α,α-Difluoro-α-phenylsulfanylmethyl carbanion equivalent: a novel gem-difluoromethylenation of carbonyl compounds

Article abstract of DOI:10.1016/j.tet.2006.04.015

α,α-Difluoro-α-phenylsulfanyl-α-trimethylsilylmethane (PhSCF₂SiMe₃) has been demonstrated as an α,α-difluoro-α-phenylsulfanylmethyl carbanion equivalent. gem-Difluorophenylsulfanylmethylation of carbonyl compounds has been successful

Full text of DOI:10.1016/j.tet.2006.04.015

Tetrahedron 62 (2006) 5973–5985
a,a-Difluoro-a-phenylsulfanylmethyl carbanion equivalent:
a novel gem-difluoromethylenation of carbonyl compounds
a
a
Manat Pohmakotr,a, Kanhokthron Boonkitpattarakul, Winai Ieawsuwan,
*
Suwatchai Jarussophon,a Nongnaphat Duangdee,b Patoomratana Tuchindaa
and Vichai Reutrakula,
*
aDepartment of Chemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
bDepartment of Science Services, Ministry of Science and Technology, Rama VI Road, Bangkok 10400, Thailand
Received 12 January 2006; revised 23 March 2006; accepted 6 April 2006
Available online 11 May 2006
Abstract—a,a-Difluoro-a-phenylsulfanyl-a-trimethylsilylmethane (PhSCF2SiMe3) has been demonstrated as an a,a-difluoro-a-phenyl-
sulfanylmethyl carbanion equivalent. gem-Difluorophenylsulfanylmethylation of carbonyl compounds has been successfully achieved by
using PhSCF2SiMe3 in the presence of TBAF in THF. The adducts have been converted to the corresponding gem-difluoroalkenes by a novel
pyrolytic and/or FVP elimination of the b-hydroxy-a-phenylsufinyl derivatives under reduced pressure.
Ó 2006 Elsevier Ltd. All rights reserved.
O
C
1. Introduction
F
C
F
F
C
OH
C
R2
F
C
OSiMe3
C
R2
R1
R2
PhS
R1
+
PhS
R1
PhS
PhS
SiMe3
TBAF (10 mol%)
Organofluorine chemistry is receiving remarkable interest
due to the enormous utility of organofluorine compounds
in several fields, such as medicine, biology, agriculture and
analytical chemistry.1 The development of synthetic routes
of such compounds and investigations for the use of new
fluorinated compounds as building blocks are of great
importance. Of particular interest is the introduction of a
gem-difluoromethylene group into organic molecules, which
have been the subject of recent reports by several prominent
research groups such as those of Prakash et al.,2 Hu3 and
Qing.4 In continuation with our research on utilizing bromo-
difluorophenylsulfanylmethane as the gem-difluoromethyl-
ene building block,5 we have investigated the utilization of
a,a-difluoro-a-phenylsulfanyl-a-trimethylsilylmethane (1)2b
as the synthetic equivalent of difluorinated carbanion 2
(Scheme 1).6 In this paper, we wish to report our findings
on the chemistry of the carbanion 2 and also provide novel
examples of pyrolytic elimination of b-hydroxy-a-phenyl-
sulfinyl derivatives to gem-difluoroalkenes.
F
F
°
THF, 78 C to rt,
overnight
1
3
4
F
C
F
2
Scheme 1.
2. Results and discussion
We first examined the nucleophilic difluorophenylsulfanyl-
methylation of benzaldehyde using compound 1 under the
catalysis of fluoride ion (Scheme 1). It was found that the
reaction of 1 (1.1 equiv) with benzaldehyde (1 equiv) took
place between ꢀ78 ꢁC and room temperature over 15 h in
the presence of 10 mol % of anhydrous tetra-n-butylammo-
nium fluoride (TBAF) in dry THF,7 giving the desired 3a
and 4a in 52 and 31% yields, respectively, after chromato-
graphy on silica gel. The reactions employing 20 or
50 mol % of TBAF afforded lower yields of the expected
adducts 3a and 4a.8 Thus, the standard conditions using
10 mol % of TBAF at ꢀ78 ꢁC to room temperature over-
night were used for the reactions of 1 with other carbonyl
compounds. It was found that fluoride-catalyzed condensa-
tion of 1 with aromatic aldehydes gave mixtures of 3 and 4
in good yields (Table 1, entries 1–4 and 7–9), whereas
Keywords: Difluoro(phenylsulfanyl)trimethylsilane; gem-Difluoroalkene;
gem-Difluoromethylenation; Fluoride-catalyzed reaction; Carbonyl com-
pounds.
* Corresponding authors. Tel.: +66 2 2015158; fax: +66 2 6445126; e-mail:
scmpk@mahidol.ac.th
0040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.04.015

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M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
Table 1. Fluoride-catalyzed condensation of 1 with carbonyl compounds
Entry Carbonyl compounds
3 (%)a 4 (%)a 3+4 (%)a
should be mentioned here that the sulfoxide elimination of
5b–f proceeded equally well under both neat pyrolysis and
FVP, while 5l and 5o proceeded only under FVP conditions
as summarized in Table 2 (entries 6 and 7). Our synthetic
route thus provides a general entry to gem-difluoromethyle-
nation of carbonyl compounds.2d,2e,11
1
2
Benzaldehyde
3a (52) 4a (31) 83
3b (41) 4b (48) 89
4-Methoxybenzaldehyde
2,4-Dimethoxybenzaldehyde
3,4-Dimethoxybenzaldehyde 3d (37) 4d (48) 85
3
3c (28)
4c (60) 88
4
5
6
7
8
Cinnamaldehyde
2-Methoxycinnamaldehyde
4-Methylbenzaldehyde
4-Bromobenzaldehyde
2-Furaldehyde
n-Butanal
Crotonaldehyde
1-Tetralone
6-Methoxy-1-tetralone
Acetophenone
Benzophenone
Cyclohexanone
Cyclopentanone
Acetone
3e (50)
3f (53)
3g (35) 4g (51) 86
3h (61) 4h (31) 92
3i (73)
3j (69)
3k (70)
3l (22)
3m (21) 4m (29) 50
3n (30) 4n (21) 51
4e (18) 68
4f (37) 90
The mechanism for the formation of gem-difluoroalkene 6
from the corresponding sulfoxide 5 is unclear but can be
rationalized as proposed in Scheme 3. An intramolecular
nucleophilic addition of the hydroxyl group to the electron
deficient sulfur atom of 5 (due to the electronegativity of
a,a-difluoro atoms) furnishes a cyclic intermediate 7, which
undergoes fragmentation to give gem-difluoroalkene 6.
9
—
—
—
73
69
70
10
11
12
13
14
15
16
17
18
19
4l (26) 48
3o (33) 4o (6)
39
63
45
65
60
3p (63)
3q (45)
3r (65)
3s (60)
—
—
—
—
O
S
OH
Ph S O
Ph
OH
R1
R2
Pyrolysis
R1
R2
2-Cyclohexenone
F
F
F
F
a
Isolated yield.
5
7
aromatic ketones afforded moderate yields of 3 and 4 (en-
tries 12–15). The reactions proceeded well with aliphatic al-
dehydes and ketones (Table 1, entries 10 and 16–18) to give
the adduct 3 as the sole products. Interestingly, 1,2-addition
products were obtained, when 1 was combined with a,b-
unsaturated carbonyl compounds, indicating the nature of
non-stabilized carbanion 2 (Table 1, entries 5, 6, 11 and
19).9 The silyl ether 4b could be converted into the corre-
sponding adduct 3b in quantitative yield by employing KF
in acetonitrile/THF at room temperature overnight.
O
S
F
F
R1
R2
+
Ph
OH
6
Scheme 3.
In conclusion, we have demonstrated that a,a-difluoro-a-
phenylsulfanyl-a-trimethylsilylmethane (1) can serve as a
practical and useful synthetic equivalent of a,a-difluoro-
a-phenylsulfanylmethyl carbanion 2, which is not easy to
access. Both aldehydes and ketones undergo facile a,a-
difluorophenylsulfanylmethylation with 1 in the presence of
10 mol % TBAF in THF, providing gem-difluoro substituted
alcohols in moderate to good yields. We have also illustrated
that these adducts can be used as useful precursors for
preparing gem-difluoroalkenes through the b-hydroxy-a-
phenylsulfinyl derivatives.
The synthetic utility of this reaction for the synthesis of gem-
difluoromethylene compounds as described in Scheme 1 was
further demonstrated by transformation of selected adduct 3
to gem-difluoroalkene 6. Logically, we expected that the
pyrolysis of the sulfoxide 5, obtained from the oxidation of
the aromatic aldehyde adduct 3 with MCPBA would lead to
the corresponding a,a-difluoromethylketones (Scheme 2).10
Thus, the oxidation of 3b proceeded smoothly by using
1.1 equiv MCPBA in THF at ꢀ78 ꢁC to room temperature
overnight (15 h) to give the corresponding sulfoxide 5b in
74% yield. To our surprise, neat pyrolysis of 3b at 200 ꢁC
under reduced pressure (0.05 mmHg) furnished gem-difluoro-
alkene 6b in 79% yield instead of the expected a,a-difluoro-
methyl 4-methoxyphenyl ketone. Similar result was
observed when flash vacuum pyrolysis (FVP) of 5b was
performed. A good yield of 6b (82%) resulted (Table 2,
entries 1). Moreover, this novel synthetic conversion was ex-
tended to compounds 3c–f, 3l and 3n to give gem-difluoro-
alkenes 6c–f, 6l and 6n in moderate to good yields. It
3. Experimental
3.1. General methods
The 1H and 13C NMR spectra were recorded on either
a Bruker DPX-300 or a Bruker DPX-400 spectrometer in
CDCl3 using tetramethylsilane as an internal standard. The
19F NMR spectra were recorded on a Bruker DPX-400
(376 MHz) spectrometer and chemical shifts (d) were mea-
sured with fluorotrichloromethane (d¼0) as an internal stan-
dard. The IR spectra were recorded on either a Jasco A-302
or a Perkin Elmer 683 infrared spectrometer. The electron
impact mass spectra were recorded by using Thermo
Finnigan Polaris Q mass spectrometer. The high resolution
mass spectra were recorded on HR-TOF-MS Micromass
model VQ-TOF2. Elemental analyses were performed on
a Perkin Elmer Elemental Analyzer 2400 CHN. Melting
points were recorded on a Buchi 501 melting point apparatus
and are uncorrected.
F
C
F
OH
C
O
PhS
F
C
F
OH
C
MCPBA
PhS
R1
R1
°
THF, -78 C
R2
R2
3
5
Pyrolysis
R1
R2
F
F
6
Tetrahydrofuran (THF) was distilled from sodium–benzo-
phenone ketyl. Dry dichloromethane (CH2Cl2) and dry
Scheme 2.

M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
5975
Table 2. Preparation of gem-difluoroalkene 6
Entry
3
5a
6
Conditions, % yield of 6b
200 ꢁC
(0.05 mmHg)
FVP
(temp, 0.05 mmHg)
OH
CF2SPh
O
F
1
2
3
3b
3c
3d
79%
74%
71%
82% (425 ꢁC)
70% (425 ꢁC)
68% (425 ꢁC)
F
MeO
MeO
MeO
MeO
6b
5b (74%)
OMe OH
CF2SPh
OMe
O
F
F
F
F
5c (69%)
6c
OH
O
MeO
MeO
MeO
MeO
CF2SPh
6d
5d (70%)
OH
O
F
CF2SPh
F
4
5
3e
3f
70%
78%
60% (425 ꢁC)
6e
5e (50%)
OMe
OH
F
O
CF2SPh
F
70% (425 ꢁC)
OMe
6f
5f (60%)
O
F
F
HO
CF2SPh
6
3l
—
—
41% (518 ꢁC)
6l
5l (68%)
O
F
F
HO CF2SPh
7
3o
80% (518 ꢁC)
5o (71%)
6o
a
Number in parenthesis is the isolated yield of 5 from 3 and obtained as a mixture of diastereomers.
Isolated yield.
b
N,N-dimethylformamide (DMF) were obtained by distilling
3.2. Preparation of compounds 3 and 4 by fluoride-
catalyzed condensation of compound 1 with carbonyl
compounds
over phosphorus pentoxide and calcium hydride, respec-
tively. Other common solvents (dichloromethane, hexane,
ethyl acetate and acetone) were distilled before use.
3.2.1. 2,2-Difluoro-1-phenyl-2-phenylsulfanylethanol
(3a) and 2,2-difluoro-1-phenyl-2-phenylsulfanyl-1-tri-
methylsiloxyethane (4a). General procedure: To a mixture
of compound 1 (2.32 g, 10 mmol) and benzaldehyde (1.06 g,
10 mmol) in THF (25 mL), was added TBAF (1.0 mL,
1.0 mmol, 1 M solution in THF). The reaction mixture was
stirred at ꢀ78 ꢁC, followed by slow warming up to room
temperature overnight. The solution was quenched with
a saturated aqueous NH4Cl solution and extracted with
EtOAc (3ꢂ70 mL). The organic phase was washed
The starting compound PhSCF2SiMe3 (1) was prepared
according to the literature procedure.2b
The reactions of compound 1 with carbonyl compounds
were run under an argon atmosphere. All glasswares and
syringes were oven-dried and kept in a desiccator before use.
Radial chromatography (chromatotron) and column chro-
matography were performed by using Merck silica gel 60
F254 (Art. 7749) and silica gel 60H (Art. 7736), respectively.

5976
M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
successively with brine, water and dried over anhydrous
Na2SO4. After solvent removal, the crude product was puri-
fied by column chromatography (SiO2, 5% EtOAc in hex-
anes) to give a pale yellow liquid of 3a (1.373 g, 52%
yield) and a white powder of 4a (1.035 g, 31% yield,
137(100), 109 (45), 94 (24), 77 (16). Anal. Calcd for
C15H14F2O2S: C, 60.80; H, 4.76. Found: C, 60.73; H, 4.94.
4b: 1H NMR (400 MHz, CDCl3): d 7.60–7.56 (m, 2H,
ArH), 7.42–7.30 (m, 5H, ArH), 6.91 (m, 2H, ArH), 4.96
(dd, J¼10.8, 7.7 Hz, 1H, CHOSiMe3), 3.80 (s, 3H, OCH3),
0.13 (s, 9H, OSi(CH3)3). 13C NMR (100 MHz, CDCl3):
d 160.6 (C), 136.9 (2ꢂCH), 130.0 (CH), 129.8 (2ꢂCH),
129.6 (t, J¼283.3 Hz, CF2), 129.4 (2ꢂCH), 127.4 (C),
126.8 (C), 114.1 (2ꢂCH), 77.7 (t, J¼27.0 Hz, CH), 55.8
(CH3), 0.6 (3ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ83.55 (dd, J¼203.0, 11.2 Hz, 1F), ꢀ80.59 (dd,
J¼203.0, 7.4 Hz, 1F). IR (neat): nmax 3063w, 2956s,
2924s, 2855s, 1644w, 1611s, 1586m, 1513s, 1463s, 1442s,
1421w, 1377m, 1330w, 1340m, 1288m, 1251s, 1205m,
1171s, 1121s, 1103s, 1065s, 1038s, 984s, 943w, 858s,
875s, 844s, 809m, 780m, 746s, 711w, 703w, 689m, 638w,
1
mp¼45–46 ꢁC). 3a: H NMR (400 MHz, CDCl3): d 7.63–
7.58 (m, 2H, ArH), 7.54–7.48 (m, 2H, ArH), 7.49–7.35
(m, 6H, ArH), 5.02 (dd, J¼11.3, 7.9 Hz, 1H, CHOH), 2.62
(br s, 1H, CHOH). 13C NMR (100 MHz, CDCl3): d 137.1
(2ꢂCH), 135.9 (C), 130.6 (CH), 129.8 (CH), 129.7
(2ꢂCH), 129.6 (t, J¼283.1 Hz, CF2), 129.0 (2ꢂCH),
128.5 (2ꢂCH), 126.5 (C), 76.8 (t, J¼26.6 Hz, CH). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ85.18 (dd, J¼209.3,
11.2 Hz, 1F), ꢀ81.60 (dd, J¼209.3, 7.5 Hz, 1F). IR (neat):
nmax 3419br s, 3065m, 3036m, 2901w, 1958w, 1889w,
1811w, 1604w, 1581w, 1496m, 1475s, 1455s, 1441s,
1394m, 1309m, 1201m, 1158s, 1059s, 1028s, 984s, 966s,
919w, 848m, 802m, 750s, 699s, 637s cmꢀ1. EIMS: m/z (%
relative intensity) 266 (M+, 68), 249 (40), 247 (9), 227 (7),
171 (36), 160 (77), 109 (23), 107 (51), 80 (100), 78 (51),
65 (6), 51 (14). Anal. Calcd for C14H12F2OS: C, 63.14; H,
601m, 573m, 561m, 534m, 497m, 444m, 417m cmꢀ1
.
EIMS: m/z (% relative intensity) 278 (3), 244 (5), 229 (4),
211 (5), 210 (17), 209 (100), 167 (12), 139 (5), 135 (10),
75 (5), 73 (43). HRMS Calcd for C18H22F2O2SSi (M+):
368.1078; found: 368.1075.
1
4.54. Found: C, 63.28; H, 4.44. 4a: H NMR (300 MHz,
CDCl3): d 7.63–7.53 (m, 2H, ArH), 7.53–7.43 (m, 2H,
ArH), 7.43–7.29 (m, 6H, ArH), 5.10 (dd, J¼10.9, 7.5 Hz,
1H, CHOSiMe3), 0.15 (s, 9H, OSi(CH3)3). 13C NMR
(75 MHz, CDCl3): d 136.9 (d, J¼41.1 Hz, C), 136.3
(2ꢂCH), 129.4 (CH), 128.9 (t, J¼284.0 Hz, CF2), 128.8
(2ꢂCH), 128.7 (CH), 128.0 (3ꢂCH), 126.9 (C), 77.6 (t,
J¼27.4 Hz, CH), ꢀ0.1 (3ꢂCH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ83.49 (dd, J¼203.8, 11.1 Hz, 1F),
ꢀ80.14 (dd, J¼204.4, 7.0 Hz, 1F). IR (Nujol): nmax
3062w, 3036w, 2924s, 2855s, 1952w, 1881w, 1658w,
1584w, 1455s, 1442s, 1417w, 1377m, 1358w, 1337w,
1309w, 1280w, 1250s, 1202m, 1173m, 1120s, 1108s,
1075s, 1060s, 1026m, 1003w, 983s, 925w, 878s, 847s,
803m, 748s, 728s, 699s, 690s, 662w, 634m, 612s, 505s,
439w, 419w cmꢀ1. EIMS: m/z (% relative intensity) 338
(M+, 0.18), 199 (16), 181 (5), 180 (16), 179 (100), 118 (5),
109 (10), 90 (5), 77 (4), 75 (5), 73 (63). HRMS Calcd for
C17H20F2OSSi (M+): 338.0972; found: 338.0972.
3.2.3. 2,2-Difluoro-1-(2,4-dimethoxyphenyl)-2-phenyl-
sulfanylethanol (3c) and 2,2-difluoro-1-(2,4-dimethoxy-
phenyl)-2-phenylsulfanyl-1-trimethylsiloxyethane (4c).
The reaction of 1 (1.86 g, 8 mmol) with 2,4-dimethoxybenz-
aldehyde (1.33 g, 8 mmol) and TBAF (0.8 mL, 0.8 mmol,
1 M solution in THF) gave a pale yellow liquid of 3c
(0.742 g, 28% yield) and a colourless liquid of 4c (1.911 g,
1
60% yield). 3c: H NMR (400 MHz, CDCl3): d 7.70–7.59
(m, 2H, ArH), 7.45–7.3 (m, 4H, ArH), 6.55 (dd, J¼8.5,
2.4 Hz, 1H, ArH), 6.52 (d, J¼2.4 Hz, 1H, ArH), 5.36 (dd,
J¼12.6, 8.6 Hz, 1H, CHOH), 3.88 (s, 3H, OCH3), 3.85 (s,
3H, OCH3), 1.7 (br s, 1H, CHOH). 13C NMR (100 MHz,
CDCl3): d 162.0 (C), 159.4 (C), 137.0 (2ꢂCH), 131.1
(CH), 130.2 (CH), 130.0 (t, J¼284.0 Hz, CF2), 129.5
(2ꢂCH), 127.1 (C), 116.5 (C), 105.4 (CH), 99.6 (CH),
73.7 (t, J¼26.6 Hz, CH), 56.3 (CH3), 56.0 (CH3). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ84.90 (dd, J¼204.0,
13.4 Hz, 1F), ꢀ81.98 (dd, J¼204.4, 7.8 Hz, 1F). IR (neat):
nmax 3460br s, 3062w, 3005w, 2940m, 2839m, 1614s,
1589s, 1464s, 1509s, 1440s, 1421s, 1296s, 1268s, 1210s,
1160s, 1126s, 1035s, 981s, 965s, 936m, 921m, 835s,
3.2.2. 2,2-Difluoro-1-(4-methoxyphenyl)-2-phenylsul-
fanylethanol (3b) and 2,2-difluoro-1-(4-methoxy-
phenyl)-2-phenylsulfanyl-1-trimethylsiloxyethane (4b).
The reaction of 1 (1.86 g, 8 mmol) with 4-methoxybenzalde-
hyde (1.09 g, 8 mmol) and TBAF (0.8 mL, 0.8 mmol, 1 M
solution in THF) gave a pale yellow liquid of 3b (0.970 g,
41% yield) and a white powder of 4b (1.425 g, 48% yield,
mp¼39–40.5 ꢁC). 3b: 1H NMR (400 MHz, CDCl3):
d 7.64–7.56 (m, 2H, ArH), 7.47–7.33 (m, 5H, ArH), 6.97–
6.90 (m, 2H, ArH), 4.97 (dd, J¼10.9, 8.3 Hz, 1H, CHOH),
3.83 (s, 3H, OCH3), 2.68 (br s, 1H, CHOH). 13C NMR
(100 MHz, CDCl3): d 160.9 (C), 137.0 (2ꢂCH), 130.4
(CH), 129.7 (2ꢂCH), 129.68 (2ꢂCH), 129.62 (t,
J¼283.6 Hz, CF2), 128.0 (C), 126.6 (C), 114.4 (2ꢂCH),
76.5 (t, J¼26.6 Hz, CH), 55.9 (CH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ85.11 (dd, J¼208.5, 11.1 Hz, 1F),
ꢀ82.26 (dd, J¼208.3, 8.1 Hz, 1F). IR (neat): nmax 3446br
s, 3062w, 3006w, 2960w, 2936w, 2910w, 2839w, 2028w,
1892w, 1772w, 1613s, 1586m, 1515s, 1474m, 1441s,
1306m, 1252s, 1177s, 1159s, 1056s, 1029s, 983s, 966s,
858m, 835m, 792s, 750s, 704m, 691s cmꢀ1. EIMS: m/z (%
relative intensity) 296 (M+, 1), 279 (4), 167 (15), 139 (15),
781m, 751s, 704s, 692m, 642m, 593w, 570m, 502m cmꢀ1
.
EIMS: m/z (% relative intensity) 326 (M+, 0.08), 242 (14),
167 (100), 139 (12), 137 (24), 109 (6), 91 (5), 77 (5).
HRMS Calcd for C16H16F2O3 (M+): 326.0788; found:
1
326.0788. 4c: H NMR (300 MHz, CDCl3): d 7.52–7.42
(m, 3H, ArH), 7.39–7.25 (m, 3H, ArH), 6.52 (dd, J¼8.6,
2.2 Hz, 1H, ArH), 6.41 (d, J¼2.1 Hz, 1H, ArH), 5.51 (dd,
J¼10.6, 8.4 Hz, 1H, CHOSiMe3), 3.8 (s, 6H, OCH3), 0.10
(s, 9H, OSi(CH3)3). 13C NMR (75 MHz, CDCl3): d 161.0
(C), 157.9 (C), 136.1 (2ꢂCH), 130.3 (CH), 129.2 (t,
J¼284.8 Hz, CF2), 129.1 (CH), 128.6 (2ꢂCH), 127.1 (C),
118.0 (C), 104.6 (CH), 97.9 (CH), 69.6 (dd, J¼28.4,
25.7 Hz, CH), 55.5 (CH3), 55.2 (CH3), 0.2 (3ꢂCH3). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ84.12 (dd, J¼201.0,
10.8 Hz, 1F), ꢀ81.98 (dd, J¼201.0, 8.1 Hz, 1F). IR (neat):
nmax 3062w, 3004m, 2959s, 2838m, 1614s, 1589s, 1507s,
1465s, 1440s, 1420m, 1361m, 1329w, 1305s, 1293s,
1264s, 1253s, 1209s, 1159s, 1126s, 1097s, 1035s, 982s,
937m, 922m, 879s, 844s, 793w, 775w, 750s, 704m, 691s,
637w, 610w, 568m, 519w, 502m, 478w cmꢀ1. EIMS: m/z

M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
5977
(% relative intensity) 398 (M+, 0.06), 240 (18), 239 (100),
209 (4), 166 (6), 165 (22), 77 (5), 73 (33). HRMS Calcd
for C19H24F2O3SSi (M+): 398.1183; found: 398.1182.
NMR (100 MHz, CDCl3): d 137.2 (2ꢂCH), 136.5 (C),
135.9 (CH), 130.6 (CH), 129.8 (2ꢂCH), 129.6 (t,
J¼286.0 Hz, CF2), 129.3 (2ꢂCH), 129.1 (CH), 127.5
(2ꢂCH), 126.4 (C), 123.1 (CH), 75.7 (t, J¼27.0 Hz, CH).
19F NMR (376 MHz, CDCl3/CFCl3): d ꢀ85.12 (dd,
J¼209.0, 9.1 Hz, 1F), ꢀ83.13 (dd, J¼209.0, 8.4 Hz, 1F).
IR (neat): nmax 3392br m, 3061m, 3028w, 2911w, 1955w,
1885w, 1803w, 1654m, 1599w, 1579m, 1497m, 1475s,
1449m, 1441s, 1388m, 1309m, 1164s, 1058s, 966s, 861m,
748s, 704s, 691s cmꢀ1. EIMS: m/z (% relative intensity)
292 (M+, 4), 275 (26), 235 (3), 165 (5), 162 (9), 160 (20),
133 (100), 116 (44), 103 (9), 92 (7), 77 (13), 65 (4), 55
(32). Anal. Calcd for C16H14F2OS: C, 65.73; H, 4.83.
Found: C, 65.97; H, 4.91. 4e: 1H NMR (300 MHz,
CDCl3): d 7.65 (d, J¼6.5 Hz, 2H, ArH), 7.51–7.24 (m, 8H,
ArH), 6.75 (d, J¼15.8 Hz, 1H, PhCH]CH), 6.30 (dd,
J¼15.8, 6.2 Hz, 1H, PhCH]CH), 4.64 (app. dd, J¼15.4,
8.1 Hz, 1H, CHOSiMe3), 0.22 (s, 9H, OSi(CH3)3). 13C
NMR (75 MHz, CDCl3): d 136.4 (2ꢂCH), 136.1 (C),
134.0 (CH), 129.4 (CH), 128.9 (t, J¼283.0 Hz, CF2),
128.8 (2ꢂCH), 128.5 (2ꢂCH), 128.1 (CH), 126.8
(2ꢂCH), 126.4 (t, J¼2.0 Hz, C), 124.3 (CH), 76.3 (t,
J¼27.5 Hz, CH), 0.1 (3ꢂCH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ83.07 (dd, J¼204.0, 7.9 Hz, 1F),
ꢀ81.24 (dd, J¼204.0, 8.5 Hz, 1F). IR (neat): nmax 3066w,
3029w, 2958s, 2925s, 2863s, 1959w, 1890w, 1815w,
1474s, 1450s, 1441s, 1377m, 1357w, 1332s, 1305w,
1251s, 1205w, 1164m, 1117s, 1085s, 1067s, 1042s, 1022s,
974s, 917w, 878s, 844s, 779m, 750s, 705m, 692s, 672m,
3.2.4. 2,2-Difluoro-1-(3,4-dimethoxyphenyl)-2-phenyl-
sulfanylethanol (3d) and 2,2-difluoro-1-(3,4-dimethoxy-
phenyl)-2-phenylsulfanyl-1-trimethylsiloxyethane (4d).
The reaction of 1 (1.86 g, 8 mmol) with 3,4-dimethoxybenz-
aldehyde (1.329 g, 8 mmol) and TBAF (0.8 mL, 0.8 mmol,
1 M solution in THF) gave a white powder of 3d (0.967 g,
37% yield, mp¼92–93 ꢁC) and a white powder of 4d
(1.542 g, 48% yield, mp¼61–62 ꢁC). 3d: 1H NMR
(400 MHz, CDCl3): d 7.61–7.55 (m, 2H, ArH), 7.45–7.33
(m, 3H, ArH), 7.06–6.99 (m, 2H, ArH), 6.87 (d, J¼8.1 Hz,
1H, ArH), 4.96 (dd, J¼10.9, 8.2 Hz, 1H, CHOH), 3.90 (s,
3H, OCH3), 3.89 (s, 3H, OCH3), 2.35 (br s, 1H, CHOH).
13C NMR (100 MHz, CDCl3): d 150.3 (C), 149.5 (C),
137.1 (2ꢂCH), 130.5 (CH), 129.7 (2ꢂCH), 129.6 (t,
J¼283.1 Hz, CF2), 128.3 (C), 126.5 (C), 121.2 (CH),
111.3 (CH), 111.2 (d, J¼1.2 Hz, CH), 76.6 (t, J¼26.4 Hz,
CH), 56.6 (CH3), 56.5 (CH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ84.72 (dd, J¼208.4, 10.9 Hz, 1F),
ꢀ82.17 (dd, J¼208.4, 8.2 Hz, 1F). IR (neat): nmax 3480s,
3082m, 3060m, 3011m, 2969m, 2943m, 2913m, 2842m,
2597w, 2031w, 1961w, 1733w, 1608s, 1594s, 1515s,
1471s, 1456s, 1442s, 1387m, 1346m, 1309m, 1256s,
1141s, 1096s, 1056s, 1019s, 990s, 930m, 869m, 821w,
785s, 764s, 745s, 690s, 663m cmꢀ1. EIMS: m/z (% relative
intensity) 326 (M+, 1), 167 (100), 139 (57), 124 (15), 109
(8), 108 (6), 95 (4), 79 (5), 77 (8), 65 (3). HRMS Calcd
for C16H16F2O3S (M+): 326.0788; found: 326.0788. 4d: 1H
NMR (300 MHz, CDCl3): d 7.52 (d, J¼7.6 Hz, 2H, ArH),
7.39–7.22 (m, 3H, ArH), 7.02–6.90 (m, 2H, ArH), 6.78 (d,
J¼8.2 Hz, 1H, ArH), 4.91 (dd, J¼11.0, 7.5 Hz, 1H,
CHOSiMe3), 3.85 (s, 6H, 2ꢂOCH3), 0.10 (s, 9H,
OSi(CH3)3). 13C NMR (75 MHz CDCl3): d 149.3 (C),
148.6 (C), 136.3 (2ꢂCH), 129.4 (CH), 129.2 (C), 128.9 (t,
J¼283.0 Hz, CF2), 128.8 (2ꢂCH), 126.7 (C), 120.5 (CH),
110.8 (CH), 110.3 (CH), 77.2 (t, J¼27.2 Hz, CH), 55.9
(CH3), 55.8 (CH3), ꢀ0.1 (3ꢂCH3). 19F NMR (376 MHz,
CDCl3/CFCl3) d ꢀ83.44 (dd, J¼203.0, 11.0 Hz, 1F),
ꢀ80.69 (dd, J¼203.0, 7.3 Hz, 1F). IR (neat): nmax 3056w,
3015m, 2956s, 2925s, 2855s, 1605m, 1591m, 1519s,
1466s, 1442s, 1420m, 1377m, 1360m, 1337w, 1308w,
1264s, 1256s, 1233s, 1168m, 1152s, 1141s, 1102s, 1066s,
1037m, 1023s, 992s, 938s, 874s, 853s, 803m, 775m,
767m, 749s, 728m, 703w, 691m, 625m, 604w, 586m,
571w, 498m, 456w, 417w cmꢀ1. EIMS: m/z (% relative
intensity) 398 (M+, 2), 274 (5), 240 (17), 239 (100), 165
(14), 109 (5), 77 (4), 73 (51). HRMS Calcd for
C19H24F2O3SSi (M+): 398.1183; found: 398.1185.
638w, 611w, 600w, 543m, 499m, 459m, 419m cmꢀ1
.
EIMS: m/z (% relative intensity): 207 (5), 206 (18), 205
(100), 146 (5), 116 (9), 115 (23), 77 (4), 73 (45). HRMS
Calcd for C19H22F2OSSi (M+): 364.1128; found: 364.0031.
3.2.6. 1,1-Difluoro-4-(2-methoxyphenyl)-1-phenylsul-
fanyl-3-buten-2-ol (3f) and 1,1-difluoro-4-(2-methoxy-
phenyl)-1-phenylsulfanyl-2-trimethylsiloxy-3-butene
(4f). The reaction of 1 (1.86 g, 8 mmol) with 2-methoxy-
cinnamaldehyde (1.298 g, 8 mmol) and TBAF (0.8 mL,
0.8 mmol, 1 M solution in THF) gave a pale yellow liquid
of 3f (1.367 g, 53% yield) and a white powder of 4f
(1.138 g, 37% yield, mp¼43.5–45 ꢁC). 3f: 1H NMR
(300 MHz, CDCl3): d 7.66 (d, J¼6.7 Hz, 2H, ArH), 7.53–
7.36 (m, 4H, ArH), 7.35–7.25 (m, 1H, ArH), 7.17 (d,
J¼16.1 Hz, 1H, PhCH]CH), 7.02–6.85 (m, 2H, ArH),
6.33 (dd, J¼16.1, 6.6 Hz, 1H, PhCH]CH), 4.63 (dd,
J¼15.7, 8.1 Hz, 1H, CHOH), 3.89 (s, 3H), 2.51 (br s, 1H,
CHOH). 13C NMR (75 MHz, CDCl3): d 157.1 (C), 136.5
(2ꢂCH), 130.5 (CH), 129.8 (CH), 129.5 (CH), 129.1
(2ꢂCH), 129.0 (t, J¼283.5 Hz, CF2), 127.4 (CH), 126.0
(C), 124.9 (C), 123.0 (t, J¼2.3 Hz, CH), 120.7 (CH), 111.0
(CH), 75.60 (t, J¼26.8 Hz, CH), 55.5 (CH3). 19F NMR
(376 MHz, CDCl3/CFCl3): d ꢀ85.15 (dd, J¼208.9, 9.2 Hz,
1F), ꢀ83.33 (dd, J¼208.0, 8.4 Hz, 1F). IR (Nujol): nmax
3264br s, 2924s, 2855s, 2722w, 1651w, 1597m, 1580w,
1489s, 1463s, 1439s, 1377m, 1349m, 1294m, 1247s,
1175w, 1154m, 1118w, 1100w, 1087w, 1053s, 1028s,
981m, 959s, 866m, 852w, 779m, 758s, 747s, 725w, 703w,
3.2.5. 1,1-Difluoro-4-phenyl-1-phenylsulfanyl-3-buten-2-
ol (3e) and 1,1-difluoro-4-phenyl-1-phenylsulfanyl-2-tri-
methylsiloxy-3-butene (4e). The reaction of 1 (2.32 g,
10 mmol) with cinnamaldehyde (1.29 g, 9.8 mmol) and
TBAF (1.0 mL, 1.0 mmol, 1 M solution in THF) gave
a pale yellow liquid of 3e (1.420 g, 50% yield) and a white
1
powder of 4e (0.661 g, 18% yield, mp¼39–40 ꢁC). 3e: H
690m, 630w, 582w, 554w, 530w, 498w, 448w cmꢀ1
.
NMR (400 MHz, CDCl3): d 7.68–7.62 (m, 2H, ArH),
7.48–7.26 (m, 8H, ArH), 6.83 (d, J¼15.9 Hz, 1H,
PhCH]CH), 6.28 (dd, J¼15.9, 6.3 Hz, 1H, PhCH]CH),
4.68–4.58 (m, 1H, CHOH), 2.12 (br s, 1H, CHOH). 13C
EIMS: m/z (% relative intensity): 322 (M+, 5), 164 (11),
163 (100), 145 (10), 135 (21), 107 (11), 91 (7), 77 (6), 55
(16). HRMS Calcd for C17H16F2O2S (M+): 322.0839; found:
322.0844. 4f: 1H NMR (300 MHz, CDCl3): d 7.62 (d,

5978
M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
J¼7.8 Hz, 2H, ArH), 7.51–7.18 (m, 5H, ArH), 7.05 (d,
J¼16.0 Hz, 1H, PhCH]CH), 6.98–6.82 (m, 2H of ArH),
6.28 (dd, J¼16.1, 6.7 Hz, 1H, PhCH]CH), 4.61 (app. dd,
J¼16.1, 7.9 Hz, 1H, CHOSiMe3), 3.86 (s, 3H, OCH3), 0.2
(s, 9H, OSi(CH3)3). 13C NMR (75 MHz, CDCl3): d 157.0
(C), 136.4 (2ꢂCH), 129.4 (2ꢂCH), 129.2 (CH), 129.0 (t,
J¼283.5 Hz, CF2), 128.8 (2ꢂCH), 127.3 (CH), 126.7 (C, t,
J¼2.0 Hz), 125.2 (C), 124.6 (t, J¼2.4 Hz, CH), 120.6 (CH),
111.0 (CH), 77.0 (t, J¼27.2 Hz, CH), 55.0 (CH3), 0.2
(3ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3): d ꢀ83.35
(dd, J¼203.5, 9.0 Hz, 1F), ꢀ81.59 (dd, J¼202.8, 8.8 Hz,
1F). IR (Nujol): nmax 3057w, 2998m, 2958s, 2926s, 2855s,
1650w, 1599m, 1580m, 1492s, 1466s, 1439s, 1377w,
1356m, 1338m, 1298m, 1265m, 1251s, 1179s, 1158m,
1128s, 1105s, 1079s, 1047s, 1030s, 973s, 883s, 842s,
814w, 758s, 750s, 703m, 688s, 671w, 639w, 610w, 583w,
524m, 502m, 439w cmꢀ1. EIMS: m/z (% relative intensity):
394 (M+, 0.63), 237 (6), 236 (19), 235 (100), 177 (5), 147
(4), 146 (11), 145 (27), 117 (4), 77 (2), 73 (37). HRMS
Calcd for C20H24F2O2SSi (M+): 394.1234; found: 394.1234.
73 (30). HRMS Calcd for C18H22F2OSSi (M+): 352.1128;
found: 352.1128.
3.2.8. 2,2-Difluoro-1-(4-bromophenyl)-2-phenylsulfanyl-
ethanol (3h) and 2,2-difluoro-1-(4-bromophenyl)-2-
phenylsulfanyl-1-trimethylsiloxyethane (4h). The reaction
of 1 (1.86 g, 8 mmol) with 4-bromobenzaldehyde (1.48 g,
8 mmol) and TBAF (0.8 mL, 0.8 mmol, 1 M solution in
THF) gave a white powder of 3h (1.679 g, 61% yield,
mp¼69–69.5 ꢁC) and a white powder of 4h (1.039 g, 31%
1
yield, mp¼94–96 ꢁC). 3h: H NMR (400 MHz, CDCl3):
d 7.61–7.50 (m, 4H, ArH), 7.47–7.41 (m, 1H, ArH), 7.41–
7.33 (m, 4H, ArH), 4.96 (dd, J¼11.1, 7.6 Hz, 1H, CHOH),
2.86 (br s, 1H, CHOH). 13C NMR (100 MHz, CDCl3):
d 137.1 (2ꢂCH), 134.7 (C), 132.1 (2ꢂCH), 130.7 (CH),
130.1 (2ꢂCH), 129.8 (2ꢂCH), 129.3 (t, J¼283.0 Hz, CF2),
126.1 (C), 124.0 (C), 76.2 (t, J¼26.9 Hz, CH). 19F NMR
(376 MHz, CDCl3/CFCl3):
d
ꢀ85.65 (dd, J¼210.4,
10.9 Hz, 1F), ꢀ81.55 (dd, J¼210.6, 7.8 Hz, 1F). IR
(Nujol): nmax 3585s, 2955s, 2926s, 2855s, 1592m, 1472m,
1441m, 1404w, 1377m, 1306w, 1226w, 1194w, 1169w,
1150w, 1117w, 1102w, 1080s, 1047s, 1011m, 985s, 955w,
845w, 819m, 772s, 752s, 692m, 659w, 631w, 618w, 534w,
502m, 419w cmꢀ1. EIMS: m/z (% relative intensity): 345
(M+, 6), 343 (6), 328 (6), 187 (58), 185 (56), 161 (13), 160
(100), 159 (21), 157 (20), 110 (8), 109 (9), 108 (5), 78
(26), 77 (37), 51 (10). HRMS Calcd for C14H11F2OS (M+):
343.9682; found: 343.9677. 4h: 1H NMR (400 MHz,
CDCl3): d 7.60–7.47 (m, 4H, ArH), 7.40–7.30 (m, 5H,
ArH), 4.96 (dd, J¼10.6, 7.3 Hz, 1H, CHOSiMe3), 0.13 (s,
9H, OSi(CH3)3). 13C NMR (100 MHz, CDCl3): d 137.0
(2ꢂCH), 136.6 (C), 131.9 (2ꢂCH), 130.2 (3ꢂCH), 129.5
(2ꢂCH), 129.2 (t, J¼284.1, 283.4 Hz, CF2), 127.0 (C),
123.5 (C), 77.5 (t, J¼27.4 Hz, CH), 0.5 (3ꢂCH3). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ83.64 (dd, J¼204.8,
11.0 Hz, 1F), ꢀ80.04 (dd, J¼204.8, 7.0 Hz, 1F). IR
(Nujol): nmax 3065w, 2956s, 2924s, 2855s, 1658w, 1591m,
1486m, 1463m, 1441m, 1404m, 1377m, 1346w, 1306w,
1292w, 1255s, 1200m, 1173m, 1124s, 1110s, 1096s,
1066s, 1025w, 1011m, 985s, 953m, 860s, 845s, 797s, 773s,
751s, 703s, 690m, 657m, 634w, 600w, 512m, 498m, 454m,
416w cmꢀ1. EIMS: m/z (% relative intensity): 417 (M+,
0.8), 322 (4), 309 (5), 307 (6), 280 (10), 279 (64), 278
(12), 277 (64), 261 (8), 260 (25), 259 (93), 258 (29), 257
(68), 198 (5), 197 (5), 196 (9), 170 (5), 109 (5), 91 (4), 77
(5), 74 (82), 73 (100). Anal. Calcd for C17H19BrF2OSSi:
C, 48.92; H, 4.59. Found: C, 49.32; H, 4.47.
3.2.7. 2,2-Difluoro-1-(4-methylphenyl)-2-phenylsulfanyl-
ethanol (3g) and 2,2-difluoro-1-(4-methylphenyl)-2-
phenylsulfanyl-1-trimethylsiloxyethane (4g). The reaction
of 1 (1.86 g, 8 mmol) with 4-methylbenzaldehyde (0.96 g,
8 mmol) and TBAF (0.2 mL, 0.2 mmol, 1 M solution in
THF) gave a white powder of 3g (0.786 g, 35% yield,
mp¼49–50 ꢁC) and a white powder of 4g (1.437 g, 51%
1
yield, mp¼55–57 ꢁC). 3g: H NMR (400 MHz, CDCl3):
d 7.63–7.54 (m, 2H, ArH), 7.47–7.31 (m, 5H, ArH), 7.21
(d, J¼7.9 Hz, 2H, ArH), 4.98 (t, J¼9.6 Hz, 1H, CHOH),
2.68 (br s, 1H, CHOH), 2.38 (s, 3H, CH3). 13C NMR
(100 MHz, CDCl3): d 139.7 (C), 137.0 (2ꢂCH), 132.9 (C),
130.4 (CH), 129.7 (2ꢂCH), 129.6 (2ꢂCH), 129.6 (t,
J¼283.0 Hz, CF2), 128.3 (2ꢂCH), 126.6 (C), 76.7 (t,
J¼26.7 Hz, CH), 21.9 (CH3). 19F NMR (376 MHz, CDCl3/
CFCl3): d ꢀ85.14 (dd, J¼209.0, 11.3 Hz, 1F), ꢀ82.03 (dd,
J¼208.9, 7.4 Hz, 1F). IR (Nujol): nmax 3331br m, 2955s,
2925s, 2855s, 1516w, 1459m, 1441m, 1377m, 1310w,
1279w, 1241w, 1201w, 1182w, 1158m, 1149m, 1116w,
1061m, 1021m, 1002w, 970m, 860w, 824w, 779m, 749m,
719w, 691m, 621w, 568w, 519w, 498w cmꢀ1. EIMS: m/z
(% relative intensity): 280 (M+, 0.7), 171 (5), 162 (4), 161
(7), 160 (91), 123 (12), 122 (10), 121 (97), 110 (7), 109
(7), 103 (5), 93 (100), 91 (77), 77 (30), 65 (10), 51 (8).
HRMS Calcd for C15H14F2OS (M+): 280.0733; found:
1
280.0731. 4g: H NMR (400 MHz, CDCl3): d 7.63–7.51
(2H, m, ArH), 7.44–7.29 (5H, m, ArH), 7.18 (d, J¼7.9 Hz,
2H, ArH), 4.97 (dd, J¼10.8, 7.8 Hz, 1H, CHOSiMe3), 2.37
(s, 3H, CH3), 0.14 (s, 9H, OSi(CH3)3). 13C NMR
(100 MHz, CDCl3): d 139.1 (C), 136.9 (2ꢂCH), 134.4 (C),
130.0 (CH), 129.6 (t, J¼283.5 Hz, CF2), 129.4 (4ꢂCH),
128.5 (2ꢂCH), 127.4 (C), 77.9 (t, J¼27.2 Hz, CH), 21.9
(CH3), 0.6 (3ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ83.35 (dd, J¼203.9, 11.0 Hz, 1F), ꢀ80.40 (dd,
J¼203.2, 7.6 Hz, 1F). IR (Nujol): nmax 3407br w, 2926s,
2730w, 2305w, 1948w, 1923w, 1878w, 1711w, 1614w,
1583w, 1513m, 1461s, 1442s, 1414w, 1377s, 1303w,
1253s, 1202m, 1173m, 1126s, 1103s, 1065s, 1028m, 984s,
954w, 878s, 844s, 805m, 775m, 746s, 706w, 689s, 632w,
640w, 601w, 554m, 513s, 496w, 443w, 419w cmꢀ1. EIMS:
m/z (% relative intensity): 333 (2), 263 (4), 213 (24), 193
(100), 171 (3), 151 (3), 133 (3), 119 (4), 104 (2), 77 (2),
3.2.9. 2,2-Difluoro-1-(furan-2-yl)-2-phenylsulfanyletha-
nol (3i). The reaction of 1 (0.464 g, 2 mmol) with 2-furalde-
hyde (0.185 g, 1.9 mmol) and TBAF (0.2 mL, 0.2 mmol,
1 M solution in THF) gave a pale yellow liquid of 3i
(0.363 g, 73% yield). 3i: 1H NMR (300 MHz, CDCl3):
d 7.6 (d, J¼6.9 Hz, 2H, ArH), 7.49–7.31 (m, 4H, ArH),
6.53 (d, J¼3.2 Hz, 1H, ArH), 6.43 (dd, J¼3.0, 1.8 Hz, 1H,
ArH), 5.01 (dd, J¼15.4, 9.3 Hz, 1H, CHOH), 2.77 (d,
J¼6.6 Hz, 1H, CHOH). 13C NMR (75 MHz, CDCl3):
d 148.4 (t, J¼1.95 Hz, C), 143.2 (CH), 136.5 (2ꢂCH),
130.0 (CH), 129.1 (2ꢂCH), 127.8 (t, J¼283.6 Hz, CF2),
125.5 (t, J¼2.25 Hz, C), 110.6 (CH), 110.0 (CH), 70.5 (t,
J¼28.2 Hz, CH). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ85.03 (dd, J¼210.9, 10.6 Hz, 1F), ꢀ83.46 (dd,
J¼210.9, 9.0 Hz, 1F). IR (neat): nmax 3418s, 3064m,

M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
5979
2913w, 1960w, 1888w, 1808w, 1738w, 1621w, 1584w,
1504m, 1475s, 1442s, 1384m, 1310m, 1266m, 1232m,
1212m, 1150s, 1063s, 1015s, 972s, 927s, 886s, 798s, 747s,
705s, 691s cmꢀ1. EIMS: m/z (% relative intensity) 256
(M+, 56), 239 (46), 219 (14), 171 (11), 160 (60), 127 (5),
110 (9), 109 (7), 99 (10), 98 (5), 97 (100), 77 (5), 69 (30),
65 (6), 51 (8). Anal. Calcd for C12H10F2O2S: C, 56.24; H,
3.93. Found: C, 56.32; H, 3.65.
of 3l (0.529 g, 22% yield) and a white powder of 4l
(0.78 g, 26% yield, mp¼34–35.5 ꢁC). 3l: 1H NMR
(400 MHz, CDCl3): d 7.80–7.74 (m, 1H, ArH), 7.62–7.56
(m, 2H, ArH), 7.45–7.33 (m, 3H, ArH), 7.32–7.23 (m, 2H,
ArH), 7.20–7.14 (m, 1H, ArH), 2.86 (t, J¼6.3 Hz, 2H,
PhCH2CH2), 2.47 (ddd, J¼13.8, 10.2, 3.5 Hz, 1H,
CHHCOH), 2.28 (br s, 1H, COH), 2.21–2.11 (m, 1H,
CHHCOH), 2.11–2.00 (m, 1H, CH2CHHCH2), 1.95–1.83
(m, 1H, CH2CHHCH2). 13C NMR (100 MHz, CDCl3):
d 139.6 (C), 137.2 (2ꢂCH), 135.2 (C), 132.5 (t,
J¼287.9 Hz, CF2), 130.3 (CH), 129.8 (CH), 129.6
(2ꢂCH), 129.3 (CH), 128.7 (t, J¼3.4 Hz, CH), 127.0 (C),
126.9 (CH), 76.63 (t, J¼21.7 Hz, C), 34.9 (CH2), 31.4
(CH2), 19.5 (CH2). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ83.0 (d, J¼203.7 Hz, 1F), ꢀ79.0 (d, J¼203.7 Hz, 1F).
IR (neat): nmax 3446br s, 3061m, 3025m, 2943s, 2880m,
2839m, 1957w, 1826w, 1671w, 1583w, 1492s, 1475s,
1452s, 1441s, 1369m, 1331m, 1248m, 1191m, 1140m,
1121s, 1060s, 1024s, 984s, 906s, 876m, 842m, 749s,
704m, 691s cmꢀ1. EIMS: m/z (% relative intensity) 306
(M+, 0.4), 289 (52), 269 (73), 160 (12), 147 (100), 130
(46), 128 (10), 117 (6), 109 (3), 91 (30), 77 (3), 65 (3).
Anal. Calcd for C17H16F2OS: C, 66.65; H, 5.26. Found: C,
3.2.10. 1,1-Difluoro-1-phenylsulfanylpentan-2-ol (3j).
The reaction of 1 (0.464 g, 2 mmol) with n-butanal
(0.144 g, 2 mmol) and TBAF (0.2 mL, 0.2 mmol, 1 M solu-
tion in THF) gave a pale yellow liquid of 3j (0.319 g, 69%
yield). 3j: 1H NMR (300 MHz, CDCl3): d 7.62 (d,
J¼6.6 Hz, 2H, ArH), 7.47–7.33 (m, 3H, ArH), 3.89 (dq,
J¼8.9, 2.7 Hz, 1H, CHOH), 1.96 (br s, 1H, CHOH), 1.83–
1.52 (m, 3H, 2H of CH2CH2 and 1H and CHHCH3), 1.50–
1.32 (m, 1H, CHHCH3), 0.97 (t, J¼7.1 Hz, 3H, CH3). 13C
NMR (75 MHz, CDCl3): d 136.4 (2ꢂCH), 129.9 (t,
J¼281.9 Hz, CF2), 129.8 (CH), 129.0 (2ꢂCH), 125.8 (t,
J¼2.2 Hz, C), 73.9 (t, J¼26.0 Hz, CH), 32.4 (t, J¼1.6 Hz,
CH2), 18.7 (CH2), 13.7 (CH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ86.43 (dd, J¼209.5, 9.8 Hz, 1F),
ꢀ83.13 (dd, J¼209.5, 9.1 Hz, 1F). IR (neat): nmax 3404br
s, 3064w, 2963s, 2935s, 2876s, 1956w, 1885w, 1806w,
1711w, 1584w, 1475s, 1442s, 1383m, 1309m, 1269m,
1222w, 1182s, 1121s, 1057s, 1028s, 991s, 897m, 857m,
749s, 705s, 691s, 668m cmꢀ1. EIMS: m/z (% relative inten-
sity) 232 (M+, 30), 215 (2), 178 (6), 160 (100), 159 (9), 137
(5), 126 (15), 123 (7), 110 (71), 109 (21), 97 (5), 84 (8), 78
(18), 77 (16), 66 (14), 65 (3), 55 (33). Anal. Calcd for
C11H14F2OS: C, 56.88; H, 6.07. Found: C, 56.84; H, 6.21.
1
66.86; H, 5.30. 4l: H NMR (400 MHz, CDCl3): d 7.88–
7.78 (m, 1H, ArH), 7.64–7.52 (m, 2H, ArH), 7.43–7.29
(m, 3H, ArH), 7.28–7.18 (m, 2H, ArH), 7.15–7.07 (m, 1H,
ArH), 2.84 (t, J¼6.4 Hz, 2H, PhCH2CH2), 2.7–2.5 (m, 1H,
CHHCOH), 2.18–1.99 (m, 2H, 1H of CHHCOSiMe3 and
1H of CH2CHHCH2), 1.98–1.76 (m, 1H, CH2CHHCH2),
0.07 (s, 9H, OSi(CH3)3). 13C NMR (100 MHz, CDCl3):
d 139.1 (C), 137.2 (2ꢂCH), 136.3 (C), 132.8 (t,
J¼289.6 Hz, CF2), 130.1 (CH), 129.9 (CH), 129.3
(2ꢂCH), 129.2 (CH), 128.8 (CH), 128.1 (C), 126.0 (CH),
79.3 (t, J¼23.0 Hz, C), 35.0 (CH2), 29.7 (CH2), 19.6
(CH2), 2.6 (3ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ78.90 (d, J¼200.1 Hz, 1F), ꢀ78.13 (d, J¼200.1 Hz,
1F). IR (CHCl3): nmax 3065w, 3009m, 2957s, 2899m,
2841w, 1954w, 1884w, 1604w, 1583w, 1489m, 1474m,
1450m, 1441m, 1407w, 1342w, 1284m, 1253s, 1146s,
1095s, 1084s, 1056s, 1013m, 948m, 992s, 924s, 901s,
886s, 845s, 629m, 586w, 556m cmꢀ1. EIMS: m/z (% relative
intensity) 269 (4), 221 (6), 220 (20), 219 (100), 177 (4), 159
(5), 130 (4), 129 (10), 77 (2), 73 (39). HRMS Calcd for
C20H24F2OSSi (M+): 378.1285; found: 378.1291.
3.2.11. (E)-1,1-Difluoro-1-phenylsulfanylpent-3-en-2-ol
(3k). The reaction of 1 (0.464 g, 2 mmol) with crotonalde-
hyde (0.140 g, 2 mmol) and TBAF (0.2 mL, 0.2 mmol,
1 M solution in THF) gave a pale yellow liquid of 3k
(0.321 g, 70% yield). 3k: 1H NMR (300 MHz, CDCl3):
d 7.63 (d, J¼6.6 Hz, 2H, ArH), 7.47–7.37 (m, 3H, ArH),
6.02–5.88 (m, 1H, CH3CH]CH), 5.65–5.53 (m, 1H,
CH3CH]CH), 4.37 (app. dd, J¼16.2, 8.9 Hz, 1H,
CHOH), 1.95 (br s, 1H, CHOH), 1.78 (dd, J¼6.6, 0.7 Hz,
3H, CH3). 13C NMR (75 MHz, CDCl3): d 136.9 (2ꢂCH),
133.4 (CH), 130.3 (CH), 129.5 (2ꢂCH), 129.4 (t,
J¼282.5 Hz, CF2), 126.3 (t, J¼2.0 Hz, C), 125.2 (t,
J¼2.4 Hz, CH), 75.5 (t, J¼26.7 Hz, CH), 18.4 (CH3). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ85.82 (dd, J¼207.8,
9.5 Hz, 1F), ꢀ83.78 (dd, J¼207.8, 9.0 Hz, 1F). IR (neat):
nmax 3404br s, 3063m, 2970m, 2943m, 2918m, 2857m,
1957w, 1887w, 1807w, 1674m, 1584m, 1475s, 1442s,
1379m, 1309m, 1286m, 1170s, 1134m, 1058s, 964s,
924m, 823m, 750s, 704s, 691s, 663m cmꢀ1. EIMS: m/z (%
relative intensity) 230 (M+, 100), 213 (42), 193 (4), 160
(87), 159 (11), 139 (3), 110 (33), 109 (16), 84 (4), 77 (13),
71 (35), 65 (13), 53 (12). Anal. Calcd for C11H12F2OS: C,
57.37; H, 5.25. Found: C, 57.41; H, 5.22.
3.2.13. 1-(Difluoro(phenylsulfanyl)methyl)-6-methoxy-
1,2,3,4-tetrahydronaphthalen-1-ol (3m) and (1-(difluoro
(phenylsulfanyl)methyl)-6-methoxy-1,2,3,4-tetrahydro-
naphthalen-1-yloxy)trimethylsilane (4m). The reaction
of 1 (1.86 g, 8 mmol) with 6-methoxy-1-tetralone (1.41 g,
8 mmol) and TBAF (0.8 mL, 0.8 mmol, 1 M solution in
THF) gave a pale yellow liquid of 3m (0.587 g, 21% yield)
and a colourless liquid of 4m (0.976 g, 29% yield). 3m: 1H
NMR (300 MHz, CDCl3): d 7.71 (d, J¼8.8 Hz, 1H, ArH),
7.65–7.55 (m, 2H, ArH), 7.49–7.31 (m, 3H, ArH), 6.82
(dd, J¼8.8, 2.7 Hz, 1H, ArH), 6.70 (d, J¼2.7 Hz, 1H,
ArH), 3.82 (s, 3H, OCH3), 2.84 (t, J¼6.2 Hz, 2H,
PhCH2CH2), 2.53–2.25 (m, 2H, CH2COH), 2.25–1.76 (m,
3H, 2H of CH2CH2CH2 and COH). 13C NMR (75 MHz,
CDCl3): d 159.4 (C), 140.7 (C), 136.4 (2ꢂCH), 131.9
(CF2, t, J¼288.0 Hz), 129.6 (CH), 128.8 (3ꢂCH), 126.8
(d, J¼1.6 Hz, C), 126.5 (d, J¼2.8 Hz, C), 113.4 (CH),
112.5 (CH), 75.73 (t, J¼21.6 Hz, C), 55.1 (OCH3), 34.2
3.2.12. 1-(Difluoro(phenylsulfanyl)methyl)-1,2,3,4-
tetrahydronapthalen-1-ol (3l) and (1-(difluoro(phenyl-
thio)methyl)-1,2,3,4-tetrahydronaphthalen-1-yloxy)tri-
methylsilane (4l). The reaction of 1 (1.86 g, 8 mmol) with
a-tetralone (1.17 g, 8 mmol) and TBAF (0.8 mL,
0.8 mmol, 1 M solution in THF) gave a pale yellow liquid

5980
M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
(d, J¼2.2 Hz, CH2), 30.2 (CH2), 18.9 (CH2). 19F NMR
(376 MHz, CDCl3/CFCl3): d ꢀ83.37 (d, J¼203.0 Hz, 1F),
ꢀ79.24 (d, J¼203.0 Hz, 1F). IR (neat): nmax 3463s,
3061w, 3002w, 2942m, 2838w, 1957w, 1890w, 1609s,
1576m, 1505s, 1474s, 1465m, 1441s, 1322m, 1286m,
1244s, 1190m, 1120s, 1047s, 1023s, 985s, 909s, 892m,
870m, 839m, 817m, 790w, 751s, 704m, 691s, 660w, 632w,
587w, 557w, 503m, 420w cmꢀ1. EIMS: m/z (% relative in-
tensity) 336 (M+, 1), 321 (5), 320 (19), 319 (76), 318
(100), 300 (19), 299 (43), 298 (34), 297 (11), 279 (7), 209
(35), 207 (23), 206 (20), 178 (17), 177 (45), 159 (11).
HRMS Calcd for C18H18F2O2S (M+): 336.0995; found:
CDCl3): d 141.6 (d, J¼1.4 Hz, C), 136.4 (2ꢂCH), 130.8
(t, J¼289.0 Hz, CF2), 129.2 (CH), 128.6 (3ꢂCH), 127.9
(CH), 127.7 (2ꢂCH), 127.2 (t, J¼1.8 Hz, C), 127.1 (CH),
80.6 (t, J¼25.0 Hz, C), 23.7 (t, J¼2.1 Hz, CH3), 2.22
(3ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3): d ꢀ84.08
(d, J¼199.8 Hz, 1F), ꢀ82.49 (d, J¼199.8 Hz, 1F). IR
(neat): nmax 3418w, 3062w, 3027w, 3002w, 2959m, 2899w,
1953w, 1885w, 1584w, 1496w, 1475m, 1441m, 1376m,
1253s, 1237s, 1202m, 1099s, 1081s, 1064s, 1028s, 988m,
963s, 948s, 863s, 844s, 804w, 750s, 699s, 691s, 661w,
627w, 596m, 504m cmꢀ1. EIMS: m/z (% relative intensity)
352 (M+, 0.08), 241 (5), 195 (4), 194 (17), 193 (100), 163
(5), 123 (4), 104 (6), 103 (5), 75 (5), 73 (50). HRMS
Calcd for C18H22F2OSSi (M+): 352.1128; found: 352.1129.
1
336.1003. 4m: H NMR (400 MHz, CDCl3): d 7.76 (d,
J¼8.8 Hz, 1H, ArH), 7.65–7.52 (m, 2H, ArH), 7.46–7.28
(m, 3H, ArH), 6.81 (dd, J¼8.8, 2.8 Hz, 1H, ArH), 6.64
(d, J¼2.7 Hz, 1H, ArH), 3.84 (s, 3H, OCH3), 2.82
(t, J¼6.4 Hz, 2H, PhCH2CH2), 2.49–2.63 (m, 1H,
CHHCOSiMe3), 2.17–1.98 (m, 1H of CHHCOSiMe3 and
1H of CH2CHHCH2), 1.96–1.77 (m, 1H, CH2CHHCH2),
0.07 (s, 9H, OSi(CH3)3). 13C NMR (100 MHz, CDCl3):
d 159.9 (C), 140.8 (C), 137.1 (2ꢂCH), 132.9 (t,
J¼289.5 Hz, CF2), 131.6 (t, J¼2.6 Hz, CH), 129.9 (CH),
129.3 (2ꢂCH), 128.5 (C), 128.3 (C), 113.4 (CH), 112.4
(CH), 79.1 (t, J¼23.4 Hz, C), 55.7 (CH3), 35.2 (CH2), 30.3
(CH2), 19.8 (CH2), 2.6 (3ꢂCH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ79.47 (d, J¼199.4 Hz, 1F), ꢀ78.31 (d,
J¼199.4 Hz, 1F). IR (neat): nmax 3440br w, 3062w, 2956s,
2837m, 1884w, 1609s, 1576m, 1500s, 1475m, 1465m,
1441m, 1341m, 1324m, 1283m, 1251s, 1196m, 1135s,
1086s, 1052s, 1011m, 992s, 952m, 906m, 894m, 881s,
842s, 774m, 793m, 750s, 705m, 691s, 633w, 597w, 573w,
530w, 503m cmꢀ1. EIMS: m/z (% relative intensity) 408
(M+, 0.1), 284 (2), 249 (100), 159 (7), 91 (1), 77 (3), 73
(36). HRMS Calcd for C21H26F2O2SSi (M+): 408.1391;
found: 408.1391.
3.2.15. 2,2-Difluoro-1,1-diphenyl-2-phenylsulfanyletha-
nol (3o) and (2,2-difluoro-1,1-diphenyl-2-phenylsulfanyl-
ethoxy)trimethylsilane (4o). The reaction of 1 (0.698 g,
3 mmol) with benzophenone (0.546 g, 3 mmol) and TBAF
(0.3 mL, 0.3 mmol, 1 M solution in THF) gave a white pow-
der of 3o (0.348 g, 33% yield, mp¼45–46 ꢁC) and a white
1
powder of 4o (86.1 mg, 6% yield, mp¼92–94 ꢁC). 3o: H
NMR (400 MHz, CDCl3): d 7.67–7.61 (m, 4H, ArH),
7.61–7.56 (m, 2H, ArH), 7.46–7.31 (m, 9H, ArH), 3.1 (br
s, 1H, COH). 13C NMR (75 MHz, CDCl3): d 140.3 (2ꢂC),
136.6 (2ꢂCH), 131.2 (t, J¼290.9 Hz, CF2), 129.7 (CH),
128.9 (2ꢂCH), 128.2 (2ꢂCH), 127.9 (4ꢂCH), 127.8 (t,
J¼1.9 Hz, CH), 127.8 (3ꢂCH), 126.4 (C), 81.6 (t,
J¼23.9 Hz, C). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ77.88 (2F, s). IR (Nujol): nmax 3473m, 3059w, 2955s,
2925s, 2855s, 1493w, 1459m, 1449m, 1377w, 1343w,
1310w, 1184w, 1169w, 1152w, 1094w, 1054m, 1040m,
1020m, 931w, 897m, 826m, 749m, 700m, 639m, 501w,
424w, 327w cmꢀ1. EIMS: m/z (% relative intensity) 342
(M+, 31), 325 (24), 275 (5), 247 (10), 213 (22), 185 (5),
184 (14), 183 (100), 166 (6), 165 (17), 106 (23), 105 (56),
77 (19), 51 (6). HRMS Calcd for C20H16F2OS (M+):
342.0890; found: 342.0892. 4o: 1H NMR (300 MHz,
CDCl3): d 7.64–7.19 (m, 15H, ArH), ꢀ0.05 (s, 9H,
OSi(CH3)3). 13C NMR (75 MHz, CDCl3): d 142.5 (2ꢂC),
136.7 (2ꢂCH), 131.8 (t, J¼292.7 Hz, CF2), 129.4 (CH),
128.8 (2ꢂCH), 128.7 (4ꢂCH), 127.8 (2ꢂCH), 127.6
(4ꢂCH), 127.1 (d, J¼2.3 Hz, C), 84.5 (t, J¼23.7 Hz, CF2),
1.7 (3ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ77.66 (s, 2F). IR (Nujol): nmax 3416br w, 3063w,
2926s, 2855s, 1951w, 1895w, 1808w, 1711w, 1601w,
1581w, 1494w, 1461s, 1447s, 1406w, 1377m, 1307w,
1263m, 1247s, 1217w, 1195m, 1178w, 1163m, 1152m,
1104s, 1076s, 1063s, 1040s, 1021m, 999w, 936m, 912m,
879s, 847s, 825s, 755s, 742s, 697s, 637m, 628m, 536w,
503m, 425w cmꢀ1. EIMS: m/z (% relative intensity): 414
(M+, 0.12), 303 (13), 255 (100), 166 (34), 73 (61). HRMS
Calcd for C23H24F2OSSi (M+): 414.1285; found: 414.1292.
3.2.14. 1,1-Difluoro-2-phenyl-1-phenylsulfanylpropan-2-
ol (3n) and (1,1-difluoro-2-phenyl-1-phenylsulfanyl-
propan-2-yloxy)trimethylsilane (4n). The reaction of 1
(1.86 g, 8 mmol) with acetophenone (0.96 g, 8 mmol) and
TBAF (0.8 mL, 0.8 mmol, 1 M solution in THF) gave
a pale yellow liquid of 3n (0.669 g, 30% yield) and a colour-
less liquid of 4n (0.740 g, 21% yield). 3n: 1H NMR
(400 MHz, CDCl3): d 7.64 (d, J¼7.8 Hz, 2H, ArH), 7.58–
7.52 (m, 2H, ArH), 7.46–7.31 (m, 6H, ArH), 2.62 (br s,
1H, COH), 1.85 (s, 3H, CH3). 13C NMR (100 MHz,
CDCl3): d 140.7 (C), 137.2 (2ꢂCH), 131.6 (t, J¼287.5 Hz,
CF2), 130.3 (CH), 129.7 (3ꢂCH), 128.9 (CH), 128.7
(2ꢂCH), 127.0 (t, J¼1.7 Hz, CH), 126.8 (C), 78.6 (t,
J¼24.4 Hz, C), 25.1 (t, J¼1.9 Hz, CH3). 19F NMR
(376 MHz, CDCl3/CFCl3): d ꢀ84.70 (d, J¼204.5 Hz, 1F),
ꢀ82.00 (d, J¼204.5 Hz, 1F). IR (neat): nmax 3474br s,
3062m, 2995m, 2943w, 1957w, 1889w, 1811w, 1762w,
1671w, 1603w, 1584w, 1497m, 1475s, 1449s, 1442s,
1380m, 1374m, 1179m, 1149m, 1055s, 1028s, 984s, 914s,
801m, 749s, 701s, 676m cmꢀ1. EIMS: m/z (% relative inten-
sity) 280 (M+, 8), 263 (19), 243 (1), 241 (2), 213 (11), 185
(13), 160 (64), 123 (10), 121 (100), 110 (10), 109 (8), 103
(7), 77 (15), 65 (6), 51 (9). HRMS Calcd for C15H14F2OS
(M+): 280.0733; found: 280.0733. 4n: 1H NMR (300 MHz,
CDCl3): d 7.48 (d, J¼7.4 Hz, 2H, ArH), 7.39 (d,
J¼6.6 Hz, 2H, ArH), 7.3–7.1 (m, 6H, ArH), 1.78 (s, 3H,
CH3), 0.10 (s, 9H, OSi(CH3)3). 13C NMR (75 MHz,
3.2.16. 1-(Difluoro(phenylsulfanyl)methyl)cyclohexanol
(3p). The reaction of 1 (0.464 g, 2 mmol) with cyclohexa-
none (0.196 g, 2 mmol) and TBAF (0.2 mL, 0.2 mmol,
1 M solution in THF) gave a white powder of 3p (0.325 g,
63% yield, mp¼55–56 ꢁC). 3p: 1H NMR (300 MHz,
CDCl3): d 7.61–7.49 (m, 2H, ArH), 7.40–7.24 (m, 3H,
ArH), 1.88–1.47 (m, 9H, 8H of (CH2)4CHH and COH),
1.24–1.04 (m, 1H, (CH2)4CHH). 13C NMR (75 MHz,
CDCl3): d 136.7 (2ꢂCH), 132.1 (t, J¼285.5 Hz, CF2),

M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
5981
129.6 (CH), 128.9 (2ꢂCH), 126.2 (t, J¼1.9 Hz, C), 75.9 (t,
J¼23.0 Hz, C), 31.0 (2ꢂCH2, t, J¼1.6 Hz), 25.3 (2ꢂCH2),
20.8 (CH2). 19F NMR (376 MHz, CDCl3/CFCl3): d
ꢀ87.42 (s, 2F). IR (Nujol): nmax 3602w, 3412br m, 2927s,
2855s, 2724w, 1711w, 1583w, 1461s, 1377s, 1267m,
1192m, 1154m, 1078m, 1039m, 989m, 975m, 951m,
NMR (75 MHz, CDCl3): d 136.6 (2ꢂCH), 135.4 (CH),
131.3 (t, J¼285.8 Hz, CF2), 129.6 (CH), 128.9 (2ꢂCH),
126.1 (t, J¼1.7 Hz, C), 124.53 (dd, J¼3.3, 1.3 Hz, CH),
73.6 (t, J¼23.4 Hz, C), 30.3 (CH2), 24.9 (CH2), 17.7
(CH2). 19F NMR (376 MHz, CDCl3/CFCl3): d ꢀ87.3 (d,
J¼203.0 Hz, 1F), ꢀ85.7 (d, J¼203.0 Hz, 1F). IR (neat):
nmax 3418br s, 3062w, 3035w, 2941s, 2873m, 2834w,
1818w, 1650w, 1583w, 1474s, 1441s, 1397w, 1383w,
1350w, 1324w, 1262w, 1195m, 1161s, 1032s, 996s, 967s,
934s, 895s, 838m, 750s, 735s, 704m, 691s, 650w, 593w,
502m cmꢀ1. EIMS: m/z (% relative intensity): 256 (M+, 2),
239 (7), 160 (27), 110 (8), 109 (10), 98 (7), 97 (100), 79
(31), 77 (25), 65 (7), 55 (10). HRMS Calcd for
C13H14F2OS (M+): 256.0733; found: 256.0733.
906m, 884m, 847w, 811m, 747m, 704w, 690m cmꢀ1
.
EIMS: m/z (% relative intensity) 258 (M+, 100), 241 (28),
221 (13), 191 (14), 160 (38), 110 (12), 109 (10), 99 (34),
81 (99), 80 (31), 77 (8), 65 (5). Anal. Calcd for
C13H16F2OS: C, 60.44; H, 6.24. Found: C, 60.60; H, 6.19.
3.2.17. 1-(Difluoro(phenylsulfanyl)methyl)cyclopentanol
(3q). The reaction of 1 (0.464 g, 2 mmol) with cyclopenta-
none (0.168 g, 2 mmol) and TBAF (0.2 mL, 0.2 mmol,
1 M solution in THF) gave a white powder of 3q (0.219 g,
45% yield, mp¼37–38 ꢁC). 3q: 1H NMR (400 MHz,
CDCl3): d 7.67–7.62 (m, 2H, ArH), 7.47–7.36 (m, 3H,
ArH), 2.16–2.05 (m, 2H, CH2CH2CH2), 1.8–1.56 and
1.95–1.8 (m, 7H, 6H of (CH2)2CH2CH2 and COH). 13C
NMR (100 MHz, CDCl3): d 137.2 (2ꢂCH), 131.9 (t,
J¼283.5 Hz, CF2), 130.3 (CH), 129.6 (2ꢂCH), 126.9 (C),
86.5 (C, t, J¼24.7 Hz), 36.5 (2ꢂCH2), 25.1 (2ꢂCH2). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ84.60 (s, 2F). IR
(Nujol): nmax 3335br s, 3064m, 2958s, 2874s, 1951w,
1880w, 1802w, 1582w, 1474s, 1440s, 1396s, 1330m,
1291m, 1265m, 1238m, 1137m, 1052s, 995s, 946s, 920s,
895s, 747s, 690s, 625m, 499s, 418w cmꢀ1. EIMS: m/z (%
relative intensity) 244 (M+, 100), 227 (12), 207 (10), 205
(8), 160 (7), 110 (6), 109 (3), 85 (4), 77 (1), 68 (26), 65
(3). Anal. Calcd for C12H14F2OS: C, 59.00; H, 5.78.
Found: C, 59.33; H, 5.98.
3.3. Desilylation of compound 4b to provide
compound 3b
A solution of compound 4b (2.066 g, 5.62 mmol) in CH2Cl2
(10 mL) was treated with potassium fluoride (KF) in CH3CN
(10 mL). The reaction mixture was stirred at room tempera-
ture overnight and quenched with a saturated NH4Cl solu-
tion and extracted with EtOAc (3ꢂ50 mL). The organic
phase was washed successively with brine, water and dried
over anhydrous Na2SO4. After solvent removal, the crude
product was purified by chromatotron (SiO2, 5% EtOAc in
hexanes) to give a pale yellow liquid of 3b (1.528 g, 91%
yield).
3.4. Preparation of sulfoxide 5
3.4.1. 2,2-Difluoro-1-(4-methoxyphenyl)-2-phenylsulfinyl-
ethanol (5b). General procedure: A solution of compound
3b (269.7 mg, 0.9 mmol) in THF (15 mL) at ꢀ78 ꢁC was
treated with a solution of 70% m-chloroperbenzoic acid
(MCPBA) (235.3 mg, 0.94 mmol) in THF (5 mL). The reac-
tion mixture was stirred at ꢀ78 ꢁC and slowly warmed to
room temperature overnight. The reaction was quenched
with a saturated NaHCO3 solution (50 mL). The aqueous
layer was extracted with CH2Cl2 (3ꢂ20 mL). The combined
extracts were dried over anhydrous Na2SO4. After solvent
removal, the crude product was purified by column chroma-
tography (SiO2, 20% EtOAc in hexanes and then 2% MeOH
in hexanes) to give a white powder of 5b as a mixture (62:38)
of two diastereomers (210.5 mg, 74% yield, mp¼111–
3.2.18. 1,1-Difluoro-2-methyl-1-phenylsulfanylpropan-2-
ol (3r). The reaction of 1 (0.464 g, 2 mmol) with acetone
(0.116 g, 2 mmol) and TBAF (0.2 mL, 0.2 mmol, 1 M solu-
tion in THF) gave a pale yellow liquid of 3r (0.283 g, 65%
1
yield). 3r: H NMR (300 MHz, CDCl3): d 7.69–7.56 (m,
2H, ArH), 7.46–7.31 (m, 3H, ArH), 2.11 (br s, 1H, COH),
1.45 (s, 6H, 2ꢂCH3). 13C NMR (75 MHz, CDCl3): d 136.6
(2ꢂCH), 131.6 (t, J¼285.3 Hz, CF2), 129.6 (CH), 128.9
(2ꢂCH), 126.0 (t, J¼1.7 Hz, C), 75.0 (t, J¼24.1 Hz, C),
24.1 (t, J¼1.8 Hz, 2ꢂCH3). 19F NMR (376 MHz, CDCl3/
CFCl3): d ꢀ86.42 (s, 2F). IR (neat): nmax 3419br s, 3064m,
2991s, 2943m, 1956w, 1886w, 1811w, 1636w, 1584s,
1475s, 1442s, 1376s, 1250m, 1200s, 1158m, 1099s, 1054s,
1016s, 979s, 953s, 854m, 833s, 750s, 704m, 691s,
664m cmꢀ1. EIMS: m/z (% relative intensity) 218 (M+,
100), 201 (24), 199 (5), 181 (7), 160 (18), 151 (5), 135 (3),
123 (2), 110 (13), 109 (8), 77 (3), 65 (7), 59 (19). Anal.
Calcd for C10H12F2OS: C, 55.03; H, 5.54. Found: C,
55.05; H, 5.20.
1
115 ꢁC). H NMR (500 MHz, CDCl3/MeOD): d 7.67 and
7.63 (d each, J¼7.0 and 6.8 Hz, respectively, 2H, ArH),
7.59–7.46 (m, 3H, ArH), 7.4–7.3 (m, 2H, ArH), 6.87 and
6.83 (d each, J¼7.9 and 8.0 Hz, respectively, 2H, ArH),
5.23 (d, J¼23.5 Hz) and 4.90 (t, J¼12.7 Hz) (1H, CHOH),
3.74 and 3.72 (s each, 3H, OCH3), 3.35 (br s, 1H, CHOH).
13C NMR (125 MHz, CDCl3/MeOD): d 159.9 and 159.8
(C), 136.0 and 135.3 (C), 132.4 and 132.2 (CH), 129.1 and
128.8 (2ꢂCH), 129.7 (2ꢂCH), 126.8 and 126.6 (C), 126.3
and 126.2 (CH), 113.6 and 113.4 (2ꢂCH), 71.5 (t,
J¼21.9 Hz) and 68.9 (dd, J¼29.1, 19.1 Hz) (CH), 55.0 and
54.9 (CH3). 19F NMR (470 MHz, CDCl3/MeOD/CFCl3):
d ꢀ117.92 and ꢀ117.66 (d each, J¼213.4 and 220.0 Hz,
1F), ꢀ114.14 and ꢀ112.58 (d each, J¼213.8 and 220.0 Hz,
1F). IR (KBr): nmax 3266s, 3068w, 2998w, 2954m, 2929m,
2908m, 2835w, 2679w, 2551w, 2055w, 1735w, 1719w,
1609s, 1587w, 1509s, 1459m, 1445s, 1420w, 1350w,
1330w, 1304m, 1294m, 1250s, 1202s, 1175s, 1110s, 1085s,
3.2.19. 1-(Difluoro(phenylsulfanyl)methyl)cyclohex-2-
enol (3s). The reaction of 1 (0.464 g, 2 mmol) with 2-cyclo-
hexenone (0.192 g, 2 mmol) and TBAF (0.2 mL, 0.2 mmol,
1 M solution in THF) gave a pale yellow liquid of 3s
(0.307 g, 60% yield). 3s: 1H NMR (300 MHz, CDCl3):
d 7.68–7.54 (m, 2H, ArH), 7.47–7.28 (m, 3H, ArH), 6.15
(dq, J¼10.1, 2.8 Hz, 1H, CH]CHCOH), 5.86 (d,
J¼10.1 Hz, 1H, CH]CHCOH), 2.23–2.03 (m, 3H, 2H
of CH2CH]CH and COH), 2.02–1.92 (m, 2H,
CH2CH2COH), 1.85–1.71 (m, 2H, CH2CH2CH2). 13C

5982
M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
1041s, 975s, 846m, 824w, 793s, 785s, 754s, 748s, 699m,
688m, 626w, 5814m, 568s, 529s, 481m, 450m cmꢀ1
J¼224.4 Hz) and ꢀ109.86 (dd, J¼218.2, 9.6 Hz), (1F). IR
(CHCl3): nmax 3673w, 3597w, 3392br m, 3066w, 3019s,
2963m, 2938m, 2840m, 1960w, 1608m, 1596m, 1519s,
1465s, 1446s, 1423m, 1344w, 1309w, 1267s, 1188m,
1158s, 1143s, 1108s, 1087s, 1026s, 984m, 909m, 867w,
646w, 625w, 590w, 566w cmꢀ1. EIMS: m/z (% relative
intensity) 342 (M+, 1), 324 (4), 216 (100), 187 (51), 169
(38), 139 (41), 126 (38), 78 (42), 77 (24). Anal. Calcd for
C16H16F2O3S: C, 56.13; H, 4.71. Found: C, 56.22; H, 4.30.
.
EIMS: m/z (% relative intensity) 312 (M+, 9), 295 (42), 187
(13), 186 (93), 170 (22), 167 (38), 139 (100), 137 (33), 135
(12), 127 (19), 126 (95), 109 (36), 108 (13), 97 (10), 94
(18), 79 (13), 78 (89), 77 (27). HRMS Calcd for
C15H14F2O3S (M+): 312.0632; found: 312.0628.
3.4.2. 2,2-Difluoro-1-(2,4-dimethoxyphenyl)-2-phenyl-
sulfinylethanol (5c). Treatment of compound 3c
(451.6 mg, 1.38 mmol) in THF (20 mL) with a solution of
70% MCPBA (358 mg, 1.45 mmol) in THF (8 mL) afforded
a white powder of 5c as a mixture (54:46) of two diastereo-
3.4.4. 1,1-Difluoro-4-phenyl-1-phenylsulfinyl-3-buten-2-
ol (5e). Treatment of compound 3e (369.5 mg, 1.26 mmol)
in THF (21 mL) with a solution of 70% MCPBA (320 mg,
1.32 mmol) in THF (6 mL) afforded a white powder of 5e
as a mixture (60:40) of two diastereomers (212 mg, 50%
yield, mp¼110–114 ꢁC). 1H NMR (400 MHz, CDCl3):
d 7.84–7.71 (m, 2H, ArH), 7.67–7.53 (m, 3H, ArH), 7.47–
7.38 (m, 2H, ArH), 7.38–7.24 (m, 3H, ArH), 6.88 (d,
J¼16 Hz, 1H, PhCH]CH), 6.34 and 6.27 (dd each,
J¼15.6, 7.0 and 16.0, 6.0 Hz, respectively, 1H,
PhCH]CH), 5.05 (dd, J¼21.0, 5.0 Hz) and 4.98–4.86
(m), (1H, CHOH), 4.11 and 3.40 (br s each, 1H, CHOH).
13C NMR (100 MHz, CDCl3): d 137.3 and 136.6 (CH),
136.4 and 136.2 (2ꢂC), 133.4 (CH), 129.9 (2ꢂCH), 129.3
(2ꢂCH), 129.1 and 127.6 (CH), 127.5 (2ꢂCH), 127.1
(2ꢂCH), 121.9 and 121.8 (CH), 73.4 and 70.9 (CH, t each,
J¼22.8 and 27.4 Hz, respectively). 19F NMR (376 MHz,
1
mers (324.4 mg, 69% yield, mp¼108–111 ꢁC). H NMR
(400 MHz, CDCl3): d 7.84–7.71 (m, 2H, ArH), 7.64–7.50
(m, 3H, ArH), 7.36 and 7.31 (d each, J¼8.4 and 8.4 Hz,
respectively, 1H, ArH), 6.55–6.40 (m, 2H, ArH), 5.65 (d,
J¼24 Hz) and 5.42 (dd, J¼17.4, 8.6 Hz) (1H, CHOH),
4.12 (br s, 1H, CHOH), 3.86 and 3.80 (s each, 3H, OCH3),
3.82 and 3.76 (s each, 3H, OCH3). 13C NMR (100 MHz,
CDCl3): d 162.3 and 162.1 (C), 159.5 and 159.4 (C), 137.5
and 137.0 (C), 133.2 and 133.0 (CH), 131.2 and 131.1
(CH), 129.7 and 129.6 (2ꢂCH), 127.1 and 127.0 (2ꢂCH),
125.7 and 125.1 (CF2, dd each, J¼305.1, 295.3 and 306.0,
295.0 Hz, respectively), 115.2 and 115.0 (C), 105.6 and
105.4 (CH), 99.6 and 99.4 (CH), 70.5 and 67.8 (CH, dd
each, J¼22.7, 22.7 and 29.0, 19.6 Hz, respectively), 56.4
and 56.1 (2ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ119.48 and ꢀ117.49 (dd each, J¼216.8, 17.2 and
223.0, 24.0 Hz, respectively, 1F), ꢀ111.41 (d, J¼
223.0 Hz) and ꢀ109.49 (dd, J¼216.4, 8.0 Hz), (1F). IR
(CHCl3): nmax 3674w, 3598w, 3495br m, 3066w, 3013m,
2964m, 2941m, 2841w, 2455w, 1888w, 1719w, 1614s,
1589s, 1509s, 1466s, 1446s, 1439m, 1422m, 1296s,
1269m, 1185m, 1160s, 1128s, 1086s, 1039s, 999w, 974m,
CDCl3/CFCl3):
d
ꢀ118.49 and ꢀ116.78 (dd each,
J¼220.6, 11.8 and 224.8, 20.7 Hz, respectively, 1F),
ꢀ112.62 (d, J¼224.7 Hz) and ꢀ109.98 (dd, J¼220.6,
10.9 Hz), (1F). IR (KBr): nmax 3285br s, 3058m, 3027m,
2897w, 2688w, 2364w, 2345w, 1891w, 1813w, 1648w,
1496m, 1475m, 1446s, 1424m, 1358w, 1331w, 1306w,
1282w, 1262w, 1192s, 1115s, 1085s, 1062s, 1034s, 1020s,
998s, 970s, 950s, 869w, 850w, 804w, 767s, 748s, 728m,
689s, 669w, 605w, 547m, 521s, 488m, 444m cmꢀ1. EIMS:
m/z (% relative intensity) 308 (46), 291 (100), 233 (31),
186 (21), 182 (76), 146 (26), 133 (32), 126 (62), 115 (50),
78 (64), 77 (20). HRMS Calcd for C16H14F2O2S (M+):
308.0683; found: 308.0678.
936w, 922m, 839m, 825m, 638w, 593w, 566m cmꢀ1
.
EIMS: m/z (% relative intensity) 342 (M+, 0.27), 217 (35),
216 (41), 198 (13), 197 (100), 187 (18), 169 (28), 167
(50), 165 (23), 151 (17), 149 (12), 139 (64), 137 (32),
126 (39), 121 (72), 109 (21), 91 (38), 78 (40), 77 (36).
HRMS Calcd for C16H16F2O4S (M+): 342.0737; found:
342.0732.
3.4.5. 1,1-Difluoro-4-(2-methoxyphenyl)-1-phenylsul-
finyl-3-buten-2-ol (5f). Treatment of compound 3f
(190 mg, 0.59 mmol) in THF (9 mL) with a solution of
70% MCPBA (149 mg, 0.62 mmol) in THF (3 mL) afforded
a white powder of 5f as a mixture (65:35) of two diastereo-
3.4.3. 2,2-Difluoro-1-(3,4-dimethoxyphenyl)-2-phenyl-
sulfinylethanol (5d). Treatment of compound 3d
(372.3 mg, 1.14 mmol) in THF (18 mL) with a solution of
70% MCPBA (294 mg, 1.19 mmol) in THF (6 mL) afforded
a white powder of 5d as a mixture (51:49) of diastereomers
(275 mg, 70% yield, mp¼121–125 ꢁC). 1H NMR
(400 MHz, CDCl3): d 7.79–7.69 (m, 2H, ArH), 7.66–7.51
(m, 3H, ArH), 7.11–6.95 (m, 2H, ArH), 6.89 and 6.85 (d
each, J¼8.8 and 8.4 Hz, respectively, 1H, ArH), 5.43–5.31
(m, 1H, CHOH), 4.22 (br s, 1H, CHOH), 3.90 and 3.88 (s
each, 6H, 2ꢂCH3). 13C NMR (100 MHz, CDCl3): d 150.6
and 150.4 (C), 149.8 and 149.6 (C), 136.6 (d, J¼3.5 Hz)
and 136.3 (CH), 133.4 and 133.2 (CH), 129.8 and 127.0
(2ꢂCH), 127.5 and 127.1 (C), 127.0 (2ꢂCH), 124.9 and
124.2 (CF2, dd each, J¼303.0, 295.6 and 309.8, 291.4 Hz,
respectively), 121.6 and 121.1 (CH), 111.4 (2ꢂCH), 73.9
and 71.3 (CH, dd each, J¼21.7, 21.7 and 28.9, 19.5 Hz, re-
spectively), 56.5 (2ꢂCH3). 19F NMR (376 MHz, CDCl3/
CFCl3): d ꢀ119.81 and ꢀ117.39 (dd each, J¼218.2, 14.2
and 224.4, 22.1 Hz, respectively, 1F), ꢀ110.75 (d,
1
mers (118.9 mg, 60% yield, mp¼127–130 ꢁC). H NMR
(400 MHz, CDCl3): d 7.79 and 7.77 (d each, J¼8.0 and
7.6 Hz, respectively, 1H, ArH), 7.65–7.53 (m, 3H, ArH),
7.47 (dd, J¼7.6, 1.6 Hz, 1H, ArH), 7.32–7.23 (m, 1H,
ArH), 7.18 and 7.17 (d each, J¼16.0 and 16.0 Hz, respec-
tively, 1H, ArH), 6.97–6.84 (m, 2H, 1H of ArH and 1H of
PhCH]CH), 6.38 and 6.31 (dd each, J¼16.0, 7.2 and
16.0, 6.8 Hz, respectively, 1H, PhCH]CH), 5.09–5.00 and
4.90–4.80 (m each, 1H, CHOH), 3.84 and 3.83 (s each,
3H, CH3), 3.10 (br s, 1H, CHOH). 13C NMR (100 MHz,
CDCl3): d 157.8 and 157.7 (C), 137.1 and 136.3 (C), 133.2
(CH), 132.5 and 131.9 (CH), 130.4 and 130.2 (CH), 129.7
(2ꢂCH), 128.2 and 128.1 (CH), 127.1 (2ꢂCH), 125.4 and
125.2 (C), 122.4 and 122.3 (CH), 121.3 (CH), 111.6 (CH),
73.8 and 71.4 (CH, dd each, J¼22.9, 22.9 and 28.5,
20.6 Hz, respectively), 56.10 (CH3). 19F NMR (376 MHz,
CDCl3/CFCl3): d ꢀ118.4 and ꢀ117.1 (dd each, J¼219.8,

M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
5983
12.4 and 223.5, 21.0 Hz, respectively, 1F), ꢀ112.4 (d,
J¼223.5 Hz) and ꢀ110.4 (dd, J¼219.8, 10.3 Hz), (1F). IR
(neat): nmax 3354br s, 3063w, 3003w, 2939w, 2839w,
1897w, 1732m, 1714m, 1650m, 1599s, 1579m, 1489s,
1464s, 1446s, 1374w, 1357w, 1293s, 1247s, 1194s,
1163m, 1104s, 1049s, 998m, 977s, 951s, 867m, 751s,
688s, 606w, 583w, 526m, 489m, 433w, 417w cmꢀ1. EIMS:
m/z (% relative intensity) 338 (M+, 1.22), 212 (100), 192
(63), 164 (41), 126 (44), 115 (33), 91 (48), 78 (66). HRMS
Calcd for C17H16F2O3S (M+): 338.0788; found: 338.0788.
(m, 2H, ArH), 7.67–7.38 (m, 8H, ArH), 7.37–7.24 (m, 3H,
ArH), 5.18 (br s, 1H, COH). 13C NMR (100 MHz,
CDCl3): d 140.4 (C), 139.5 (C), 136.3 (C), 133.5 (CH),
129.8 (2ꢂCH), 129.4 (CH), 129.3 (2ꢂCH), 129.0 (CH),
128.6 (2ꢂCH), 128.4 (2ꢂCH), 128.0 (CH), 127.9 (CH),
127.1 (2ꢂCH), 123.0 (dd, J¼318.7, 299.9 Hz, CF2), 82.5
(t, J¼19.9, 19.8 Hz, C). 19F NMR (376 MHz, CDCl3/
CFCl3): d ꢀ112.44 (d, J¼220.2 Hz, 1F), ꢀ98.60 (d,
J¼220.2 Hz, 1F). IR (KBr): nmax 3255s, 3053m, 1491m,
1450s, 1411m, 1289w, 1261w, 1172m, 1120s, 1083s,
1063s, 1039s, 1021s, 998m, 905m, 821m, 749s, 706s,
698s, 687s, 659m, 618m, 572m, 512m, 483m, 437m,
397w cmꢀ1. EIMS: m/z (% relative intensity) 359 (M++1,
3.32), 213 (62), 185 (40), 183 (19), 166 (17), 165 (100),
127 (12), 126 (33), 106 (5), 105 (35), 78 (37), 77 (45), 50
(15). Anal. Calcd for C20H16F2O2S: C, 67.02; H, 4.50.
Found: C, 67.10; H, 4.08.
3.4.6. 1-(Difluoro(phenylsulfinyl)methyl)-1,2,3,4-tetra-
hydronapthalen-1-ol (5l). Treatment of compound 3l
(309.0 mg, 1.00 mmol) in THF (15 mL) with a solution of
70% MCPBA (273 mg, 1.10 mmol) in THF (4 mL) afforded
a diastereomeric mixture of 5l, which was separated by
radial chromatography (20% EtOAc in hexanes) to give
123 mg (38% yield, mp¼139–142 ꢁC) of diastereomer A
and 97 mg (30% yield, mp¼115–118 ꢁC) of diastereomer
3.5. Preparation of 1,1-difluoroalkene 6
1
B. Diastereomer A: H NMR (400 MHz, CDCl3): d 7.91–
7.81 (m, 1H, ArH), 7.70 (d, J¼8.0 Hz, 2H, ArH), 7.63–
7.47 (m, 3H, ArH), 7.36–7.23 (m, 2H, ArH), 7.22–7.12
(m, 1H, ArH), 2.92–2.77 (m, 2H, PhCH2), 2.77–2.64 (m,
1H, CHHOH), 2.45 (br s, 1H, COH), 2.13–1.94 (m, 2H,
1H of CHHOH and 1H of CH2CHHCH2), 1.93–1.75 (m,
1H, CH2CHHCH2). 13C NMR (100 MHz, CDCl3): d 139.7
(C), 137.1 (C), 134.9 (C), 133.2 (CH), 129.9 (CH), 129.6
(2ꢂCH), 129.5 (CH), 128.3 (d, J¼2.7 Hz, CH), 127.5
(2ꢂCH), 126.8 (CH), 124.6 (dd, J¼317.0, 300.0 Hz, CF2),
76.7 (t, J¼19.3 Hz, C), 34.0 (CH2), 29.4 (CH2), 19.2
(CH2). 19F NMR (376 MHz, CDCl3/CFCl3): d ꢀ115.73 (d,
J¼219.5 Hz, 1F), ꢀ99.57 (d, J¼219.6 Hz, 1F).
3.5.1. 1,1-Difluoro-2-(4-methoxyphenyl)ethene (6b).12
General procedure A: Sulfoxide 5b (110 mg, 0.35 mmol)
was heated at 170–200 ꢁC (0.05 mmHg) to give a pure oil
of 6b (47.1 mg, 79% yield), which was trapped at ꢀ78 ꢁC
(see Fig. 1).
1
Diastereomer B: H NMR (400 MHz, CDCl3): d 7.78 (d,
J¼7.6, 3H, ArH), 7.69–7.57 (m, 3H, ArH), 7.33–7.16 (m,
3H, ArH), 4.10 (br s, 1H, COH), 2.97–2.86 (m, 2H,
PhCH2), 2.86–2.77 (m, 1H, CHHCOH), 2.52–2.40 (m, 1H,
CHHCOH), 2.18–2.00 (m, 2H, CH2CH2CH2). 13C NMR
(100 MHz, CDCl3): d 139.4 (C), 136.2 (C), 133.8 (C),
133.4 (CH), 129.8 (2ꢂCH), 129.6 (CH), 129.5 (CH),
129.2 (d, J¼4.3 Hz, CH), 127.2 (2ꢂCH), 126.9 (CH),
124.1 (dd, J¼319.1, 295.3 Hz, CF2), 76.7 (t, J¼3 Hz, C),
35.4 (CH2), 29.9 (CH2), 19.4 (d, J¼2.6 Hz, CH2). 19F
Figure 1.
General procedure B: Flash vacuum pyrolysis of sulfoxide
5b (105.2 mg, 0.34 mmol) (conditions: oven temperature
120 ꢁC, column temperature 425 ꢁC; pressure 0.05 mmHg)
gave a pure oil of 6b (46.4 mg, 82% yield), which was trap-
ped at ꢀ78 ꢁC (see Fig. 2); H NMR (300 MHz, CDCl3):
1
NMR (376 MHz, CDCl3/CFCl3):
d
ꢀ115.31 (d,
J¼220.9 Hz, 1F), ꢀ100.50 (d, J¼221.5 Hz, 1F). IR (KBr):
nmax 3238s, 3081w, 3014w, 2959m, 2919m, 2887w,
2837w, 2817w, 2613w, 2489w, 1655w, 1601w, 1486m,
1477m, 1456m, 1448m, 1431m, 1414w, 1353w, 1341m,
1292w, 1232w, 1200m, 1184w, 1166m, 1149s, 1131s,
1078s, 1065m, 1030s, 1021s, 980s, 959m, 910w, 891m,
874s, 807w, 766s, 752s, 686s, 659m, 623m, 582m, 518m,
495m, 466m, 436m, 897w cmꢀ1. EIMS: m/z (% relative
intensity) 177 (14), 164 (5), 159 (10), 149 (23), 147 (31),
130 (12), 129 (100), 128 (32), 127 (18), 126 (73), 91 (21),
78 (48), 77 (10), 73 (2), 65 (5). Anal. Calcd for
C17H16F2O2S: C, 63.34; H, 5.00. Found: C, 63.34; H, 5.16.
d 7.25 (d, J¼8.4 Hz, 2H, ArH), 6.87 (d, J¼8.7 Hz, 2H,
ArH), 5.20 (dd, J¼26.4, 3.8 Hz, 1H, CH]CF2), 3.79 (s,
3H, OCH3). 13C NMR (75 MHz, CDCl3): d 158.6 (t,
J¼2.1 Hz, C), 155.8 (dd, J¼294.8, 284.9 Hz, CF2), 128.8
(2ꢂCH, dd, J¼6.3, 3.4 Hz), 122.7 (t, J¼6.1 Hz, C), 114.1
(2ꢂCH), 81.5 (dd, J¼29.0, 14.1 Hz, CH), 55.2 (CH3). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ86.86 (d, J¼36.9 Hz,
1F), ꢀ85.04 (dd, J¼43.8, 36.7 Hz, 1F). IR (neat): nmax
3450w, 3038m, 3006m, 2959m, 2938m, 2912m, 2839m,
2666w, 2550w, 2066w, 2024w, 1886w, 1733s, 1613s,
1578m, 1515s, 1466m, 1443m, 1421m, 1351s, 1317w,
1299s, 1248s, 1182s, 1166s, 1113w, 551s, 523s,
475w cmꢀ1. EIMS: m/z (% relative intensity) 170 (M+,
100), 139 (9), 127 (10), 107 (3), 77 (1).
3.4.7. 2,2-Difluoro-1,1-diphenyl-2-phenylsulfinylethanol
(5o). Treatment of compound 3o (662.6 mg, 1.93 mmol) in
THF (20 mL) with a solution of 70% MCPBA (496 mg,
2.02 mmol) in THF (10 mL) afforded a white powder of
5o (493.1 mg, 71% yield, mp¼158–161 ꢁC); 1H NMR
(400 MHz, CDCl3): d 7.88–7.78 (m, 2H, ArH), 7.77–7.67
3.5.2. 1,1-Difluoro-2-(2,4-methoxyphenyl)ethene (6c).
According to general procedure A, neat pyrolysis of sulf-
oxide 5c (104.2 mg, 0.30 mmol) at 170–200 ꢁC (0.05 mmHg)
gave a pure oil of 6c (44.5 mg, 74% yield). According to

5984
M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
Figure 2.
general procedure B, flash vacuum pyrolysis of sulfoxide
5c (103.0 mg, 0.30 mmol) (conditions: oven temperature
120 ꢁC, column temperature 425 ꢁC; pressure 0.05 mmHg)
gave a pure oil of 6c (42.1 mg, 70% yield); 1H NMR
(400 MHz, CDCl3): d 7.38 (dd, J¼8.4, 1.2 Hz, 1H, ArH),
6.51 (dd, J¼8.4, 2.4 Hz, 1H, ArH), 6.46 (d, J¼25.6,
5.6 Hz, 1H, ArH), 5.56 (dd, J¼25.8, 5.5 Hz, 1H,
CH]CF2), 3.82 (s, 6H, 2ꢂCH3). 13C NMR (75 MHz,
CDCl3): d 159.9 (C), 157.2 (dd, J¼4.1, 1.5 Hz, C), 155.9
(dd, J¼292.8, 284.8 Hz, CF2), 128.8 (dd, J¼8.8, 2.2 Hz,
CH), 111.8 (t, J¼5.0 Hz, C), 104.7 (CH), 98.4 (CH), 75.8
(dd, J¼29.7, 14.6 Hz, CH), 55.5 (CH3), 55.4 (CH3). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ86.31 (dd, J¼36.6,
25.6 Hz, 1F), ꢀ86.11 (dd, J¼36.6, 6.4 Hz, 1F). IR (neat):
nmax 3446w, 3005w, 2942w, 2840w, 1868w, 1732s, 1614s,
1582s, 1508s, 1465s, 1439m, 1420m, 1346m, 1312s,
1291s, 1236s, 1210s, 1169s, 1115m, 1036s, 993w, 942s,
general procedure B, flash vacuum pyrolysis of sulfoxide
5e (168.5 mg, 0.547 mmol) (conditions: oven temperature
120 ꢁC, column temperature 425 ꢁC; pressure 0.05 mmHg)
gave a crude pyrolyzate, which was purified by chromatotron
(SiO2, hexanes) to give a pale yellow oil 6e (54.8 mg, 60%
1
yield); H NMR (400 MHz, CDCl3): d 7.42–7.35 (m, 2H,
ArH), 7.35–7.29 (m, 2H, ArH), 7.29–7.21 (m, 1H, ArH),
6.68 (ddd, 1H, J¼15.8, 10.8, 1.2 Hz, 1H, PhCH]CH),
6.48 (d, J¼15.8 Hz, 1H, PhCH]CH), 5.14 (dddd, J¼24.1,
10.8, 1.5, 0.6 Hz, 1H, CH]CF2). 13C NMR (100 MHz,
CDCl3): d 157.5 (dd, J¼295.4, 289.8 Hz, CF2), 137.5 (C),
131.7 (dd, J¼11.4, 3.3 Hz, CH), 129.3 (2ꢂCH), 128.3
(CH), 126.8 (2ꢂCH), 118.5 (CH), 83.5 (dd, J¼27.6,
16.8 Hz, CH). 19F NMR (376 MHz, CDCl3/CFCl3):
d ꢀ87.46 (d, J¼26.4 Hz, 1F), ꢀ85.74 (t, J¼25.4 Hz, 1F).
IR (neat): nmax 3447br m, 3084w, 3062w, 3028w, 2960m,
2926m, 2853m, 2646w, 2363w, 1812m, 1717s, 1648w,
1630w, 1597w, 1578w, 1519w, 1498w, 1451w, 1418w,
1353m, 1329m, 1295m, 1276s, 1210w, 1184s, 1116w,
1073w, 1028w, 962m, 934s, 851w, 828m, 747m, 692m,
605w, 563w, 516w, 505w cmꢀ1. EIMS: m/z (% relativeinten-
sity) 166 (M+, 28), 149 (100), 115 (54), 105 (46), 95 (35), 91
(35), 77 (50).
836m, 792w, 753w, 688w, 630w, 588w, 547w, 466w cmꢀ1
.
EIMS: m/z (% relative intensity) 200 (M+, 100), 185 (22),
157 (10), 149 (5), 121 (5). HRMS Calcd for C10H10F2O2
(M+): 200.0649; found: 200.0653.
3.5.3. 1,1-Difluoro-2-(3,4-methoxyphenyl)ethene (6d).
According to general procedure A, neat pyrolysis of sulf-
oxide 5d (101.3 mg, 0.29 mmol) at 170–200 ꢁC (0.05 mmHg)
gave a pure oil of 6d (40.9 mg, 71% yield). According to
general procedure B, flash vacuum pyrolysis of sulfoxide
5d (117.0 mg, 0.34 mmol) (conditions: oven temperature
120 ꢁC, column temperature 425 ꢁC; pressure 0.05 mmHg)
gave a pure oil of 6d (46.0 mg, 68% yield); 1H NMR
(400 MHz, CDCl3): d 6.91–6.80 (m, 3H, ArH), 5.21 (dd,
J¼26.4, 3.9 Hz, 1H, CH]CF2), 3.89 (s, 3H, CH3), 3.88 (s,
3H, CH3). 13C NMR (100 MHz, CDCl3): d 156.5 (dd,
J¼294.7, 285.1 Hz, CF2), 149.6 (C), 148.8 (C), 123.6 (t,
J¼6.0 Hz, C), 121.0 (t, J¼4.4 Hz, CH), 111.9 (CH), 111.1
(d, J¼4.4 Hz, CH), 82.5 (dd, J¼15.5, 13.7 Hz, CH), 56.5
(2ꢂCH3). 19F NMR (376 MHz, CDCl3/CFCl3): d ꢀ86.54
(dd, J¼36.5, 3.8 Hz, 1F), ꢀ84.81 (dd, J¼36.7, 25.4 Hz,
1F). IR (neat): nmax 3546w, 3004m, 2959m, 2939m,
2912m, 2838m, 2592w, 2018w, 1836w, 1731s, 1607m,
1585m, 1519s, 1466s, 1418s, 1345s, 1322s, 1293s, 1269s,
1246s, 1212s, 1178s, 1157s, 1145s, 1028s, 978m, 918s,
892m, 857s, 826m, 805m, 764m, 746m, 638m, 596w,
562m, 405w cmꢀ1. EIMS: m/z (% relative intensity) 200
(M+, 100), 185 (25), 157 (14), 139 (5), 127 (6), 110 (11),
109 (51), 107 (19), 77 (3). HRMS Calcd for C10H10F2O2
(M+): 200.0649; found: 200.0655.
3.5.5. (E)-1-(4,4-Difluoro-1,3-butadienyl)-2-methoxy-
benzene (6f). According to general procedure A, neat pyrol-
ysis of sulfoxide 5f (107.5 mg, 0.32 mmol) at 170–200 ꢁC
(0.05 mmHg) gave a pure oil of 6f (48.7 mg, 78% yield).
According to general procedure B, flash vacuum pyrolysis
of sulfoxide 5f (104.0 mg, 0.31 mmol) (conditions: oven
temperature 120 ꢁC, column temperature 425 ꢁC; pressure
0.05 mmHg) gave a pure oil of 6f (43.5 mg, 70% yield);
1H NMR (400 MHz, CDCl3): d 7.46 (dd, J¼7.3, 1.6 Hz,
1H, ArH), 7.25–7.20 (m, 1H, ArH), 6.98–6.91 (m, 1H,
ArH), 6.88 (dd, J¼8.3, 1.0 Hz, 1H, ArH), 6.82 (d, J¼
16.1 Hz, 1H, PhCH]CH), 6.70 (ddd, J¼16.0, 10.7,
1.2 Hz, 1H, PhCH]CH), 5.17 (ddd, J¼23.7, 10.7, 0.3 Hz,
1H, CH]CF2), 3.87 (s, 3H, OCH3). 13C NMR (100 MHz,
CDCl3): d 157.3 (dd, J¼295.1, 289.3 Hz, CF2), 157.2 (C),
131.3 (C), 129.2 (CH), 127.2 (CH), 126.6 (dd, J¼11.3,
3.2 Hz, CH), 121.4 (CH), 119.1 (dd, J¼4.1, 2.2 Hz, CH),
111.5 (CH), 84.1 (dd, J¼17.2, 16.8 Hz, CH), 56.1 (CH3).
19F NMR (376 MHz, CDCl3/CFCl3):
d
ꢀ88.17 (d,
J¼27.8 Hz, 1F), ꢀ86.40 (dd, J¼27.7, 23.7 Hz, 1F). IR
(neat): nmax 3415w, 3004w, 2927m, 2839w, 2644w, 1812w,
1716s, 1625w, 1597m, 1578w, 1489s, 1465m, 1438m,
1354s, 1295m, 1279m, 1246s, 1180s, 1104w, 1052w,
1030m, 970m, 934s, 854w, 841w, 821w, 775w, 749s,
731w, 607w, 578w, 508w cmꢀ1. EIMS: m/z (% relative in-
tensity) 196 (M+, 14), 165 (43), 118 (61), 77 (24), 63 (75),
50 (100). HRMS Calcd for C11H10F2O (M+): 196.0700;
found: 196.0699.
3.5.4. (E)-1-(4,4-Difluoro-1,3-butadienyl)benzene (6e).11b
According to general procedure A, neat pyrolysis of sulf-
oxide 5e (120.5 mg, 0.39 mmol) at 170–200 ꢁC (0.05 mmHg)
gave a pure oil of 6e (45.1 mg, 70% yield). According to

M. Pohmakotr et al. / Tetrahedron 62 (2006) 5973–5985
5985
V. A., Ed.; Wiley: Chichester, UK, and New York, NY, 1999;
(c) Selective Fluorination in Organic and Bioorganic
Chemistry; Welch, J. T., Ed.; American Chemical Society:
Washington, DC, 1990; (d) Hiyama, T. Organofluorine
Compounds Chemistry and Applications; Springer: New York,
NY, 2000; (e) Katazume, T.; Yamazaki, T. Experimental
Methods in Organic Fluorine Chemistry; Kodonsha: Tokyo,
1998; (f) Kitazume, T.; Yamaziki, T. Top. Curr. Chem. 1997,
193, 91–130; (g) Percy, J. M. Top. Curr. Chem. 1997, 193,
131–195; (h) Wang, R.-W.; Qing, F.-L. Org. Lett. 2005, 7,
2189–2192; (i) Ye, J.-D.; Liao, X.; Piccirilli, J. A. Org. Lett.
2005, 70, 7902–7910; (j) Liu, Y.; Ahmed, Y.; Hill, B.; Taylor,
S. D. Org. Biomol. Chem. 2005, 3, 3329–3335.
3.5.6. 1-(Difluoromethylene-1,2,3,4-tetrahydronaptha-
lene (6l).11b According to general procedure B, flash vac-
uum pyrolysis of sulfoxide 5l (110.1 mg, 0.34 mmol)
(conditions: oven temperature 205 ꢁC, column temperature
425 ꢁC; pressure 0.05 mmHg) gave a crude pyrolyzate,
which was purified by chromatotron (SiO2, hexanes) to
1
give a colourless oil of 6l (25.0 mg, 41% yield); H NMR
(300 MHz, CDCl3): d 7.5 (d, J¼7.4 Hz, 1H, ArH), 7.17–
6.98 (m, 3H, ArH), 2.72 (t, J¼6.2 Hz, 2H, PhCH2), 2.47–
2.33 (m, 2H, CH2CH2CH2), 1.84–1.70 (m, 2H, CH2COH).
13C NMR (100 MHz, CDCl3): d 152.8 (dd, J¼294.3,
282.7 Hz, CF2), 137.6 (d, J¼6.0 Hz, C), 129.0 (CH), 127.3
(d, J¼1.5 Hz, C), 127.1 (d, J¼1.6 Hz, C), 126.6 (CH),
126.1 (CH), 88.2 (dd, J¼23.6, 8.6 Hz, C), 30.4 (CH2),
23.3 (t, J¼2.1 Hz, CH2), 22.2 (t, J¼1.4 Hz, CH2). 19F
NMR (376 MHz, CDCl3/CFCl3): d ꢀ88.5 (d, J¼42.1 Hz,
1F), ꢀ88.1 (d, J¼43.7 Hz, 1F). IR (neat): nmax 3065w,
3025w, 2931s, 2857m, 1855m, 1713s, 1602w, 1488m,
1453m, 1350w, 1323m, 1270w, 1231s, 1160w, 1119m,
1071w, 989s, 945w, 909w, 878w, 784w, 759s, 727w,
688w cmꢀ1. EIMS: m/z (% relative intensity) 180 (M+,
39), 159 (21), 147 (100), 129 (72), 91 (25), 77 (6).
2. (a) Prakash, G. K. S.; Hu, J.; Mathew, T.; Olah, G. A. Angew.
Chem., Int. Ed. 2003, 42, 5216–5219 and references cited;
(b) Prakash, G. K. S.; Hu, J.; Olah, G. A. J. Org. Chem.
2003, 68, 4457–4463 and references cited; (c) Prakash,
G. K. S.; Hu, J.; Olah, G. A. Org. Lett. 2004, 6, 4315–4317;
(d) Prakash, G. K. S.; Hu, J.; Wang, Y.; Olah, G. A. Angew.
Chem., Int. Ed. 2004, 43, 5203–5206; (e) Prakash, G. K. S.;
Hu, J.; Wang, Y.; Olah, G. A. Eur. J. Org. Chem. 2005,
2218–2223; (f) Prakash, G. K. S.; Hu, J.; Wang, Y.; Olah,
G. A. J. Fluorine Chem. 2005, 126, 1361–1367.
3.5.7. 1,1-Difluoro-2,2-diphenylethene (6n).11b According
to general procedure B, flash vacuum pyrolysis of sulfoxide
5n (110.8 mg, 0.31 mmol) (conditions: oven temperature
205 ꢁC, column temperature 425 ꢁC; pressure 0.05 mmHg)
gave a crude pyrolyzate, which was purified by chromatotron
(SiO2, hexanes) to give a colourless oil 6n (53.6 mg, 80%
3. (a) Li, Y.; Hu, J. Angew. Chem., Int. Ed. 2005, 44, 5882–5886;
(b) Ni, C.; Hu, J. B. Tetrahedron Lett. 2005, 46, 8273–8277.
4. Qin, Y.-Y.; Qiu, X.-L.; Yang, Y.-Y.; Meng, W.-D.; Qing, F.-L.
J. Org. Chem. 2005, 70, 9040–9043.
5. (a) Reutrakul, V.; Thongpaisanwong, T.; Tuchinda, P.;
Kuhakarn, C.; Pohmakotr, M. J. Org. Chem. 2004, 69, 6913–
6915; (b) Pohmakotr, M.; Ieawsuwan, W.; Tuchinda, P.;
Kongsaeree, P.; Prabpai, S.; Reutrakul, V. Org. Lett. 2004, 6,
4547–4550.
6. After we had completed our investigation and the preparation
of this manuscript was at the advanced stage, Prakash has
also reported the reaction of PhSCF2SiMe3 with carbonyl com-
pounds employing tetrabutylammoniumtriphenyldifluoro-
silicate: Prakash, G. K. S.; Hu, J. B.; Wang, Y.; Olah, G. A.
J. Fluorine Chem. 2005, 126, 529–534.
1
yield); H NMR (300 MHz, CDCl3): d 7.32–7.12 (m, 10H,
ArH). 13C NMR (75 MHz, CDCl3): d 153.8 (t, J¼291.5 Hz,
CF2), 134.3 (2ꢂC), 129.6 (3ꢂCH, t, J¼3.3 Hz), 128.4
(4ꢂCH), 127.5 (3ꢂCH), 96.2 (t, J¼18.0 Hz, C). 19F NMR
(376 MHz, CDCl3/CFCl3): d ꢀ88.27 (s, 2F). IR (neat): nmax
3086w, 3061w, 3027w, 2927w, 2484w, 1952w, 1879w,
1810w, 1707s, 1599w, 1578w, 1541w, 1498m, 1446s,
1338w, 1323w, 1245s, 1211s, 1158w, 1075w, 1035w,
1001m, 985s, 933w, 912m, 844w, 761s, 732w, 696s, 636m,
600m, 515m cmꢀ1. EIMS: m/z (% relative intensity) 216
(100), 197 (13), 195 (11), 165 (86).
7. Cox, D. P.; Terpinski, J.; Lawrynowicz, W. J. Org. Chem. 1984,
49, 3216–3219.
8. These results may be due to the cleavage of the silyl ether
derivative 4a to the corresponding alkoxide intermediate lead-
ing to decomposition.
Acknowledgements
9. Wakselman has reported fluoride-catalyzed nucleophilic addi-
tion reactions of phenyldifluoromethyl- and phenoxydifluoro-
methyltrimethylsilanes with carbonyl compounds: Guidotti,
J.; Metz, F.; Tordeux, M.; Wakselman, C. Synlett 2004,
1759–1762.
We thank The Higher Education Development Project:
Postgraduate Education and Research Program in
Chemistry (PERCH) for financial support and The
Thailand Research Fund for the Senior Research Scholar
Award to V.R. The Development and Promotion of
Science and Technology Talent Project is also gratefully
acknowledged for a scholarship to W.I.
10. Reutrakul, V.; Kruahong, T.; Pohmakotr, M. Tetrahedron Lett.
1994, 35, 4851–4852.
11. For recent preparation of gem-difluoroalkenes, see: (a)
Hagooly, A.; Rozen, S. J. Fluorine Chem. 2005, 126, 1239–
1245 and references cited; (b) Nowak, I.; Robins, M. J. Org.
Lett. 2005, 7, 721–724; (c) Anilkumar, R.; Burton, D. J.
J. Fluorine Chem. 2005, 126, 835–843; (d) Ichikawa, J.;
Miyazaki, H.; Sakoda, K.; Wada, Y. J. Fluorine Chem. 2004,
125, 585–593; (e) Ichikawa, J.; Wada, Y.; Fujiwara, M.;
Supplementary data
Supplementary data associated with this article can be found
in the online version, at doi:10.1016/j.tet.2006.04.015.
References and notes
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