Preparation, X-ray structure, and reactivity of 2-iodylpyridines: Recyclable hypervalent iodine(V) reagents

Article abstract of DOI:10.1021/jo200163m

2-Iodylpyridine and four examples of 3-alkoxy-2-iodylpyridines were prepared by oxidation of the respective 2-iodopyridines with 3,3-dimethyldioxirane. Structures of 2-iodylpyridine, 2-iodyl-3- isopropoxypyridine, and 2-iodyl-3-propoxypyridine were established by single-crystal X-ray diffraction analysis. 2-Iodyl-3-propoxypyridine has moderate solubility in organic solvents (e.g., 1.1 mg/mL in acetonitrile) and can be used as a recyclable reagent for oxidation of sulfides and alcohols. The reduced form of this reagent, 2-iodo-3-propoxypyridine, can be effectively separated from the reaction mixture by treatment with diluted sulfuric acid and recovered from the acidic aqueous solution by adding aqueous sodium hydroxide.

Full text of DOI:10.1021/jo200163m

ARTICLE
pubs.acs.org/joc
Preparation, X-ray Structure, and Reactivity of 2-Iodylpyridines:
Recyclable Hypervalent Iodine(V) Reagents
†
†
‡
,†
Akira Yoshimura, Christopher T. Banek, Mekhman S. Yusubov, Victor N. Nemykin,* and
,†
Viktor V. Zhdankin*
†
Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, Minnesota 55812, United States
The Siberian State Medical University and The Tomsk Polytechnic University, 634050 Tomsk, Russia
‡
S Supporting Information
b
ABSTRACT: 2-Iodylpyridine and four examples of 3-alkoxy-
2
2
-iodylpyridines were prepared by oxidation of the respective
-iodopyridines with 3,3-dimethyldioxirane. Structures of 2-io-
dylpyridine, 2-iodyl-3-isopropoxypyridine, and 2-iodyl-3-pro-
poxypyridine were established by single-crystal X-ray diffraction
analysis. 2-Iodyl-3-propoxypyridine has moderate solubility in
organic solvents (e.g., 1.1 mg/mL in acetonitrile) and can be
used as a recyclable reagent for oxidation of sulfides and
alcohols. The reduced form of this reagent, 2-iodo-3-propox-
ypyridine, can be effectively separated from the reaction mixture by treatment with diluted sulfuric acid and recovered from the
acidic aqueous solution by adding aqueous sodium hydroxide.
1
. INTRODUCTION
reagents and do not have the disadvantages of the polymeric
reagents. All previously reported nonpolymeric recyclable io-
danes belong to iodine(III) compounds, and the reduced form of
these reagents can be effectively recovered from the reaction
6
Hypervalent iodine reagents have emerged as versatile and
environmentally benign reagents for various synthetically useful
oxidative transformations. Particularly useful are hypervalent
1
6
aÀd
5
mixture using liquid/liquid biphase fluorous techniques,
liquid/solid,
iodine(V) compounds (λ -iodanes), such as DessÀMartin per-
6eÀm
6nÀt
or liquid/liquid baseÀacid biphasic protocols.
iodinane (DMP), 2-iodoxybenzoic acid (IBX), and their analo-
gues, which are selective oxidants commonly used in the
In this paper, we present the synthesis, structural characteriza-
tion, and reactivity of first nonpolymeric recyclable hypervalent
iodine(V) reagents based on the readily available derivatives of
2-iodopyridine. These new reagents are useful for oxidation of
sulfides and alcohols, and the reduced form of these reagents can
be effectively recovered from the reaction mixture using liquid/
liquid acidÀbase biphasic protocols.
2
synthesis of natural products. However, despite their impor-
tance, IBX and its derivatives are not perfect reagents and have
some serious drawbacks. IBX is potentially explosive, and it is
insoluble in common organic solvents due to the strong inter-
molecular secondary bonding creating a three-dimensional poly-
meric structure. DMP is highly sensitive to moisture, which
makes difficult storage and handling of this oxidant. In addition,
IBX, DMP, and analogues are not perfect with respect to the
principles of Green Chemistry since they are normally used as the
3
2. RESULTS AND DISCUSSION
4
nonrecyclable, stoichiometric reagents. Numerous research
2.1. Preparation and Structural Investigation of 2-Iodyl-
groups have tried to improve hypervalent iodine(V)-based5
pyridines. 2-Iodylpyridines 2aÀe were prepared by oxidation of
reagents by developing their polymer-supported analogues,
the respective 2-iodopyridines 1 with 3,3-dimethyldioxirane
5
aÀf
5gÀj
such as polymer-supported variants of IBX, IBX-amides,
IBX-esters, N-(2-iodylphenyl)acylamides, and 2-iodylphenol
(
(
DMDO) similarly to the previously reported procedure
Scheme 1). The starting 2-iodopyridine 1a was from a com-
5g,h
5k
7
5l
ethers. Despite the utility of the polymer-supported iodine(V)
reagents, they still have several disadvantages. These reagents
require a multistep preparation and have lower reactivity compared
to the corresponding monomeric analogies, and moreover, the
repeated use of these polymers leads to significant degradation due to
the benzylic oxidation of the polystyrene chain. Accordingly,
substantial recent research efforts have been devoted to the
development of simple, nonpolymeric, recyclable iodanes, which
show reactivities similar to those of the original hypervalent iodine
mercial source, while 2-iodopyridine ethers 1bÀe were prepared
in high yields by the alkylation of commercially available 3-hy-
droxy-2-iodopyridine with appropriate alkyl halides under basic
conditions by the known procedure.
Products 2 precipitated from the reaction mixture and were
8
isolated in excellent yields in analytically pure form as white
Received: January 23, 2011
Published: April 04, 2011
r 2011 American Chemical Society
3812
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|J. Org. Chem. 2011, 76, 3812–3819

The Journal of Organic Chemistry
ARTICLE
microcrystalline solids by filtration followed by washing with
acetone and drying in vacuum. All products were analyzed by
NMR, IR, elemental analysis, and compounds 2a, 2c, and 2d, by
and the other IdO bond being almost perpendicular to it.
In addition, similar to the described earlier o-substituted iodyl-
phenol ethers, compounds 2c and 2d have intramolecular
7b
13
X-ray crystallography. In particular, C NMR spectra of pro-
I
O(ether) contacts ranging between 2.909 and 3.053 Å.
3
3 3
ducts 2 showed characteristic signals of the C-IO ipso-carbon at
In general, the first coordination sphere for compounds 2a, 2c,
2
7,9
about 152 ppm, which is typical of iodylarenes. The CÀO ipso-
carbon for the ethers 2cÀe showed at 156À158 ppm. IR spectra
of all compounds 2 showed two intense peak of IO at 780À770
2
À1
and 750 cm . 2-Iodylpyridines 2aÀe are stable at room
temperature and do not possess explosive properties upon
heating or impact. A slow decomposition is observed during
heating of the compound 2 in a capillary tube above the melting
point. Compounds 2d and 2e are soluble in dichloromethane,
chloroform, and acetonitrile, while products 2aÀc have a rela-
tively low solubility in organic solvents.
Structures of 2-iodylpyridines 2a, 2c, and 2d were established
by single-crystal X-ray crystallography (Figures 1À3). X-ray data
of products 2a, 2c, and 2d demonstrate the presence of, typical
for iodine(V) compounds, complex intra- and/or intermolecular
interactions. Although all compounds were crystallized using
water as a solvent or in the presence of moist air, only compounds
2
a and 2c have water molecules in the unit cells, while the
n-propyl-containing compound 2d crystallizes without any sol-
vent molecules. In all three molecules studied, IdO and IÀC
bond distances are in the typical range of 1.80 and 2.15 Å, respec-
7,9a,9b,9dÀ9f,9i
tively, which is characteristic for iodyl compounds.
Similarly, OdIdO bond angles in 2a, 2c, and 2d (101À102°)
are close to those expected for iodine(V) pseudoheterocycle
angles with one IdO bond located within the pyridine ring plane
Figure 2. (a) Perspective view of 2-iodyl-3-isopropoxypyridine 2c (two
Scheme 1. Preparation of 2-Iodylpyridines 2aÀe
independent molecules per unit cell) with 50% ellipsoid probability.
o
Selected distances [Å] and angles [ ]: I(1)ÀC(1) 2.144(6), I(2)ÀC(9)
2
1
.158(5), I(1)ÀO(1) 1.810(5), I(1)ÀO(2) 1.797(4), I(2)ÀO(4)
.798(5), I(2)ÀO(5) 1.798(4), C(1)ÀI(1)ÀO(1) 97.2(2), C(1)À
I(1)ÀO(2) 96.0(2), C(9)ÀI(2)ÀO(4) 95.0(2), C(9)ÀI(2)ÀO(5)
9
6.0(2), O(1)ÀI(1)ÀO(2) 102.3(2), O(4)ÀI(2)ÀO(5) 101.2(2).
(b) Intra- and intermolecular secondary bonding in 2c. Selected
distances [Å]: I(1) O(2A) 2.756(5), I(2)ÀO(5A) 2.651(4), I(1)À
3
3 3
N(2B) 3.023(5), I(2)ÀN(1) 3.028(5), I(1)ÀO(3) 2.909(5), I(2)À
O(6) 3.009(5).
o
Figure 1. (a) Perspective view of 2-iodylpyridine 2a with 50% ellipsoid probability. Selected distances [Å] and angles [ ]: I(1)ÀC(1) 2.152(2),
I(1)ÀO(1) 1.8101(16), I(1)ÀO(2) 1.8179(17), C(1)ÀI(1)ÀO(1) 94.35(8), C(1)ÀI(1)ÀO(2) 92.86(8), O(1)ÀI(1)ÀO(2) 101.70(8). (b) Intra-
and intermolecular secondary bonding in 2a. Selected distances [Å]: I(1) O(2B) 2.6326(16), I(1) O(3) 2.6999(17), I(1)ÀN(1A) 2.772(2).
3
3 3
3 3 3
3
813
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The Journal of Organic Chemistry
ARTICLE
o
Figure 3. (a) Perspective view of 2-iodyl-3-propoxypyridine 2d with 50% ellipsoid probability. Selected distances [Å] and angles [ ]: I(1)ÀC(1)
2
.1500(18), I(1)ÀO(1) 1.8049(13), I(1)ÀO(2) 1.8028(14), C(1)ÀI(1)ÀO(1) 96.51(7), C(1)ÀI(1)ÀO(2) 95.66(7), O(1)ÀI(1)ÀO(2) 101.60(7).
(b) Intra- and intermolecular secondary bonding in 2d. Selected distances [Å]: I(1) O(2B) 2.6592(14), I(1) O(1A) 2.744(1), I(1)ÀO(3)
3
3 3
3 3 3
3.052(2).
and 2d can be described as distorted octahedral configuration
with three covalent bonds and three relatively long intra- and/or
intermolecular contacts. It is interesting to see, however, that the
pyridine ring nitrogen atom is involved into the intermolecular
interactions in molecules 2a and 2c, because such N I short
The secondary interactions between the molecules of 2d are
quite different from those observed in 2a and 2c (Figure 3). First,
solvent molecules are absent in the unit cell. Second, and more
important, nitrogen atoms are not involved into intermolecular
network. Indeed, the closest observed for 2d N I distance is
3
3 3
3 3 3
contacts have never previously been reported for organoiodine-
V) compounds and are relatively uncommon for iodine(III)
∼3.43 Å, which is significantly larger than the sum of the van der
Waals radii of the iodine and nitrogen atoms. Instead, in addition
to three covalent bonds and one short intramolecular O-
(ether) I contact, each molecule of 2d forms two short
(
1
0
compounds. For example, the N I distances in the com-
plexes of alkynyliodonium tetrafluoroborates with 1,10-phenan-
3
3 3
3
3 3
1
0g
throline are in the range of 2.9À3.2 Å. The first coordination
sphere of the iodine atom in 2a consists of two short IdO bonds,
one IÀC bond, and three intermolecular contacts (Figure 1).
The shortest one (2.633 Å) originates from the O(2B) atom of
the neighboring molecule, while the second oxygen atom of the
OdIdO fragment does not participate in intermolecular bond-
ing. In addition, the nitrogen N(1A) atom from the pyridine ring
of another neighboring molecule provides quite short additional
secondary bonding (2.772 Å). Finally, the iodine atom also
interacts with the solvent water oxygen atom O(3) at 2.700 Å
distance. As a result, each molecule of 2a interacts with two other
neighboring molecules and solvent water forming a polymeric
zigzag chain.
The solvate water molecules, on the other hand, are not
involved in intermolecular bonding in compound 2c (Figure 2).
Instead, they are involved in formation of the solvent channel, which
separates double-helix type polymeric chains of 2c. These solvent
channels are ordered by the hydrogen bonds between hydrogen
atoms of water molecules and perpendicular to the pyridine ring
plane O(1) and O(4) oxygen atoms of the OdIdO fragment.
Although there are two independent molecules of 2c observed
per unit cell, their intra- and intermolecular coordination
motifs are similar. Each iodine center has three covalent bonds
(2.659À2.744 Å) intermolecular contacts with two oxygen
atoms located at two neighboring IdO fragments (Figure 3).
Such secondary interactions result in the polymeric zigzag
conformation of 2d. Since the nitrogen atom of the pyridine
ring in 2d is not involved in the secondary bonding, it is available
for solventÀsolute interaction, which could be responsible for
the higher solubility of 2d compared to compounds 2a and 2c.
2.2. Oxidations with 2-Iodylpyridines. We investigated the
oxidation of sulfides to sulfoxides and alcohols to aldehydes or
ketones using compound 2d because this compound has good
solubility in organic solvents (0.8 mg/mL in dichloromethane
and 1.1 mg/mL in acetonitrile). The oxidation of sulfides was
initially carried out with 0.6 equiv of reagent 2d under conditions
1
1
previously used in the similar reactions of IBX-esters, 2-iodyl-
7b 7a
phenol ethers, and IBX-amides. However, the yield of sulf-
oxides 3 under these conditions was relatively low, only 50À79%,
even after 24 h (Table 1, entries 1 and 2), which is probably
explained by partial decomposition of reagent 2d during reaction.
We have found that the yield of sulfoxides can be significantly
improved by performing the oxidation with 1.0 equiv of reagent
2d in acetonitrile under reflux conditions. Under these condi-
tions, the oxidation of methyl phenyl sulfide is complete in 1.5 h
affording product 3a in quantitative yield (Table 1, entry 3).
Similar reactions of several other aryl alkyl sulfides give the
respective sulfoxides 3 in high isolated yields (Table 1, entries
4À9). The oxidation of a dialkyl sulfide affords the respective
sulfoxide in a lower yield (Table 1, entry 10).
(
two IdO bonds with ∼1.8 Å bond distances and one IÀC
bond with ∼2.15 Å bond distance), one intramolecular
O(ether) I bond (∼3.0 Å), and two intermolecular bonds
3
3 3
(
one short, i.e., 2.651À2.756 Å, IdO
I bond and one long, i.
3
3 3
e., 3.023À3.028 Å, N
I bond). Overall, each molecule of 2c
The reaction conditions for the oxidation of alcohols with
reagent 2d were optimized using 1-phenyl ethanol (Table 2,
entries 1À3). Similarly to the oxidation of sulfides, the best yields
are obtained by performing the oxidation with 1.0 equiv of
3
3 3
interacts with three other neighboring molecules forming
double-helix polymeric chains isolated by the solvent water
channels.
3
814
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The Journal of Organic Chemistry
ARTICLE
a
a
Table 1. Oxidation of Sulfides to Sulfoxides with 2d
Table 2. Oxidation of Alcohols with 2d
a
Reaction conditions: alcohol (0.1 mmol), reagent 2d (0.1 mmol),
b
MeCN (1 mL), reflux, unless noted otherwise. Preparative yields of
2
was used. Numbers in parentheses show yields determined from H
NMR spectra of the reaction mixture.
c
,4-dinitrophenylhydrazone derivatives of 4. 0.6 equiv of reagent 2d
d
1
of primary alcohols to carboxylic acids or esters was observed
under these conditions.
The reactivity of reagent 2d in the oxidations of sulfides and
alcohols is generally similar to the reactivity of 2-iodylphenol
7b
ethers. However, compared to previously reported nonpoly-
7,9
meric organoiodine(V) oxidants, reagent 2d has the advantage
of being easily recyclable from the reaction mixture using a simple
acidÀbase liquidÀliquid biphasic protocol. We found that the
reduced form of reagent 2d, 2-iodo-3-propoxypyridine 1d, can be
effectively separated from the reaction mixture (after initial
addition of aqueous solution of Na S O in order to reduce
the excessive reagent 2d) by treatment with diluted sulfuric acid
and recovered in 95À99% from the acidic aqueous solution by
the addition of aqueous sodium hydroxide followed by extraction
with ethyl acetate. The recovered 2-iodo-3-propoxypyridine 1d
can be reoxidized to 2-iodyl-3-propoxypyridine 2d by DMDO in
almost quantitative yield (Scheme 1).
a
Reaction conditions: sulfide (0.1 mmol), reagent 2d (0.1 mmol),
b
MeCN (1 mL), reflux, unless noted otherwise. Yields of isolated
products. 0.6 equiv of reagent 2d was used.
c
reagent 2d in acetonitrile under reflux conditions (Table 2, entry 3).
To standardize the procedure and obtain reliable information
about preparative yields of the relatively volatile products 4, we
isolated aldehydes 4bÀd and fÀh and ketones 4a,c,i as solid 2,4-
dinitrophenylhydrazone derivatives after addition of a standard
solution of 2,4-dinitrophenylhydrazine to the reaction mixture.
Isolated yields of the hydrazone derivatives of products 4
obtained by the oxidation of various alcohols with reagent 2d
under standard conditions are shown in Table 2, entries 1À11.
The yields of carbonyl products formed in the oxidation of
2
2 3
3. CONCLUSIONS
3
-pentanol, 1-octanol, and 2-cyclohexenol (entries 12À14) were
In summary, we have prepared 2-iodylpyridine 2a and four
1
determined from H NMR spectra of reaction mixtures after
removal of solvent. In general, the oxidation of primary and
secondary benzylic and aliphatic alcohols proceeds selectively
affording the respective carbonyl compounds in good yields. The
oxidation of alcohols derived from heteroaromatic compounds
proceeds much slower (Table 2, entries 8 and 9). No overoxidation
3-alkoxy-2-iodylpyridines 2bÀe by oxidation of the respective
2-iodopyridines with 3,3-dimethyldioxirane. Structures of 2-io-
dylpyridine 2a, 2-iodyl-3-isopropoxypyridine 2c, and 2-iodyl-
3-propoxypyridine 2d were established by single-crystal X-ray
diffraction analysis. According to X-ray structural data, the nitro-
gen atom of the pyridine moiety is involved in intermolecular
3
815
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The Journal of Organic Chemistry
ARTICLE
interactions with hypervalent iodine atom in molecules 2a and 2c
but not in the molecule 2d. 2-Iodyl-3-propoxypyridine 2d has
good solubility in organic solvents and can be used as a recyclable
reagent for oxidation of sulfides and alcohols. The reduced form
of this reagent, 2-iodo-3-propoxypyridine 1d, can be effectively
separated from the reaction mixture by treatment with diluted
sulfuric acid and recovered in 95À99% from the acidic aqueous
solution by neutralizing it with aqueous sodium hydroxide.
a stirred mixture of the appropriate 2-iodopyridine derivative 1 at room
temperature. The reaction mixture immediately changed from colorless
solution to white suspension. The mixture was stirred at room tempera-
ture for 1 h, and the resulting white microcrystalline precipitate was
separated by filtration. The precipitate was washed with acetone and
dried in vacuum to afford analytically pure product 2.
2-Iodylpyridine (2a). Oxidation of a commercial sample of 2-iodo-
pyridine 1a (0.40 g, 1.95 mmol) according to the general procedure
afforded 0.45 g (97%) of product 2a, isolated as white crystals: mp
À1
9
9.3À101.2 °C (dec). IR (KBr) cm 3134, 1571, 1455, 1411, 758, 738.
1
4. EXPERIMENTAL SECTION
6
H NMR (DMSO-d ): δ 8.53 (d, J = 5 Hz, 1H), 8.12 (td, J = 9.3, 2 Hz,
H), 7.98 (d, J = 9.3 Hz, 1H), 7.61 (dd, J = 9.3, 5 Hz, 1H). C NMR
13
1
All reactions were performed under dry nitrogen atmosphere with
flame-dried glassware. All commercial reagents were ACS reagent grade
and used without further purification. Dichloromethane was distilled
(
DMSO-d ): δ 170.9, 150.3, 139.6, 127.2, 121.1. Anal. Calcd for
6
5 4 2
C H INO : C, 25.34; H, 1.70; I, 53.55; N, 5.91. Found: C, 25.23; H,
1.84; I, 53.62; N, 5.74.
from CaH immediately prior to use. Diethyl ether was distilled from
2
Single crystals of product 2a suitable for X-ray crystallographic
Na/benzophenone. Dimethyldioxirane (as 0.1 M solution in acetone)
was prepared from commercial acetone and oxone by a known
analysis were obtained by slow crystallization from water. X-ray diffrac-
tion data were collected on a Bruker APEX CCD diffractometer using
graphite-monochromated Mo KR radiation (λ = 0.71073 Å) at
À100 °C. Absorption corrections were applied to the data using the
DIFABS method. The structure was solved by the Patterson method and
12
method. 2-Iodopyridine 1a was from a commercial source, and
3
-alkoxy-2-iodopyridines 1bÀe were prepared in high yields by the
alkylation of commercially available 3-hydroxy-2-iodopyridine with
appropriate alkyl halides under basic conditions by the known
procedure. All other reagents and solvents were of commercial quality
8
2
refined by full-matrix least-squares refinement on F using Crystals for
from freshly opened containers. NMR spectra were recorded at 500
MHz ( H NMR) and 125 MHz ( C NMR). Chemical shifts (δ) are
Windows program. Crystal data for 2a: C H INO x H O, M = 255.01,
5 4 2 2
1
13
monoclinic, space group P21/c, a = 6.2624(7) Å, b = 14.4474(16) Å, c =
3
reported in parts per million.
General Procedure for Preparation of 2-Iodopyridines
8.0465(9) Å, β = 107.3260(10)°, V = 694.98(13) Å , Z = 4, T = 173 K,
À1
3
μ(λ = 0.80000 Å) = 4.552 mm , dcalc = 2.437 g/cm , 1659 reflections
8
(
1bÀe) . To a solution of 2-iodo-3-hydroxypyridine in dry DMF was
measured, 1587 unique, R
= 0.0138, wR =0.0337 (I > 3σ(I)), R =
1 2 1
added potassium carbonate or sodium hydride under stirring. After
0 min the appropriate alkyl bromide or alkyl iodide was added to the
0.0148, wR = 0.0344 (all data), GOF = 1.0552. For further details on
2
1
crystal structure of compound 2a, see the CIF file.
reaction mixture. The reaction was stirred at 50 °C for 3 h. The solvent
was evaporated in vacuum, and the residue was extracted with ethyl
acetate and separated by column chromatography using 1:3 mixture
EtOAc/hexanes to afford analytically pure product 1.
2-Iodyl-3-methoxypyridine (2b). Oxidation of 2-iodo-3-methoxypyr-
idine 1b (0.21 g, 0.88 mmol) according to the general procedure
afforded 0.22 g (92%) of product 2b, isolated as white crystals: mp
À1
147À147.4 °C (dec). IR (KBr) cm 3076, 3045, 2939, 2852, 1556,
8a
1
2-Iodo-3-methoxypyridine (1b) . Reaction of iodomethane (0.75 g,
1458, 1408, 1278, 1002, 772, 753. H NMR (DMSO-d ): δ 8.27 (dd, J =
6
5
.4 mmol) and NaH (0.22 g, 5.4 mmol) with 2-iodo-3-hydroxypyridine
4.5, 1.5 Hz, 1H), 7.72 (dd, J = 8.5, 1.5 Hz, 1H), 7.63 (dd, J = 8.5, 4.5 Hz,
1
3
(
(
1.00 g, 4.5 mmol) according to the general procedure afforded 0.76 g
71%) of product 1b, isolated as white colorless needles (recrystallized
1H), 3.9 (s, 3H). C NMR (DMSO-d ): δ 156.1, 152.3, 141.2, 127.8,
6
120.9, 57. Anal. Calcd for C H INO : C, 26.99; H, 2.26; N, 5.25. Found:
6
6
3
2
1
from dichloromethane): mp 57.7À58.3 °C (lit. 55À57 °C). H NMR
CDCl ): δ 8.01 (dd, J = 4.5, 1.5 Hz, 1H), 7.21 (dd, J = 8.3, 4.5 Hz, 1H),
.01 (dd, J = 8.3, 1.5 Hz, 1H), 3.91 (s, 3H).
C, 27.07; H, 2.16; N, 5.22.
(
7
3
2-Iodyl-3-isopropoxypyridine (2c). Oxidation of 2-iodo-3-isopropox-
ypyridine 1c (0.20 g, 0.76 mmol) according to the general procedure
afforded 0.20 g (92%) of product 2c, isolated as white crystals: mp
8a
2
-Iodo-3-isopropoxypyridine (1c) . Reaction of 2-bromopropane
À1
(0.72 g, 5.9 mmol) and K CO (2.80 g, 20 mmol) with 2-iodo-3-
2
3
110.8À111.5 °C (dec); IR (KBr) cm 3071, 2982, 2948, 1550, 1454,
1
hydroxypyridine (1.00 g, 4.5 mmol) according to the general procedure
afforded 0.86 mg (73%) of product 1c as colorless oil. H NMR
1409, 1280, 1103, 790, 770, 757. H NMR (DMSO-d ): δ 8.25 (dd, J =
6
1
4.5, 1.5 Hz, 1H), 7.76 (dd, J = 8.5, 1.5 Hz, 1H), 7.6 (dd, J = 8.5, 4.5 Hz,
13
(CDCl ): δ 7.97 (dd, J = 4.5, 1.5 Hz, 1H), 7.16 (dd, J = 8, 4.5 Hz,
1H), 4.84 (sept, J = 6 Hz, 1H), 1.34 (d, J = 6 Hz, 6H). C NMR
3
1
H), 6.99 (dd, J = 8, 1.5 Hz, 1H), 4.56 (sept, J = 6 Hz, 1H), 1.41 (d, J = 6
(DMSO-d ): δ 157.7, 152, 142, 129, 123.4, 73.7, 22.3. Anal. Calcd for
6
13
Hz, 6H). C NMR (CDCl
-Iodo-3-propoxypyridine (1d) . Reaction of 1-iodopropane (1.15 g,
.8 mmol) and K CO (3.10 g, 23 mmol) with 2-iodo-3-hydroxypyr-
idine (1.00 g, 4.5 mmol) according to the general procedure afforded
3
): 153.9, 142.5, 123.3, 119.8, 114, 72.6, 21.9.
C H INO : C, 32.56; H, 3.42; N, 4.75. Found: C, 32.46; H, 3.36;
8
10
3
8a
2
N, 4.87.
6
2
3
Single crystals of product 2c suitable for X-ray crystallographic analysis
were obtained by slow crystallization from a hexaneÀdichloromethane
solution in a refrigerator. X-ray diffraction data were collected on Rigaku
RAPID II diffractometer using graphite-monochromated Mo KR radiation
(λ = 0.71073 Å) at À150 °C. Absorption corrections were applied to the
data using a multiscan method. The structure was solved by the Patterson
1
0
(
.84 g (73%) of product 1d as colorless oil. H NMR (CDCl
dd, J = 4.8, 1 Hz, 1H), 7.16 (dd, J = 7.9, 4.8 Hz, 1 H), 6.97 (dd, J = 7.9, 1
Hz, 1H), 3.99 (t, J = 6.3 Hz, 2H), 1.88 (m, 2H), 1.26 (t, J = 7.3 Hz, 6H).
3
): δ 7.97
1
3
C NMR (CDCl
-Iodo-3-butoxypyridine (1e) . Reaction of 1-bromobutane (0.93 g,
.8 mmol) and K CO (3.10 g, 23 mmol) with 2-iodo-3-hydroxypyr-
3
): 154.7, 142.4, 123.4, 117.7, 112.3, 70.9, 22.4, 10.7.
8b
2
2
method and refined by full-matrix least-squares refinement on F using
6
Crystals for Windows program. Crystal data for 2c: C H INO x 2H O,
2
3
8
10
3
2
idine (1.00 g, 4.5 mmol) according to the general procedure afforded
M = 331.10, triclinic, space group P-1, a = 9.1841(3) Å, b = 10.3130(5) Å,
c = 12.2949(8) Å, R = 82.634(6)°, β = 85.041(6)°, γ = 82.063(6)°, V =
1
1
(
4
.07 g (85%) of product 1e as colorless oil. H NMR (CDCl
dd, J = 4.5, 1.5 Hz, 1H), 7.17 (dd, J = 8, 4.5 Hz, 1H), 6.97 (dd, J = 8,
.5 Hz, 1H), 4.03 (t, J = 6.5 Hz, 2H), 1.84 (m, 2H), 1.57 (m, 2H), 1.01 (t,
3
): δ 7.98
3
À1
1141.04(10) Å , Z = 4, T = 123 K, μ(λ = 0.80000 Å) = 2.809 mm , d
calc
=
3
1 2
1.927 g/cm , 32 057 reflections measured, 5201 unique, R = 0.0432, wR =
13
J = 7.3 Hz, 3H). C NMR (CDCl
9.1, 31, 19.3, 13.8.
General Procedure for Oxidation of 2-Iodopyridines. A
3
): 154.8, 142.4, 123.4, 117.7, 112.3,
0.0926 (I>2σ(I)), R =0.0573, wR =0.1031 (all data), GOF = 0.9781. For
1 2
6
further details on the crystal structure of compound 2c, see the CIF file.
2-Iodyl-3-propoxypyridine (2d). Oxidation of 2-iodo-3-propoxypyr-
idine 1d (0.22 g, 0.87 mmol) according to the general procedure
12
freshly prepared solution of dimethyldioxirane in acetone was added to
3
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dx.doi.org/10.1021/jo200163m |J. Org. Chem. 2011, 76, 3812–3819

The Journal of Organic Chemistry
ARTICLE
1
7
afforded 0.24 g (96%) of product 2d, isolated as white crystals: mp
2-Chloroethyl Phenyl Sulfoxide (3f) . Reaction of 2-chloroethyl
À1
1
1
4
1
1
16.5À117 °C (with decomposition). IR (KBr) cm 3063, 2950, 2910,
phenyl sulfide (17 mg, 0.1 mmol) according to the general procedure
afforded 17 mg (89%) of product 3f, isolated as an amorphous solid. H
1
1
548, 1462, 1420, 1280, 1002, 773, 760. H NMR (CDCl
3
): δ 8.3 (d, J =
Hz, 1 H), 7.46 (m, 1H), 7.38 (d, J = 8 Hz, 1H), 4.14 (t, J = 6.3 Hz, 2H),
NMR (CDCl
3
): δ 7.66À7.64 (m, 2H), 7.58À7.53 (m, 3H), 4À3.95 (m,
13
1
H), 3.69À3.64 (m, 1H), 3.19À3.15 (m, 2H).
.9 (m, 2H), 1.06 (t, J = 7.3 Hz, 3H). C NMR (DMSO-d
52.3, 141.2, 127.8, 121.5, 71.0, 21.6, 10.2. Anal. Calcd for C
6
): δ 156.3,
3
10INO :
1
8
Benzyl Phenyl Sulfoxide (3g) . Reaction of benzyl phenyl sulfide (20
mg, 0.1 mmol) according to the general procedure afforded 21 mg
8
H
C, 32.56; H, 3.42; N, 4.75. Found: C, 32.53; H, 3.38; N, 4.69.
(
95%) of product 3g, isolated as colorless crystals (recrystallized from
Single crystals of product 2d suitable for X-ray crystallographic
analysis were obtained by slow crystallization from a hexaneÀdichloro-
methane solution in a refrigerator. X-ray diffraction data were collected
on Rigaku RAPID II diffractometer using graphite-monochromated Mo
KR radiation (λ = 0.71073 Å) at room temperature. Absorption
corrections were applied to the data using a multiscan method. The
structure was solved by the Patterson method and refined by full-matrix
1
0,11
1
hexaneÀdichloromethane); 122.4À123.6 °C (lit.
122À123 °C). H
NMR (CDCl
3
): δ 7.48À7.37 (m, 5H), 7.3À7.23 (m, 3H), 6.98 (d, J =
7
.5 Hz, 2H), 4.1 (d, J = 12.5 Hz, 1H), 4.0 (d, J = 12.5 Hz, 1H).
1
7,19
Dioctylsulfoxide (3h)
. Reaction of dioctylsulfide (26 mg, 0.1
mmol) according to the general procedure afforded 17 mg (63%) of
product 3h, isolated as colorless needles (recrystallized from hexaneÀ
1
9
1
2
dichloromethane); 70.5À71 °C (lit. 75À76 °C). H NMR (CDCl ):
least-squares refinement on F using Crystals for Windows program.
3
δ 2.72À2.59 (m, 4H), 1.8À1.73 (m, 4H), 1.45À1.38 (m, 4H), 1.35À
Crystal data for 2d: C H INO , M = 295.08, monoclinic, space group
8
10
3
1
.25 (m, 16H), 0.88 (t, J = 6.8 Hz, 3H).
P21/n, a = 6.57260(10) Å, b = 12.6845(2) Å, c = 11.8472(8) Å, β =
3
General Procedure for the Oxidation of Alcohols with
-Iodyl-3-propoxypyridine (2d). To a solution of 2-iodyl-3-pro-
9
3
7.126(7)°, V = 980.07(7) Å , Z = 4, T = 298 K, μ(λ = 0.80000 Å) =
À1
3
2
.243 mm , dcalc = 2.000 g/cm , 18 700 reflections measured, 2259
poxypyridine 2d (30 mg, 0.1 mmol) in 1 mL of dry MeCN was added the
appropriate alcohol (0.1 mmol). The reaction mixture was stirred at
reflux for several hours. After the reaction was complete, a standard
solution of 1.5 mL of 2,4-dinitrophenylhydrazine (prepared from 200
unique, R = 0.0145, wR = 0.0346 (I > 2σ(I)), R = 0.0166, wR =
1
2
1
2
0
.0353 (all data), GOF = 1.0008. For further details on the crystal
structure of compound 2d, see the CIF file.
-Butoxy-2-iodylpyridine (2e). Oxidation of 3-butoxy-2-iodopyridine
3
1
0
1
1
8
2
1
3
e (0.15 g, 0.54 mmol) according to the general procedure afforded
2 4
mg of 2,4-dinitrophenylhydrazine, 1 mL of concd H SO , 10 mL of
.17 g (99%) of product 2e, isolated as white crystals: mp 117.6À
EtOH, and 2 mL of H O) was added. The precipitate of 2,4-dinitro-
2
À1
17.8 °C (dec). IR(KBr) cm 3036, 2958, 2886, 1553, 1449, 1413, 1296,
phenylhydrazone 4 was filtered, washed with water, and dried in vacuum.
1
20,21
064, 781, 766. H NMR (CDCl ): δ 8.3 (d, J = 4.5 Hz, 1H), 7.51 (dd, J =
2,4-Dinitrophenylhydrazone of Acetophenone (4a)
. Reaction of
3
.5, 4.5 Hz, 1H), 7.42 (d, J = 8.5 Hz, 1H), 4.2 (t, J = 6.5 Hz, 2H), 1.87 (m,
1-phenylethanol (12 mg, 0.1 mmol) according to the general procedure
afforded 24 mg (80%) of product 4a, isolated as orange needles
(recrystallized from hexaneÀdichloromethane): mp 246À246.7 °C
13
H), 1.54 (m, 2H), 1.0 (t, J = 7.5 Hz, 3H). C NMR (CDCl
52.9, 142.8, 121.7, 70.5, 30.7, 19.1, 13.8. Anal. Calcd for C
4.97; H, 3.91; N, 4.53. Found: C, 34.80; H, 3.87; N, 4.48.
3
): δ 158.9,
12INO : C,
9
H
3
2
1
1
(lit. mp 248À249 °C). H NMR (CDCl ): δ 11.37 (s, 1H), 9.18 (d,
3
General Procedure for the Oxidation of Sulfides with
-Iodyl-3-propoxypyridine (2d). To a solution of 2-iodyl-3-pro-
J = 1.8 Hz, 1H), 8.37 (dd, J = 9.5, 1.8 Hz, 1H), 8.14 (d, J = 9.5 Hz, 1H),
2
7.9À7.84 (m, 2H), 7.52À7.4 (m, 3H) 2.48 (s, 3H).
2
1,22
poxypyridine 2d (30 mg, 0.1 mmol) in 1 mL of dry MeCN was added the
2,4-Dinitrophenylhydrazone of Benzaldehyde (4b)
. Reaction of
appropriate sulfide (0.1 mmol). The reaction was stirred at reflux for
benzyl alcohol (11 mg, 0.1 mmol) according to the general procedure
several hours (see Table 1). Then saturated aqueous Na
was added, the mixture was extracted with ethyl acetate, and the organic
phase dried over anhydrous MgSO and concentrated. Purification by
2
S
2
O
3
(1.5 mL)
afforded 26 mg (91%) of product 4b, isolated as light orange needles
22
(recrystallized from hexaneÀdichloromethane): 235.8À237 °C (lit.
1
241À242 °C). H NMR (CDCl
): δ 11.33 (s, 1H), 9.16 (s, 1H),
3
4
flash column chromatography (hexaneÀethyl acetate, 3:1) gave pure
8.44À8.3 (m, 1H), 8.22À8.04 (m, 2H), 7.84À7.73 (m, 2H), 7.56À7.4
22,23
product 3.
(m, 3H), 7.32À7.2 (m, 2H).
13
Methyl Phenyl Sulfoxide (3a) . Reaction of methyl phenyl sulfide
2,4-Dinitrophenylhydrazone of p-Methoxybenzaldehyde (4c)
.
(
(
7
12 mg, 0.1 mmol) according to the general procedure afforded 14 mg
Reaction of p-methoxybenzyl alcohol (14 mg, 0.1 mmol) according to
the general procedure afforded 28 mg (89%) of product 4c, isolated as
red needles (recrystallized from hexaneÀdichloromethane): mp 254.1À
1
100%) of product 3a, isolated as a yellow oil. H NMR (CDCl ): δ
3
.67À7.65 (m, 2H), 7.54À7.51 (m, 3H), 2.73 (s, 3H).
14
23
1
Ethyl Phenyl Sulfoxide (3b) . Reaction of ethyl phenyl sulfide (14
mg, 0.1 mmol) according to the general procedure afforded 15 mg
255 °C (lit. mp 256À257 °C). H NMR (CDCl
3
) δ 11.28 (s, 1H),
9.15 (s, 1H), 8.34 (d, J = 10 Hz, 1H), 8.08 (d, J = 10 Hz, 1H), 7.72 (d, J =
6.8 Hz, 2H), 6.48 (d, J = 6.8 Hz, 2H), 3.88 (s, 3H).
1
(100%) of product 3b, isolated as a yellow oil. H NMR (CDCl
3
): δ
.62À7.61 (m, 2H), 7.54À7.50 (m, 3H), 2.94À2.87 (m, 1H),
.81À2.73 (m, 1H), 1.2 (t, J = 7.5 Hz, 3H).
22
7
2
2,4-Dinitrophenylhydrazone of m-Nitrobenzaldehyde (4d) . Reac-
tion of m-nitrobenzyl alcohol (15 mg, 0.1 mmol) according to the
general procedure afforded 24 mg (73%) of product 4d, isolated as a
15
4
-Methoxyphenyl Methyl Sulfoxide (3c) . Reaction of 4-methoxy-
22
phenyl methyl sulfide (15 mg, 0.1 mmol) according to the general
yellow solid (recrystallized from ethanol): mp 282À283 °C (lit. mp
1
procedure afforded 14 mg (82%) of product 3c, isolated as a brown oil.
292À293 °C). H NMR (DMSO-d
6
): δ 11.80 (s, 1H), 8.89 (d, J = 2.5
1
H NMR (CDCl ): δ 7.6 (d, J = 8.5 Hz, 2H), 7.04 (d, J = 8.5 Hz, 2H),
Hz, 1H), 8.83 (s, 1H), 8.57 (s, 1H), 8.44 (dd, J = 9.8, 2.5 Hz, 1H), 8.31
(d, J = 7.7 Hz, 1H), 8.25 (d, J = 7.7 Hz, 1H), 8.16 (d, J = 9.8 Hz, 1H), 7.80
(t, J = 7.7 Hz, 1H).
2,4-Dinitrophenylhydrazone of 1-Indanone (4e) . Reaction of
1-indanol (13 mg, 0.1 mmol) according to the general procedure afforded
31mg(99%) ofproduct 4e, isolatedasorangeneedles (recrystallizedfrom
3
3
.86 (s, 3H), 2.73 (s, 3H).
15
4
-Chlorophenyl Methyl Sulfoxide (3d) . Reaction of 4-chlorophenyl
2
3
methyl sulfide (16 mg, 0.1 mmol) according to the general procedure
afforded 17 mg (100%) of product 3d, isolated as a yellow oil. H NMR
1
(CDCl
3
): δ 7.6 (d, J = 8.3 Hz, 2H), 7.52 (d, J = 8.3 Hz, 2H), 2.72 (s, 3H).
16
23
4
-Bromophenyl Methyl Sulfoxide (3e) . Reaction of 4-bromophenyl
hexaneÀdichloromethane): mp 259À259.6 °C (lit. mp 256À258 °C).
1
methyl sulfide (20 mg, 0.1 mmol) according to the general procedure
3
H NMR (CDCl ): δ 11.11 (s, 1H), 9.17 (d, J = 2.5 Hz, 1H), 8.36 (d, J =
afforded 18 mg (82%) of product 3e, isolated as colorless needles
9.5 Hz, 1H), 8.13 (d, J = 9.5 Hz, 1H), 7.89 (d, J = 7.5 Hz, 2H), 7.46À7.35
22,23
1
6b
(
8
8
recrystallized from hexaneÀdichloromethane); 82.4À83.3 °C (lit.
(m, 3H), 3.28 (t, J = 6.1 Hz, 2H), 2.99 (t, J = 6.1 Hz, 2H).
2,4-Dinitrophenylhydrazone of Nicotinaldehyde (4f)
1
2.5À84 °C). H NMR (CDCl
3
): δ 7.68 (d, J = 8.3 Hz, 2H), 7.53 (d, J =
. Reaction
.3 Hz, 2H), 2.72 (s, 3H).
of 3-pyridinylmethanol (11 mg, 0.1 mmol) according to the general
3
817
dx.doi.org/10.1021/jo200163m |J. Org. Chem. 2011, 76, 3812–3819

The Journal of Organic Chemistry
ARTICLE
procedure afforded 19 mg (66%) of product 4f, isolated as orange plates
2-iodyl-3-propoxypyridine 2d (30 mg, 0.1 mmol) in 1 mL of dry MeCN
was added 1-phenylethanol (12 mg, 0.1 mmol). The reaction mixture
was stirred at reflux for 3 h, and then saturated aqueous solution of
(
(
1
8
recrystallized from hexaneÀdichloromethane): mp 257.4À258 °C
23 1
lit. mp 259À261 °C). H NMR (CDCl
3
): δ 11.40 (s, 1H), 9.17 (s,
H), 8.94 (s, 1H), 8.69 (d, J = 5 Hz, 1H), 8.40 (d, J = 9 Hz, 1H),
.18À8.08 (m, 3H), 7.46À7.38 (m, 1H).
,4-Dinitrophenylhydrazone of Thiophene-2-carbaldehyde (4g) .
Na
2
S
2
O
3
(1.5 mL) and 20% H
2
SO
4
(3À5 mL) were added. The mixture
was extracted with ethyl acetate, and to the organic phase, 2À3 mL of
standard solution of 2,4-dinitrophenylhydrazine was added. The pre-
cipitate of 2,4-dinitrophenylhydrazone 4a was filtered, washed with
water, and dried in vacuum, to give 4a (22 mg, 73%). To the aqueous
layer was added 20% NaOH (5À7 mL), and then the mixture was
extracted with ethyl acetate. The organic phase was dried over anhy-
2
3
2
Reaction of 2-thiophenylmethanol (11 mg, 0.1 mmol) according to the
general procedure afforded 21 mg (72%) of product 4e, isolated as
orange plates (recrystallized from hexaneÀdichloromethane): mp
2
3
1
2
(
23À224.3 °C (lit. mp 239À241 °C). H NMR (CDCl
3
): δ 11.29
s, 1H), 9.15 (d, J = 2.3 Hz, 1H), 8.37 (dd, J = 9.5, 2.3 Hz, 1H), 8.31 (s,
4
drous MgSO and concentrated in vacuum to give 2-iodo-3-propox-
1H), 8.03 (d, J = 9.5 Hz, 1H), 7.49 (d, J = 4.3 Hz, 1H), 7.37 (d, J = 4.3 Hz,
ypyridine (25 mg, 95%).
1
H), 7.13 (m, 2H).
2
3
2
,4-Dinitrophenylhydrazone of 3-Phenyl-1-propanal (4h) . Reac-
’
ASSOCIATED CONTENT
tion of 3-phenyl-1-propanol (14 mg, 0.1 mmol) according to the general
procedure afforded 21 mg (69%) of product 4h, isolated as orange plates
S
Supporting Information. X-ray data for compounds 2a,
2
3
b
(
recrystallized from hexaneÀdichloromethane): mp 160À161 °C (lit.
1
2c, and 2d (CIF) and copies of NMR spectra for all compounds.
This material is available free of charge via the Internet at http://
pubs.acs.org.
mp 156À157 °C). H NMR (CDCl
3
): δ 11.02 (s, 1H), 9.12 (s, 1H), 8.3
(
2
2
d, J = 9.8 Hz, 1H), 7.90 (d, J = 9.8 Hz, 1H), 7.56 (s, 1H), 7.35À7.31 (m,
H), 7.26À7.24 (m, 3H), 2.98 (t, J = 7.5 Hz, 2H), 2.79 (t, J = 7.5 Hz,
H).
20,23
’ AUTHOR INFORMATION
2
,4-Dinitrophenylhydrazone of Cycloheptanone (4i)
. Reaction
of cycloheptanol (11 mg, 0.1 mmol) according to the general procedure
Corresponding Author
vzhdanki@d.umn.edu; vnemykin@d.umn.edu.
afforded 18 mg (62%) of product 4i, isolated as yellow needles (recrystal-
*
2
3
lized from hexaneÀdichloromethane): mp 147À147.2 °C (lit. mp
1
1
47À148 °C). H NMR (CDCl
3
): δ 11.05 (s, 1H), 9.13 (d, J = 2.5
Hz, 1H), 8.3 (dd, J = 9.5, 2.5 Hz, 1H), 7.99 (d, J = 9.5 Hz, 1H), 2.66À2.60
’ ACKNOWLEDGMENT
(
m, 2H), 2.59À2.54 (m, 2H), 1.92À1.82 (m, 2H), 1.76À1.62 (m, 6H).
-Pentanone (4j). Reaction of 3-pentanol (9 mg, 0.1 mmol) with
-iodyl-3-propoxypyridine 2d (30 mg, 0.1 mmol) in 1 mL of dry MeCN,
This work was supported by a research grant from the
National Science Foundation (CHE-1009038) and by NSF-
MRI award (MRI - 0922366). VVZ and MSY are also thankful
to the Government of Russia for support of their cooperative
research program on hypervalent iodine chemistry (FCP, GK
3
2
after 2.5 h reflux followed by evaporation of solvent, afforded 3-pentanone
1
in 61% yield as determined by H NMR using 1,1,2,2-tetrachloroethane as
1
an internal standard. H NMR of the product is identical to the spectra
0
2.740.11.5211; Zayavka 2010-1.5-000-010-044).
published in the Spectral Database for Organic Compounds, SDBS (http://
riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng).
Octanal (4k). Reaction of 1-octanol (13 mg, 0.1 mmol) with 2-iodyl-
’
REFERENCES
(1) For books and selected reviews on hypervalent iodine
3-propoxypyridine 2d (30 mg, 0.1 mmol) in 1 mL of dry MeCN, after 2 h
chemistry, see:( a) Varvoglis, A. Hypervalent Iodine in Organic Synthesis;
Academic Press: London, 1997. (b) Hypervalent Iodine Chemistry;
Wirth, T., Ed.; Springer-Verlag, Berlin, 2003. (c) Koser, G. F. Aldrichi-
mica Acta 2001, 34, 89–102. (d) Koser, G. F. Adv. Heterocycl. Chem.
reflux followed by evaporation of solvent, afforded 1-octanal in 75% yield
1
as determined by H NMR using 1,1,2,2-tetrachloroethane as an internal
1
standard. H NMR of the product is identical to the spectra published in
the Spectral Database for Organic Compounds, SDBS (http://riodb01.
ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng).
2004, 86, 225–292. (e) Moriarty, R. M. J. Org. Chem. 2005,
70, 2893–2903. (f) Quideau, S.; Pouysegu, L.; Deffieux, D. Synlett
2008, 467–495. (g) Ladziata, U.; Zhdankin, V. V. ARKIVOC 2006,
2-Cyclohexene-1-one (4l). Reaction of 2-cyclohexene-1-ol (10 mg,
0
1
.1 mmol) with 2-iodyl-3-propoxypyridine 2d (30 mg, 0.1 mmol) in
No. ix, 26–58. (h) Ciufolini, M. A.; Braun, N. A.; Canesi, S.; Ousmer, M.;
Chang, J.; Chai, D. Synthesis 2007, 3759–3772. (i) Zhdankin, V. V. Sci.
Synth. 2007, 31a (Ch. 31.4.1), 161–234. (j) Zhdankin, V. V.; Stang, P. J.
Chem. Rev. 2008, 108, 5299–5358. (k) Ladziata, U.; Zhdankin, V. V.
Synlett 2007, 527–537. (l) Dohi, T.; Kita, Y. Chem. Commun.
2009, 2073–2085. (m) Ochiai, M.; Miyamoto, K. Eur. J. Org. Chem.
2008, 4229–4239. (n) Yusubov, M. S.; Zhdankin, V. V. Mendeleev
Commun. 2010, 20, 185–191. (o) Zhdankin, V. V. ARKIVOC 2009,
No. i, 1–62. (p) Uyanik, M.; Ishihara, K. Chem. Commun.
mL of dry MeCN, after 2.5 h reflux followed by evaporation of solvent,
1
afforded 2-cyclohexene-1-one in 66% yield as determined by H NMR
using 1,1,2,2-tetrachloroethane as an internal standard. H NMR of the
1
product is identical to the spectra published in the Spectral Database for
Organic Compounds, SDBS (http://riodb01.ibase.aist.go.jp/sdbs/cgi-
bin/cre_index.cgi?lang=eng).
Typical Procedure for the Oxidation of Organic Sulfides
with the Recovery of 2-Iodo-3-propoxypyridine (1d). To a
solution of 2-iodyl-3-propoxypyridine 2d (30 mg, 0.1 mmol) in 1 mL of
dry MeCN was added benzyl phenyl sulfide (20 mg, 0.1 mmol). The
reaction mixture was stirred at reflux for 2.5 h, and then a saturated
2
2
009, 2086–2099. (q) Ngatimin, M.; Lupton, D. W. Aust. J. Chem.
010, 63, 653–658. (r) Yusubov, M. S.; Nemykin, V. N.; Zhdankin, V. V.
Tetrahedron 2010, 66, 5745–5752. (s) Satam, V.; Harad, A.; Rajule, R.;
Pati, H. Tetrahedron 2010, 66, 7659–7706. (t) Uyanik, M.; Ishihara, K.
Aldrichimica Acta 2010, 43, 83–91. (u) Merritt, E. A.; Olofsson, B.
Angew. Chem., Int. Ed. 2009, 48, 9052–9070. (v) Merritt, E. A.; Olofsson,
B. Synthesis 2011, 517–538. (w) Brand, J. P.; Gonzalez, D. F.; Nicolai, S.;
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aqueous solution of Na
added. The mixture was extracted with ethyl acetate, and the organic
phase was dried over anhydrous MgSO and concentrated to give pure
2
S
2
O
3
(1.5 mL) and 20% H
2
SO
4
(3À5 mL) were
4
product 3g (20 mg, 91%). The aqueous layer was mixed with 20%
NaOH (5À7 mL) and then extracted with ethyl acetate The organic
(2) For a recent Perspective on organoiodine(V) reagents in organic
4
extract was dried over anhydrous MgSO and concentrated in vacuum to
synthesis, see: Zhdankin, V. V. J. Org. Chem. 2011, 76, 1185–1197.
give 26 mg (99%) of 2-iodo-3-propoxypyridine 1d.
Typical Procedure for the Oxidation of Alcohols with the
Recovery of 2-Iodo-3-propoxypyridine (1d). To a solution of
(
3) IBX can explode under impact or heating above 200 °C. See:
(a) Plumb, J. B.; Harper, D. J. Chem. Eng. News 1990, 68, 3. (b) Frigerio,
M.; Santagostino, M.; Sputore, S. J. Org. Chem. 1999, 64, 4537–4538.
3
818
dx.doi.org/10.1021/jo200163m |J. Org. Chem. 2011, 76, 3812–3819

The Journal of Organic Chemistry
4) In the only available report, it has been shown that IBX can be
ARTICLE
(
(10) To our knowledge, no X-ray crystal structures with N
I
3
3 3
recovered in a low yield (about 50%) after reaction with alcohols in ethyl
interactions in organoiodine(V) compounds have previously been
acetate: More, J. D.; Finney, N. S. Org. Lett. 2002, 4, 3001–3003.
reported. For X-ray structures of iodine(III) compounds with I
N
3
3 3
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3
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