
ence of iodine effectively provides iodomethoxylation and
iodohydroxylation products 7a–j and 8a,c,e–j, respectively,
in 72–94% yields (Table 1). Reaction of cyclohexene (5c)
with 2 in MeOH in the presence of iodine at room temper-
ature gave trans-1-iodo-2-methoxycyclohexane (7c) in an
81% preparative yield. The addition proceeds in the
expected anti-fashion, thereby exerting high trans-stereo-
selectivity. The stereoselective formation of trans-products
7 and 8 might be a result from the presence of bridged iod-
onium intermediates. And, the regioselectivity of our work
is ascribed to the selective attack of a nucleophile (MeOH
or H2O) on the more substituted carbon of the cyclic
iodonium ion.
7a/7a0 R = Me 857
8a/8a0 R = H 728
+
I
OR
I
OR
5a
OMe
I
7b/ 7b0827
+
5b
5c
I
OMe
I
7c R = Me 812g
8c R = H 767,9
OR
I
Treatment of the reaction mixture with Amberlite IRA
9006 (hydrocarbonate or hydroxide form) and subsequent
filtration followed by removal of the solvent under reduced
pressure provided pure iodo-functionalized products. For-
mation of any other by-products was not encountered.
Amberlite IRA 900 was used to remove the access of
reagent 2, iodine, and the by-product m-iodobenzoic acid
from the crude mixtures.
7d 8510
OMe
H
5d
OR
7e R = Me 832g
8e R = H 842g
5e
I
Reactions of m-iodosylbenzoic acid (2) with alkynes
6a–f in the presence of iodine in MeOH lead to the diiododi-
methoxylation products 9a–f in 67–90% yields (Table 2).
To date, diiododimethoxylation of alkynes has been rarely
described in the literature.13a,b If (dichloroiodo)benzene
OR
I
7f R = Me 912g
8f R = H 872g
5f
I
RO
7g R = Me 942g
8g R = H 902g
HCl
5g
HO2C
I
NMe3
O2C
I
4
3
OR
preparation
of reagent 2
purification
and recovery
5h
7h R = Me 9211
8h R = H 907
Ac2O, H2O2
(ref. 5a)
I
NMe3
X
X = OH or HCO3
I
O
OR
I
I
R1
R2
R3
R3
R4
I
7i/7i0 R = Me 7212
8i/8i0 R = H 729
O
HO
+
2
n
R1
R4
+
3
R2
OR
5i
OR
I2, CH3CN, ROH, r.t.
5
7 (R= Me), 8 (R= H)
or
or
iodomethoxylation
with reagent 2
R1
R2
OR
R1
I
OH
I
6
7j R = Me 87
8j R = H 87
RO
OH
R2
RO
5j
I
9 (R= Me)
a
Isolated yield of pure products.
Products referenced.
b
Scheme 1.

1508
M. S. Yusubov et al. / Tetrahedron Letters 49 (2008) 1506–1509
Me
was applied instead of 2, only the ketal 9e of a,a-diiodo-
acetophenone was obtained from phenylethyne (6e). In
other reactions with (dichloroiodo)benzene, the tentative
products of ketals 9a–d,f decomposed once flash chromato-
graphy on silica gel was attempted. These results clearly
demonstrate the usefulness and preference of tagged m-iodo-
sylbenzoic acid (2) over other iodine(III) reagents.2g
Reaction of pent-4-yn-1-ol (6d) with iodine and 2 in
MeOH provided 2-(diiodomethyl)-2-methoxytetrahydro
furan (9d). It is plausible to suggest that the iodocyclization
of 6d firstly yields cyclized intermediate 10 followed by iodo-
methoxylation of the exocyclic double bond to produce the
final product 9d (Scheme 2).
I2, 2
O
I
I
MeOH, r.t.
O
OH
O
10
I
9d
6d
Scheme 2.
MeOH
H2O
HO2C
OH
I
2
OH
HO2C
I
OMe
OH
I2
I2
3
+ 2 HOI
3 + 2 MeOI
Based on the results5b of iodine(III)-mediated iodination
of arenes, we suggest that the methoxy or hydrated form of 2
oxidizes iodine to MeOI (in MeOH) or HOI (in H2O) which
serves as a reactive electrophilic intermediate (Scheme 3).
In conclusion, the inexpensive and easy-to-handle
hypervalent iodine reagent m-iodosylbenzoic acid (2) was
successfully applied for the iodomethoxylation and iodo-
hydroxylation of alkenes and alkynes under mild condi-
tions. This tagged reagent and the aryliodide by-product
Scheme 3.
are easily removed from the reaction mixture by simple
treatment with an anion exchange resin. This methodology
allows easier preparation and simplified purification of
organoiodo compounds.
Acknowledgments
Table 2
Iodomethoxylation of alkynes 6 with m-iodosylbenzoic acid 214,15
This work was funded by the Fonds der Chemischen
Industrie. In addition, K.W.C., M.S.Y. and R.Y.Y. are
grateful for the support of Brain Korea 21 program in
Korea.
I
1. I2, 2, MeOH, r.t.
R1
MeO
I
R1
R2
+ 3
2. IRA 900,
R2
(HCO3- form)
MeO
6a-f
9a-f
References and notes
Alkyne 6
Product 9
Yielda (%)
83
MeO
1. (a) Smith, M. B.; March, J. Advanced Organic Chemistry, 5th ed.;
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2001; pp 191–248.
OMe
I
I
6a
9a
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Synlett 2000, 1175–1177; (g) Tohma, H.; Morioka, H.; Takizawa, S.;
Arisawa, M.; Kita, Y. Tetrahedron 2001, 57, 345–352; (h) Ficht, S.;
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Tsukayama, M. Synthesis 2002, 2490–2496; (n) Cheng, D.-P.; Chen,
Z.-C. Synth. Commun. 2002, 32, 2155–2159; (o) Tohma, H.; Maeg-
awa, T.; Takizawa, S.; Kita, Y. Adv. Synth. Catal. 2002, 344, 328–337;
(p) Kirschning, A.; Kunst, E.; Ries, M.; Rose, L.; Scho¨nberger, A.;
MeO
OMe
99
78
I
I
6b
9b
I
I
OMe
MeO
9c
6c
OH
OMe
I
O
76
90
I
6d
9d
I
I
OMe
MeO
6e
9e
Me
I
I
Me
84
OMe
MeO
9f
6f
a
Isolated yield of pure products.

M. S. Yusubov et al. / Tetrahedron Letters 49 (2008) 1506–1509
1509
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in MeOH (0.5 mL) were added alkynes 6a–f (0.15 mmol) in MeOH
(0.5 mL), and the reaction mixture was stirred at room temperature
for 1 h. Then, dichloromethane (1.0 mL) was added and the resulting
solution was cooled to 5 °C. IRA 900 (350–400 mg, hydroxide form)
was added and the mixture was stirred for 5 min in the dark. The resin
was removed by filtration and the solution was concentrated under
reduced pressure to afford pure diiodoketals 9a–f as judged by NMR-
spectroscopy.
15. Spectral data for 7k, 8k and new compounds. 2-Iodo-3-methoxy-3-
phenylpropan-1-ol (7k): Oil: 1H NMR: d 2.89 (1H, OH, s), 3.27 (3H,
OCH3, s), 3.81 (1Ha, CH2, m), 3.95 (1Hb, CH2, m), 4.34 (1H, CH–
OMe, m), 4.52 (1H, CH–I, m); IR (neat) m 3356 (OH), 1123 and 1085
4. (a) Thottumkara, A. P.; Vinod, T. K. Tetrahedron Lett. 2002, 43, 569–
572; (b) Tohma, H.; Maruyama, A.; Maeda, A.; Maegawa, T.; Dohi,
T.; Shiro, M.; Morita, T.; Kita, Y. Angew. Chem., Int. Ed. 2004, 42,
3595–3598; (c) Yusubov, M. S.; Drygunova, L. A.; Zhdankin, V. V.
Synthesis 2004, 2289–2292; (d) Dohi, T.; Maruyama, A.; Yoshimura,
M.; Morimoto, K.; Tohma, H.; Shiro, M.; Kita, Y. Chem. Commun.
2005, 2205–2207; (e) Dohi, T.; Morimoto, K.; Takenaga, N.;
Maruyama, A.; Kita, Y. Chem. Pharm. Bull. 2006, 54, 1608–1610;
(f) Dohi, T. J. Pharm. Soc. Jpn. 2006, 126, 757–766; (g) Moroda, A.;
Togo, H. Tetrahedron 2006, 62, 12408–12414; (h) Dohi, T.; Morim-
oto, K.; Takenaga, N.; Goto, A.; Maruyama, A.; Kiyono, Y.; Tohma,
H.; Kita, Y. J. Org. Chem. 2007, 72, 109–116; (i) Justik, M. W.
Tetrahedron Lett. 2007, 48, 3003–3007.
5. (a) Yusubov, M. S.; Gilmkhanova, M. P.; Zhdankin, V. V.;
Kirschning, A. Synlett 2007, 563–566; (b) Yusubov, M. S.; Yusubova,
R. Ya.; Chi, K.-W.; Park, J. Y.; Kirschning, A. Beilstein J. Org.
Chem. 2007, 3, 19; (c) Katritzky, A. R.; Savage, G. P.; Gallos, J. K.;
Durst, H. D. J. Chem. Soc., Perkin Trans. 2 1990, 1515–1518.
6. Amberlite IRA 900 (chloride form) was obtained from Supelco.
7. Iranpoor, N.; Shekarriz, M. Tetrahedron 2000, 56, 5209–5211.
8. Cerritelli, S.; Chiarini, M.; Cerichelli, G.; Capone, M.; Marsili, M.
Eur. J. Org. Chem. 2004, 623–630.
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Nunez, M.-E. Org. Lett. 1999, 2125–2128.
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11. Mahajan, V. A.; Shinde, P. D.; Gajare, A. S.; Karthikeyan, M.;
Wakharkar, R. D. Green Chem. 2002, 325–327.
12. This transformation has been reported before: (a) Sato, T.; Tamura,
K.; Nagayoshi, K. Chem. Lett. 1983, 5, 791–794; (b) Davidson, R. I.;
Kropp, P. J. J. Org. Chem. 1982, 47, 1904–1909; (c) Schauble, J. H.;
Trauffer, E. A.; Deshpande, P. P.; Evans, R. D. Synthesis 2005, 1333–
1339.
13. (a) Janas, J. J.; Asirvatham, E. T.; McNelis, E. Oxid. Commun. 1985/
86, 8, 65; (b) Bovonsombat, P.; McNelis, E. Tetrahedron Lett. 1992,
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(C–OH and C–O–C), 762 and 690 (C–I) cmꢀ1
.
2-Iodo-1-phenylpropane-1,3-diol (8k): Colorless solid: mp 84–86 °C;
1H NMR: d 2.72 (1H, OH, s), 3.14 (1H, OH, s), 3.82 (1Ha, CH2, m),
3.96 (1Hb, CH2, m), 4.44 (1H, CH–OMe, d), 5.04 (1H, CH–I, m); IR
(neat) m 3380 (OH), 1074 (C–O), 780 and 684 (C–I) cmꢀ1
.
3-Iodo-6-methoxycyclohex-1-ene (7e): Oil: 1H NMR: d 2.00–2.08 (4H,
CH2, m), 3.34 (3H, OCH3, s), 3.99 (1H, CH–OMe, m), 4.43 (1H, CH–
I, m), 5.72 (1H, @CH, m), 5.93 (1H, @CH, m); 13C NMR: d 25.4 (CI),
30.0 (CH2), 30.1 (CH2), 57.0 (OCH3), 80.6 (COMe), 124.1 (@C–
COMe), 130.9 (@C–CI); IR (neat) m 1125 (C–O–C), 926 (C@C), 644
(C–I) cmꢀ1. Anal. Calcd for C7H11IO: C, 35.32; H, 4.66. Found: C,
35.17; H, 4.73.
1,1-Diiodo-2,2-dimethoxyhexane (9a): Oil: 1H NMR: d 0.94 (3H, CH3,
t), 1.34–1.43 (4H, CH2, m), 2.02 (2H, CH2, t), 3.33 (6H, CH3, s) 5.39
(1H, CI2H, s); 13C NMR: d ꢀ15.10 (CI2), 12.2 (CH3), 21.8 (CH2), 26.4
(CH2), 33.7 (CH2), 50.4 (OCH3), 98.8 (C(OMe)2); IR (neat) m 1075
and 1042 (C–O–C), 682 and 640 (C–I) cmꢀ1. Anal. Calcd for
C8H16I2O2: C, 24.14; H, 4.05. Found: C, 23.89; H, 4.18.
4,4-Diiodo-5,5-dimethoxyoctane (9b): Oil: 1H NMR: d 0.97 (3H, CH3,
t), 1.05 (3H, CH3, t), 1.54–1.62 (4H, CH2, m), 2.03 (2H, CH2–
C(OMe)2, t), 2.23 (2H, CH2–CI2, t), 3.56 (6H, CH3, s); IR (neat) m
1095 and 1056 (C–O–C), 678 and 632 (C–I) cmꢀ1. Elemental analysis
and 13C NMR could not be obtained for 9c due to slow decompo-
sition of the sample on storage.
(2,2-Diiodo-1,1-dimethoxyethyl)cyclohexane or1,1-Diiodo-2,2-dimeth-
oxyethyl-2-cyclohexylethane (9c): Colorless solid: mp 34–35 °C
(decomp.); 1H NMR: d 1.12–1.26 (6H, CH2, m), 1.66 (2H, CH3, m),
1.77 (1Ha, CH2, m), 1.89 (1Hb, CH2, m), 2.28 (H, CH, m), 3.45 (6H,
CH3, s), 5.47 (1H, CI2, s); 13C NMR: d ꢀ18.5 (CHI2), 26.3 (CH2), 27.1
(CH2), 29.2 (CH2), 43.9 (CH), 50.6 (OCH3), 51.8 (OCH3), 97.1
(C(OMe)2). Anal. Calcd for C10H18I2O2: C, 28.32; H, 4.28. Found: C,
28.70; H, 4.65.
2-Diiodomethyl-2-methoxytetrahydrofuran (9d): Oil: 1H NMR: d 2.05
(2H, CH2, m), 2.35 (1H, CH2, m), 2.44 (H, CH2, m), 3.22 (6H, CH3, s),
4.11 (2H, CH2, m), 5.52 (1H, CI2H, s); 13C NMR: d ꢀ20.1 (CI2), 25.8
(CH2), 38.1 (CH2), 48.2 (OCH3), 71.5 (CH2–O), 108.0 (O–C–OMe); IR
(neat) m 1050 and 1022 (C–O–C), 690 and 647 (C–I) cmꢀ1. Anal. Calcd
for C6H10I2O2: C, 19.59; H, 2.74. Found: C, 19.44; H, 2.81.
1,1-Diiodo-2,2-dimethoxyethyl-2-phenylethane (9e): Colorless solid: mp
84–86 °C (decomp.); 1H NMR: d 3.32 (6H, OCH3, s), 5.56 (1H, CI2H,
s), 7.30–7.35 (3Harom., m) 7.62–7.67 (2Harom., m); 13C NMR: d ꢀ19.4
(CI2), 49.0 (OCH3), 97.4 (C(OMe)2), 125.8, 127.3, 128.0, 133.7 (Carom.);
IR (KBr) m 1089 and 1045 (C–O–C), 679 and 635 (C–I) cmꢀ1. Anal.
Calcd for C10H12I2O2: C, 28.73; H, 2.89. Found: C, 28.86; H, 2.85.
2,2-Diiodo-1,1-dimethoxyethyl-1-phenylpropane (9f): Colorless solid:
mp 65–66 °C (decomp.); 1H NMR: d 2.86 (3H, CH3, s), 3.59 (6H,
OCH3, s), 7.37–7.40 (3Harom., m) 7.64–7.66 (2Harom., m); 13C NMR: d
15.1 (CH3), 45.3 (CI2), 53.89 (ICH3), 102.3 (C(OMe)2), 126.2, 128.0,
131.2, 132.5 (Carom.); IR (KBr) m 1068 and 1015 (C–O–C), 694 and 665
(C–I) cmꢀ1. Anal. Calcd for C11H14I2O2: C, 30.58; H, 3.27. Found: C,
30.71; H, 3.59.
14. Typical procedure for iodomethoxylation. Alkenes 5a–c,e (0.3 mmol)
were added to a mixture of iodine (25.4 mg, 0.10 mmol) and m-
iodosylbenzoic acid (2) (29 mg, 0.11 mmol) in MeOH (0.5 mL) and
the reaction mixture was stirred at room temperature for 1 h (the
reactions were monitored by TLC). Then, dichloromethane (1.0 mL)
was added and the resulting solution was cooled to 5 °C. IRA 900
(350–400 mg, hydrocarbonate form) was added and the mixture was
stirred for 5 min. The resin was removed by filtration and the solution
was concentrated under reduced pressure to afford pure methoxyiod-
ides 7a–c,e as judged by NMR-spectroscopy. m-Iodobenzoic acid (3)
can be easily regenerated from the IRA 900 resin 4 by treatment with
aqueous HCl and reoxidized to reagent
2 without additional
purification as described in Ref. 5a. For the iodomethoxylation of
alkenes 5d,g–k, a molar ratio of alkene:2:iodine = 0.2:0.11:0.2 (mmol)
was employed, instead. The iodohydroxylation was carried out
accordingly accept that MeCN–H2O (5:1, 0.5 mL) was employed as
solvent instead of MeOH.
Typical procedure for diiododimethoxylation. To a solution of iodine
(28 mg, 0.11 mmol) and m-iodosylbenzoic acid (2) (29 mg, 0.11 mmol)