The addition of perfluoroalkanesulfinyl chlorides to alkoxyallenes

Article abstract of DOI:10.1016/j.jfluchem.2008.12.007

The addition reaction of perfluoroalkanesulfinyl chlorides to alkoxyallenes was achieved under mild conditions. Two kinds of perfluoroalkyl alkenyl sulfoxides, β-alkoxyvinyl perfluoroalkyl sulfoxides and α-perfluoroalkanesulfinyl enones or enals, were obt

Full text of DOI:10.1016/j.jfluchem.2008.12.007

Journal of Fluorine Chemistry 130 (2009) 329–331
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Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
The addition of perfluoroalkanesulfinyl chlorides to alkoxyallenes
*
Ling-Jun Chen, Jin-Tao Liu
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China
A R T I C L E I N F O
A B S T R A C T
Article history:
The addition reaction of perfluoroalkanesulfinyl chlorides to alkoxyallenes was achieved under mild
Received 11 November 2008
Received in revised form 16 December 2008
Accepted 16 December 2008
Available online 27 December 2008
conditions. Two kinds of perfluoroalkyl alkenyl sulfoxides,
b
-alkoxyvinyl perfluoroalkyl sulfoxides and
a
-perfluoroalkanesulfinyl enones or enals, were obtained selectively depending on the structure of
alkoxyallenes.
ß 2008 Elsevier B.V. All rights reserved.
Keywords:
Perfluoroalkanesulfinyl chloride
Alkoxyallene
Alkenyl sulfoxide
Addition reaction
1. Introduction
2. Results and discussion
Alkenyl sulfoxides are valuable intermediates for the con-
struction of many biologically active molecules, particularly by
virtue of their reactivity as dienophiles for Diels–Alder reactions,
acceptors for Michael additions, and excellent partners in
Pauson–Khand reactions [1–6]. Although the synthesis and
reaction of alkenyl sulfoxides have been well studied, their
fluorine-containing analogues are seldom reported [7]. Due to the
strong electron-withdrawing effect of perfluoroalkyl group, it is
reasonable to believe that the reactivity of perfluoroalkyl alkenyl
sulfoxides can be enhanced by the introduction of perfluoroalkyl
moiety [8]. Recently, Wakselman and coworkers reported the
synthesis of some fluoroalkyl vinyl sulfoxides by the elimination
The investigation started with the addition reaction of the
simplest alkoxyallene, methoxyallene (2a), with perfluoroalkane-
sulfinyl chlorides. Treatment of 2a with 2-chlorotetrafluoroetha-
nesulfinyl chloride (1a) in dichloromethane gave the desired
product b-alkoxyvinyl sulfoxide (3a) in only 10% yield. To improve
the yield of 3a, various conditions were screened and the best
result was obtained when the reaction was performed at 0 8C to
room temperature without any solvents. Using the same condi-
tions other alkoxyallenes and perfluoroalkanesulfinyl chlorides
were examined. As shown in Table 1, changing the perfluoroalkyl
group or alkyl group had little influence on the yield of the
corresponding products.
of HCl from
b
-substituted perfluoroalkyl sulfoxides, and com-
It is noteworthy that only one isomer of 3 was formed in each
addition reaction on the basis of carefully studying the 1H NMR
spectra of crude products. The configuration of 3 was further
assigned as trans for RFSO and alkoxy group by the NOE experiment
of 3a. The NOE effect was observed between proton Ha of CH2Cl
group and Hb of methoxy group (Fig. 2).
pared their activities with phenyl vinyl sulfoxides in Diels–Alder
reaction [7,9].
During our continuous study on the reaction of perfluoroalk-
anesulfinyl chlorides (1) [10], it was found that perfluoroalkyl
alkenyl sulfoxides could be easily prepared by the addition
reaction of 1 and alkoxyallenes (2), and two kinds of perfluoroalkyl
Under similar conditions, we next studied the reaction of 1a and
alkenyl sulfoxides,
b
-alkoxyvinyl perfluoroalkyl sulfoxides (3) and
alkoxyallenes with alkyl substituent at
no expected -alkoxyvinyl sulfoxides (3) but
fluoroethanesulfinyl) enones (4) were obtained. The results are
summarized in Table 2. With -substituted alkoxyallene 2h, the
-(2-chlorotetrafluoroethanesul-
a
-position. To our surprise,
a
-perfluoroalkanesulfinyl enones or enals (4), were obtained with
b
a-(2-chlorotetra-
different alkoxyallenes (Fig. 1). The results are reported in this
paper.
g
reaction gave the corresponding
a
finyl) enal 4d in good yield.
When phenoxyallene (2i) was used, no addition reaction
occurred (Table 1, entry 6). Similarly, alkyl substituted allenes,
such as undeca-1,2-diene and nona-1,2-diene, did not react with 1
* Corresponding author. Fax: +86 21 64166128.
E-mail address: jtliu@mail.sioc.ac.cn (J.-T. Liu).
0022-1139/$ – see front matter ß 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2008.12.007

330
L.-J. Chen, J.-T. Liu / Journal of Fluorine Chemistry 130 (2009) 329–331
Table 2
The reaction of perfluoroalkanesulfinyl chlorides with substituted alkoxyallenes.
Fig. 1.
b-Alkoxyvinyl perfluoroalkyl sulfoxides (3) and a-perfluoroalkanesulfinyl
enones or enals (4).
Entry
2
R1
R2
R3
Product
Isolated yield (%)
Table 1
1
2
3
4
2e
2f
Me
Me
Et
n-Pr
H
4a
4b
4c
4d
67
76
65
82
The reaction of perfluoroalkanesulfinyl chlorides with alkoxyallenes.
n-Bu
Ph(CH2)3
H
H
2g
2h
H
Et
Me2C(OEt)
good regio- and stereoselectivity, providing a novel method for
the preparation of multi-functional perfluoroalkyl alkenyl
sulfoxides.
Entry
1
RF
2
R1
Product
Isolated yield (%)
3. Experimental
1
2
3
4
5
6
1a
1a
1a
1b
1c
1a
ClC2F4
ClC2F4
ClC2F4
n-C4F9
n-C6F13
ClC2F4
2a
2b
2c
2b
2b
2i
Me
Et
3a
3b
3c
3d
3e
–
47
61
77
78
68
NR
3.1. General
Bn
Et
Melting points were uncorrected. 1H NMR spectra were
recorded in CDCl3 on a Bruker AM-300 spectrometer (300 MHz)
with TMS as internal standard. 19F NMR spectra were taken on a
Bruker AM-300 (282 MHz) spectrometer using CFCl3 as external
standard. IR spectra were obtained with a Nicolet AV-360 spe-
ctrophotometer. Mass spectra and high-resolution mass spectra
(HRMS) were obtained on a Finnigan GC-MS 4021 and a Finnigan
MAT-8430 spectrometer, respectively. Alkoxyallenes 2a–2i were
prepared via base induced isomerization of alkynyl ether using the
Brandsma’s procedure [11–13].
Et
Ph
either. As a comparison, the reaction of tert-butanesulfinyl chloride
with methoxyallene under similar conditions was tried, but it was
very complicated and no desired product was obtained.
In all reactions, the addition took place at
b-carbon of allenes
selectively. On the basis of the above results, a possible mechanism
was proposed for this addition reaction as shown in Scheme 1. The
reaction of 2 and perfluoroalkanesulfinyl chlorides gives inter-
mediate B, which undergoes further transformations to give the
final product through path 1 or path 2 depending on the structure
of 2. In the case of unsubstituted alkoxyallenes (R2 R3 H), the
reaction gives the usual addition products 3 through path 1, while
3.2. Typical experiment procedure for the preparation of
perfluoroalkyl alkenyl sulfoxides
Under stirring, 1a (0.5 mmol) was added dropwise to 2a
(1 mmol) at 0 8C. After addition, the mixture was warmed to room
temperature over 2 h, and then stirred at room temperature for 1 h
(monitored by TLC). After completion of the reaction, the mixture
was concentrated to remove volatile compounds. The residue was
purified by column chromatography on silica gel (ethyl acetate:
hexane = 1:10) to give 3a.
a
-sulfinyl enones or enals 4 are formed through path 2 when
substituted alkoxyallenes are used, probably due to both steric and
conjugation effects. Alkoxy group is essential to this reaction and it
might act as an electron-donor to make 2 form intermediate A.
This can be further proved by the fact that alkyl allenes and
phenoxyallene do not react with 1. In the latter case the con-
jugation between the lone electron pair of oxygen and aromatic
ring weakens the electron-donor ability of oxygen.
3.2.1. (E)-3-Chloro-2-(2-chlorotetrafluoroethanesulfinyl)-1-
In summary, the reaction of perfluoroalkanesulfinyl chlorides
with alkoxyallenes was achieved under mild conditions with
methoxyprop-1-ene (3a)
White solid, m.p.: 34–35 8C. IR (KBr):
1018 cmÀ1 1H NMR (300 MHz, CDCl3):
n
2953, 1635, 1160, 1121,
.
d 7.05 (s, 1H), 4.42, 4.30
(AB, JAB = 12.9 Hz, 2H), 4.05 (s, 3H). 19F NMR (282 MHz, CDCl3):
d
À67.52 (m, 2F); À108.53, À122.06 (AB, JAB = 230.1 Hz, 2F). ESI-MS
m/z: 289 [M+1]+. Anal. Calcd for C6H6Cl2F4O2S: C, 24.93; H, 2.09.
Found: C, 25.28; H, 2.07.
3.2.2. (E)-3-Chloro-2-(2-chlorotetrafluoroethanesulfinyl)-1-
ethoxyprop-1-ene (3b)
Oil. IR (neat):
(300 MHz, CDCl3):
4.27 (q, J = 7.2 Hz, 2H), 1.43 (t, J = 7.2 Hz, 3H). 19F NMR (282 MHz,
CDCl3):
À67.10 (m, 2F), À108.21, À121.48 (AB, JAB = 229.7 Hz, 2F).
n
2985, 1631, 1167, 1122, 1017 cmÀ1
.
1H NMR
d
7.13 (s, 1H), 4.43, 4.32 (AB, JAB = 12.3 Hz, 2H),
d
13C NMR (75 MHz, CDCl3):
d 160.28, 112.38, 72.68, 32.33, 15.29. EI-
MS m/z: 303 [M+1]+, 167 [M-ClC2F4]+. HRMS Calcd for
Fig. 2. 1H-1H NOESY of 3a.
C7H8Cl2F4O2S [M]+: 301.9612. Found: 301.9558.

L.-J. Chen, J.-T. Liu / Journal of Fluorine Chemistry 130 (2009) 329–331
331
Scheme 1. Proposed mechanism for the addition reaction.
3.2.3. (E)-3-Chloro-2-(2-chlorotetrafluoroethanesulfinyl)-1-
2.82 (td, J1 = 7.5 Hz, J2 = 3.0 Hz, 2H), 1.69–1.64 (m, 2H), 1.41–1.34
(m, 2H), 0.98 (t, J = 7.5 Hz, 3H). 19F NMR (282 MHz, CDCl3):
À68.37 (m, 2F), À107.73, À121.40 (AB, JAB = 225.7 Hz, 2F). ESI-MS
m/z: 316.7 [M+Na]+, 348.8 [M+MeOH+Na]+. Anal. Calcd for
C9H11ClF4O2S: C, 36.68; H, 3.76. Found: C, 37.08; H, 3.98.
benzyloxy-1-ene (3c)
d
Oil. IR (neat):
NMR (300 MHz, CDCl3):
(AB, JAB = 12.6 Hz, 2H), 4.44, 4.34 (AB, JAB = 12.6 Hz, 2H). 19F NMR
(282 MHz, CDCl3):
À69.98 (m, 2F), À108.15, À121.02 (AB,
JAB = 231.3 Hz, 2F). 13C NMR (75 MHz, CDCl3):
159.84, 134.53,
n
3036, 1633, 1184, 1119, 800, 737, 698 cmÀ1. 1H
7.43–7.34 (m, 5H), 7.18 (s, 1H), 5.22, 5.19
d
d
d
3.2.8. 2-(2-Chlorotetrafluoroethanesulfinyl)-6-phenylhex-1-en-3-
129.28, 129.08, 127.76, 113.27, 77.64, 32.23. ESI-MS m/z: 365
[M+1]+. HRMS Calcd for C12H10Cl2F4O2S [M+1]+: 364.9799. Found:
364.9787.
one (4c)
Oil. IR (neat):
(300 MHz, CDCl3):
2H), 2.82–2.78 (m, 2H), 2.68 (t, J = 7.5 Hz, 2H), 1.69–1.64 (m, 2H).
19F NMR (282 MHz, CDCl3):
À121.32 (AB, J = 221.4 Hz, 2F). ESI-MS m/z: 378.9 [M+Na]+, 410.8
[M+MeOH+Na]+. Anal. Calcd for C14H13ClF4O2S: C, 47.13; H, 3.67;
Found: C, 47.18; H, 3.96.
n
2936, 1719, 1686, 1180, 1122 cmÀ1
.
1H NMR
d
7.33–7.16 (m, 5H), 6.91, 6.89 (AB, J = 2.4 Hz,
3.2.4. (E)-3-Chloro-2-perfluorobutanesulfinyl-1-ethoxyprop-1-ene
d
À68.26 to À68.28 (m, 2F), À107.58,
(3d)
Oil. IR (neat):
(300 MHz, CDCl3):
4.28 (q, J = 7.2 Hz, 2H), 1.43 (t, J = 7.2 Hz, 3H). 19F NMR (282 MHz,
n
d
2987, 1632, 1240, 1207, 1149 cmÀ1
7.14 (s, 1H), 4.43, 4.30 (AB, JAB = 12.6 Hz, 2H),
.
1H NMR
CDCl3):
d
À81.26 (m, 3F), À109.95, À123.15 (AB, JAB = 245.2 Hz, 2F),
3.2.9. 2-(2-Chlorotetrafluoroethanesulfinyl)-4-ethoxy-4-
À121.31, À122.67 (AB, JAB = 301.3 Hz, 2F), À126.43 (m, 2F). 13C
methylpent-2-enal (4d)
NMR (75 MHz, CDCl3):
MS m/z: 387.0 [M+1]+. HRMS Calcd for C9H8ClF9O2S [M+1]+:
386.9877. Found: 386.9863.
d
160.72, 112.10, 72.75, 32.13, 15.17. ESI-
Oil. IR (neat):
NMR (300 MHz, CDCl3):
J1 = 6.9 Hz, J2 = 2.1 Hz, 2H), 1.55 (s, 6H), 1.21 (t, J = 6.9 Hz, 3H). 19
NMR (282 MHz, CDCl3):
n
2982, 1676, 1623, 1181, 1122, 1070 cmÀ1
.
1H
d
10.68 (s, 1H), 7.17 (s, 1H), 3.54 (qd,
F
d
À67.98 (m, 2F), À107.98, À122.61 (AB,
3.2.5. (E)-3-Chloro-2-perfluorohexylsulfinyl-1-ethoxyprop-1-ene
JAB = 223.4 Hz, 2F). ESI-MS m/z: 325.0 [M+1]+, 357.0 [M+1+MeOH]+.
Anal. Calcd for C10H13ClF4O3S: C, 36.99; H, 4.04; Found: C, 37.28; H,
4.22.
(3e)
Oil. IR (neat):
(300 MHz, CDCl3):
4.28 (q, J = 6.9 Hz, 2H), 1.43 (t, J = 6.9 Hz, 3H). 19F NMR (282 MHz,
CDCl3):
À81.22 (m, 3F), À109.75, À122.80 (AB, JAB = 249.7 Hz, 2F),
n
2985, 1632, 1236, 1140, 1089 cmÀ1
.
1H NMR
d
7.13 (s, 1H), 4.37, 4.30 (AB, JAB = 12.6 Hz, 2H),
Acknowledgement
d
À120.25, À121.80 (AB, JAB = 305.4 Hz, 2F), À122.84 (m, 2F),
Financial support from the National Natural Science Foundation
of China (No. 20572124) is gratefully acknowledged.
À123.33 (m, 2F), À126.59 (m, 2F). 13C NMR (75 MHz, CDCl3):
d
160.58, 112.16, 72.73, 32.22, 15.21. ESI-MS m/z: 486.9 [M+1]+,
509.0 [M+Na]+. HRMS Calcd for C11H8ClF13O2S [M+1]+: 486.9809.
Found: 486.9769.
References
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[11] S. Hoff, L. Brandsma, J.F. Arens, Recl. Trav. Chim. Pays Bas 87 (1968) 916–924.
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Soc. 100 (1981) 372–375.
3.2.6. 2-(2-Chlorotetrafluoroethanesulfinyl)-hex-1-en-3-one (4a)
Oil. IR (neat):
(300 MHz, CDCl3):
2.80 (td, J1 = 7.2 Hz, J2 = 3.0 Hz, 2H), 1.75–1.68 (m, 2H), 0.98 (t,
J = 7.2 Hz, 3H). 19F NMR (282 MHz, CDCl3):
n .
2966, 1712, 1625, 1179, 1122 cmÀ1 1H NMR
d
7.03 (d, J = 2.1 Hz, 1H), 6.93 (d, J = 2.1 Hz, 1H),
d
À68.30 (m, 2F),
À107.69, À121.325 (AB, JAB = 219.3 Hz, 2F). EI-MS m/z: 281 [M+1]+,
145 [M-C2F4Cl]+. Anal. Calcd for C8H9ClF4O2S: C, 34.23; H, 3.23.
Found: C, 34.03; H, 3.72.
3.2.7. 2-(2-Chlorotetrafluoroethanesulfinyl)-hept-1-en-3-one (4b)
Oil. IR (neat):
(300 MHz, CDCl3):
n .
2964, 1712, 1625, 1164, 1121 cmÀ1 1H NMR
d
7.26 (d, J = 2.1 Hz, 1H), 6.93 (d, J = 2.1 Hz, 1H),
[13] G. Pourcelot, C.R. Hebd, Seances Acad. Sci. 260 (1965) 2847–2850.