(NH4)2S2O8-Mediated Diiodination of Alkynes with Iodide in Water: Stereospecific Synthesis of (E)-Diiodoalkenes

Article abstract of DOI:10.1055/s-0034-1379910

A new approach to the stereospecific diiodination of alkynes under mild conditions has been developed. This protocol employs ammonium persulfate as an oxidant and iodide as an iodine source, and provides a highly efficient and general method for the prepa

Full text of DOI:10.1055/s-0034-1379910

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2015, 47, 2081–2087
paper
2081
Q. Jiang et al.
Paper
Synthesis
(NH4)2S2O8-Mediated Diiodination of Alkynes with Iodide in
Water: Stereospecific Synthesis of (E)-Diiodoalkenes
R1
Qing Jiang
I
(NH4)2S2O8 (3.0 equiv)
R1
R2
XI
+
Jing-Yu Wang
H2O, 60 °C, 12 h
R2
I
Can-Cheng Guo*
X = K, Na, NH4
R1, R2: aryl, alkyl, carbonyl, ester
24 examples
72–97%
College of Chemistry and Chemical Engineering, Hunan University,
Changsha 410082, P. R. of China
ccguo@hnu.edu.cn
Received: 10.02.2015
Accepted after revision: 18.03.2015
Published online: 22.04.2015
dination of alkynes with KI in MeCN–H2O; however, in most
cases, mixtures of 1,2-diiodo alkenes and α,α-diiodoke-
tones were obtained in moderate yields.6h Despite some ad-
vances, the quest for a simple and green method for the
diiodination of alkynes with excellent functional group
compatibility, high efficiency, broad substrate scope, and
operational simplicity remains of considerable interest to
synthetic organic chemists.
DOI: 10.1055/s-0034-1379910; Art ID: ss-2015-h0101-op
Abstract A new approach to the stereospecific diiodination of alkynes
under mild conditions has been developed. This protocol employs am-
monium persulfate as an oxidant and iodide as an iodine source, and
provides a highly efficient and general method for the preparation of a
broad range of (E)-diiodoalkenes in water.
Water is inexpensive, safe, and an ideal green solvent,
and can potentially provide benefits for chemical syntheses
in terms of resource economy, energy efficiency, and health
and environmental safety.7 Furthermore, water has unique
chemical and physical properties that allow reactivities to
be realized that cannot be attained in organic solvents.
Moreover, employing water as solvent can reduce the need
for organic solvents, simplify the workup procedures, and
allow mild conditions.8 Despite the advantages that water
offers, the development of organic reactions that run in
pure water as reaction medium without the addition of any
organic cosolvents is still much underdeveloped and re-
mains both challenging and of great value.
Herein, we wish to report a diiodination of alkynes with
iodide in water in the presence of persulfate salt. This pro-
tocol provides a highly efficient and environmentally be-
nign method for the preparation of a wide range of (E)-diio-
doalkenes in water, and the method exhibits broad sub-
strate scope and excellent functional group tolerance.
Recently, we developed the K2S2O8-mediated oxybromi-
nation of alkenes with KBr in water,9 and oxyhalogenation
of alkynes with NaX in the presence of water.10 When phe-
nylacetylene was submitted to the mixture of KI and water
in the presence of K2S2O8, a diiodination, not the expected
oxyiodination, occurred during the reaction to produce the
(E)-1,2-diiodostyrene. This unexpected result prompted us
to undertake further investigations. Initially, we chose phe-
nylacetylene as a model reaction to test the reaction condi-
Key words persulfate salts, diiodination, alkenes, alkynes, water
Dihaloalkenes are valuable intermediates in organic
synthesis and they are often employed for transition-met-
al-catalyzed cross-coupling reactions.1,2 Among them, 1,2-
diiodoalkenes have attracted attention because of their im-
portant roles in a wide variety of functional group transfor-
mations and direct coupling reactions for forming new car-
bon–carbon bonds, either involving organo-copper, organo-
lithium, or metal-catalyzed cross-coupling reactions.3 De-
spite the utility of vicinal diiodoalkenes, synthetic access to
such compounds presents a challenge. Earlier studies have
shown that they could be prepared stereospecifically by di-
rect addition of iodine to alkynes.4 However, the reactions
proceeded very slowly and with low conversion. Later on,
various additives such as alumina or CuI were included to
improve the efficiency of the reaction; however, such ap-
proaches present additional problems in purification and
environmental concerns.5 Furthermore, hazardous I2 or IX
was used as an iodide, and harmful solvents such as di-
chloromethane, acetonitrile (MeCN), methanol, and petro-
leum ether were used in all cases.6 In 2008, Stavber report-
ed a sodium nitrite-catalyzed aerobic oxidative diiodina-
tion of alkynes with KI in the presence of H2SO4 in MeCN in
which terminal alkynes were diiodinated in quantitative
yield, but internal alkynes gave a mixture of E/Z isomers.6g
Recently, Madabhushi developed an oxone-mediated diio-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 2081–2087

2082
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Synthesis
tions. Selected conditions in this study are listed in Table 1.
When the reaction was carried out in the presence of KI
(2.0 equiv) and K2S2O8 (2.5 equiv) in water at 60 °C for 12
hours, the desired product 2a was obtained in 92% yield
(Table 1, entry 1). Control experiments showed that the re-
action did not proceed in the absence of K2S2O8 (Table 1, en-
try 2). The use of (NH4)2S2O8 and NH4I as oxidant and iodine
source, respectively, could afford the desired product in a
yield of 84% (Table 1, entry 3). Remarkably, increasing the
amount of (NH4)2S2O8 and NH4I improved the yield to 95%
(Table 1, entry 4), whereas further increase of the equiva-
lent amount of (NH4)2S2O8 or NH4I did not improve the yield
further (Table 1, entries 5 and 6). The diiodination reaction
afforded lower yield when performed at higher (80 °C) or
lower (40 °C) temperature (Table 1, entries 7 and 8). We
found that the use of organic solvent inhibited the reaction
to some extent. Gratifyingly, other iodine sources, such as
KI and NaI, gave comparable results (Table 1, entries 12 and
13). In addition, no (Z)-1,2-diiodostyrene was detected un-
der any of the conditions tested. Finally, reaction of pheny-
lacetylene with molecular iodine in water provided the
product 2a in 86% yield (Table 1, entry 14). Under these
conditions, although the use of molecular iodine could de-
liver a good result, the post-treatment was generally trou-
blesome, and it was difficult to completely remove the deep
color from the reaction mixture.
With the establishment of the optimal conditions, the
scope of this diiodination was then explored. The scope of
the reaction with phenylacetylenes in the diiodination with
NH4I or KI was examined first (Table 2). With either elec-
tron-donating or electron-withdrawing groups such as al-
kyl (2b–g), alkoxyl (2h), and halide groups (2i–k) at the pa-
ra- and meta-position of the phenyl ring, the reaction pro-
ceeded smoothly, affording the corresponding products in
88–97% yields (Table 2, entries 2–11). Moreover, aromatic
internal alkynes also underwent diiodination efficiently to
give the products in 87–96% yields (Table 2, entries 12–16).
a
Table 2 Scope of the Diiodination of Alkynes Mediated by (NH4)2S2O8
R1
I
R2
method A or B
R1
R2
+
XI
I
1
2
Entry
Product R1
R2
Yield
Yield
(method A)b (method B)b
1
2
2a
2b
2c
2d
2e
2f
Ph
H
92
93
91
90
91
88
90
94
92
90
89
92
90
91
88
89
86
92
80
72
90
84
82
73
94
96
93
93
94
92
92
97
97
93
94
96
95
94
93
90
91
88
85
76
93
89
86
76
4-MeC6H4
3-MeC6H4
4-EtC6H4
4-PrC6H4
4-BuC6H4
H
3
H
Table 1 Optimization of the Reaction Conditionsa
4
H
5
H
6
H
oxidant
I
+
XI
7
2g
2h
2i
4-Me(CH2)4C6H4
H
solvent, temp
I
8
4-MeOC6H4
4-FC6H4
4-ClC6H4
4-BrC6H4
Ph
H
1a
2a
9
H
Entry Oxidant (equiv)
XI (equiv)
Solvent
Temp
(°C)
Yield
(%)b
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
2j
H
2k
2l
H
1
2
K2S2O8 (2.5)
none
KI (2.0)
H2O
60
60
60
60
60
60
80
40
60
60
60
60
60
60
92
0
Me
Et
KI (2.0)
H2O
2m
2n
2o
2p
2q
2r
Ph
3
(NH4)2S2O8 (2.5)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.5)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
(NH4)2S2O8 (3.0)
none
NH4I (2.0)
NH4I (2.5)
NH4I (2.0)
NH4I (3.0)
NH4I (2.5)
NH4I (2.5)
NH4I (2.5)
NH4I (2.5)
NH4I (2.5)
KI (2.5)
H2O
84
95
93
92
32
77
38
45
78
98
96
86
Ph
Pr
4
H2O
Ph
Bu
Ph
Pr
5
H2O
Ph
6
H2O
Pr
7
H2O
Me(CH2)4
HO(CH2)2
HO(CH2)3
HO(CH2)4
Me
H
8
H2O
2s
2t
H
9
CH3CN
EtOH
EtOH–H2Oc
H2O
H
10
11
12
13
14
2u
2v
2w
2x
H
CO2Me
CO2Me
Ac
H
NaI (2.5)
I2 (2.5)
H2O
H
H2O
a Reaction conditions: Method A: alkyne (0.5 mmol), (NH4)2S2O8 (3.0 equiv),
NH4I (2.5 equiv), H2O (1 mL), 60 °C, 12 h. Method B: alkyne (0.5 mmol ),
(NH4)2S2O8 (3.0 equiv), KI (2.5 equiv), H2O (1 mL), 60 °C, 12 h.
a Reaction conditions: 1a (0.5 mmol), solvent (1 mL), 12 h.
b Yield determined by GC analysis.
c Ratio 1:1.
b The cited yields are of material isolated by column chromatography.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 2081–2087

2083
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Synthesis
To our delight, besides aromatic alkynes, aliphatic alkynes
could react with NH4I or KI to provide the desired diiodina-
tion products in 72–91% yields (Table 2, entries 17–21).
Conjugated alkynyl carboxylic acid derivatives and ketone
also gave the desired products in 73–89% yield (Table 2, en-
tries 22–24). As shown in Table 2, a variety of functional
groups, including F, Cl, Br, ether, ester, ketone and hydroxyl,
were tolerated under the reaction conditions, which en-
ables potential applications in further functionalization.11 It
should be noted that the iodination reaction occurred ex-
clusively through anti-addition to alkynes in all cases.
Moreover, the stereochemistries of diiodoalkenes were con-
firmed by comparing NMR data with reported values. In ad-
dition, according to experimental observations, the present
reaction is heterogeneous, and might exhibit an ‘on water’
effect.7d,e
(Scheme 1). Among them, oxazoles and benzofurans are an
important structural motif that is frequently found in natu-
ral and unnatural compounds,16 enediynes and maleic di-
esters exhibit some biological properties such as antitumor
activity,17 and 1,3-enyne moieties are ubiquitous in many
naturally occurring and biologically active compounds such
as calichemicin γ1, which is an effective antitumor antibiot-
ic, and terbinafine, which is a potent drug for superficial
fungal infections.18
Although the exact mechanism of this reaction is still
not clear, on the basis of these preliminary results and on
reported precedents,3–7,19 a plausible reaction pathway is
proposed (Scheme 2). Initially, oxidation of the iodide ion
by the persulfate ion generates molecular iodine. The for-
mation of I2 has been confirmed by observation of a color
change from red to deep-blue when starch was added into
the solution. Finally, the molecular iodine undergoes elec-
trophilic anti-addition onto the alkyne to give the corre-
sponding (E)-1,2-diiodoakene.
To demonstrate the synthetic utility of this diiodination
reaction, we conducted the reaction on a gram scale and
obtained 2a in 83% yield (Equation 1), thus demonstrating
the scalability of this reaction.
2–
2–
2I –
I2
2 SO4
S2O8
R1
+
+
I
R2
R2
(NH4)2S2O8 (3.0 equiv)
I2
I
+
R1
+
KI
H2O, 60 °C, 24 h
I
I
2a
83%
1a
Scheme 2 Possible reaction pathway
1.02 g
Equation 1
In summary, we have developed a novel protocol for the
synthesis of (E)-diiodoalkenes by metal-free diiodination of
alkynes under mild conditions. This transformation is envi-
ronmentally benign in adoption of readily available ammo-
nium persulfate as oxidant, nontoxic iodide as iodine re-
source, and water as solvent. The protocol exhibits broad
substrate scope and high functional group tolerance. Our
current efforts are directed toward the further application
of the products and the further development of organic re-
actions in pure water.
(E)-(1,2-diiodovinyl)benzenes can be converted into
various useful heterocycles and valuable synthons, such as
oxazoles,12 2-ethynylbenzofurans,13 2-en-4-ynenitriles,1c,e
2-en-4-ynoates,1c,e enediynes,14 and maleic diesters15
O
Ph
N
R
Ph
ref. 13
All commercially available compounds were purchased from com-
mercial suppliers and used without further purification unless other-
wise noted. 1H and 13C NMR spectra were recorded on an Inova-400
(Varian) spectrometer operating at 400 MHz (1H NMR) and 100 MHz
O
Ph
ref. 12
ref. 1c,e
NC
Ph
I
(
13C NMR), in CDCl3 or DMSO-d6 using TMS as internal standard. Col-
umn chromatography was performed on 200–300 mesh silica gel.
Thin-layer chromatography (TLC) was performed on Silicycle 250 mm
silica gel F-254 plates. Multiplicities are indicated as s (singlet), d
(doublet), t (triplet), q (quartet), and m (multiplet), and coupling con-
stants (J) are reported in hertz. Petroleum ether (PE) refers to the hy-
drocarbon fraction boiling in the 60–90 °C range.
I
ref. 1c,e
ref. 15
ref. 14
RO2C
Ph
CO2R
CO2R
Ph
Diiodination of Alkynes; General Procedures
Ph
Method A: To a 25 mL Schlenck tube were added (NH4)2S2O8 (3.0
equiv), NH4I (2.5 equiv), alkyne (0.5 mmol), and H2O (1 mL). The reac-
tion mixture was warmed to 60 °C (oil bath) and stirred for 12 h. The
mixture was cooled to r.t., and EtOAc (5 mL) and H2O (2 mL) were
Ph
Ph
Scheme 1 Transformations of (E)-(1,2-diiodovinyl)benzenes
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 2081–2087

2084
Q. Jiang et al.
Paper
Synthesis
added. The organic layer was separated, and the aqueous phase was
extracted with EtOAc (2 × 10 mL). The combined organic layers were
dried over anhydrous Na2SO4, filtered, and concentrated. The residue
was purified by column chromatography to give the pure sample.
13C NMR (101 MHz, CDCl3): δ = 15.3, 28.8, 80.3, 96.8, 127.9, 128.6,
140.6, 145.3.
HRMS (EI): m/z [M]+ calcd for C10H10I2: 383.8866; found: 383.8857.
Method B: To a 25 mL Schlenck tube were added (NH4)2S2O8 (3.0
equiv), NH4I (2.5 equiv), alkynes (0.5 mmol), and H2O (1 mL). The re-
action mixture was warmed to 60 °C (oil bath) and stirred for 12 h.
The mixture was cooled to r.t., and EtOAc (5 mL) and H2O (2 mL) were
added. The organic layer was separated, and the aqueous phase was
extracted with EtOAc (2 × 10 mL). The combined organic layers were
dried over anhydrous Na2SO4, filtered, and concentrated. The residue
was purified by column chromatography to give the pure sample.
(E)-1-(1,2-Diiodovinyl)-4-propylbenzene (2e)
Purified by flash chromatography (PE).
Yield: 181.1 mg (91%) (method A) or 187.1 mg (94%) (method B); red
oil.
IR (neat): 3061, 2925, 2864, 1604, 1497, 1455, 1149, 819, 776, 595
cm–1
.
1H NMR (400 MHz, CDCl3): δ = 0.96 (t, J = 8.0 Hz, 3 H), 1.61–1.70 (m,
2 H), 2.59 (t, J = 8.0 Hz, 2 H), 7.16 (d, J = 8.0 Hz, 2 H), 7.22 (s, 1 H), 7.29
(d, J = 8.0 Hz, 2 H).
(E)-(1,2-Diiodovinyl)benzene (2a)6g
[CAS Reg. No.: 71022-74-7]
13C NMR (101 MHz, CDCl3): δ = 14.0, 24.3, 37.9, 80.2, 96.8, 128.4,
128.5, 140.3, 143.8.
Purified by flash chromatography (PE).
HRMS (EI): m/z [M]+ calcd for C11H12I2: 397.9023; found: 397.9032.
Yield: 163.8 mg (92%) (method A) or 167.3 mg (94%) (method B); col-
orless solid; mp 73–75 °C.
1H NMR (400 MHz, CDCl3): δ = 7.26 (s, 1 H), 7.36 (s, 5 H).
(E)-1-Butyl-4-(1,2-diiodovinyl)benzene (2f)
Purified by flash chromatography (PE).
13C NMR (101 MHz, CDCl3): δ = 80.8, 96.2, 128.4, 128.5, 129.0, 143.1.
HRMS (EI): m/z [M]+ calcd for C8H6I2: 355.8553; found: 355.8545.
Yield: 181.3 mg (88%) (method A) or 189.5 mg (92%) (method B);
pale-yellow oil.
(E)-1-(1,2-Diiodovinyl)-4-methylbenzene (2b)6h
[CAS Reg. No.: 219517-81-4]
IR (neat): 3066, 2954, 2926, 2858, 1607, 1498, 1458, 1150, 829, 777,
597 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 0.94 (t, J = 6.8 Hz, 3 H), 1.34–1.42 (m,
2 H), 1.57–1.65 (m, 2 H), 2.61 (t, J = 8.0 Hz, 2 H), 7.16 (d, J = 8.0 Hz,
2 H), 7.22 (s, 1 H), 7.28 (t, J = 8.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 14.0, 22.5, 33.3, 35.6, 80.1, 96.8, 128.4,
128.5, 140.2, 144.1.
Purified by flash chromatography (PE).
Yield: 172.1 mg (93%) (method A) or 177.6 mg (96%) (method B); red
oil.
1H NMR (400 MHz, CDCl3): δ = 2.35 (s, 2 H), 7.15 (d, J = 8.0 Hz, 2 H),
7.21 (s, 1 H), 7.26 (d, J = 8.0 Hz, 2 H).
HRMS (EI): m/z [M]+ calcd for C12H14I2: 411.9179; found: 411.9175.
13C NMR (101 MHz, CDCl3): δ = 21.5, 80.4, 96.8, 128.6, 129.2, 139.1,
140.2.
(E)-1-(1,2-Diiodovinyl)-4-pentylbenzene (2g)6h
[CAS Reg. No.: 1446467-81-7]
HRMS (EI): m/z [M]+ calcd for C9H8I2: 369.8710; found: 369.8697.
Purified by flash chromatography (PE).
(E)-1-(1,2-Diiodovinyl)-3-methylbenzene (2c)
Yield: 191.7 mg (90%) (method A) or 196.0 mg (92%) (method B);
pale-yellow oil.
1H NMR (400 MHz, CDCl3): δ = 0.90 (t, J = 6.8 Hz, 3 H), 1.33–1.34 (m,
4 H), 1.61–1.64 (m, 2 H), 2.60 (t, J = 8.0 Hz, 2 H), 7.15 (d, J = 8.0 Hz,
2 H), 7.21 (s, 1 H), 7.28 (d, J = 6.8 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 14.2, 22.6, 30.9, 31.6, 35.9, 80.2, 96.9,
128.4, 128.6, 140.2, 144.1.
Purified by flash chromatography (PE).
Yield: 168.4 mg (91%) (method A) or 172.1 mg (93%) (method B);
pale-yellow oil.
IR (neat): 3061, 2917, 2856, 1588, 1478, 1201, 1134, 1091, 795, 760,
698, 603 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 2.36 (s, 3 H), 7.11–7.15 (m, 3 H), 7.22–
7.25 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 21.5, 80.7, 96.6, 125.6, 128.4, 129.1,
HRMS (EI): m/z [M]+ calcd for C13H16I2: 425.9336; found: 425.9342.
129.8, 138.2, 143.0.
HRMS (EI): m/z [M]+ calcd for C9H8I2: 369.8710; found: 369.8700.
(E)-1-(1,2-Diiodovinyl)-4-methoxybenzene (2h)
[CAS Reg. No.: 61926-36-1]
Purified by flash chromatography (PE–CH2Cl2, 7:1).
(E)-1-(1,2-Diiodovinyl)-4-ethylbenzene (2d)
Yield: 181.4 mg (94%) (method A) or 187.2 mg (97%) (method B);
pale-yellow oil.
Purified by flash chromatography (PE).
Yield: 172.8 mg (90%) (method A) or 178.6 mg (93%) (method B); or-
ange oil.
IR (neat): 3051, 2922, 2837, 1601, 1504, 1299, 1254, 1177, 1026, 812,
763 cm–1
.
IR (neat): 3063, 2962, 2927, 1608, 1498, 1454, 1240, 1150, 850, 828,
1H NMR (400 MHz, CDCl3): δ = 3.81 (s, 3 H), 6.86 (d, J = 8.0 Hz, 2 H),
7.18 (s, 1 H), 7.33 (t, J = 12.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 55.4, 80.0, 96.7, 113.7, 130.3, 135.5,
776, 595 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 1.25 (t, J = 8.0 Hz, 3 H), 2.65 (q, J =
8.0 Hz, 2 H), 7.18 (d, J = 6.8 Hz, 2 H), 7.21 (s, 1 H), 7.28–7.30 (m, 2 H).
159.8.
HRMS (EI): m/z [M]+ calcd for C9H8OI2: 385.8659; found: 385.8657.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 2081–2087

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Synthesis
(E)-1-(1,2-Diiodovinyl)-4-fluorobenzene (2i)
[CAS Reg. No.: 1041003-09-1]
HRMS (EI): m/z [M]+ calcd for C10H10I2: 383.8866; found: 383.8858.
(E)-1-Phenyl-1,2-diiodo-1-pentene (2n)
Purified by flash chromatography (PE).
Purified by flash chromatography (PE).
Yield: 172.0 mg (92%) (method A) or 181.4 mg (97%) (method B); or-
ange oil.
Yield: 181.1 mg (91%) (method A) or 187.1 mg (94%) (method B); or-
ange oil.
IR (neat): 2957, 2924, 2865, 1453, 1105, 751, 692, 583, 566 cm–1
1H NMR (400 MHz, CDCl3): δ = 1.06 (t, J = 6.8 Hz, 3 H), 1.67–1.77 (m,
2 H), 2.84 (t, J = 8.0 Hz, 2 H), 7.20 (d, J = 8.0 Hz, 2 H), 7.28 (d, J = 8.0 Hz,
1 H), 7.34 (t, J = 8.0 Hz, 2 H).
IR (neat): 3062, 1597, 1500, 1220, 1153, 1095, 858, 833, 780, 594 cm–1
.
.
1H NMR (400 MHz, CDCl3): δ = 7.05 (t, J = 8.0 Hz, 2 H), 7.27 (s, 1 H),
7.33–7.36 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 81.6, 94.9, 115.6 (d, JC–F = 22 Hz), 130.6
(d, JC–F = 9.0 Hz), 139.1 (d, JC–F = 4.0 Hz), 162.5 (d, JC–F = 248 Hz).
HRMS (EI): m/z [M]+ calcd for C8H5FI2: 373.8459; found: 373.8464.
13C NMR (101 MHz, CDCl3): δ = 13.0, 21.9, 52.1, 94.7, 105.2, 128.2,
128.4, 128.5, 148.3.
HRMS (EI): m/z [M]+ calcd for C11H12I2: 397.9023; found: 397.9017.
(E)-1-Chloro-4-(1,2-diiodovinyl)benzene (2j)
[CAS Reg. No.: 943032-01-7]
(E)-1-Phenyl-1,2-diiodo-1-hexene (2o)
Purified by flash chromatography (PE).
Purified by flash chromatography (PE).
Yield: 175.5 mg (90%) (method A) or 181.4 mg (93%) (method B);
pale-yellow oil.
IR (neat): 2919, 1482, 1098, 1011, 852, 828, 781, 593 cm–1
1H NMR (400 MHz, CDCl3): δ = 7.28–7.30 (m, 3 H), 7.33–7.35 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 81.8, 94.6, 128.8, 130.0, 134.9, 141.5.
HRMS (EI): m/z [M]+ calcd for C8H5ClI2: 389.8164; found: 389.8164.
Yield: 181.3 mg (88%) (method A) or 191.6 mg (93%) (method B);
pale-yellow oil.
IR (neat): 2962, 2926, 2861, 1486, 1446, 1111, 750, 692, 571, 638 cm–1
1H NMR (400 MHz, CDCl3): δ = 1.01 (t, J = 6.8 Hz, 3 H), 1.42–1.51 (m,
2 H), 1.62–1.70 (m, 2 H), 2.85 (t, J = 8.0 Hz, 2 H), 7.19 (d, J = 8.0 Hz,
2 H), 7.26 (t, J = 8.0 Hz, 1 H), 7.33 (t, J = 8.0 Hz, 2 H).
.
.
13C NMR (101 MHz, CDCl3): δ = 14.8, 21.9, 30.6, 50.4, 94.5, 105.4,
128.4, 128.5, 131.6, 148.2.
(E)-1-Bromo-4-(1,2-diiodovinyl)benzene (2k)
HRMS (EI): m/z [M]+ calcd for C12H14I2: 411.9179; found: 411.9195.
Purified by flash chromatography (PE).
Yield: 193.1 mg (89%) (method A) or 204.4 mg (94%) (method B); col-
orless solid; mp 62–64 °C.
(E)-1,2-Diiodo-1,2-diphenylethene (2p)21
[CAS Reg. No.: 20432-11-5]
IR (KBr): 3059, 1476, 1067, 1009, 844, 814, 771, 593 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.22 (d, J = 8.0 Hz, 2 H), 7.27 (s, 1 H),
7.49 (d, J = 12.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 82.0, 94.8, 123.2, 130.3, 131.8, 142.0.
HRMS (EI): m/z [M]+ calcd for C8H5BrI2: 433.7659; found: 433.7667.
Purified by flash chromatography (PE–EtOAc, 50:1).
Yield: 187.9 mg (87%) (method A) or 194.4 mg (90%) (method B); col-
orless solid; mp 181–183 °C.
1H NMR (400 MHz, DMSO-d6): δ = 7.33–7.6 (m, 6 H), 7.43–7.47 (m,
4 H).
(E)-1,2-Diiodo-1-phenyl-1-propene (2l)6g
[CAS Reg. No.: 268550-89-6]
13C NMR (101 MHz, DMSO-d6): δ = 99.7, 128.6, 128.8, 129.1, 148.2.
HRMS (EI): m/z [M]+ calcd for C14H10I2: 431.8866; found: 431.8866.
Purified by flash chromatography (PE).
(E)-4,5-Diiodooct-4-ene (2q)6f
[CAS Reg. No.: 124471-41-6]
Yield: 170.2 mg (92%) (method A) or 177.6 mg (96%) (method B); red
oil.
1H NMR (400 MHz, CDCl3): δ = 2.79 (s, 3 H), 7.22 (d, J = 8.0 Hz, 2 H),
7.27 (t, J = 8.0 Hz, 1 H), 7.34 (t, J = 8.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 40.3, 95.7, 96.5, 128.3, 128.4, 128.5,
Purified by flash chromatography (PE).
Yield: 156.5 mg (86%) (method A) or 165.6 mg (91%) (method B);
pale-yellow oil.
148.1.
1H NMR (400 MHz, CDCl3): δ = 0.96 (t, J = 8.0 Hz, 3 H), 154–1.62 (m,
2 H), 2.68 (t, J = 8.0 Hz, 2 H).
HRMS (EI): m/z [M]+ calcd for C9H8I2: 369.8710; found: 369.8714.
13C NMR (101 MHz, CDCl3): δ = 12.9, 21.7, 52.6, 102.1.
HRMS (EI): m/z [M]+ calcd for C8H14I2: 363.9179; found: 363.9183.
(E)-1-Phenyl-1,2-diiodo-1-butene (2m)20
[CAS Reg. No.: 64454-37-1]
(E)-1,2-Diiodohept-1-ene (2r)6f
[CAS Reg. No.: 192763-37-4]
Purified by flash chromatography (PE).
Yield: 172.8 mg (90%) (method A) or 182.4 mg (95%) (method B);
pale-yellow oil.
1H NMR (400 MHz, CDCl3): δ = 1.17 (t, J = 8.0 Hz, 3 H), 2.87 (q, J =
8.0 Hz, 2 H), 7.20 (d, J = 8.0 Hz, 2 H), 7.27 (t, J = 8.0 Hz, 1 H), 7.33 (t,
J = 8.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 13.1, 44.9, 93.8, 106.6, 128.2, 128.5,
128.6, 148.1.
Purified by flash chromatography (PE).
Yield: 143.5 mg (82%) (method A) or 154.0 mg (88%) (method B); col-
orless oil.
1H NMR (400 MHz, CDCl3): δ = 0.92 (t, J = 6.8 Hz, 3 H), 1.31–1.40 (m,
4 H), 1.51–1.58 (m, 2 H), 2.50 (t, J = 8.0 Hz, 2 H), 6.80 (s, 1 H).
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13C NMR (101 MHz, CDCl3): δ = 14.0, 22.5, 27.9, 30.4, 44.7, 79.0, 104.5.
HRMS (EI): m/z [M]+ calcd for C7H12I2: 349.9023; found: 349.9022.
(E)-3,4-Diiodobut-3-en-2-one (2x)
Purified by flash chromatography (PE–EtOAc, 15:1).
Yield: 117.5 mg (73%) (method A) or 122.4 mg (76%) (method B);
pale-yellow oil.
(E)-3,4-Diiodobut-3-en-1-ol (2s)13
[CAS Reg. No.: 1126638-97-8]
IR (neat): 3055, 2955, 2917, 1700, 1525, 1353, 1230, 1152, 971, 781,
604 cm–1
.
Purified by flash chromatography (PE–EtOAc, 7:1).
1H NMR (400 MHz, CDCl3): δ = 2.43 (s, 3 H), 7.19 (s, 1 H).
13C NMR (101 MHz, CDCl3): δ = 27.4, 80.0, 95.6, 197.8.
HRMS (EI): m/z [M]+ calcd for C4H4I2O: 321.8346; found: 321.8351.
Yield: 129.6 mg (80%) (method A) or 137.7 mg (85%) (method B); or-
ange oil.
1H NMR (400 MHz, CDCl3): δ = 2.14–2.50 (br s, 1 H), 2.80–2.83 (m,
2 H), 3.83 (t, J = 8.0 Hz, 2 H), 7.02 (s, 1 H).
13C NMR (101 MHz, CDCl3): δ = 47.5, 60.7, 82.2, 99.0.
Gram-Scale Reaction; General Procedure
HRMS (EI): m/z [M]+ calcd for C4H6I2O: 323.8503; found: 323.8496.
To a 25 mL Schlenck tube were added (NH4)2S2O8 (30 mmol, 3.0
equiv), KI (25 mmol, 2.5 equiv), phenylacetylene (10 mmol), and H2O
(15 mL). The reaction mixture was warmed to 60 °C (oil bath) and
stirred for 24 h. The mixture was cooled to r.t., and EtOAc (30 mL) was
added. The organic layer was separated, and the aqueous phase was
extracted with EtOAc (3 × 30 mL). The combined organic layers were
dried over anhydrous Na2SO4, filtered, and concentrated. The residue
was purified by column chromatography to give desired product (E)-
(1,2-diiodovinyl)benzene (2.95 g, 83%).
(E)-4,5-Diiodopent-4-en-1-ol (2t)
Purified by flash chromatography (PE–EtOAc, 6:1).
Yield: 121.7 mg (72%) (method A) or 128.4 mg (76%) (method B); or-
ange oil.
IR (neat): 3325, 3066, 2943, 2873, 1436, 1213, 1175, 1060, 768,
565 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 1.18 (br s, 1 H), 1.71–1.78 (m, 2 H),
2.58 (t, J = 8.0 Hz, 2 H), 3.62 (t, J = 6.8 Hz, 2 H), 6.79 (s, 1 H).
13C NMR (101 MHz, CDCl3): δ = 31.0, 41.5, 61.1, 79.8, 103.3.
Acknowledgment
HRMS (EI): m/z [M]+ calcd for C5H8I2O: 337.8659; found: 337.8645.
This work was supported by the National Natural Science Foundation
of China (Grant No. 21372068).
(E)-5,6-Diiodohex-5-en-1-ol (2u)
Purified by flash chromatography (PE–EtOAc, 6:1).
Supporting Information
Yield: 158.4 mg (90%) (method A) or 163.7 mg (93%) (method B); or-
ange oil.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0034-1379910.
S
u
p
p
o
nrtIo
g
f
rmoaitn
S
u
p
p
ortiInfogrmoaitn
IR (neat): 3318, 3067, 2918, 2862, 1447, 1210, 1062, 770, 630,
565 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 1.61–1.62 (m, 4 H), 2.43 (br s, 1 H),
2.55 (t, J = 8.0 Hz, 2 H), 2.67 (t, J = 6.8 Hz, 2 H), 6.85 (s, 1 H).
References
13C NMR (101 MHz, CDCl3): δ = 24.6, 31.1, 44.4, 62.5, 79.8, 104.0.
HRMS (EI): m/z [M]+ calcd for C6H10I2O: 351.8816; found: 351.8806.
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[CAS Reg. No.: 500912-97-0]
Purified by flash chromatography (PE–EtOAc, 10:1).
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 2081–2087