Iron-Catalyzed Carboiodination of Alkynes

Article abstract of DOI:10.1055/s-0037-1609448

An iron-catalyzed carboiodination of alkynes with alkyl iodides at room temperature was developed. This method could provide synthetically useful vinyl iodides with general alkyl chains, fluoroalkyl group, ester, and cyano group. Conjugated alkynes or unconjugated alkynes were both suitable for this transformation. A radical pathway was proposed for the mechanism and acetyl tert -butyl peroxide was selected as the radical initiator. Alkenes could also be applied to this chemistry and produce more complex alkyl iodides.

Full text of DOI:10.1055/s-0037-1609448

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2018, 50, A–G
special topic
A
en
W. Deng et al.
Special Topic
Synthesis
Iron-Catalyzed Carboiodination of Alkynes
Weili Denga,b
Yajun Lib
You-Gui Li*a
Hongli Bao*b
R2
R2 = alkyl
R1
I
I
R1 = aryl, alkyl
cat. Fe(OTf)3
Alkyl
Alkyl
R2
R1
TBPA
MTBE, r.t., 12 h, N2
Alkyl
I
TBPA
MTBE, r.t., 12 h, N2
0
0
0
0
0-
0
0
3
1-
0
3
0
5-
0
8
9
19 examples
up to 98% yield
4 examples
84–93% yield
a School of Chemistry and Chemical Engineering, Hefei University
of Technology, 193 Tunxi Road, Hefei 230009, P. R. of China
liyg@hfut.edu.cn
b Key Laboratory of Coal to Ethylene Glycol and Its Related Tech-
nology, Center for Excellence in Molecular Synthesis, Fujian Insti-
tute of Research on the Structure of Matter, University of
Chinese Academy of Sciences, 155 Yangqiao Road West, Fuzhou,
Fujian 350002, P. R. of China
hlbao@fjirsm.ac.cn
Published as part of the Special Topic Modern Radical Methods and
their Strategic Applications in Synthesis
Received: 01.02.2018
Accepted after revision: 13.03.2018
Published online: 16.04.2018
group for the cascade synthesis of γ-lactam derivatives.13
Later on, Daoust’s group further developed this method
with ynol ethers as the alkyne substrates14 and found that
water could be used as the reaction medium.15 Curran’s
group16 and Stephenson’s group17 discovered that general
alkyl iodides could undergo the carboiodination of alkynes
upon irradiation of light. Interestingly, Betrand and co-
worker found that dialkylzinc showed its ability as an initi-
ator for the sequential radical addition cyclization.18 Al-
though developments have been achieved, new methods
are still highly required. In recent years, we have focused
our efforts on the functionalization of unsaturated C–C
bonds via radical chemistry.19 Herein, we present an iron-
catalyzed carboiodination of alkynes in a radical mecha-
nism. As far as we are aware, use of the iron catalyst in a
radical carboiodination of alkynes with a simple alkyl group
has not been previously attempted.
The model reaction was initiated with the terminal
alkyne but-3-yn-2-one (1a) and a general alkyl iodide 2-iodo-
butane (2a) in the presence of an initiator and a metal cata-
lyst (Table 1). Based on our previous studies,19 Fe(OTf)3 was
chosen as the catalyst and TBPA (acetyl tert-butyl peroxide)
was selected as the initiator.19c Because TBPA features the
just right reactivity that it can selectively grab the iodine
atom from alkyl iodides to activate them rather than react
with the terminal alkynes to afford vinyl radicals. An isolat-
ed yield of the desired product 3 as high as 72% was ob-
tained when the reaction was performed in DME at room
temperature (Table 1, entry 1). The regioselectivity was 9:1
and (Z)-3 was found to be the major product. When
Fe(OTf)2 was used as the catalyst, similar result was
achieved (entry 2). However, other iron metals, such as
FeBr3, FeCl3, and FeCl2, and also other metal triflates, such
as Cu(OTf)2, AgOTf, Zn(OTf)2, CuOTf, Nd(OTf)3, Sc(OTf)3,
Y(OTf)3, and La(OTf)3 all failed to provide the desired prod-
uct (entries 3 and 4). In consideration of the reproducibility
DOI: 10.1055/s-0037-1609448; Art ID: ss-2018-c0057-st
Abstract An iron-catalyzed carboiodination of alkynes with alkyl
iodides at room temperature was developed. This method could pro-
vide synthetically useful vinyl iodides with general alkyl chains, fluoroal-
kyl group, ester, and cyano group. Conjugated alkynes or unconjugated
alkynes were both suitable for this transformation. A radical pathway
was proposed for the mechanism and acetyl tert-butyl peroxide was se-
lected as the radical initiator. Alkenes could also be applied to this
chemistry and produce more complex alkyl iodides.
Key words iron catalysis, radical, alkyl iodides, alkynes, carboiodina-
tion
Difunctionalization of C≡C bonds is an attractive meth-
od to establish functionalized alkenes, which are one of the
most broadly existing structural motifs present in organic
molecules.1 Significant progress has been achieved by tran-
sition-metal-catalyzed carbon–carbon or carbon–hetero-
atom (e.g., C–O, C–N, or C–X) bond formation with C≡C
bonds. Specially, radical process has particular appeal for
performing new transformations because of its widespread
application in chemistry and even biology.2 In this context,
carboiodination of alkynes in a radical pathway3 has at-
tracted considerable attention because vinyl iodide is an
important intermediate in organic synthesis.4 Generally,
carboiodination of alkynes with fluoroalkyl iodides as the
carbon and iodine sources is the most frequently studied
topic, as the easy accessibility of the fluoroalkyl radical ini-
tiated by Na2S2O4/NaHCO3,5 AIBN,6 Et3B,7 transition metals,8
organic peroxides,9 Zn,10 or light.11 The studies on carboio-
dination of alkynes with simple alkyl halides, however, are
less developed with only less research papers being docu-
mented. In 1989, Oshima and Utimoto et al. reported an
Et3B-induced radical addition of alkyl iodides to acetylenes
in good yields.12 This methodology was employed by Li’s
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–G

B
W. Deng et al.
Special Topic
Synthesis
of the reaction, Fe(OTf)3 showed a better performance than
Fe(OTf)2. Thus, further investigations of this reaction were
performed with Fe(OTf)3 as the catalyst. Next, the solvent
was screened. Ether solvents such as THF, 1,4-dioxane, and
MTBE delivered the desired product 3 and MTBE offered the
highest regioselectivity (entries 5–7). Although the sol-
vents, such as MeCN, CH2Cl2, DCE, and toluene could be
used as the solvent for the reaction, the regioselectivities of
the desired product were about 1:2.3 to 1:3.6, which were
lower than the ratio provided by MTBE (entries 8–11 vs en-
try 7). Other solvents, such as DMSO, DMF, and hexane
could not be used as the solvent for the reaction (entries
12–14). A lower initiator loading was performed, but both
the yield of the product and the regioselectivity dropped
(entry 15). Without any metal, only trace amount of the de-
sired product was detected (entry 16). Thus, the reaction
conditions as described in entry 7 of Table 1 were selected
as the optimal reaction conditions.
With the optimal reaction conditions in hand, the sub-
strate scope of alkyl iodides and alkynes were studied (Fig-
ure 1). General secondary alkyl iodides, such as 2-iodo-
butane, cyclohexyl iodide, and cyclopentyl iodide, could un-
dergo the cascade radical relay and atom-transfer radical
addition reaction, and provided the corresponding vinyl
iodides 3–8 with Z-selectivities, which were determined by
1H NMR data and the known compound 5.20 Conjugated
but-3-yn-2-one and ethyl propiolate were good radical ac-
ceptors for this reaction. Reaction between general second-
ary alkyl iodide and substituted phenylacetylenes gave low
efficiencies (Figure 1; 7 and 8).21 Excellent yields were ob-
tained when activated alkyl iodides were employed. Ethyl
2-iodopropanoate reacted smoothly with substituted phe-
nylacetylenes and afforded the corresponding vinyl iodides
9–15 with almost quantitative yields with E-selectivities,
1
which were determined by H NMR data and the known
compounds 16 and 17.2j,22 While fluoroalkyl iodides tolerat-
ed the reaction conditions and offered the corresponding
Table 1 Optimization of the Reaction Conditionsa
O
cat. (10 mol%)
TBPA (1.0 equiv)
I
I
+
I
I
solvent (2 mL)
N2, r.t., 12 h
I
O
1a
2a
3
O
O
O
O
3, 72%, E/Z = 1:12
4, 74%, E/Z = 1:75
5, 75%, E/Z = 1:3
Entry
Catalyst (10 mol%)
Solvent
Yield (%)b (E/Z)
I
1
2
Fe(OTf)3
Fe(OTf)2
other ironsc
other triflatesd
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
Fe(OTf)3
–
DME
73 (1:9.0)
72 (1:9.4)
trace
I
DME
I
3
DME
F
O
O
F3C
4
DME
trace
6, 68%, E/Z = 1:2.3
7, 41%, E/Z = 1:20
8, 38%, E/Z = 1:11
5
THF
42 (1:2.1)
50 (1:2.2)
72 (1:12)
66 (1:3.6)
43 (1:2.3)
56 (1:2.7)
49 (1:2.8)
trace
I
I
I
6
1,4-dioxane
MTBE
MeCN
CH2Cl2
DCE
7
CO2Et
CO2Et
10, 97%, E/Z = 2.2:1
CO2Et
8
9, 93%, E/Z = 2.3:1
11, 98%, E/Z = 1.9:1
9
I
I
O
I
10
11
12
13
14
15e
16f
O
toluene
DMSO
DMF
F3C
CO2Et
CO2Et
12, 93%, E/Z = 2.2:1
CO2Et
13, 92%, E/Z = 3.3:1
14, 92%, E/Z = 1.7:1
trace
I
I
F
I
hexane
MTBE
MTBE
trace
62 (1:3.2)
trace
CF2CO2Et
CO2Et
CO2Et
15, 97%, E/Z = 2.6:1
17, 83%, single isomer
16, 40%, single isomer
a Reaction conditions: 1a (1.0 equiv), 2a (3.0 equiv), catalyst (10 mol%),
TBPA (1.0 equiv) in 2 mL of solvent at r.t. for 12 h under N2 atmosphere.
DME: 1,2-dimethoxyethane; MTBE: methyl tert-butyl ether.
b Yield of the isolated product. E/Z value was determined by 1H NMR spec-
troscopy.
I
I
I
I
F
CF3
CF3
c Other irons: FeBr3, FeCl3, and FeCl2.
CN
F
CN
CN
d Other triflates: Cu(OTf)2, AgOTf, Zn(OTf)2, CuOTf, Nd(OTf)3, Sc(OTf)3,
Y(OTf)3, and La(OTf)3.
O
e TBPA used: 0.5 equiv.
18, 77%, E/Z = 15:1 19, 73%, E/Z = 1.8:1 20, 70%, E/Z = 2.4:1 21, 76%, E/Z = 1.7:1
f No metal was used.
Figure 1 Substrate scope of alkyl iodides and alkynes
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–G

C
W. Deng et al.
Special Topic
Synthesis
vinyl iodides 17 and 18, iodoacetonitrile reacted with sub-
stituted phenylacetylenes and gave the corresponding vinyl
iodides 19–21 with a cyano group. Interestingly, when ethyl
2-iodo-2-methylpropionate and ethyl iododifluoroacetate
reacted with phenylacetylene, exclusively E-selective prod-
ucts 16 and 17 were obtained, respectively.
This methodology could also be used for carboiodina-
tion of unactivated alkynes and unactivated alkenes, pro-
viding the unconjugated vinyl iodides and secondary alkyl
iodides, respectively (Figure 2). Unconjugated vinyl iodides
2223 and 23 were synthesized from the aliphatic alkynes
and fluoroalkyl iodides in high yields. The reaction between
aliphatic alkenes and fluoroalkyl iodides provided the sec-
ondary alkyl iodides with excellent performance.
radical intermediate F, which then undergoes atom transfer
radical addition with alkyl iodide substrate to afford the fi-
nal product.
In conclusion, we have developed the first iron-cata-
lyzed carboiodination of alkynes with simple alkyl iodides
as both the carbon source and the iodine source, providing
synthetically useful vinyl iodides under mild reaction con-
ditions. The alkyl iodides with general alkyl chains, fluoro-
alkyl group, ester, and cyano group could be applied as the
substrates, while conjugated alkynes or unconjugated
alkynes are both suitable for this transformation. Alkenes
could also be used in this chemistry and produce more
complex alkyl iodides. Acetyl tert-butyl peroxide was se-
lected as the radical initiator. A cascade radical relay and
atom transfer radical addition was supposed to be the reac-
tion mechanism.
I
I
I
F
CF3
CF3
C6H13
C6H13
CF2CO2Et
CF2CF2Cl
23, 75%, E/Z=6.2:1
All reactions were carried out under an atmosphere of N2 in a flame-
dried glassware with magnetic stirring, unless otherwise indicated.
Commercially obtained reagents were used directly as received. Sol-
vents were dried by Innovative Technology Solvent Purification Sys-
tem. Liquids and solutions were transferred via syringe. All reactions
were monitored by TLC. GC-MS data were recorded on Thermo ISQ
QD. 1H and 13C NMR spectra were recorded on Bruker BioSpin Avance
III HD spectrometer. Data for 1H NMR spectra are reported relative to
CHCl3 as an internal standard (7.26 ppm) and are reported as follows:
chemical shift (ppm), multiplicity, coupling constant (Hz), and inte-
gration. Data for 13C NMR spectra are reported relative to CHCl3 as an
internal standard (77.23 ppm) and are reported in terms of chemical
shift (ppm). HRMS data were recorded on Waters Micromass GCT Pre-
mier or Thermo Fisher Scientific LTQ FT Ultra mass spectrometer.
22, 75%, E/Z=5.4:1
24, 88%
F
CF2CO2Et
CF3
CF3
I
I
F
25, 84%
26, 92%
I
CF2CF3
27, 93%
Figure 2 Substrate scope of the unactivated alkynes and alkenes
Based on the understanding of this chemistry, a radical
mechanism is proposed (Scheme 1). Initially, Fe(OTf)3 is re-
duced to the active catalyst Fe(II) A.19 Then Fe(II) A can be
oxidized by acetyl tert-butyl peroxide through a single-
electron transfer affording complex Fe(III) B and tert-butox-
yl radical C, which would decompose to generate an ace-
tone and a methyl radical D. Iodine atom exchange with
alkyl iodide generates the alkyl radical E. The resulting
alkyl radical reacts directly with the alkyne to form a vinyl
Iron-Catalyzed Carboiodination of But-3-yn-2-one (1a); (Z)-3-
Iodo-5-methylhept-3-en-2-one (3, E/Z = 1:12); Typical Procedure
To a flame-dried Schlenk tube was added Fe(OTf)3 (25 mg, 0.05 mmol,
10 mol%), followed by the addition of MTBE (2 mL) under N2 atmo-
sphere. Then but-3-yn-2-one (1a; 34 mg, 0.5 mmol, 1 equiv), 2-io-
dobutane (2a; 276 mg, 1.5 mmol, 3 equiv), and tert-butyl peroxyace-
tate (66 mg, 0.5 mmol, 1 equiv) were added sequentially. The mixture
was stirred at r.t. for 12 h. Afterwards, the reaction solution was dilut-
ed with EtOAc and filtered through a plug of diatomite. The filtrate
was concentrated by rotary evaporation under reduced pressure and
the residue was purified by column chromatography on silica gel
(EtOAc/PE 100:1) to afford product 3 as a pale yellow liquid; yield:
90.7 mg (0.36 mmol, 72%).
O
O
O
1H NMR (400 MHz, CDCl3): δ = 6.69 (d, J = 9.1 Hz, 0.92 H), 6.24 (d, J =
10.6 Hz, 0.07 H), 2.72–2.51 (m, 1 H), 2.47 (s, 2.72 H), 2.45 (s, 0.25 H),
1.48 (pent, J = 7.2 Hz, 2 H), 1.06 (d, J = 6.7 Hz, 2.91 H), 0.97 (d, J = 6.6
Hz, 0.32 H), 0.90 (t, J = 7.5 Hz, 3.03 H), 0.82 (t, J = 7.4 Hz, 0.44 H).
FeX2
Fe(OTf)3
A
FeX3, X = OTf or OAc
B
O
13C NMR (100 MHz, CDCl3): δ = 197.85, 192.76, 158.21, 154.76,
110.89, 99.99, 44.11, 39.45, 29.58, 29.16, 28.80, 25.47, 19.90, 18.39,
11.79.
HRMS (ESI): m/z calcd for [C8H13IONa]+ ([M + Na]+): 274.9903; found:
274.9901.
R
R
I
C
O
–
R1
I
R
I
R
Me
R
R1
R
R1
Me
I
D
E
F
(Z)-4-Cyclohexyl-3-iodobut-3-en-2-one (4, E/Z = 1:75)
Scheme 1 Proposed reaction mechanism
Pale yellow liquid; yield: 102.9 mg (74%).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–G

D
W. Deng et al.
Special Topic
Synthesis
1H NMR (400 MHz, CDCl3): δ = 6.74 (d, J = 8.7 Hz, 1 H), 2.59–2.43 (m, 4
Ethyl (E)-4-Iodo-2-methyl-4-(p-tolyl)but-3-enoate (9, E/Z = 2.3:1)
H), 1.81–1.65 (m, 5 H), 1.41–1.28 (m, 2 H), 1.27–1.15 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 192.80, 157.38, 110.05, 46.84, 30.67,
25.68, 25.36, 25.25.
HRMS (ESI): m/z calcd for [C10H15IONa]+ ([M + Na]+): 301.0060; found:
Pale yellow liquid; yield: 160.0 mg (93%).
1H NMR (400 MHz, CDCl3): δ = 7.36 (d, J = 8.2 Hz, 0.54 H), 7.21 (d, J =
8.1 Hz, 1.53 H), 7.16–7.08 (m, 2 H), 6.49 (d, J = 10.3 Hz, 0.75 H), 6.01
(d, J = 8.8 Hz, 0.26 H), 4.23–4.09 (m, 2 H), 3.60–3.50 (m, 0.27 H), 3.20–
3.09 (m, 0.77 H), 2.34 (s, 3 H), 1.37 (d, J = 7.1 Hz, 0.87 H), 1.32–1.24
(m, 3 H), 1.20 (d, J = 7.0 Hz, 2.44 H).
301.0058.
Ethyl (Z)-3-Cyclohexyl-2-iodoacrylate20 (5, E/Z = 1:3)
13C NMR (100 MHz, CDCl3): δ = 173.84, 173.19, 140.70, 139.94,
138.53, 138.51, 138.34, 136.39, 129.01, 128.87, 128.52, 128.32,
106.40, 97.60, 60.94, 60.89, 48.49, 42.51, 21.29, 21.11, 17.79, 17.27,
14.26, 14.19.
HRMS (ESI): m/z calcd for [C14H17IO2Na]+ ([M + Na]+): 367.0165;
found: 367.0165.
Pale yellow liquid; yield: 115.5 mg (75%).
1H NMR (400 MHz, CDCl3): δ = 6.96 (d, J = 9.0 Hz, 0.75 H), 6.69 (d, J =
10.0 Hz, 0.25 H), 4.27–4.19 (m, 2 H), 2.82 (qt, J = 11.2, 3.5 Hz, 0.25 H),
2.48–2.35 (m, 0.78 H), 1.79–1.59 (m, 6 H), 1.33–1.28 (m, 4 H), 1.26–
1.16 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 163.98, 163.13, 160.50, 157.11, 92.70,
83.21, 62.61, 62.14, 45.93, 42.50, 32.10, 30.55, 25.73, 25.70, 25.42,
25.28, 14.21, 14.08.
Ethyl (E)-4-Iodo-2-methyl-4-(m-tolyl)but-3-enoate (10, E/Z = 2.2:1)
Pale yellow liquid; yield: 166.8 mg (97%).
1H NMR (400 MHz, CDCl3): δ = 7.21–6.96 (m, 4 H), 6.40 (d, J = 10.3 Hz,
0.73 H), 5.95 (d, J = 8.8 Hz, 0.26 H), 4.13–4.01 (m, 2 H), 3.52–3.41 (m,
0.27 H), 2.93–2.76 (m, 0.75 H), 2.25 (s, 3 H), 1.32–1.06 (m, 6 H).
Ethyl (Z)-3-Cyclopentyl-2-iodoacrylate (6, E/Z = 1:2.3)
Pale yellow liquid; yield: 100.0 mg (68%).
13C NMR (100 MHz, CDCl3): δ = 173.61, 173.19, 142.64, 141.23,
140.75, 138.02, 136.96, 129.35, 129.22, 129.01, 128.23, 128.14,
125.89, 125.46, 97.53, 60.98, 60.91, 48.47, 42.53, 21.44, 21.36, 17.83,
17.30, 14.30, 14.23.
HRMS (ESI): m/z calcd for [C14H17IO2Na]+ ([M + Na]+): 367.0165;
found: 367.0169.
1H NMR (400 MHz, CDCl3): δ = 7.08 (d, J = 9.1 Hz, 0.69 H), 6.76 (d, J =
10.0 Hz, 0.30 H), 4.32–4.12 (m, 2 H), 3.22 (sext, J = 8.5 Hz, 0.33 H),
2.81 (sext, J = 8.3 Hz, 0.69 H), 2.00–1.82 (m, 2 H), 1.78–1.52 (m, 4 H),
1.43–1.25 (m, 5 H).
13C NMR (100 MHz, CDCl3): δ = 164.08, 163.11, 160.52, 157.80, 93.15,
82.92, 62.59, 62.14, 47.54, 43.92, 33.00, 31.96, 25.63, 25.28, 14.23,
14.10.
Ethyl (E)-4-Iodo-2-methyl-4-phenylbut-3-enoate (11, E/Z = 1.9:1)
HRMS (ESI): m/z calcd for [C10H15IO2Na]+ ([M + Na]+): 317.0009;
Pale yellow liquid; yield: 161.7 mg (98%).
found: 317.0010.
1H NMR (400 MHz, CDCl3): δ = 7.38 (d, J = 6.7 Hz, 0.73 H), 7.29–7.14
(m, 4.51 H), 6.43 (d, J = 10.3 Hz, 0.65 H), 5.97 (d, J = 8.8 Hz, 0.35 H),
4.15–4.00 (m, 2 H), 3.52–3.42 (m, 0.35 H), 3.05 (dq, J = 10.3, 7.0 Hz,
0.66 H), 1.28 (d, J = 7.2 Hz, 1.12 H), 1.22–1.14 (m, 3 H), 1.11 (d, J = 7.0
Hz, 2.04 H).
13C NMR (100 MHz, CDCl3): δ = 173.76, 173.12, 142.65, 141.31,
140.97, 137.21, 128.66, 128.58, 128.41, 128.38, 128.25, 106.23, 97.22,
61.00, 60.95, 48.49, 42.51, 17.81, 17.28, 14.30, 14.22.
(Z)-1-(2-Cyclohexyl-1-iodovinyl)-4-(trifluoromethyl)benzene (7,
E/Z = 1:20)
Pale yellow liquid; yield: 77.9 mg (41%).
1H NMR (400 MHz, CDCl3): δ = 7.61–7.37 (m, 4 H), 6.38 (d, J = 10.3 Hz,
0.10 H), 5.79 (d, J = 8.4 Hz, 0.90 H), 2.48–2.36 (m, 0.92 H), 2.02–1.96
(m, 0.11 H), 1.91–1.63 (m, 5 H), 1.44–1.12 (m, 5 H).
13C NMR (100 MHz, CDCl3): δ = 150.21, 146.56, 145.82, 129.91 (q, J =
32.6 Hz), 128.94, 125.11 (q, J = 3.8 Hz), 123.94 (q, J = 270.3 Hz),
100.08, 46.73, 41.37, 32.57, 31.43, 25.88, 25.57.
HRMS (ESI): m/z calcd for [C13H15IO2Na]+ ([M + Na]+): 353.0009;
found: 353.0009.
19F NMR (376 MHz, CDCl3): δ = –62.51 (s, 0.1 × 3 F), –62.61 (s, 0.9 × 3
F).
HRMS (EI+): m/z calcd for [C15H16F3I]+ ([M]+): 380.0249; found:
380.0239.
Ethyl (E)-4-Iodo-4-(3-methoxyphenyl)-2-methylbut-3-enoate (12,
E/Z = 2.2:1)
Pale yellow liquid; yield: 167.4 mg (93%).
1H NMR (400 MHz, CDCl3): δ = 7.28–7.17 (m, 1 H), 7.05 (d, J = 8.1 Hz,
0.35 H), 7.02–6.98 (m, 0.33 H), 6.89 (d, J = 7.7 Hz, 0.69 H), 6.86–6.78
(m, 1.66 H), 6.49 (d, J = 10.3 Hz, 0.66 H), 6.07 (d, J = 8.8 Hz, 0.33 H),
4.21–4.09 (m, 2 H), 3.87–3.74 (m, 3 H), 3.59–3.49 (m, 0.33 H), 3.17
(dq, J = 10.2, 7.0 Hz, 0.67 H), 1.36 (d, J = 7.1 Hz, 1.07 H), 1.31–1.24 (m,
3 H), 1.20 (d, J = 7.0 Hz, 2.04 H).
13C NMR (100 MHz, CDCl3): δ = 173.71, 173.12, 159.23, 159.18,
144.03, 142.47, 140.97, 137.30, 129.40, 129.18, 121.01, 120.76,
114.45, 114.22, 114.12, 113.81, 105.83, 96.88, 60.99, 60.94, 55.36,
55.29, 48.42, 42.58, 17.80, 17.24, 14.28, 14.22.
(Z)-1-(2-Cyclohexyl-1-iodovinyl)-3-fluorobenzene (8, E/Z = 1:11)
Pale yellow liquid; yield: 62.7 mg (38%).
1H NMR (400 MHz, CDCl3): δ = 7.24–7.12 (m, 2 H), 7.08 (d, J = 10.1 Hz,
0.91 H), 6.97 (d, J = 7.8 Hz, 0.13 H), 6.93–6.81 (m, 1 H), 6.24 (d, J = 10.3
Hz, 0.10 H), 5.67 (d, J = 8.4 Hz, 0.90 H), 2.42–2.24 (m, 0.93 H), 1.96–
1.88 (m, 0.14 H), 1.82–1.53 (m, 5 H), 1.35–1.06 (m, 5 H).
13C NMR (100 MHz, CDCl3): δ = 162.28 (d, J = 246.1 Hz), 145.33 (d, J =
7.8 Hz), 144.89, 129.48 (d, J = 8.4 Hz), 124.29 (d, J = 2.8 Hz), 115.78 (d,
J = 22.8 Hz), 114.82 (d, J = 21.2 Hz), 100.33 (d, J = 2.6 Hz), 46.63, 41.32,
32.57, 31.47, 25.91, 25.68, 25.60, 25.38.
HRMS (ESI): m/z calcd for [C14H17IO3Na]+ ([M + Na]+): 383.0115;
found: 383.0115.
19F NMR (376 MHz, CDCl3): δ = –112.70 (s, 0.1 F), –113.52 (s, 0.9 F).
HRMS (EI+): m/z calcd for [C14H16FI]+ ([M]+): 330.0281; found:
330.0275.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–G

E
W. Deng et al.
Special Topic
Synthesis
Ethyl (E)-4-Iodo-4-(2-methoxyphenyl)-2-methylbut-3-enoate (13,
E/Z = 3.3:1)
1H NMR (400 MHz, CDCl3): δ = 7.36–7.27 (m, 5 H), 6.72 (t, J = 10.9 Hz,
1 H), 3.95 (q, J = 7.2 Hz, 2 H), 1.18 (t, J = 7.2 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 162.53 (t, J = 33.2 Hz), 140.66, 133.04
(t, J = 28.5 Hz), 129.48, 128.08, 127.84 (t, J = 1.9 Hz), 110.87 (t, J =
248.5 Hz), 108.77 (t, J = 10.2 Hz), 63.17, 13.72.
Pale yellow liquid; yield: 165.6 mg (92%).
1H NMR (400 MHz, CDCl3): δ = 7.25–7.15 (m, 1 H), 7.14–7.04 (m, 1 H),
6.89–6.75 (m, 2 H), 6.47 (d, J = 8.8 Hz, 0.76 H), 5.78 (d, J = 8.8 Hz, 0.23
H), 4.10 (q, J = 7.1 Hz, 0.59 H), 4.03 (q, J = 7.1 Hz, 1.67 H), 3.77 (d, J =
3.1 Hz, 3 H), 3.50–3.40 (m, 0.23 H), 2.93–2.77 (m, 0.79 H), 1.29 (d, J =
7.1 Hz, 0.79 H), 1.23–1.14 (m, 3 H), 1.10 (d, J = 7.1 Hz, 2.55 H).
13C NMR (100 MHz, CDCl3): δ = 173.90, 173.31, 156.26, 155.64,
141.99, 138.58, 132.62, 130.31, 130.00, 129.92, 129.80, 129.79,
120.45, 120.22, 111.34, 111.26, 99.99, 99.28, 60.87, 60.75, 55.61,
55.50, 47.84, 42.88, 17.30, 16.86, 14.27, 14.19.
19F NMR (376 MHz, CDCl3): δ = –93.76.
(E)-1-Methoxy-3-[3,4,4,4-tetrafluoro-1-iodo-3-(trifluorometh-
yl)but-1-en-1-yl]benzene (18, E/Z = 15:1)
Pale yellow liquid; yield: 164.8 mg (77%).
1H NMR (400 MHz, CDCl3): δ = 7.22 (t, J = 7.9 Hz, 1 H), 6.91–6.71 (m, 3
H), 6.41 (d, J = 24.0 Hz, 1 H), 3.79 (s, 3 H).
13C NMR (100 MHz, CDCl3): δ = 158.74, 142.85, 129.03, 123.26 (d, J =
14.0 Hz), 119.57 (dq, J = 27.6 Hz), 118.91, 114.56, 112.07 (d, J = 2.8
Hz), 109.01, 93.64–90.55 (m), 55.23.
19F NMR (376 MHz, CDCl3): δ = –76.55 (d, J = 8.9 Hz), –76.74 (d, J = 8.0
Hz), –184.96 (hept, J = 8.0 Hz), –188.41 (hept, J = 8.9 Hz).
HRMS (ESI): m/z calcd for [C14H17IO3Na]+ ([M + Na]+): 383.0115;
found: 383.0110.
Ethyl (E)-4-Iodo-2-methyl-4-[4-(trifluoromethyl)phenyl]but-3-
enoate (14, E/Z = 1.7:1)
Pale yellow liquid; yield: 183.1 mg (92%).
HRMS (EI+): m/z calcd for [C12H8F7IO]+ ([M]+): 427.9508; found:
427.9514.
1H NMR (400 MHz, CDCl3): δ = 7.62–7.53 (m, 2.84 H), 7.42 (d, J = 8.0
Hz, 1.26 H), 6.56 (d, J = 10.5 Hz, 0.62 H), 6.15 (d, J = 8.8 Hz, 0.38 H),
4.23–4.09 (m, 2 H), 3.59–3.49 (m, 0.38 H), 3.06 (dq, J = 10.5, 7.0 Hz,
0.64 H), 1.38 (d, J = 7.1 Hz, 1.17 H), 1.31–1.24 (m, 3 H), 1.20 (d, J = 7.0
Hz, 1.98 H).
(E)-4-Iodo-4-phenylbut-3-enenitrile (19, E/Z = 1.8:1)
Pale yellow liquid; yield: 98.2 mg (73%).
1H NMR (400 MHz, CDCl3): δ = 7.47–7.24 (m, 5 H), 6.45 (t, J = 7.5 Hz,
0.64 H), 6.00 (t, J = 6.6 Hz, 0.36 H), 3.38 (d, J = 6.5 Hz, 0.74 H), 2.97 (d,
J = 7.5 Hz, 1.35 H).
13C NMR (100 MHz, CDCl3): δ = 141.68, 139.99, 129.34, 129.22,
128.85, 128.66, 128.53, 128.45, 128.05, 125.83, 116.74, 116.41,
111.66, 101.80, 26.54, 19.99.
13C NMR (100 MHz, CDCl3): δ = 173.45, 172.70, 145.99, 144.78,
142.17, 139.20, 130.40 (q, J = 32.4 Hz), 130.35 (q, J = 32.4 Hz), 128.96,
128.84, 125.44 (q, J = 3.7 Hz), 125.22 (q, J = 3.8 Hz), 103.77, 94.48,
61.12, 61.10, 48.45, 42.61, 17.60, 17.14, 14.21, 14.14.
19F NMR (376 MHz, CDCl3): δ = –62.61, –62.75.
HRMS (EI+): m/z calcd for [C14H14F3IO2]+ ([M]+): 397.9991; found:
HRMS (ESI): m/z calcd for [C10H8INNa]+ ([M + Na]+): 291.9594; found:
291.9592.
397.9983.
Ethyl (E)-4-(2-Fluorophenyl)-4-iodo-2-methylbut-3-enoate (15,
E/Z = 2.6:1)
(E)-4-Iodo-4-(p-tolyl)but-3-enenitrile (20, E/Z = 2.4:1)
Pale yellow liquid; yield: 99.1 mg (70%).
Pale yellow liquid; yield: 168.8 mg (97%).
1H NMR (400 MHz, CDCl3): δ = 7.35 (d, J = 8.2 Hz, 0.64 H), 7.22–7.12
(m, 3.51 H), 6.43 (t, J = 7.5 Hz, 0.71 H), 5.97 (t, J = 6.5 Hz, 0.30 H), 3.38
(d, J = 6.6 Hz, 0.61 H), 2.99 (d, J = 7.4 Hz, 1.49 H), 2.36 (s, 3 H).
13C NMR (100 MHz, CDCl3): δ = 139.49, 139.35, 138.92, 137.13,
129.48, 129.17, 128.35, 128.31, 128.01, 124.95, 116.85, 116.53,
111.93, 102.24, 26.55, 21.37, 21.21, 19.98.
1H NMR (400 MHz, CDCl3): δ = 7.27–7.12 (m, 2.18 H), 7.10–6.91 (m,
2.11 H), 6.56 (d, J = 10.3 Hz, 0.73 H), 5.93 (d, J = 8.8 Hz, 0.28 H), 4.15–
3.99 (m, 2 H), 3.45 (pent, J = 7.2 Hz, 0.29 H), 2.88 (dq, J = 9.7, 7.1 Hz,
0.75 H), 1.30 (d, J = 7.1 Hz, 0.89 H), 1.24–1.12 (m, 5.63 H).
13C NMR (100 MHz, CDCl3): δ = 173.50, 172.84, 158.71 (d, J = 247.9
Hz), 158.30 (d, J = 248.75 Hz), 143.73, 140.86 (d, J = 2.5 Hz), 131.44 (d,
J = 2.0 Hz), 131.24 (d, J = 13.3 Hz), 130.49, 130.45 (d, J = 8.3 Hz),
130.04 (d, J = 8.3 Hz), 128.86 (d, J = 15.6 Hz), 124.20 (d, J = 3.7 Hz),
123.86 (d, J = 3.7 Hz), 94.85, 87.21, 61.02, 60.94, 48.16, 43.00, 17.39,
17.09, 14.23, 14.13.
HRMS (ESI): m/z calcd for [C11H10INNa]+ ([M + Na]+): 305.9750; found:
305.9747.
(E)-4-(4-Fluorophenyl)-4-iodobut-3-enenitrile (21, E/Z = 1.7:1)
19F NMR (376 MHz, CDCl3): δ = –112.64, –113.71.
HRMS (ESI): m/z calcd for [C13H14FIO2Na]+ ([M + Na]+): 370.9915;
Pale yellow liquid; yield: 109.1 mg (76%).
1H NMR (400 MHz, CDCl3): δ = 7.47–7.41 (m, 0.75 H), 7.31–7.24 (m,
1.48 H), 7.12–7.00 (m, 2 H), 6.47 (t, J = 7.5 Hz, 0.63 H), 5.97 (t, J = 6.5
Hz, 0.37 H), 3.39 (d, J = 6.5 Hz, 0.76 H), 2.98 (d, J = 7.5 Hz, 1.33 H).
13C NMR (100 MHz, CDCl3): δ = 163.11 (d, J = 250.1 Hz), 162.67 (d, J =
250.4 Hz), 136.07 (d, J = 3.5 Hz), 130.17 (d, J = 8.4 Hz), 130.03 (d, J =
8.5 Hz), 129.14, 125.97, 116.38 (d, J = 40.8 Hz), 115.97 (d, J = 22.0 Hz),
115.44 (d, J = 21.8 Hz), 110.01, 100.40, 26.50, 19.94.
found: 370.9916.
Ethyl (E)-4-Iodo-2,2-dimethyl-4-phenylbut-3-enoate22 (16, E Only)
Pale yellow liquid; yield: 68.8 mg (40%).
1H NMR (400 MHz, CDCl3): δ = 7.24–7.12 (m, 5 H), 6.46 (s, 1 H), 3.65
(q, J = 7.2 Hz, 2 H), 1.13 (s, 6 H), 1.07 (t, J = 7.1 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 175.00, 146.20, 142.51, 128.25,
128.07, 127.96, 96.31, 60.73, 47.26, 26.92, 13.94.
19F NMR (376 MHz, CDCl3): δ = –110.89, –111.81.
HRMS (EI+): m/z calcd for [C10H7FIN]+ ([M]+): 286.9607; found:
286.9610.
Ethyl (E)-2,2-Difluoro-4-iodo-4-phenylbut-3-enoate2j (17, E Only)
Pale yellow liquid; yield: 146.1 mg (83%).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–G

F
W. Deng et al.
Special Topic
Synthesis
Ethyl (E)-2,2-Difluoro-4-iododec-3-enoate23 (22, E/Z = 5.4:1)
HRMS (EI+): m/z calcd for [C12H9F8I]+ ([M]+): 431.9621; found:
431.9615.
Pale yellow liquid; yield: 135.1 mg (75%).
1H NMR (400 MHz, CDCl3): δ = 6.40 (t, J = 13.2 Hz, 1 H), 4.33 (q, J = 7.1
Hz, 2 H), 2.60 (t, J = 7.5 Hz, 2 H), 1.54 (pent, J = 7.1 Hz, 2 H), 1.40–1.28
(m, 9 H), 0.89 (t, J = 6.6 Hz, 3 H).
(5,5,6,6,6-Pentafluoro-3-iodohexyl)benzene (27)
Pale yellow liquid; yield: 175.8 mg (93%).
1H NMR (400 MHz, CDCl3): δ = 7.33–7.26 (m, 2 H), 7.25–7.18 (m, 3 H),
4.29–4.19 (m, 1 H), 2.98–2.66 (m, 4 H), 2.15–2.06 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 139.89, 128.63, 128.51, 126.41, 118.56
(qt, J = 284.0 Hz, J = 35.4 Hz), 115.14 (tq, J = 255.5 Hz, J = 37.7 Hz),
41.71 (t, J = 2.2 Hz), 41.55 (t, J = 20.7 Hz), 35.68, 20.05.
13C NMR (100 MHz, CDCl3): δ = 163.20 (t, J = 34.4 Hz), 131.22 (t, J =
27.1 Hz), 119.67 (t, J = 7.6 Hz), 111.54 (t, J = 252.3 Hz), 63.32, 40.74,
31.53, 29.86, 28.05, 22.51, 14.03, 13.90.
19F NMR (376 MHz, CDCl3): δ = –97.74.
(E)-(5-Chloro-4,4,5,5-tetrafluoro-2-iodopent-2-en-1-yl)benzene
(23, E/Z = 6.2:1)
19F NMR (376 MHz, CDCl3): δ = –85.85, –114.71 to –119.73 (m).
HRMS (EI+): m/z calcd for [C12H12F5I]+ ([M]+): 377.9904; found:
Pale yellow liquid; yield: 141.8 mg (75%).
377.9894.
1H NMR (400 MHz, CDCl3): δ = 7.41–7.31 (m, 3 H), 7.26–7.20 (m, 2 H),
6.55 (t, J = 13.8 Hz, 1 H), 4.08 (s, 2 H).
Funding Information
13C NMR (100 MHz, CDCl3): δ = 136.78, 129.00, 128.74, 127.55 (t, J =
23.6 Hz), 127.42, 122.86 (tt, J =38.7 Hz), 120.01 (t, J = 5.3 Hz), 113.46
(tt, J = 33.9 Hz), 46.65 (t, J = 2.9 Hz).
19F NMR (376 MHz, CDCl3): δ = –71.33 to –71.42 (m), –104.25 (t, J =
5.8 Hz).
We thank NSFC (Grant Nos. 21502191 and 21672213), Strategic Prior-
ity Research Program of the Chinese Academy of Sciences (Grant No.
XDB20000000), The 100 Talents Program, ‘The 1000 Youth Talents
Program’, and Haixi Institute of CAS (CXZX-2017-P01) for financial
HRMS (EI+): m/z calcd for [C11H8ClF4I]+ ([M]+): 377.9295; found:
support.
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Supporting Information
1,1,1,2-Tetrafluoro-4-iodo-2-(trifluoromethyl)decane (24)
Pale yellow liquid; yield: 179.1 mg (88%).
Supporting information for this article is available online at
1H NMR (400 MHz, CDCl3): δ = 4.38–4.28 (m, 1 H), 3.00–2.76 (m, 2 H),
1.87–1.68 (m, 2 H), 1.60–1.47 (m, 1 H), 1.44–1.26 (m, 7 H), 0.90 (t, J =
6.6 Hz, 3 H).
https://doi.org/10.1055/s-0037-1609448.
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References
13C NMR (100 MHz, CDCl3): δ = 120.60 (m), 91.99 (m), 40.84 (d, J = 2.9
Hz), 39.67 (d, J = 18.2 Hz), 31.56, 29.66, 28.13, 22.97, 22.55, 14.01.
(1) Selected recent reviews on difunctionalization of carbon–
carbon multiple bonds: (a) Gao, P.; Song, X.-R.; Liu, X.-Y.; Liang,
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19F NMR (376 MHz, CDCl3): δ = –76.76 (d, J = 523.7 Hz), –185.57.
HRMS (EI+): m/z calcd for [C11H15F7I]+ ([M]+): 407.0107; found:
407.0104.
Ethyl 2,2-Difluoro-4-iodo-5-phenylpentanoate24 (25)
(2) Selected recent reviews and papers on difunctionalization of
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Pale yellow liquid; yield: 154.6 mg (84%).
1H NMR (400 MHz, CDCl3): δ = 7.36–7.25 (m, 3 H), 7.22–7.15 (m, 2 H),
4.40–4.28 (m, 3 H), 3.30–3.15 (m, 2 H), 2.99–2.70 (m, 2 H), 1.35 (t, J =
7.2 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 163.42 (t, J = 32.3 Hz), 138.83, 129.03,
128.62, 127.23, 115.22 (t, J = 253.4 Hz), 63.31, 47.22 (d, J = 1.4 Hz),
44.36 (t, J = 23.4 Hz), 21.94 (t, J = 3.8 Hz), 13.92.
19F NMR (376 MHz, CDCl3): δ = –100.74 to –107.24 (m).
1-Fluoro-4-[4,5,5,5-tetrafluoro-2-iodo-4-(trifluoromethyl)pen-
tyl]benzene (26)
Pale yellow liquid; yield: 198.7 mg (92%).
1H NMR (400 MHz, CDCl3): δ = 7.18–7.11 (m, 2 H), 7.05–6.97 (m, 2 H),
4.46–4.35 (m, 1 H), 3.29–3.04 (m, 2 H), 3.03–2.82 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 162.06 (d, J = 246.0 Hz), 134.41 (d, J =
3.3 Hz), 130.49 (d, J = 8.1 Hz), 120.61 (qt, J = 286.5, 28.5 Hz), 115.47 (d,
J = 21.3 Hz), 93.81–90.20 (m), 46.41 (d, J = 3.1 Hz), 38.98 (d, J = 18.3
Hz), 22.03.
19F NMR (376 MHz, CDCl3): δ = –75.90 to –77.65 (m), –115.07,
–185.08 to –185.30 (m).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–G

G
W. Deng et al.
Special Topic
Synthesis
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