New oxidative transformations of alkenes and alkynes under the action of diacetoxyiodobenzene

Article abstract of DOI:10.1007/s11172-005-0027-8

Treatment of alkenes and alkynes with diacetoxyiodobenzene activated by mineral and organic acids predominantly results in oxidative rearrangement. 1,4-Diphenylbutadiene in MeOH gives 3,4-dimethoxy-1,4-diphenylbut-1-ene.

Full text of DOI:10.1007/s11172-005-0027-8

Russian Chemical Bulletin, International Edition, Vol. 53, No. 8, pp. 1735—1742, August, 2004
1735
New oxidative transformations of alkenes and alkynes
under the action of diacetoxyiodobenzene
a
b
c
M. S. Yusubov,a,b G. A. Zholobova, I. L. Filimonova, and KiꢀWhan Chi
ꢀ
aTomsk Polytechnical University,
30 prosp. Lenina, 634004 Tomsk, Russian Federation.
Eꢀmail: yusubov@mail.ru
bSiberian State Medical University,
2 Moskovskii trakt, 634050 Tomsk, Russian Federation
cUlsan University,
680ꢀ749 Ulsan, Republic of Korea
Treatment of alkenes and alkynes with diacetoxyiodobenzene activated by mineral and
organic acids predominantly results in oxidative rearrangement. 1,4ꢀDiphenylbutadiene in
MeOH gives 3,4ꢀdimethoxyꢀ1,4ꢀdiphenylbutꢀ1ꢀene.
Key words: polyvalent iodine compounds, diacetoxyiodobenzene, alkenes, alkynes, oxidaꢀ
tive rearrangement.
Scheme 1
Diacetoxyiodobenzene (DIB) is one of the most acꢀ
cessible, stable, and popular compounds of polyvalent
iodine.1—7. In contrast to the majority of related comꢀ
pounds, DIB is weakly electrophilic and does not react
with most alkenes and alkynes. However, more nucleoꢀ
philic unsaturated compounds such as cyclopentadiene
and cyclooctaꢀ1,5ꢀdiene in boiling AcOH afford mixtures
of bisacetoxylation products.2,8 The electrophilicity of
DIB can be enhanced by activators (I2, HBF4, Ph4PI,
Et4NBr, Me3SiN3, PhSeSePh, and LiClO4), which afꢀ
fect, in one way or another, the direction of the reaction
and the nature of the final products.9—16
Recently,17 we found that DIB activated by H2SO4
reacts with various alkenes to give rearrangement or addiꢀ
tion products. In the present work, we performed a more
detailed study of the factors affecting the reactions of DIB
with alkenes in the presence of mineral or organic acids in
the temperature range from –20 to 25 °C (Table 1).
The reaction of styrene (1a) with DIB in MeOH in the
presence of H2SO4 was complete in 20 min to give
phenylacetaldehyde dimethyl acetal (2) in 87% yield. The
same reaction in MeCN + 50% aqueous H2SO4 afforded
phenylacetaldehyde (3a) in 80% yield (Scheme 1).
In addition to H2SO4, tolueneꢀpꢀsulfonic acid (TsOH)
and the cationꢀexchange resin KUꢀ2ꢀ8 (H+) were assayed
as activators (see Table 1, entries 6, 7).
The use of the cationꢀexchange resin seems to be preꢀ
ferred: the yield of acetal 2 increases to 92% and the
catalyst can be removed simply by filtration (see Table 1,
entry 7).
The oxidative rearrangement of αꢀmethylstyrene (1b)
under the action of DIB and H2SO4 gave ketone 3b rather
than its acetal in 20 min (Scheme 2).
The yields of products 2 and 3a were found to depend
on the reaction temperature and the isolation proceꢀ
dure (see Table 1, entries 1—8). The best results were
achieved at T ≤ –20 °C with neutralization of H2SO4 with
10% NaHCO3 and column chromatography on Al2O3
(see Table 1, entry 1). Otherwise, the yield of product 2
was 10—15% lower (see Table 1, entries 2—5). According
to GLC/MS data, phenylacetic acid (4), methyl phenylꢀ
acetate 5, and benzaldehyde (6) were the byꢀproducts.
Scheme 2
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1669—1675, August, 2004.
1066ꢀ5285/04/5308ꢀ1735 © 2004 Springer Science+Business Media, Inc.

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Yusubov et al.
Table 1. Oxidation of compounds 1a—c, 13, 14a,b, 18, 20, 23,
and 26a (1 mmol) with DIB (1.0—1.1 mmol) (T is the reaction
temperature and t is the reaction time)
was also attained with H3PO4 (2 h, 20 °C) (see Table 1,
entry 12).
Entry Subꢀ Actiꢀ Solventa T/°C t/min Proꢀ
Yieldb
(%)
Scheme 3
strate vator
duct
1
2
3
4
5
6
7
8
1a H2SO4 MeOH –20
1a H2SO4 MeOH –20
1a H2SO4 MeOH –10
20
20
20
20
20
120
720
20
20
20
2
2
2
2
2
2
2
3a
3b
3b
3c
3c
87 c
69 d
76 c
72 c
70 e
84
1a H2SO4 MeOH
0
1a H2SO4 MeOH –20
1a TsOHf MeOH
1a KUꢀ2ꢀ8g MeOH
20
20
Based on the GLC/MS data, one can assume that
transformations of alkenes 1a—c proceed in two pathways
(Scheme 4). The main pathway is the oxidative rearrangeꢀ
ment yielding carbonyl compounds 3a—c and trace
amounts of related products 7, 8a—c, and 9a—c; the side
pathway involves oxidation into compounds 10a,b—12a,b.
Nonterminal alkenes behave in a different way. For
instance, the oxidation of (E)ꢀstilbene (13) with the
DIB—H2SO4 system was nonselective and gave a mixture
of compounds 3c, 8c, 9c, and 10b—12b (see Table 1,
entries 13—15). This fact is explained by the poor solubilꢀ
ity and low nucleophilicity of (E)ꢀstilbene.18,19 Interestꢀ
ingly, the reaction of well soluble (Z)ꢀstilbene with a comꢀ
plex of iodosylbenzene with BF3•Et2O in CH2Cl2 at
–10 °C affords diphenylacetaldehyde (10b) in 80% yield
as a result of oxidative rearrangement.20
Cyclohexenes 14a,b react with DIB to give mixꢀ
tures of oxidative rearrangement and addition products
(Scheme 5). In the case of cyclohexene (14a), rearrangeꢀ
ment is a main reaction pathway; the yield of cycloꢀ
pentanecarbaldehyde (15a) reaches 42% (see Table 1,
entry 16). 1ꢀMethylcyclohexene (14b) was converted into
acetylcyclopentane (15b) in a noticeably lower yield
of 22% (see Table 1, entry 18). It should be noted that the
ring contraction of cyclohexene (14a) was observed earꢀ
lier20 with the use of related reagents in CH2Cl2.
92
1a H2SO4 MeCN –20
1b H2SO4 MeOH –20
1b H2SO4 MeOH –10
1c H2SO4i MeOH –15
80 h
85 h
50 h
94
9
10
11
12
13
14
15
16
17
18
19
20
21
22 j
23 k
30
1c H3РO4 MeСN
13 H2SO4 MeCN
13 H2SO4 MeOH
13 H2SO4 AcOH
20
20
20
120
120
900
90
32
24
32
42 h
39 h
22 h
59
90
90
12b
12b
12b
15a
15a
15b
19
21
21
24
24
60 1200
14a H2SO4 MeOH –15
14a H2SO4 MeCN –15
14b H2SO4 MeOH –15
140
140
140
120
120
120
240
300
18 H2SO4 MeOH
20 H2SO4i MeOH
20 H3РO4 MeСN
23 H2SO4 MeOH
23 H2SO4 MeOH
20
20
40
20
20
52
10
25
4
4
32
53
50
24
25
26a H2SO4 MeOH
26a KUꢀ2ꢀ8l MeOH
20 4320
20 4320
a 3—4 mL of solvent per mmol of the substrate.
b The yields of the isolated products.
c With 10% NaHCO3; column chromatography on Al2O3.
d With 10% NaHCO3; column chromatography on SiO2.
e Column chromatography on Al2O3.
f 2.0 mmol.
g 120 mg.
h Isolated as 2,4ꢀdinitrophenylhydrazone.
i Used as a 50% solution in MeOH (0.3 mL).
j With 1.05 equiv. of DIB.
Thus, in contrast to alkenes 1a—c, oxidative rearꢀ
rangement of cycloalkenes in the reaction with DIB actiꢀ
vated by sulfuric acid is not the main pathway. This agrees
well with data on the migration ability of an aryl radical
compared to alkyl.21
k With 2.1 equiv. of DIB.
l 360 mg.
Earlier,22—24 some alkenes were found to undergo oxiꢀ
dative rearrangement under the action of PhIO in the
presence of acids (CF3SO3H, FSO3H, and BF3•Et2O)
and PhI(OH)OTs (Koser´s reagent) to give products in
18—81% yields.
In our case, the processes appear to be similar. For
instance, the reaction of DIB with sulfuric acid gives polyꢀ
valent iodine derivatives A—D in situ, which are more
electrophilic than the starting carboxylate (Scheme 6).
The following mechanism can be proposed for the
oxidative rearrangement of alkenes 1a—c under the acꢀ
tion of reagent A (Scheme 7).
The yield of compound 3b depends on the reaction
temperature, being high (85%) at –20 °C and <50% at
–10 °C (see Table 1, entries 9, 10). In this case, benzaldeꢀ
hyde (6), benzoic acid (7), and acyloin were identified as
the byꢀproducts (GLC/MS data).
The reaction of 1,1ꢀdiphenylethene (1c) with DIB in
MeOH in the presence of H2SO4 (–15 °C, 30 min) proꢀ
ceeds similarly (Scheme 3) to give deoxybenzoin (3c) in
94% yield as the result of oxidative rearrangement (see
Table 1, entry 11). However, a temperature jump to 0 °C
did not reduce the yield of ketone 3c. Good yield (90%)

PhI(OAc)2 in oxidative rearrangements of alkenes
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 8, August, 2004
1737
Scheme 4
R = H (1a, 3a, 8a, 9a, 4, 6), Me (1b, 3b, 8b, 9b, 10a, 11a, 12a), Ph (1c, 3c, 8c, 9c, 10b, 11b, 12b)
Scheme 5 Scheme 6
R = H (a), Me (b)
Scheme 7
Scheme 8
1,4ꢀDiphenylbutadiene (18), a representative of conꢀ
jugated dienes, in the reaction with DIB yielded no oxiꢀ
dative rearrangement products at all. In this case, only
dimethoxy derivative 19 was obtained (Scheme 8) in 59%
yield (see Table 1, entry 19).
Apparently, the conjugated structure of the butadiene
prevents rearrangement. Stabilization of the carbocation
is due to conjugation with either the aromatic ring or the

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Yusubov et al.
Scheme 9
C=C bond (Scheme 9), irrespective of the way in which
the polyvalent iodine derivative adds to the double bond.
Previously,25 the reactions of conjugated dienes with
related reagents mainly afforded 1,4ꢀadducts in low yields
(12—23%).
into dicarbonyl compound 22 by heating in aqueous diꢀ
oxane in the presence of HCl (Scheme 11).
Scheme 11
The reaction of chalcone (20) with DIB under differꢀ
ent conditions (see Table 1, entries 20, 21) smoothly gave
oxo acetal 21 as the result of oxidative rearrangement
(Scheme 10). Similar results were obtained earlier19,26,27
with related reagents; however, our procedure is more
convenient and provides higher yields.
Dibenzylideneacetone (23) selectively reacts with the
first equivalent of DIB and only then with the second one
(see Table 1, entries 22, 23). Thus, by varying the amount
of the reagent, one can obtain either acetal 24 or diacetal
25 (~1 : 1 mixture of diastereomers) (Scheme 12).
Scheme 10
Reactions of alkynes with Koser´s reagent and phenylꢀ
iodosyl trifluoroacetate17,20 represent rare examples of
functionalization of this kind. We studied the oxidation of
phenylacetylene (26a), phenyl(propyl)acetylene (26b),
and diphenylacetylene (tolan) (26c) with DIB.
The oxidation of phenylacetylene (26a) with DIB in
the presence of H2SO4 or the cationꢀexchange resin
KUꢀ2ꢀ8 (H+) at ~20 °C was complete in 72 h to give a
At higher reaction temperatures, the reaction mixture
contains, in addition to the target dicarbonyl compound,
overoxidation and decarbonylation products. Decarboꢀ
nylation occurred in an attempt to hydrolyze acetal 21
Scheme 12

PhI(OAc)2 in oxidative rearrangements of alkenes
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 8, August, 2004
1739
Scheme 13
mixture of compounds 4, 5, and 27—30 (Scheme 13).
Acid 4 was isolated in 53% yield (see Table 1, enꢀ
tries 24, 25).
The oxidation of phenyl(propyl)acetylene (26b) with
this reagent in boiling MeOH occurred in a more comꢀ
plex way yielding an inseparable mixture of compounds
31—34 (Scheme 14).
gree of conversion of the starting alkyne was only 40%;
the major products were benzoic acid (7), benzoin (8c),
and benzil (9c) (Scheme 15). In MeCN with a double
excess of DIB at 20 °C, the conversion of tolan (26c) was
nearly 80%, the qualitative composition of the products
being the same. The oxidation of tolan (26c) into benzoin
(8c) is a slower step than the oxidation of ketone 8c into
benzil (9c) and benzoic acid (7).
Hence, the results obtained extend the area of appliꢀ
cation of DIB, an accessible polyvalent iodine derivative,
in reactions with alkenes and alkynes. New activators of
DIB proposed by us favor highꢀyielding oxidative rearꢀ
rangement.
Scheme 14
Experimental
IR spectra were recorded on a URꢀ20 spectrophotometer
(thin film or KBr pellets). 1H and 13C NMR spectra were reꢀ
corded on Bruker ACꢀ200 (200 and 50 MHz), AMXꢀ400
(400 MHz), and DRX 500 spectrometers (500 and 125 MHz,
respectively) in CDCl3, acetoneꢀd6, and CCl4 with Me4Si as the
internal standard. GLC/MS spectra were recorded on a Hewlett
Packard 5890/II gas chromatograph with an HP MSD 5971
quadrupole mass spectrometer as a detector (EI, 70 eV); an
HPꢀ5 quartz column was used (30 m, copolymer of diphenylꢀ
(5%) and dimethylsiloxane (95%); inner diameter 0.25 mm,
thickness of the stationary phase film 0.25 µm). Mass spectra
(EI, 70 eV) were recorded on a Finnigan MAT 8200 spectromꢀ
eter. Elemental analysis was performed with an E.A. 1106 Carlo
Erba CHNSꢀO analyzer. Melting points were measured on a
Boetius instrument. Silica gel L 40/100 µm (Chemapol) and
alumina (Brockmann activity II, neutral, pH of its aqueous
10% suspension is 9—10) (Reanal) were used for column chroꢀ
matography. TLC was carried out on Sorbfil (PTSKhꢀAFꢀAꢀUF,
PTSKhꢀPꢀAꢀUF) and Silufol UVꢀ254 plates (Kavalier).
The oxidation of tolan (26c) with DIB—H2SO4 in
boiling MeOH proceeded very slowly: after 42 h, the deꢀ
Scheme 15
Styrene (1a), methylstyrene (1b), diphenylethene (1c),
and phenylacetylene (26a) were distilled immediately before
use. Commercial stilbene (13) (m.p. 125 °C), tolan (26c)
(m.p. 62 °C), tolueneꢀpꢀsulfonic acid monohydrate (m.p.
103—106 °C), KUꢀ2ꢀ8 (H+), 96% H2SO4, and 85% H3PO4
(reagent grade) were used. Acetic acid (reagent grade) was emꢀ
ployed without additional purification; freshly distilled MeCN

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Russ.Chem.Bull., Int.Ed., Vol. 53, No. 8, August, 2004
Yusubov et al.
and MeOH were used. Cyclohexene (14a), 1ꢀmethylcyclohexene
(14b), trans,transꢀ1,4ꢀdiphenylbutaꢀ1,3ꢀdiene (18), and
1ꢀphenylpentꢀ1ꢀyne (26b) were from Aldrich. Chalcone (20)
and dibenzylideneacetone (23) were prepared by condensation
of benzaldehyde with the corresponding ketones.28
Deoxybenzoin (3c). M.p. 59—60 °C (cf. Ref. 28: m.p. 60 °C).
1H NMR (200 MHz, CDCl3), δ: 4.24 (s, 2 H, CH2); 7.27—7.28
(m, 5 H, H arom.); 7.42—7.45 (m, 3 H, H arom.); 8.00 (dd, 2 H,
H arom., J = 1.6 Hz, J = 7.0 Hz). 13C NMR (50 MHz, CDCl3),
δ: 45.26 (CH2), 126.63, 128.34, 128.44, 129.04, 129.22, 132.66,
134.43, 126.60 (C arom.), 196.32 (CO).
Benzophenone (12b) was isolated as 2,4ꢀdinitrophenylꢀ
hydrazone, m.p. 236—238 °C (cf. Ref. 28: m.p. 236 °C).
Cyclopentanecarbaldehyde (15a) was isolated as 2,4ꢀdiꢀ
nitrophenylhydrazone, m.p. 154—156 °C (cf. Ref. 31: m.p.
156—157 °C).
Synthesis of DIB. A 2ꢀL flask fitted with a mechanical stirꢀ
rer, a reflux condenser, and a thermometer was immersed in a
water bath and charged with Ac2O (610 mL) and 30% H2O2
(140 mL), which were carefully mixed. The bath temperature
was elevated to 40 °C and the reaction mixture was vigorously
stirred at this temperature for 4 h. Iodobenzene (100 g) was
added and stirring was continued for an additional 1.5 h. The
reaction mixture was left at ~20 °C for ~12 h and then diluted
with a double volume of water with ice. The precipitate that
formed was filtered off and dried in air. Recrystallization from a
minimum amount of AcOH gave DIB as lustrous crystals. The
yield of DIB was 158 g (83%), m.p. 157—159 °C (cf. Ref. 29:
m.p. 158—159 °C).
Acetylcyclopentane (15b) was isolated as 2,4ꢀdinitrophenylꢀ
hydrazone, m.p. 115—116 °C (EtOH). Found (%): C, 53.15;
H, 5.76; N, 20.01. C13H16N4O4. Calculated (%): C, 53.42;
H, 5.52; N, 19.17.
3,4ꢀDimethoxyꢀ1,4ꢀdiphenylbutꢀ1ꢀene (19). M.p. 48—50 °C
(MeOH—H2O). Found (%): C, 80.45; H, 7.50. C18H20O2. Calꢀ
culated (%): C, 80.56; H, 7.51. IR (2% solution in CCl4), ν/cm–1
:
Solution of 2,4ꢀdinitrophenylhydrazine. 2,4ꢀDinitrophenylꢀ
hydrazine (3.0 g) was dissolved in 15 mL of conc. H2SO4. The
solution was added to a stirred mixture of water (20 mL) and
95% EtOH (70 mL). The resulting solution was thoroughly stirred
and filtered.30
1108 (C—O—C), 1619 (C=C). 1H NMR (400 MHz,
CCl4—CDCl3 (3 : 1)), δ: 3.24, 3.26 (both s, 3 H each, OMe);
3.78 (dd, 1 H, =CHCH(OMe), J = 4.9 Hz, J = 7.7 Hz); 4.24 (d,
1 H, PhCH(OMe), J = 4.9 Hz); 6.15 (dd, 1 H, PhCH=CH, J =
7.7 Hz, J = 16.1 Hz); 6.40 (d, 1 H, PhCH=CH, J = 16.1 Hz);
7.20—7.37 (m, 10 H, H arom.). 13C NMR (100 MHz,
CCl4—CDCl3 (3 : 1)), δ: 56.75 (OMe), 57.03 (OMe), 85.98
(CHOMe), 86.43 (CHOMe), 126.31 (PhCH=CH), 127.53
(PhCH=CH), 126.55, 127.64, 127.77, 127.96, 128.32, 128.44,
141.01, 143.80 (C arom.).
3,3ꢀDimethoxyꢀ1,2ꢀdiphenylpropanone (21). A 50% solution
of H2SO4 (0.3 mL) in MeOH was added dropwise to a stirred
solution of chalcone (20) (244 mg, 1.08 mmol) and DIB (372 mg,
1.15 mmol) in 5.0 mL of MeOH. The reaction mixture was kept
at ~20 °C for 2.0 h and poured into 30 mL of water. The product
was extracted with ether (2×30 mL). The extract was washed
with brine (30 mL), dried with Na2SO4, and concentrated. Hexꢀ
ane (5.0 mL) was added to the residue and the crystals that
formed were filtered off and washed again with hexane (2×3 mL)
to give compound 21 as colorless crystals (262 mg, 90%), m.p.
95—96 °C (cf. Ref. 18: m.p. 94 °C). 1H NMR (400 MHz,
CDCl3), δ: 3.20, 3.44 (both s, 3 H each, OMe); 4.83 (d, 1 H,
CH, J = 8.5 Hz); 5.06 (d, 1 H, CH(OMe)2, J = 8.5 Hz);
7.27—7.28 (m, 1 H, H arom.); 7.29—7.38 (m, 2 H, H arom.);
7.40—7.41 (m, 4 H, H arom.); 7.41—7.42 (m, 1 H, H arom.);
7.95 (d, 2 H, H arom., J = 7.3 Hz). 13C NMR (100 MHz,
CDCl3), δ: 54.16 (OMe), 56.09 (OMe), 57.01 (CH), 106.94
(CH(OMe)2), 127.43, 128.42, 128.56, 128.68, 129.04, 129.08,
132.68, 135.03 (C arom.), 196.91 (CO).
Oxidation of dibenzylideneacetone (23). Procedure A. A 50%
solution of H2SO4 (0.7 mL) in MeOH was added dropwise to a
stirred solution of dibenzylideneacetone (23) (585 mg, 2.5 mmol)
and DIB (837 mg, 2.6 mmol) in 10 mL of MeOH. The reaction
mixture was kept at ~20 °C for 4 h and poured into water (30 mL).
The product was extracted with ether (2×30 mL). The extract
was washed with 10% NaHCO3 (30 mL) and brine (30 mL),
dried with Na2SO4, and concentrated. The residue was chroꢀ
matographed on silica gel. Iodobenzene (472 mg, 89%) was
isolated by elution in hexane. Further elution in hexane—AcOEt
(8 : 1) gave (E)ꢀ5,5ꢀdimethoxyꢀ1,4ꢀdiphenylpentꢀ1ꢀenꢀ3ꢀone
(24) (384 mg, 52%), m.p. 90—91 °C (hexane). Found (%):
C, 77.17; H, 6.73. C19H20O3. Calculated (%): C, 77.00; H, 6.80.
Oxidation of alkenes 1a—c, 13, 14a,b, and 18 with diacetoxyꢀ
iodobenzene in acidic media (general procedure). A solution of an
alkene (2.0 mmol) in MeOH (6—8 mL) was precooled to the
temperature specified in Table 1 and DIB (2.1 mmol) was added.
A 50% solution of H2SO4 in MeOH (0.45—0.5 mL) was added
dropwise with stirring. The reaction mixture was kept at this
temperature for the time specified in Table 1 and poured into
10% NaHCO3 (30 mL). The product was extracted with ether
(2×30 mL). The extract was washed with water (2×30 mL) and
brine (30 mL) and dried with Na2SO4. After the ether was reꢀ
moved, the residue was dissolved in benzene and chromatoꢀ
graphed on silica gel. Iodobenzene (b.p. 182—185 °C) was eluted
with hexane (cf. Ref. 28: b.p. 184—186 °C). Further elution with
hexane—benzene (4 : 1) gave products 2, 3c, 12b, and 19. Prodꢀ
ucts 3b and 15a,b were isolated as hydrazones by adding a soluꢀ
tion of 2,4ꢀdinitrophenylhydrazine (15—18 mL). The crystals
that formed were filtered off, washed with ethanol, dried, and
recrystallized from the corresponding solvents.
1,1ꢀDimethoxyꢀ2ꢀphenylethane (2). Oil, b.p. 217—220 °C
1
(750 Torr) (cf. Ref. 18: b.p. 219—221 °C (754 Torr)). H NMR
(200 MHz, CDCl3), δ: 2.78 (d, 2 H, CH2, J = 9.6 Hz); 3.22 (s,
6 H, OMe); 4.41 (t, 1 H, CH, J = 5.6 Hz, J = 11.2 Hz);
6.99—7.21 (m, 5 H, H arom.). 13C NMR (50 MHz, CDCl3), δ:
35.10 (CH2), 48.02 (OMe), 100.03 (CH), 121.68, 123.62, 124.88,
132.63 (C arom.).
Phenylacetaldehyde (3a). Diacetoxyiodobenzene (676 mg,
2.1 mmol) was added to a cooled (–20 °C) solution of styrene
(1a) (204 mg, 2.0 mmol) in 6 mL of MeCN. Then 50% H2SO4
(0.45 mL) was added dropwise with stirring. The reaction mixꢀ
ture was kept at this temperature for 20 min and then a solution
of 2,4ꢀdinitrophenylhydrazine (18 mL) was added. The crystals
that formed were filtered off, washed with cold EtOH, dried,
and recrystallized from EtOH to give phenylacetaldehyde
2,4ꢀdinitrophenylhydrazone (192 mg, 80%), m.p. 120—121 °C
(cf. Ref. 28: m.p. 121 °C).
1ꢀPhenylpropanꢀ2ꢀone (3b) was isolated as 2,4ꢀdinitroꢀ
phenylhydrazone, m.p. 157—158 °C (cf. Ref. 28: m.p. 156 °C).

PhI(OAc)2 in oxidative rearrangements of alkenes
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 8, August, 2004
1741
IR (KBr), ν/cm–1: 1094 (C—O), 1684 (C=O). 1H NMR
(200 MHz, CCl4—CDCl3 (3 : 1)), δ: 3.08, 3.36 (both s, 3 H each,
OMe); 4.17 (d, 1 H, PhCH, J = 8.7 Hz); 4.92 (d, 1 H,
CH(OMe)2, J = 7.7 Hz); 6.61 (d, 1 H, PhCH=CH, J = 16.0 Hz);
7.46 (d, 1 H, PhCH=CH, J = 16.0 Hz); 7.15—7.30 (m, 10 H,
H arom.).
Procedure B. A 50% solution of H2SO4 (0.55 mL) in MeOH
was added dropwise to a stirred solution of dibenzylideneacetone
(23) (234 mg, 1.0 mmol) and DIB (680 mg, 2.1 mmol) in 6.0 mL
of MeOH. The reaction mixture was kept at ~20 °C for 5.0 h and
poured into water (30 mL). The product was extracted with
ether (2×30 mL). The extract was washed with 10% NaHCO3
(30 mL) and brine (30 mL), dried with Na2SO4, and concenꢀ
trated. The residue was chromatographed on silica gel. Iodoꢀ
benzene (411 mg, 96%) was isolated by elution with hexane.
Further elution with hexane—benzene (3 : 1) gave compound 24
(30 mg, 10%), m.p. 90—91 °C. Elution with hexane—benzene
(1 : 2) afforded a fraction (115 mg, 32%) which was reꢀ
chromatographed to yield equal amounts of diastereomers 25´
and 25″.
washed with brine, dried with Na2SO4, and concentrated. The
residue was analyzed by GCꢀMS in the following temperature
regime: 50 °C (2 min), 50—280 °C (10 deg. min–1), and 280 °C
(5 min). The mixture contained the starting alkyne 26b (9%,
tr 10.92 min), 2ꢀmethoxyꢀ1ꢀphenylpentanꢀ1ꢀone (31) (30%,
tr 14.36 min), 1ꢀphenylpentaneꢀ1,2ꢀdione (32) (20%,
tr 13.50 min), (1,1,2,2ꢀtetramethoxypentyl)benzene (33) (5%, tr
15.16 min), and methyl 2ꢀphenylpentanoate (34) (10.5%,
tr 12.81 min) as the rearrangement product.
Oxidation of tolan (26c). Aqueous 50% H2SO4 (0.55 mL)
was added dropwise to a stirred solution of alkyne 26c (178 mg,
1.0 mmol) and DIB (644 mg, 2.0 mmol) in 5.0 mL of MeCN.
The reaction mixture was kept at 20 °C for 72 h and poured
into water (30 mL). The product was extracted with AcOEt
(2×30 mL). The extract was washed with brine, dried with
Na2SO4, and concentrated. The residue was analyzed by GCꢀMS
in the following temperature regime: 50 °C (2 min), 50—280 °C
(10 deg. min–1), and 280 °C (5 min). The identified products
were benzoic acid (7) (58%, tr 10.11 min), benzoin (8c) (13%,
tr 16.44 min), and benzil (9c) (25%, tr 18.04 min).
1,1,5,5ꢀTetramethoxyꢀ2,4ꢀdiphenylpentanꢀ3ꢀone (25´). Oil.
IR (oil), ν/cm–1: 1108 (C—O), 1696 (C=O). 1H NMR
(400 MHz, CCl4—CDCl3 (3 : 1)), δ: 3.04, 3.08 (both s, 6 H each,
OMe); 3.96, 4.79 (both d, 2 H each, CH, J = 8.3 Hz); 7.20—7.28
(m, 10 H, H arom.). 13C NMR (100 MHz, CCl4—CDCl3 (3 : 1)),
δ: 53.48 (OMe), 54.74 (OMe), 61.50 (CH), 105.03 (CH(OMe)2),
127.40, 128.23, 129.50, 134.21 (C arom.), 203.81 (CO). Highꢀ
resolution MS, found: m/z 358.17901 [M]+. C21H26O5. Calcuꢀ
lated: M = 358.17801. MS (EI), m/z (Irel (%)): 358 [M]+ (<1),
252 [M – C4H10O3]+ (3), 193 [M – C6H13O5]+ (5), 151
[C9H11O2]+ (6), 134 [C8H6O2]+ (15), 91 [C7H7]+ (16), 77
[C6H5]+ (5), 75 [C3H7O2]+ (100), 47 [CH2O2]+ (11).
This work was financially supported by the Ministry of
Education of the Russian Federation (Grant E02ꢀ5.0ꢀ
176) and the Tomsk Polytechnical University (Personal
Grant for young scientists´ researches).
References
1. V. V. Zhdankin and P. J. Stang, Chem. Rev., 2002, 102, 2523.
2. A. Varvoglis, Hypervalent Iodine in Organic Synthesis, Acaꢀ
demic Press, London, 1997, 223 pp.
1,1,5,5ꢀTetramethoxyꢀ2,4ꢀdiphenylpentanꢀ3ꢀone (25″). Oil.
IR (oil), ν/cm–1: 1108 (C—O), 1696 (C=O). 1H NMR
(400 MHz, CCl4—CDCl3 (3 : 1)), δ: 3.08, 3.40 (both s, 6 H each,
OMe); 4.02, 4.82 (both d, 2 H each, CH, J = 8.3 Hz); 6.90—7.09
(m, 10 H, H arom.). 13C NMR (100 MHz, CCl4—CDCl3 (3 : 1)),
δ: 52.98 (OMe), 55.04 (OMe), 62.22 (CH), 105.25 (CH(OMe)2),
127.05, 128.36, 129.45, 134.27 (C arom.), 204.28 (CO). Highꢀ
resolution MS, found: m/z 358.17901 [M]+. C21H26O5. Calcuꢀ
lated: M = 358.17801. MS (EI), m/z (Irel (%)): 358 [M]+ (<1),
252 [M – C4H10O3]+ (3), 193 [M – C6H13O5]+ (5), 151
[C9H11O2]+ (6), 134 [C8H6O2]+ (15), 91 [C7H7]+ (16), 77
[C6H5]+ (5), 75 [C3H7O2]+ (100), 47 [CH2O2]+ (11).
Oxidation of phenylacetylene (26a). A 50% solution of H2SO4
(0.3 mL) in MeOH was added dropwise to a stirred solution of
alkyne 26a (162 mg, 1.5 mmol) and DIB (511 mg, 1.5 mmol) in
5.0 mL of MeOH. The reaction mixture was kept at 20 °C for
72 h and then 10% NaOH (10 mL) was added. The resulting
mixture was heated at 100 °C for 10 min and poured into water
(30 mL). The aqueous layer was washed with ether (2×30 mL)
and acidified with HCl. The product was extracted with AcOEt.
The solvent was removed to give phenylacetic acid (4) (108 mg,
53%), m.p. 75—76 °C (hexane) (cf. Ref. 28: m.p. 77 °C).
Oxidation of phenyl(propyl)acetylene (26b). A 50% solution
of H2SO4 (0.25 mL) in MeOH was added dropwise to a stirred
solution of alkyne 26b (144 mg, 1.0 mmol) and DIB (322 mg,
1.0 mmol) in 5 mL of MeOH. The reaction mixture was heated
at 64 °C for 17 h, cooled, and poured into water (30 mL). The
product was extracted with AcOEt (2×30 mL). The extract was
3. T. Wirth and U. H. Hirt, Synthesis, 1999, 1271.
4. V. V. Zhdankin and P. J. Stang, Tetrahedron, 1998,
54, 10927.a
5. H. Togo and K. Sakuratani, Synlett, 2002, 1966.
6. A. Varvoglis and S. Spyroudis, Synlett, 1998, 221.
7. A. Kirschning, J. Prakt. Chem. Chem.ꢀZeit., 1998, 340, 184.
8. R. Criegee and H. Beucker, Justus Liebigs Ann. Chem., 1939,
541, 218.
9. K. Aoki and Y. Ogata, Bull. Chem. Soc. Jpn, 1968,
41, 1476.aaa
10. E. Zbiral and G. Nestler, Tetrahedron, 1970, 26, 2945.
11. J. Ehrenfreund and E. Zbiral, Tetrahedron, 1972, 28, 1697.
12. M. Tiecco, L. Testaferri, and M. Tingoli, Tetrahedron, 1990,
46, 7139.
13. A. Kirschning, C. Plumeier, and L. Rose, Chem. Commun.,
1998, 33.
14. M. Tingoli, M. Tiecco, L. Testaferri, and A. Temperini,
Synth. Commun., 1998, 28, 1769.
15. A. De Mico, R. Margarita, L. Parlanti, G. Piancatell, and
A. Vescovi, Tetrahedron, 1997, 53, 16877.
16. E. B. Merkushev, D. Sc. (Chem.) Thesis, Tomsk State Pedaꢀ
gogical Inst., Tomsk, 1985, 298 pp. (in Russian).
17. M. S. Yusubov and G. A. Zholobova, Zh. Org. Khim., 2001,
37, 1238 [Russ. J. Org. Chem., 2001, 37 (Engl. Transl.)].
18. P. B. D. De La Mare and R. Bolton, Electrophilic Additions
to Unsaturated Systems, Elsevier, Amsterdam, 1966.
19. L. R. Rebrovic and G. F. Koser, J. Org. Chem., 1984,
49, 2462.

1742
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 8, August, 2004
Yusubov et al.
20. N. S. Zefirov, R. Caple, V. A. Palyulin, B. Berglund,
R. Tykvinskii, V. V. Zhdankin, and A. S. Koz´min,
Izv. Akad. Nauk SSSR, Ser. Khim., 1988, 1452 [Bull.
Acad. Sci. USSR, Div. Chem. Sci., 1988, 37, 1289 (Engl.
Transl.)].
27. Y. Kawamura, M. Maruyama, T. Tokuoka, and
M. Tsukayama, Synthesis, 2002, 2490.
28. B. S. Furniss, A. J. Hannaford, P. W. G. Smith, and A. R.
Tatchell, Vogel´s Textbook of Practical Organic Chemistry,
5th ed., Longman, London, 1989, 1514 pp.
21. J. March, Advanced Organic Chemistry, J. Wiley and Sons,
New York, 1985.
22. R. Moriarty, J. S. Khosrowshashi, and O. Prakash, Tetraꢀ
hedron Lett., 1985, 26, 2961.
23. G. F. Koser, L. Rebrovic, and R. H. Wettach, J. Org. Chem.,
1981, 46, 4324.
24. R. M. Moriarty, R. K. Vaid, and G. F. Koser, Synlett,
1990, 365.
29. E. B. Merkushev, Preparativnye sintezy iodaromaticheskikh
soedinenii [Preparative Syntheses of IodineꢀContaining Arenes],
Tomsk Univ., Tomsk, 1985, 70 pp. (in Russian).
30. R. L. Shriner, R. C. Fuson, D. Y. Curtin, and T. C. Morrill,
The Systematic Identification of Organic Compounds, 6th ed.,
J. Wiley and Sons, New York—Chichester—Brisbane—
Toronto, 1980.
31. N. H. Andersen, P. F. Duffy, A. D. Denniston, and D. B.
Grotjahn, Tetrahedron Lett., 1978, 19, 4315.
25. R. T. Hembre, C. P. Scott, and J. R. Norton, J. Org. Chem.,
1987, 52, 3650.
26. Y. Miki, R. Fujita, and K. J. Matsushita, J. Chem. Soc.,
Perkin Trans. 1, 1998, 2533.
Received September 3, 2003;
in revised form April 16, 2004