Iodofluorination of Alkenes Using IF5-Pyridine-HF

Article abstract of DOI:10.1055/s-0034-1381003

Iodofluorination of alkenes was performed by using IF₅-pyridine-HF and a reductant such as potassium iodide or tin powder. The addition of IF to the double bond proceeded with stereo- and regioselectivity. In the reaction with internal alkenes,

Full text of DOI:10.1055/s-0034-1381003

SYNTHESIS
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©
Georg Thieme Verlag Stuttgart · New York
2015, 47, 2839–2843
2839
paper
Synthesis
S. Yano, S. Hara
Paper
Iodofluorination of Alkenes Using IF –Pyridine–HF
5
Shohei Yano
I
Shoji Hara*
IF5-pyridine-HF
R2
R2
R1
R1
KI or Sn, CH2Cl2
Graduate School of Engineering, Hokkaido University,
Sapporo, 060-8628, Japan
shara@eng.hokudai.ac.jp
F
52–86%
Received: 25.03.2015
Accepted after revision: 27.04.2015
Published online: 11.06.2015
DOI: 10.1055/s-0034-1381003; Art ID: ss-2015-f0198-op
I
IF5-pyridine-HF
reductant
R2
R2
R1
R1
F
1
2
Abstract Iodofluorination of alkenes was performed by using IF –pyri-
5
dine–HF and a reductant such as potassium iodide or tin powder. The
addition of IF to the double bond proceeded with stereo- and regiose-
lectivity. In the reaction with internal alkenes, the trans-addition prod-
uct was obtained selectively. With terminal alkenes, the addition took
place regioselectively to give 1-iodo-2-fluoroalkanes.
Scheme 1 Iodofluorination of alkenes using IF –pyridine–HF
5
Although IF –pyridine–HF is unreactive to alkenes, io-
5
dine pentafluoride was used for the iodofluorination of
5
alkenes after reduction to IF species. Therefore, in the pres-
Key words fluorine, addition, stereoselective synthesis, halogenation,
alkenes
ent study, reductants such as iodine, potassium iodide, and
sodium iodide were used to generate IF species from IF5–
pyridine–HF. All the reductants used were found to be ef-
fective for the iodofluorination of cyclododecene (1a), and
1-fluoro-2-iodocyclododecene (2a) was obtained in good
yield (Table 1)
Iodofluorination of alkenes is a convenient method for
1
the synthesis of organofluorine compounds. Iodofluorina-
tion can be performed by iodine monofluoride in situ gen-
2
erated from iodine and fluorine gas. As alternatives to the
hazardous fluorine gas and iodine, reagents for F– and I
+
a
Table 1 Iodofluorination of 1a by IF –Pyridine–HF and Reductants
5
sources have been used to generate ‘IF’ species for the iodo-
3
–
F
fluorination. However, some of the reagents for the F
+
I
source are still hazardous, while some reagents for I source
are not readily available. Moreover, the reactivity of the IF
IF5-pyridine-HF
reductant, CH2Cl2
1b
species is dependent on the reagents used. Therefore, a
more convenient and effective method for the iodofluorina-
tion reaction of alkenes is still desired. Recently, we report-
ed a stable fluorinating reagent, iodine pentafluoride–pyri-
1a
2
a
dine–hydrogen fluoride (IF –pyridine–HF), and its applica-
5
4
tion to fluorination reactions. During the course of our
1
2
I
2
78
78
78
study on the new fluorination reaction using IF –pyridine–
5
KI
HF, we found that this reagent can be employed in the iodo-
fluorination of alkenes 1 via reduction with potassium io-
dide or tin, to obtain iodofluoroalkanes 2 (Scheme 1).
3
NaI
a
Reaction conditions: IF
Cl , r.t., 17 h.
Isolated yield based on 1a.
5
–pyridine–HF (1 equiv), reductant (1 equiv),
CH
2
2
b
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Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 2839–2843

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Synthesis
S. Yano, S. Hara
Paper
The use of potassium iodide was favorable for the reac-
tion of 1a, and 2a was obtained in good yield (Table 2, entry
). In contrast, when potassium iodide was used in the re-
different reactivities. In the reaction of diene 1i, where one
double bond is less reactive than the other due to the elec-
tron-withdrawing substituent, the iodofluorination selec-
tively took place at the more reactive double bond (entry 9).
1
action of dodec-1-ene (1b), 2-fluoro-1-iodododecane (2b)
was formed as the major product, but its regioisomer, 1-
fluoro-2-iodododecane, was also formed (91:9 ratio). For
the reaction of 1b, tin powder was more suitable, and 2b
was selectively formed in 82% yield (entry 2). The present
iodofluorination reaction proceeded stereoselectively, and
trans-1-fluoro-2-iodocyclohexane (2c) was selectively
formed from cyclohexene (1c) (entry 3). Furthermore,
when trans-dec-5-ene (1e) and cis-dec-5-ene (1f) were
used, the corresponding (5S*,6R*)-5-fluoro-6-iododecane
Iodofluorination of electron-deficient alkenes is rare, and
there are only a few reported examples.3
c,m
The present
iodofluorination is applicable to a wide variety of alkenes,
including electron-deficient alkenes. When 4-methylpent-
3-en-2-one (1j) was used in the reaction, the corresponding
iodofluorination product 2j was obtained regioselectively
(entry 10).
In summary, the iodofluorination of alkenes using IF5–
pyridine–HF is reported; IF –pyridine–HF is stable fluori-
5
(
2e) and (5R*,6R*)-5-fluoro-6-iododecane (2f) were selec-
nating reagent and easy to use. The present iodofluorina-
tion reaction proceeds regio- and stereoselectively, and is
applicable to a wide variety of alkenes, including electron-
deficient alkenes.
tively formed (entries 5 and 6). As the reaction proceeded
under mild conditions, functional groups such as ester and
free hydroxy were tolerated (entries 7–10). Furthermore, it
was possible to distinguish between two double bonds of
Table 2 Iodofluorination of Alkenes Using IF –Pyridine–HF and Potassium Iodide or Tina
5
Entry
Alkene 1
Reductant
Product 2
Yieldb (%)
F
I
1
KI
78
1
a
2
a
F
F
2c
C10H21
Sn
Sn
82
54
I
C10H21
1
b
2
b
3c
I
1
c
2
c
F
I
4
KI
(52)
1
d
2
d
F
F
Bu
Bu
Bu
5
6
Bu
KI
KI
Bu
57
58
1
e
I
2
e
Bu
Bu
Bu
1
f
I
2
f
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841
Synthesis
S. Yano, S. Hara
Paper
Table 2 (continued)
Entry
Alkene 1
Reductant
Sn
Product 2
Yieldb (%)
F
7c
MeO C(CH )
77
2
2 8
I
MeO2C(CH2)8
1
g
2
g
F
8c
HO(CH2)9
Sn
KI
(86)
I
1
h
HO(CH2)9
2
h
F
CO2Et
9
CO2Et
67
1
i
I
I
2
i
O
O
F
10
KI
(67)
1
j
2
j
a
b
c
5 2 2
Reaction conditions: IF –pyridine–HF (1 equiv), KI (1 equiv), CH Cl , r.t., 17 h.
19
Isolated yield based on alkene used. In parentheses, F NMR yield.
IF –pyridine–HF (3 equiv), Sn powder (2 equiv) were used.
5
1H (400 MHz), 19F (376 MHz), and 13C NMR (100 MHz) were recorded
1-Fluoro-2-iodocyclododecane (2a)
1
13
in CDCl on a Jeol JNM-A400II FT NMR with reference to TMS ( H, C)
3
Reaction was performed using KI as the reductant, and 2a was isolat-
ed by column chromatography (silica gel, hexane) as a colorless liq-
uid; yield: 123 mg (78%).
19
and CFCl ( F), respectively. HRMS (EI) were measured on a Jeol JMS-
3
7
00TZ. Sn powder of ~45 μm and 99.5% purity was used. IF in a cylin-
5
der was supplied by Daikin Industries, Ltd. Anhyd HF in a cylinder
IR (neat): 2926, 1469, 997 cm–1
.
was purchased from Stella Chemifa Corporation. IF –pyridine–HF was
5
1
H NMR (400 MHz, CDCl ): δ = 4.48–4.31 (m, 2 H), 2.03–1.34 (m, 20
prepared from IF and pyridine–HF by the previously reported meth-
3
5
4
H).
od. Glassware can be used for the reaction, but use of Teflon or poly-
19
3s
ethylene ware is recommended.
F NMR (376 MHz, CDCl ): δ = –168.55 (br s, 1 F) (Lit. –169.5).
3
1
3
C NMR (100 MHz, CDCl ): δ = 92.8 (d, J = 178.3 Hz), 34.7 (d, 2JC-F
1
=
3
C-F
Iodofluorination of Alkenes Using KI as a Reductant; General Pro-
cedure
9.0 Hz), 33.4 (d, JC-F = 2.9 Hz), 30.4 (d, 2J = 21.9 Hz), 24.4–23.7 (4
3
1
C-F
3
C), 23.4, 22.3, 22.0, 20.5 (d, J = 4.8 Hz).
C-F
To a solution of an alkene (0.5 mmol) and IF –pyridine–HF (161 mg,
5
0
.5 mmol) in CH Cl (3 mL) at 0 °C was added KI (83 mg, 0.5 mmol),
2 2
2-Fluoro-1-iodododecane (2b)
and the mixture was stirred at 0 °C for 30 min and at r.t. for 17 h.
Then, the mixture was poured into water (20 mL) and extracted with
Et O (3 × 20 mL). The combined organic layers were washed with aq
Reaction was performed using Sn powder as the reductant, and 2b
was isolated by column chromatography (silica gel, hexane) as a
white solid; yield: 128 mg (82%); mp 27–31 °C.
2
Na S O (20 mL) and aq NaHCO3 (20 mL), and dried (MgSO ). After
2
2
3
4
IR (KBr): 2923, 1465, 884 cm–1
.
concentration, the product was isolated by column chromatography
silica gel).
1
(
H NMR (400 MHz, CDCl ): δ = 4.53–4.36 (dm, J = 49.4 Hz, 1 H), 3.35–
3
3.27 (m, 2 H), 1.77–1.69 (m, 2 H), 1.44–1.27 (m, 16 H), 0.88 (t, J = 6.8
Hz, 3 H).
Iodofluorination of Alkenes Using Sn Powder as a Reductant; Gen-
eral Procedure
1
9
3a
F NMR (376 MHz, CDCl ): δ = –171.40 to –171.76 (m, 1 F) [Lit.
3
To a solution of an alkene (0.5 mmol) and IF –pyridine–HF (481 mg,
–171.5 (m, 1 F)].
5
1
.5 mmol) in CH Cl (3 mL) at 0 °C was added Sn powder (119 mg, 1.0
13
1
2
2
2
C NMR (100 MHz, CDCl ): δ = 92.3 (d, J = 177.4 Hz), 34.9 (d, J
C-F
=
3
C-F
mmol), and the mixture was stirred at 0 °C for 30 min and at r.t. for 17
h. Then, the solid was removed by filtration through Celite, and the
filtrate was poured into water (20 mL). The product was extracted
3
21.0 Hz), 32.0, 29.7, 29.6, 29.5, 29.4, 29.3, 24.8 (d, J = 4.7 Hz), 22.9,
C-F
2
14.2, 7.26 (d, J = 24.8 Hz).
C-F
with Et O (3 × 20 mL), and the combined organic layers were washed
2
trans-1-Fluoro-2-iodocyclohexane (2c)
with aq Na S O (20 mL) and aq NaHCO (20 mL), and dried (MgSO ).
2
2
3
3
4
Reaction was performed using Sn powder as the reductant, and 2c
was isolated by column chromatography (silica gel, hexane) as a col-
orless liquid; yield: 62 mg (54%).
After concentration, the product was isolated by column chromatog-
raphy (silica gel).
IR (neat): 2941, 1449, 950 cm–1
.
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2
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Synthesis
S. Yano, S. Hara
Paper
1
19
3l
H NMR (400 MHz, CDCl ): δ = 4.65–4.48 (dm, J = 49.4 Hz, 1 H), 4.15–
F NMR (376 MHz, CDCl ): δ = –171.40 to –171.80 (m, 1 F) [Lit.
3
3
4.09 (m, 1 H), 2.41–2.36 (m, 1 H), 2.25–2.16 (m, 1 H), 2.00–1.82 (m, 2
–171.3 (m)].
H), 1.64–1.55 (m, 2 H), 1.47–1.27 (m, 2 H).
13
C NMR (100 MHz, CDCl ): δ = 174.4, 92.3 (d, 1J = 177.4 Hz), 51.6,
3
C
-
F
19
3b
2
3
F NMR (376 MHz, CDCl ): δ = –159.20 (br s, 1 F) [Lit. –160.0 (dm,
34.8 (d, J = 21.0 Hz), 34.2, 29.3, 29.2 (2 C), 29.1, 25.0, 24.7 (d, J
3.8 Hz), 7.2 (d, J = 24.8 Hz).
=
3
C-F
C-F
2
J = 40.0 Hz)].
C-F
1
3
1
C NMR (100 MHz, CDCl ): δ = 95.0 (d, J = 182.1 Hz), 36.8, 31.6 (d,
3
C-F
2JC-F = 19.1 Hz), 31.2 (d, J = 19.0 Hz), 26.5, 23.2 (d, 3JC-F = 9.6 Hz).
2
10-Fluoro-11-iodoundecan-1-ol (2h)
C-F
Reaction was performed using Sn powder as the reductant, and the
1
9
1
-Fluoro-2-iodo-1-phenylethane (2d)
yield of 2h was determined to be 86% by F NMR using fluoroben-
zene as an internal standard. Pure 2h was isolated by column chro-
Reaction was performed using KI as the reductant, and the yield of 2d
was determined to be 52% by F NMR using fluorobenzene as an in-
ternal standard, and pure 2d was isolated by column chromatography
19
matography (silica gel, hexane–Et O) as a white solid; mp 48–50 °C.
IR (KBr): 3304 (OH), 2921, 1467, 1070 cm–1
.
2
(
silica gel, hexane).
1
H NMR (400 MHz, CDCl ): δ = 4.54–4.37 (dm, J = 48.0 Hz, 1 H), 3.64
3
IR (neat): 3033, 1454, 960, 699 cm–1
.
(t, J = 6.6 Hz, 2 H), 3.37–3.24 (m, 2 H), 1.79–1.30 (m, 16 H).
1H NMR (400 MHz): δ = 7.44–7.34 (m, 5 H), 5.55 (ddd, J = 47.6, 7.6, 5.6
19
3i
F NMR (376 MHz, CDCl ): δ = –170.90 to –171.20 (m, 1 F) [Lit.
3
Hz, 1 H), 3.54–3.43 (m, 2 H).
–171.2 to –171.6 (m, 1 F)].
19F NMR (376 MHz): δ = –166.60 to –166.90 (m, 1 F) [Lit.3b
–167.10
13
C NMR (100 MHz, CDCl ): δ = 92.3 (d, J = 177.4 Hz), 63.1, 34.9 (d,
3 C-F
1
2JC-F = 21.0 Hz), 32.8, 29.5, 29.4 (2 C), 29.3, 25.8, 24.8 (d, J = 4.8 Hz),
7.22 (d, JC-F = 25.7 Hz).
3
(ddd, J = 40.8, 24.2, 16.6 Hz)].
C-F
2
1
3
2
C NMR (100 MHz): δ = 138.2 (d, JC-F = 21.0 Hz), 129.5, 129.0 (2 C),
3
1
2
1
25.9 (d, J = 6.6 Hz, 2 C), 93.4 (d, J = 180.2 Hz), 7.7 (d, J = 28.6
C-F C-F C-F
Hz).
Ethyl (E)-7-Fluoro-6-iodo-3,7-dimethyloct-2-enoate (2i)
Reaction was performed using KI as the reductant, and 2i was isolat-
(5S*,6R*)-5-Fluoro-6-iododecane (2e)
ed by column chromatography (silica gel, hexane–Et
2
O) as a colorless
liquid; yield: 115 mg (67%).
IR (neat): 2983, 1715 (C=O), 1650, 1225, 1147 cm–1
Reaction was performed using KI as the reductant, and 2a was isolat-
ed by column chromatography (silica gel, hexane) as a colorless liq-
uid; yield: 82 mg (57%).
.
1
H NMR (400 MHz, CDCl ): δ = 5.73 (s, 1 H), 4.15 (q, J = 7.2 Hz, 2 H),
3
IR (neat): 2957, 1466 cm–1
.
3.98–3.92 (m, 1 H), 2.53–2.46 (m, 1 H), 2.26–2.16 (m, 1 H), 2.16 (s, 3
1
H), 2.04–1.93 (m, 1 H), 1.90–1.79 (m, 1 H), 1.60 (d, J = 15.2 Hz, 3 H),
H NMR (400 MHz, CDCl ): δ = 4.42–4.11 (dm, J = 48.4 Hz, 1 H), 4.16–
.11 (m, 1 H), 1.96–1.24 (m, 12 H), 0.93 (t, J = 7.2 Hz, 6 H).
3
1
.55 (d, J = 15.2 Hz, 3 H), 1.28 (t, J = 14.4 Hz, 3 H).
19F NMR (376 MHz, CDCl
): δ = –133.60 (br s, 1 F).
C NMR (100 MHz, CDCl ): δ = 166.9, 157.8, 117.1, 96.4 (d, 1JC-F
4
1
9
3d
3
F NMR (376 MHz, CDCl ): δ = –173.30 to –173.60 (m, 1 F) [Lit.
3
13
–
174.05 to –174.37 (m, 1 F)].
=
3
2
3
13
C NMR (100 MHz, CDCl ): δ = 96.0 (d, 1J = 177.2 Hz), 38.5 (d, 2J
173.6 Hz), 59.9, 42.7 (d,
27.6 (d, JC-F = 24.8 Hz), 23.7 (d, JC-F = 24.8 Hz), 19.0, 14.6.
J
C-F = 24.8 Hz), 41.1, 32.6 (d,
JC-F = 3.8 Hz),
=
3
C-F
2
C-F
2
2
3
2
1.0 Hz), 34.8 (d, J = 4.8 Hz), 33.8 (d, J = 21.1 Hz), 31.9, 27.4 (d,
C-F
C-F
3
+
JC-F = 1.9 Hz), 22.8, 22.2, 14.3 (2 C).
HRMS (EI): m/z [M + Na] calcd for C12H20O FINa: 365.03842; found:
2
365.03894.
(5R*,6R*)-5-Fluoro-6-iododecane (2f)
4
-Fluoro-3-iodo-4-methylpentan-2-one (2j)
Reaction was performed using KI as the reductant, and 2f was isolat-
ed by column chromatography (silica gel, hexane) as a colorless liq-
uid; yield: 83 mg (58%).
Reaction was performed using KI as the reductant, and the yield of 2j
was determined to be 67% by F NMR using fluorobenzene as an in-
19
IR (neat): 2957, 1465 cm–1
ternal standard and pure 2j was isolated by column chromatography
.
(
silica gel, hexane–Et O) as a colorless liquid.
2
1
H NMR (400 MHz, CDCl ): δ = 4.14–3.99 (m, 2 H), 1.99–1.28 (m, 12
3
IR (neat): 2987, 1705 (C=O), 1358 cm–1
.
H), 0.93 (t, J = 7.2 Hz, 6 H).
1H NMR (400 MHz, CDCl
): δ = 4.64 (d, J = 14.8 Hz, 1 H), 2.64 (s, 3 H),
19
3
F NMR (376 MHz, CDCl ): δ = –176.10 to –176.20 (m, 1 F).
3
1.64 (d, J = 12.0 Hz, 3 H), 1.59 (d, J = 10.8 Hz, 3 H).
1
3
C NMR (100 MHz, CDCl ): δ = 95.1 (d, J = 179.3 Hz), 38.8 (d, 2JC-F
1
=
3
2
C-F
19F NMR (376 MHz, CDCl
): δ = –130.80 (br s, 1 F).
2.0 Hz), 36.1, 34.1 (d, JC-F = 20.0 Hz), 31.8, 27.3 (d, 3JC-F = 3.8 Hz),
2.5, 22.0, 14.1, 14.0.
3
2
2
1
3
C NMR (100 MHz, CDCl ): δ = 201.5, 93.9 (d, 1J = 177.3 Hz), 41.0
3
C-F
2
2
3
+
(d, JC-F = 23.9 Hz), 28.2 (d, JC-F = 3.8 Hz), 25.8 (d, JC-F = 22.9 Hz), 25.7
HRMS (EI): m/z [M] calcd for C10H20FI: 286.05937; found: 286.05908.
2
(d, J = 23.8 Hz).
C-F
HRMS (EI): m/z [M]+ calcd for C6H10OFI: 243.97604; found:
34.97507.
Methyl 10-Fluoro-11-iodoundecanoate (2g)
2
Reaction was performed using Sn powder as the reductant, and 2g
was isolated by column chromatography (silica gel, hexane–Et O) as a
2
white solid; yield: 132 mg (77%); mp 35–39 °C.
Acknowledgment
IR (KBr): 2924, 1736 (C=O), 1437, 1173 cm–1
.
1
H NMR (400 MHz, CDCl ): δ = 4.52–4.36 (dm, J = 48.5 Hz, 1 H), 3.67
We are grateful to Daikin Industries, Ltd. for their donation of IF5.
3
(s, 3 H), 3.37–3.24 (m, 2 H), 2.32 (t, J = 7.4 Hz, 2 H), 1.78–1.61 (m, 4 H),
1.46–1.30 (m, 10 H).
©
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2
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Synthesis
S. Yano, S. Hara
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Supporting Information
Matsumoto, K.; Hagiwara, R.; Ito, Y. J. Fluorine Chem. 2005, 126,
1
21. (h) Yoshino, H.; Matsubara, S.; Oshima, K.; Matsumoto, K.;
Hagiwara, R.; Ito, Y. J. Fluorine Chem. 2004, 125, 455.
i) Kobayashi, S.; Sawaguchi, M.; Ayuba, S.; Fukuhara, T.; Hara, S.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0034-1381003.
S
u
p
p
ortioIgnfrm oaitn
S
u
p
p
ortioIgnfrm oaitn
(
Synlett 2001, 1938. (j) Shellhamer, D. F.; Jones, B. C.; Pettus, B. J.;
Pettus, T. L.; Stringer, J. M.; Heasley, V. L. J. Fluorine Chem. 1998,
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