Stereoselective synthesis of vinyl sutfones by the Stille coupling of (E)-α-stannylvinyl sulfones with aryl halides

Article abstract of DOI:10.3184/030823408X360319

Palladium-catalysed hydrostannylation of acetylenic sulfones (R-C≡C-SO₂Ar) in benzene at room temperature gives stereoselectively -

Full text of DOI:10.3184/030823408X360319

592 RESEARCH PAPER
OCTOBER, 592–594
JOURNAL OF CHEMICAL RESEARCH 2008
Stereoselective synthesis of vinyl sulfones by the Stille coupling of
(E)-a-stannylvinyl sulfones with aryl halides
Ronghua Hua,b, Yan Yua and Mingzhong Caia*
aDepartment of Chemistry, Jiangxi Normal University, Nanchang 330022, P.R. China
bDepartment of Chemistry, Jinggangshan University, Jian 343009, P.R. China
Palladium-catalysed hydrostannylation of acetylenic sulfones (R–C≡C–SO2Ar) in benzene at room temperature gives
stereoselectively (E)-a-stannylvinyl sulfones in good to high yields. (E)-a-Stannylvinyl sulfones are difunctional
group reagents which undergo Stille coupling reaction with aryl halides in the presence of Pd(PPh3)4 and CuI
co-catalyst to afford stereoselectively (Z)-1,2-disubstituted vinyl sulfones in good yields.
Keywords: acetylenic sulfone, hydrostannylation, (E)-α-stannylvinyl sulfone, Stille coupling, (Z)-1,2-disubstituted vinyl sulfone
Many biologically active compounds contain the structural
unit of polysubstituted alkenes and the stereoselective
synthesis of polysubstituted alkenes remains a challenging
problem in organic synthesis.1-5 Stereodefined vinyl sulfones
are useful precursors of alkenes since the sulfone group
provides a useful functional group for further transformation
by various desulfonylation methods.6,7 In addition, vinyl
sulfones are excellent acceptors for Michael additions8
and 2π partners in cycloaddition reactions.9 The available
methods for the synthesis of vinyl sulfones mainly consist
of Horner–Emmons reactions of carbonyl compounds and
sulfonyl phosphoranes,10 Peterson reactions,11 β-elimination
of selenosulfones12 and selenosulfonation of acetylene.13
Alternative convergent processes involve the combination of
a sulfone-stabilised carbanion with a carbonyl compound. In
this regard, Knoevenagel condensation14 and Horner–Wittig
reaction15 have achieved great success giving the (E)-vinyl
sulfone as the exclusive product. The preparation of the starting
materials such as sulfonomethylphosphonates, however, could
be both inconvenient and time-consuming. Considering the
importance of vinyl sulfones, it is still of interest to develop
new routes to the synthesis of stereodefined polysubstituted
vinyl sulfones. We report here that (Z)-1,2-disubstituted vinyl
sulfones can be synthesised stereoselectively by palladium-
catalysed hydrostannylation of acetylenic sulfones, followed
by Stille coupling reaction with aryl halides in the presence of
Pd(PPh3)4 and CuI co-catalyst.
palladium-catalysed hydrostannylation of acetylenic sulfones
1 with Bu3SnH in benzene at room temperature was also highly
regio- and stereoselective, giving the corresponding (E)-
α-stannylvinyl sulfones 2 in good to high yields (Scheme 1).
The experimental results are summarised in Table 1.
Investigations of the crude products 2 by 1H NMR
spectroscopy (400 MHz) showed their isomeric purities to
be more than 98%. One olefinic proton signal of compounds
2a, 2b, 2d and 2e splits characteristically into a triplet at
d = 6.25–6.42 with coupling constant J = 5–7 Hz, which
indicated that the hydrostannylation to the acetylenic sulfones
had taken place with strong preference for the addition of
the tin atom at the carbon adjacent to the sulfonyl group.
The stereochemistry of the addition was readily apparent
1
from the H NMR spectra of compounds 2 which showed a
(3JSn-H) coupling constant of 48–52 Hz, fully in accord with
an E geometry and overall cis addition of tin hydride.24
(E)-α-Stannylvinyl sulfones 2 are difunctional group
reagents in which two synthetically versatile groups are
linked to the same olefinic carbon atom and can be considered
both as vinylstannanes and as vinyl sulfones. The palladium-
catalysed cross-coupling of organostannanes with organic
halides and triflates is known as the Stille reaction25-27 and
has become an extremely powerful tool for the formation
of carbon–carbon bonds. This coupling reaction has been
widely applied in organic synthesis since a wide variety of
functionality can be tolerated on either partner, the yields of
coupled products are high, and the organotin reagents can be
readily synthesised, purified, and stored. With a convenient
route to the (E)-α-stannylvinyl sulfones 2, we decided to
Palladium-catalysed
hydrostannylation
of
phenylthioalkynes,16 alkynyl selenides,17 and alkynyl
sulfoxides18 has been reported to be highly regio- and stereo-
selective, providing a direct route for the stereoselective
synthesis of 1,1-difunctional group reagents containing
a heteroatom and tin. Xiang and coworkers reported that
palladium-catalysed hydrostannylation of acetylenic triflones
with tributyltin hydride provided α-stannylated vinyl triflones
regiospecifically, but the reaction was not stereospecific,
affording a 1:1.7 ratio of E and Z stereoisomers.19
Table 1 Synthesis of (E)-a-stannylvinyl sulfones 2a–ea
Entry
R
Ar
Product
Yieldb/%
1
2
3
4
5
n-C4H9
n-C4H9
Ph
CH3OCH2
CH3OCH2
Ph
4-CH3C6H4
Ph
Ph
4-CH3C6H4
2a
2b
2c
2d
2e
90
88
82
83
80
We have now investigated the palladium-catalysed
hydrostannylation of acetylenic sulfones in order to provide
a simple general route for the stereoselective synthesis of (E)-
α-stannylvinyl sulfones although there have been examples
of these compounds in the literature.20-23 We found that the
aReactions were performed in the presence of 1 (1 mmol),
Bu3SnH (1.05 mmol), Pd(PPh3)4 (0.01 mmol), using benzene
(4 ml) as solvent, at room temperature for 4 h under Ar.
bIsolated yield based on the 1 used.
R
H
SO2Ar
SnBu3
Pd(PPh3)4 (1 mol %)
Benzene, r.t.
R
SO2Ar
+ Bu3SnH
1
2
Scheme 1
* Correspondent. E-mail: caimzhong@163.com

JOURNAL OF CHEMICAL RESEARCH 2008 593
were measured using a Yanaco MT-3 CHN microelemental analyser.
All reactions were carried out in pre-dried glassware (150°C, 4 h)
and cooled under a stream of dry Ar. Benzene was distilled from
sodium prior to use. DMF was dried by distillation over calcium
hydride.
establish the feasibility of using 2 in Stille coupling reactions
with aryl iodides 3. Gratifyingly, when the Stille coupling
reactions of 2 with a variety of aryl iodides 3 were conducted
in DMF at room temperature using Pd(PPh3)4 and CuI as co-
catalyst (Scheme 2), fairly rapid reactions occurred affording
stereoselectively the desired coupled products 4 in good
yields. The experimental results are summarised in Table 2.
The nature of the substituents in the aryl iodides has no
influence on the Stille reaction. The Stille coupling reactions
of (E)-α-stannylvinyl sulfones 2 with heteroaryl iodides
and 1-iodonaphthalene also proceeded smoothly to give the
corresponding coupled products in good yields (entries 7 and
8). However, we found that when Stille coupling reactions
of (E)-α-stannylvinyl sulfones 2 with aryl bromides were
attempted under the same conditions, the Stille coupling
reactions did not occur at all.
It is well documented that the Stille coupling reaction of
vinylstannanes with organic halides, in the presence of a
palladium catalyst, occurs with retention of configuration.25-27
In addition, the Z-configuration of compound 4f was
confirmed by NOESY experiments. An enhancement of the
allylic protons was observed as the vinylic proton of 4f was
irradiated. A correlation between the allylic protons and the
aromatic protons of (4-methylphenyl)sulfonyl group was
observed. The NOE results indicate that compound 4f has the
expected Z-configuration and that the cross-coupling reaction
of (E)-α-stannylvinyl sulfones with aryl iodides occurs with
retention of configuration.
General procedure for the synthesis of (E)-α-stannylvinyl sulfones
2a–e
A 25 ml, two-necked, round-bottom flask equipped with a magnetic
stir bar, and argon was charged sequentially with acetylenic sulfone
1 (1 mmol), benzene (4 ml), Pd(PPh3)4 (0.01 mmol) and Bu3SnH
(1.05 mmol). The mixture was stirred at room temperature for 4 h.
After removal of the solvent under reduced pressure, the residue was
diluted with light petroleum ether (20 ml) and filtered to remove the
palladium catalyst. The resulting solution was concentrated under
reduced pressure and the residue was purified by flash chromatography
on silica gel (eluent: light petroleum ether/Et2O, 7:1).
2a: Oil. IR (film): n (cm-1) 3066, 2958, 2927, 1713, 1587, 1446,
1285, 1138, 1082, 822, 689; 1H NMR (CDCl3): d 7.86–7.84 (m, 2H),
7.56–7.48 (m, 3H), 6.28 (t, J = 7.6 Hz, 3JSn-H = 52 Hz, 1H), 2.40–2.36
(m, 2H), 1.56–1.48 (m, 6H), 1.38–1.29 (m, 6H), 1.22–1.15 (m, 4H),
1.11–1.06 (m, 6H), 0.90 (t, J = 7.2 Hz, 9H), 0.80 (t, J = 7.2 Hz, 3H);
13C NMR (CDCl3): d 157.4, 149.0, 143.5, 132.5, 128.8, 127.1, 31.0,
30.6, 28.8, 27.3, 22.3, 13.8, 13.7, 11.4; MS: m/z 513 (M+, 1.2), 457
(16), 291 (11), 197 (18), 111 (27), 73 (100); Found: C, 55.89; H, 8.02.
Calcd for C24H42SO2Sn: C, 56.19; H, 8.19%.
2b: Oil. IR (film): n (cm-1) 2957, 2926, 1588, 1456, 1285, 1138,
1
1082, 812, 665; H NMR (CDCl3): d 7.73 (d, J = 8.4 Hz, 2H), 7.29
3
(d, J = 8.4 Hz, 2H), 6.25 (t, J = 7.6 Hz, JSn-H = 52 Hz, 1H), 2.42
(s, 3H), 2.41–2.34 (m, 2H), 1.57–1.49 (m, 6H), 1.36–1.30 (m, 6H),
1.22–1.16 (m, 4H), 1.10–1.05 (m, 6H), 0.91 (t, J = 7.2 Hz, 9H), 0.81
(t, J = 7.2 Hz, 3H); 13C NMR (CDCl3): d 156.9, 149.3, 143.2, 140.6,
129.4, 127.2, 30.9, 30.7, 28.8, 27.3, 22.3, 21.5, 13.8, 13.7, 11.4; MS:
m/z 527 (M+, 1.4), 471 (100), 469 (71), 213 (22), 211 (33), 209 (24),
91 (18); Found: C, 56.75; H, 8.09. Calcd for C25H44SO2Sn: C, 56.98;
H, 8.35%.
In conclusion, a convenient synthetic method for (Z)-
1,2-disubstituted vinyl sulfones has been developed by the
palladium-catalysed hydrostannylation of acetylenic sulfones,
followed by the Stille coupling reaction with aryl iodides
in the presence of Pd(PPh3)4 and CuI. The present method
has the advantages of readily available starting materials,
straightforward and simple procedures, mild reaction
conditions, and good yields.
2c: Oil. IR (film): n (cm-1) 3063, 2957, 2921, 1585, 1446, 1286,
1136, 1081, 878, 745; 1H NMR (CDCl3): d 7.39 (d, J = 8.4 Hz, 2H),
7.27–7.09 (m, 9H), 1.67–1.61 (m, 6H), 1.43–1.37 (m, 6H), 1.27–1.22
(m, 6H), 0.95 (t, J = 7.2 Hz, 9H); 13C NMR (CDCl3): d 154.4, 149.7,
141.4, 135.3, 131.9, 128.9, 128.2, 127.9, 127.7, 127.4, 29.0, 27.3,
13.7, 11.9; MS: m/z 533 (M+, 1.1), 477 (100), 475 (71), 199 (17),
197 (35), 195 (24), 102 (21); Found: C, 58.32; H, 6.94. Calcd for
C26H38SO2Sn: C, 58.59; H, 7.13%.
Experimental
2d: Oil. IR (film): n (cm-1) 2958, 2926, 1712, 1597, 1455, 1285,
1138, 1083, 830, 667; 1H NMR (CDCl3): d 7.86–7.83 (m, 2H),
7.60–7.53 (m, 3H), 6.42 (t, J = 5.6 Hz, 3JSn-H = 48 Hz, 1H), 4.39 (d,
J = 5.6 Hz, 2H), 3.30 (s, 3H), 1.48–1.41 (m, 6H), 1.32–1.26 (m, 6H),
1.05–1.00 (m, 6H), 0.88 (t, J = 7.2 Hz, 9H); 13C NMR (CDCl3):
d 153.8, 148.4, 142.3, 133.0, 129.0, 127.0, 70.7, 58.5, 28.7, 27.2,
13.7, 11.3; MS: m/z 501 (M+, 1.7), 445 (100), 443 (72), 441 (34),
1H NMR spectra were recorded on a Bruker AC-P400 (400 MHz)
spectrometer with TMS as an internal standard using CDCl3 as the
solvent. 13C NMR (100 MHz) spectra were recorded on a Bruker AC-
P400 (400 MHz) spectrometer using CDCl3 as the solvent. IR spectra
were determined on an FTS-185 instrument as neat films. Mass spectra
were obtained on a Finnigan 8239 mass spectrometer. Microanalyses
Table 2 Synthesis of (Z)-1,2-disubstituted vinyl sulfones 4a–ja
Entry
R
Ar
Ar1
Product
Yield/%b
1
2
n-C4H9
n-C4H9
MeOCH2
Ph
n-C4H9
n-C4H9
Ph
n-C4H9
Ph
n-C4H9
Ph
Ph
4a
4b
4c
4d
4e
4f
83
80
79
75
86
87
86
81
85
84
Ph
4-MeOCOC6H4
4-MeC6H4
Ph
3
4-MeC6H4
Ph
4-MeC6H4
4-MeC6H4
Ph
Ph
Ph
4-MeC6H4
4
5
4-ClC6H4
4-O2NC6H4
2-thienyl
1-naphthyl
3-NCC6H4
4-MeOC6H4
6
7
4g
4h
4i
8
9
10
4j
aReactions were performed with 2 (1 mmol), 3 (1.1 mmol), Pd(PPh3)4 (0.05 mmol), CuI (0.75 mmol), using DMF (8 ml) as solvent,
at room temperature for 20–24 h under Ar.
bIsolated yield based on the 2 used.
R
H
SO2Ar
SnBu3
R
H
SO2Ar
Ar1
Pd(PPh3)4/CuI
DMF, r.t.
+ Ar1I
2
3
4
Scheme 2

594 JOURNAL OF CHEMICAL RESEARCH 2008
197 (27), 195 (21), 41 (22); Found: C, 52.48; H, 7.41. Calcd for
C22H38SO3Sn: C, 52.74; H, 7.58%.
J = 8.0 Hz, 2H), 7.48–7.40 (m, 4H), 7.35–7.30 (m, 7H), 7.00–6.97
(m, 1H); 13C NMR (100 MHz, CDCl3): d 142.2, 140.4, 137.3, 136.1,
133.6, 133.1, 129.9, 129.4, 128.9, 128.6, 128.0, 127.9, 127.8, 127.2;
MS (EI): m/z 326 (M+, 2.2), 185 (56), 77 (100); Found: C, 66.41; H,
4.55. Calcd for C18H14S2O2: C, 66.23; H, 4.32%.
2e: Oil. IR (film): n (cm-1) 2959, 2925, 1713, 1598, 1456, 1285,
1138, 1085, 831, 809; 1H NMR (CDCl3): d 7.72 (d, J = 8.4 Hz, 2H),
7.31 (d, J = 8.4 Hz, 2H), 6.39 (t, J = 5.6 Hz, 3JSn-H = 48 Hz, 1H), 4.39
(d, J = 5.6 Hz, 2H), 3.30 (s, 3H), 2.43 (s, 3H), 1.47–1.42 (m, 6H),
4h: Oil. IR (neat): n (cm-1) 3061, 2956, 2920, 1630, 1506, 1447,
1306, 1151, 1085, 803; 1H NMR (400 MHz, CDCl3): d 7.80–7.60 (m,
5H), 7.44–7.18 (m, 7H), 6.24 (t, J = 7.6 Hz, 1H), 2.93–2.86 (m, 2H),
1.47–1.32 (m, 4H), 0.95 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3): d 148.2, 140.4, 140.3, 133.4, 133.1, 132.9, 132.7, 129.3,
129.1, 128.6, 128.2, 128.1, 126.4, 125.9, 125.5, 124.7, 31.4, 28.6,
22.5, 14.0; MS (EI): m/z 350 (M+, 1.2), 209 (92), 139 (93), 91 (100);
Found: C, 75.13; H, 6.44. Calcd for C22H22SO2: C, 75.39; H, 6.33%.
4i: White solid, m.p. 85–86°C. IR (KBr): n (cm-1) 3065, 2227,
1625, 1597, 1304, 1146, 1083, 749, 685; 1H NMR (400 MHz,
CDCl3): d 7.71–7.63 (m, 3H), 7.49–7.44 (m, 6H), 7.38–7.28 (m, 5H),
7.20 (s, 1H); 13C NMR (100 MHz, CDCl3): d 143.0, 142.4, 139.7,
137.2, 134.4, 133.4, 133.3, 132.9, 132.3, 129.4, 129.3, 129.2, 128.7,
128.1, 128.0, 118.1, 112.7; MS (EI): m/z 345 (M+, 17), 203 (100),
91 (26); Found: C, 72.75; H, 4.21. Calcd for C21H15NSO2: C, 73.02;
H, 4.38%.
1.32–1.26 (m, 6H), 1.04–1.00 (m, 6H), 0.88 (t, J = 7.2 Hz, 9H); 13
C
NMR (CDCl3): d 153.3, 148.7, 143.8, 139.4, 129.6, 127.1, 70.7, 58.5,
28.7, 27.2, 21.6, 13.6, 11.3; MS: m/z 515 (M+, 1.4), 459 (100), 457
(86), 455 (44), 211 (25), 209 (17), 91 (8); Found: C, 53.43; H, 7.52.
Calcd for C23H40SO3Sn: C, 53.64; H, 7.77%.
General procedure for the synthesis of (Z)-1,2-disubstituted vinyl
sulfones 4a–j
(E)-α-Stannylvinyl sulfone 2 (1.0 mmol) and aryl iodide 3 (1.1 mmol)
were dissolved in DMF (8 ml) under Ar at room temperature.
Pd(PPh3)4 (0.05 mmol) and CuI (0.75 mmol) were then added. The
mixture was stirred for 20–24 h at room temperature and monitored
by TLC (SiO2) for the disappearance of the starting (E)-α-stannylvinyl
sulfone 2. The reaction mixture was diluted with diethyl ether
(30 ml), filtered and then treated with 20% aqueous KF (10 ml) for
30 min before being dried and concentrated. The residue was purified
by column chromatography on silica gel (eluent: light petroleum
ether/Et2O, 5:1).
4j: Oil. IR (neat): n (cm-1) 2957, 2926, 1606, 1575, 1509, 1464,
1316, 1178, 1150, 688; 1H NMR (400 MHz, CDCl3): d 7.53 (d,
J = 8.0 Hz, 2H), 7.19 (d, J = 8.0 Hz, 2H), 7.13–7.11 (m, 2H), 6.78–
6.76 (m, 2H), 6.11 (t, J = 7.6 Hz, 1H), 3.79 (s, 3H), 2.86–2.82 (m,
2H), 2.38 (s, 3H), 1.47–1.32 (m, 4H), 0.93 (t, J = 7.2 Hz, 3H); 13C
NMR (100 MHz, CDCl3): d 159.7, 146.4, 143.8, 141.6, 138.3, 131.5,
129.4, 128.3, 127.7, 113.3, 55.3, 31.6, 28.5, 22.4, 21.6, 14.0; MS (EI):
m/z 344 (M+, 1.4), 209 (46), 178 (50), 165 (100), 91 (38). Found: C,
69.51; H, 6.80. Calcd for C20H24SO3: C, 69.74; H, 7.02%.
4a: Oil. IR (neat): n (cm-1) 3061, 2958, 2928, 1628, 1585, 1490,
1446, 1306, 1153, 1086, 760; 1H NMR (400 MHz, CDCl3): d 7.65 (d,
J = 7.6 Hz, 2H), 7.54–7.37 (m, 3H), 7.28–7.17 (m, 5H), 6.18 (t, J =
7.6 Hz, 1H), 2.91–2.85 (m, 2H), 1.49–1.35 (m, 4H), 0.94 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3): d 147.1, 142.0, 141.1, 135.9,
133.0, 130.2, 128.7, 128.5, 128.0, 127.7, 31.5, 28.5, 22.4, 13.9; MS
(EI): m/z 300 (M+, 100), 196 (28), 117 (47); Found: C, 72.23; H, 6.93.
Calcd for C18H20SO2: C, 71.97; H, 6.71%.
4b: Oil. IR (neat): n (cm-1) 3066, 2956, 2927, 1717, 1607 1584,
We thank the Natural Science Foundation of Jiangxi Province
(Project No. 2007GZW0172) for financial support.
1
1446, 1275, 1154, 1103, 1086, 772; H NMR (400 MHz, CDCl3): d
7.92–7.90 (m, 2H), 7.66–7.63 (m, 2H), 7.53–7.51 (m, 1H), 7.43–7.39
(m, 2H), 7.29–7.26 (m, 2H), 6.21 (t, J = 7.6 Hz, 1H), 3.91 (s, 3H),
Received 26 June 2008; accepted 4 August 2008
Paper 08/5343 doi: 10.3184/030823408X360319
Published online: 10 October 2008
2.93–2.87 (m, 2H), 1.52–1.38 (m, 4H), 0.95 (t, J = 7.2 Hz, 3H); 13
C
NMR (100 MHz, CDCl3): d 166.6, 147.8, 141.4, 140.8, 140.4, 133.3,
130.2, 130.1, 129.2, 128.9, 127.7, 52.2, 31.4, 28.5, 22.4, 13.9; MS
(EI): m/z 359 (M+ + 1, 100), 358 (M+, 85), 217 (99), 115 (78); Found:
C, 66.84; H, 6.25. Calcd for C20H22SO4: C, 67.02; H, 6.19%.
4c:Oil.IR(neat):n(cm-1)2957,2925,1643,1595,1510,1314,1148,
1112, 816, 696; 1H NMR (400 MHz, CDCl3): d 7.49 (d, J = 8.4 Hz,
2H), 7.18 (d, J = 8.0 Hz, 2H), 7.10 (d, J = 8.4 Hz, 2H), 7.04 (d,
J = 8.0 Hz, 2H), 6.25 (t, J = 4.8 Hz, 1H), 4.77 (d, J = 4.8 Hz, 2H),
3.43 (s, 3H), 2.38 (s, 3H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3):
d 144.3, 143.3, 141.2, 138.8, 137.1, 131.8, 129.7, 129.4, 128.8,
127.9, 69.8, 58.6, 21.6, 21.2; MS (EI): m/z 316 (M+, 3.6), 269 (100),
267 (67), 91 (23); Found: C, 68.15; H, 6.21. Calcd for C18H20SO3: C,
68.34; H, 6.37%.
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20 C. Booth, H. Imanieh, P. Quayle and L. Shui-Yu, Tetrahedron Lett., 1992,
33, 413.
21 M. Pohmakotr and S. Khosavanna, Tetrahedron, 1993, 49, 6483.
22 E. Shirakawa, H. Yoshida, Y. Nakao and T. Hiyama, Org. Lett., 2000, 2,
2209.
23 D. Modec and J.-P. Ferezou, Eur. J. Org. Chem., 2006, 92.
24 A.J. Leusink, H.A. Budding and J.W. Marsman, J. Organomet. Chem.,
1967, 9, 285.
25 J.K. Stille, Angew. Chem. Int. Ed. Engl., 1986, 25, 508.
26 T.N. Mitchell, Synthesis, 1992, 803.
NMR (100 MHz, CDCl3): d 144.1, 141.5, 140.3, 135.8, 133.7, 132.9,
129.9, 129.4, 128.8, 128.7, 128.4, 128.2, 128.1, 127.8; MS (EI): m/z
320 (M+, 56), 269 (23), 179 (100), 77 (31).
4e: Oil. IR (neat): n (cm-1) 2957, 2926, 1629, 1596, 1487, 1456,
1319, 1152, 1087, 684; 1H NMR (400 MHz, CDCl3): d 7.52 (d,
J = 8.4 Hz, 2H), 7.23–7.20 (m, 4H), 7.14–7.12 (m, 2H), 6.13 (t,
J = 7.6 Hz, 1H), 2.89–2.84 (m, 2H), 2.39 (s, 3H), 1.48–1.32 (m,
4H), 0.94 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 147.2,
144.2, 141.2, 138.0, 134.7, 134.5, 131.5, 129.5, 128.2, 127.7, 31.5,
28.5, 22.4, 21.6, 13.9; MS (EI): m/z 350 (M+, 37Cl, 21), 348 (M+,
35Cl, 45), 151 (100), 91 (48); Found: C, 65.13; H, 5.88. Calcd for
C19H21SO2Cl: C, 65.40; H, 6.07%.
4f: Oil. IR (neat): n (cm-1) 3067, 2958, 2927, 1626, 1597, 1520,
1
1492, 1348, 1152, 1086, 814; H NMR (400 MHz, CDCl3): d 8.12–
8.10 (m, 2H), 7.53 (d, J = 8.4 Hz, 2H), 7.41–7.38 (m, 2H), 7.23 (d,
J = 8.4 Hz, 2H), 6.22 (t, J = 7.6 Hz, 1H), 2.93–2.87 (m, 2H), 2.40
(s, 3H), 1.53–1.39 (m, 4H), 0.95 (t, J = 7.2 Hz, 3H); 13C NMR (100
MHz, CDCl3): d 148.4, 147.8, 144.6, 142.6, 140.8, 137.6, 131.1,
129.7, 127.7, 123.2, 31.3, 28.6, 22.5, 21.6, 13.9; MS (EI): m/z 359
(M+, 52), 269 (100), 267 (87), 91 (56); Found: C, 63.21; H, 5.74.
Calcd for C19H21NSO4: C, 63.49; H, 5.89%.
4g: White solid, m.p. 78–79°C. IR (KBr): n (cm-1) 3110, 1582,
1330, 1148, 1079, 728; 1H NMR (400 MHz, CDCl3): d 7.61 (d,
27 V. Farina, Pure Appl. Chem., 1996, 68, 73.
28 B.B. Jarvis, W.P. Tong and H.L. Ammon, J. Org. Chem., 1975, 40, 3189.