Acid-induced rearrangement reactions of -hydroxy-1,3-dithianes

Article abstract of DOI:10.1055/s-0029-1218658

Secondary benzylic or aliphatic -hydroxydithianes 1a-c rearrange to -thioketones when treated with acid. Related tertiary alcohols 1d-g eliminate to dithioketene ketals (e.g., 2d), which are ring-opened to thiols in some cases (1e, 1f). Allylic -hydroxydi

Full text of DOI:10.1055/s-0029-1218658

1344
PAPER
Acid-Induced Rearrangement Reactions of a-Hydroxy-1,3-dithianes
A
cid-Induce
d
Rear
a
rangement
r
of
a
-H
y
s
droxy-1,3
t
-dithian
e
es n Krohn,* Stephan Cludius-Brandt
Department Chemie, Universität Paderborn, Warburger Str. 100, 33098 Paderborn, Germany
Fax +49(5251)603245; E-mail: k.krohn@uni-paderborn.de
Received 3 October 2009; revised 23 December 2009
All substrates 1a–k were synthesized using a modified
version of the Corey and Seebach procedure.6 The sub-
strates and the resulting products after treatment with acid
are compiled in Table 1. All reactions, carried out in ace-
Abstract: Secondary benzylic or aliphatic a-hydroxydithianes 1a–
c rearrange to a-thioketones when treated with acid. Related tertiary
alcohols 1d–g eliminate to dithioketene ketals (e.g., 2d), which are
ring-opened to thiols in some cases (1e, 1f). Allylic a-hydroxy-
dithianes 1h and 1i form the thioesters 2h and 2i (homologation), tonitrile solution under reflux with addition of aqueous 6
and the tertiary alcohols 1j and 1k undergo deoxygenation to 2j and
2k.
N HCl, were carefully monitored by TLC. The acid-cata-
lyzed reactions of 1a–c afforded not the expected a-hy-
droxy carbonyl compounds, but the rearranged a-keto
thiols 2a–c. To the best of our knowledge, this type of re-
arrangement of a-hydroxydithianes with oxidation of the
hydroxy group and reduction of the dithiane is without
Key words: 1,3-dithianes, dithioacetals, 1,3-dithian-1-oxides, rear-
rangement, deoxygenation, homologation
Dithioacetals are useful protecting groups for carbonyl precedent.
compounds due to their ease of formation and their stabil-
A possible mechanism for the formation of the keto thiols
ity under acidic and basic conditions.1 In addition, they
are also umpolung reagents that play an increasing role in
natural product synthesis.2 Recently, we have systemati-
cally reinvestigated3 the scope and limitation of the Kuhn
method for cleaving 1,3-dithianes to their parent carbonyl
compounds.4 In this procedure, the monosulfoxides of the
respective 1,3-dithianes are cleaved to the carbonyl com-
pounds by treatment with acids. It turned out that the 2-
alkyl-1,3-dithianemonosulfoxides are cleaved in essen-
tially quantitative yield under much milder conditions
(20–40 °C) than originally proposed by Kuhn, irrespec-
tive of steric and electronic factors in the substrates.
is shown in Scheme 2. Thus, protonation of a sulfur atom,
elimination of the b-atom from the stabilized open chain
carbocation, enol formation, and tautomerization would
lead to the keto thiols.7
H
S+
H
S
HO
R
H
HO
R
H
HO
R
H
S
H+
+
S
S
S
– H+
O
H
OH
H
S
S
R
R
However, a-hydroxydithianes, formed by addition of
lithio-1,3-dithianes to aldehydes and ketones, are the most
important intermediates in umpolung chemistry, and their
cleavage under mild acidic conditions would be of great
interest. It is known that a-hydroxydithianes are labile un-
der acidic conditions and can undergo several rearrange-
ment reactions,5 for instance to 1,4-dithiepanes.5b
S
S
Scheme 2 Formation of keto thiols from a-hydroxydithianes
Compounds 1d and 1g both gave elimination products.
Reaction of 1d resulted in the formation of the ketene ac-
etal 2d and cyclohexene 2g was obtained from 1g. Inter-
estingly, the endocyclic double bond is more stable than
the dithiane conjugated double bond. The formation of 2g
is probably due to acid-induced isomerization of the cor-
responding ketene acetal, which is formed initially. Reac-
tions of 1e and 1f surprisingly gave the olefins 2e and 2f,
instead of the expected ketene acetals (or ring-expansion
products) in 64 and 71% yield, respectively. This unusual
reaction can possibly be induced photochemically8 or by
participation of the reductive 1,3-dithiane.9 The reactions
of 1h,i resulted in the formation of thiol esters 2h,i. The
putative mechanism for this conversion via the intermedi-
ate dithioketene acetals is shown in Scheme 3.10
In the course of our ongoing work on the deprotection of
1,3-dithianes, we have now investigated the reaction of
some a-hydroxydithianes 1 with the discovery of a num-
ber of surprising new and mechanistically interesting re-
arrangement reactions of a-hydroxydithianes (Scheme 1).
OH
R2
S
6 M HCl
in MeCN
R1
rearrangement
products 2 (see Table 1)
S
1
R
1 = alkyl, aryl; R2 = alkyl, H
Scheme 1 Rearrangement of a-hydroxydithianes
Elimination leads to the ketene acetal, which is then hy-
drolyzed stepwise via two intermediates, the carbocation
D and the orthothioester E, to give the thiol ester. The
mechanism was confirmed by conversion of isolated pure
SYNTHESIS 2010, No. 8, pp 1344–1348
Advanced online publication: 29.01.2010
DOI: 10.1055/s-0029-1218658; Art ID: T19009SS
© Georg Thieme Verlag Stuttgart · New York
x
x
.
x
x
.2
0
1
0

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Acid-Induced Rearrangement of a-Hydroxy-1,3-dithianes
1345
Table 1 Results of Rearrangement Reactions
Entry
Dithiane
Time (h)
3.5
Product
Yield (%)
OH
O
S
S
SH
1a
2a
2b
2c
48
53
45
S
OH
O
S
S
S
S
SH
SH
1b
1c
3
S
S
O
OH
35
S
OH
S
S
1d
1e
1f
1.5
2d
2e
2f
88
64
71
53
S
S
S
SH
HO
2
S
S
S
SH
HO
S
16
24
Cl
Cl
Cl
Cl
S
S
HO
S
S
S
S
1g
2g
OH
SH
1h
1i
1
2h
2i
80
50
O
S
OH
S
SH
S
20 min
O
S
S
S
S
S
1j
3
2j
79
49
HO
S
S
1k
24
2k
S
S
OH
Synthesis 2010, No. 8, 1344–1348 © Thieme Stuttgart · New York

1346
K. Krohn, S. Cludius-Brandt
PAPER
IR (KBr): 3452, 2904, 1504, 1452, 1272 cm–1.
R2
R2
O
H
OH
1H NMR (200 MHz, CDCl3): d = 1.87–2.19 (m, 2 H), 2.64–3.04 (m,
4 H), 4.12 (d, J = 8 Hz, 1 H), 4.94 (d, J = 8 Hz, 1 H), 7.28–7.52 (m,
5 H).
13C NMR (50 MHz, CDCl3): d = 25.8, 28.1, 28.7, 53.2, 75.1, 127.2,
127.5, 128.6, 128.8, 140.6.
R2
H
S
S
S
+
H+
H+
R1
R1
R1
H
H
S
S
S
1h,i
D
– H+
R2
H
R2
H
(1,3-Dithian-2-yl)(naphthalen-2-yl)methanol (1b)
Yield: 82%.
IR (KBr): 3417, 2888, 1600, 1417, 1274 cm–1.
OH
S
O
S
R1
R1
S
SH
1H NMR (200 MHz, CDCl3): d = 1.73–1.97 (m, 2 H), 2.58–2.66 (m,
2 H), 2.77–2.86 (m, 2 H), 4.21 (d, J = 7 Hz, 1 H), 5.03 (d, J = 7 Hz,
1 H), 7.46–7.87 (m, 7 H).
2h,i
E
Scheme 3 Formation of thiol esters 2h,i6
13C NMR (50 MHz, CDCl3): d = 25.4, 27.9, 28.5, 53.0, 75.1, 124.3,
ketene acetals into the thioesters. Overall, a-hydroxy alde-
hydes are transformed into the saturated esters, again with
transfer of the oxidation state, but this time with oxidation
and not reduction of the dithiane. Taken together, this
transformation is the homologation of a ketone to the cor-
responding thioester.11
125.3, 126.1, 127.7, 127.8, 127.9, 128.0, 128.3, 133.4, 137.9.
1-(1,3-Dithian-2-yl)-3-phenylpropan-1-ol (1c)
Yield: 78%.
IR (KBr): 3434, 2904, 1602, 1454, 1276 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.81–2.34 (m, 4 H), 2.65–3.04 (m,
6 H), 3.85–3.97 (m, 2 H), 7.17–7.39 (m, 5 H).
Another surprising result was the conversion of 1j and 1k
into the dithianes 2j and 2k, which proceeded in good 13C NMR (50 MHz, CDCl3): d = 26.1, 28.2, 28.7, 32.8, 36.1, 52.7,
71.8, 126.3, 128.8, 12.9, 142.1.
yields; the mechanism of this reduction is not clear but it
MS (EI): m/z (%) = 254 (40, [M]+), 119 (100), 91 (35), 77 (20), 41
(10).
must involve a reduction step, perhaps by the presence of
excess dithiane.9
HRMS: m/z calcd for C13H18OS2: 254.08001; found: 254.10492.
In summary, we found a new rearrangement reaction of
secondary benzylic and aliphatic a-hydroxydithianes 1a–c
to a-thioketones, while related allylic a-hydroxydithianes
1h and 1i gave thioesters under the same reaction condi-
tions. The open chain stabilized olefinic thiols 2e and 2f
were generated from diphenylic a-hydroxydithianes 1e
and 1f, while the reaction of the related fluorene-derived
dithiane 1d resulted in the formation of the dithioketene
acetal 2d. Remarkably, the deoxygenated products 2j and
2k were formed in the reaction of the aliphatic tertiary a-
hydroxydithianes 1j and 1k.
9-(1,3-Dithian-2-yl)-9H-fluoren-9-ol (1d)
Yield: 85%; mp 154 °C.
IR (KBr): 3534, 2923, 1654, 1446, 1274 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.64–2.13 (m, 2 H), 2.67–2.88 (m,
4 H), 3.03 (s, 1 H), 7.28–7.82 (m, 8 H).
13C NMR (50 MHz, CDCl3): d = 26.1, 30.8, 30.9, 27.8, 83.7, 120.3,
124.6, 128.3, 130.2, 140.6, 146.5.
MS (EI): m/z (%) = 300 (20, [M]+), 181 (25), 165 (30), 152 (45),
119 (100), 72 (10), 45 (5).
HRMS: m/z calcd for C17H16OS2: 300.06426; found: 300.09541.
Column chromatography was performed on silica gel 60 (particle
size 0.040–0.063 mm). Melting points were measured on a Büchi
SMP-20 melting point apparatus using one-side-open capillary
tubes and are not corrected. NMR spectra were recorded on a
Bruker ARX 200 or ARX 500 instrument at r.t. Chemical shifts are
given in ppm relative to TMS. IR spectra were measured on a Nico-
let 510P FT-IR Spectrometer. Solvents were purified, if necessary,
by standard methods. Petroleum ether (PE) used refers to the frac-
tion boiling in the range 30–50 °C.
(1,3-Dithian-2-yl)diphenylmethanol (1e)
Yield: 85%.
IR (KBr): 3534, 2923, 1654, 1450, 1270 cm–1.
1H NMR (500 MHz, CDCl3): d = 1.81–1.90 (m, 1 H), 2.04–2.11 (m,
1 H), 2.83–2.94 (m, 4 H), 3.29 (s, 1 H), 7.22–7.59 (m, 10 H).
13C NMR (50 MHz, CDCl3): d = 25.2, 30.5, 30.8, 58.6, 80.2, 126.3,
126.7, 127.4, 128.0, 128.3, 143.5.
MS (EI): m/z (%) = 302 (5, [M]+), 183 (100), 119 (65), 105 (60), 77
(25).
a-Hydroxy-1,3-dithianes 1; General Procedure
A solution of 1,3-dithiane (10 mmol) in anhyd THF (50 mL) was
cooled to –20 °C under N2. n-BuLi (11 mmol) was added dropwise
and the mixture was stirred for 1.5–2 h. The respective aldehyde/
ketone (10 mmol) in THF (10 mL) was then added at –78 °C and the
mixture was stirred for 4–5 h at this temperature. The reaction was
quenched by the addition of aq NH4Cl (30 mL) and extracted with
CH2Cl2 (2 × 50 mL). The combined organic layers were dried
(Na2SO4), the solvent was evaporated at reduced pressure, and the
residue purified by silica gel column chromatography using gradi-
ents of PE and EtOAc as the eluents.
HRMS: m/z calcd for C17H18OS2: 302.08023; found: 302.13077.
Bis(4-chlorophenyl)(1,3-dithian-2-yl)methanol (1f)
Yield: 83%; mp 116 °C.
IR (KBr): 3521, 2896, 1654, 1450, 1272 cm–1.
1H NMR (500 MHz, CDCl3): d = 1.74–2.24 (m, 2 H), 2.78–3.09 (m,
4 H), 3.53 (s, 1 H), 7.27–7.72 (m, 8 H).
13C NMR (50 MHz, CDCl3): d = 25.4, 30.8, 31.0, 58.8, 80.1, 128.3,
128.4, 128.7, 128.8, 133.9, 142.2.
MS (EI): m/z (%) = 370 (5, [M]+), 280 (20), 240 (30), 165 (35), 139
(50), 119 (100).
(1,3-Dithian-2-yl)(phenyl)methanol (1a)
Yield: 81%.
Synthesis 2010, No. 8, 1344–1348 © Thieme Stuttgart · New York

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Acid-Induced Rearrangement of a-Hydroxy-1,3-dithianes
1347
HRMS: m/z calcd for C17H16Cl2OS2: 370.00196; found: 370.01052.
MS (EI): m/z (%) = 268 (5, [M]+), 176 (10), 148 (30), 119 (100), 91
(55), 57 (75).
1-(1,3-Dithian-2-yl)-4-phenylcyclohexanol (1g)
Yield: 81%.
HRMS: m/z calcd for C14H20OS2: 268.09578; found: 268.05951.
IR (KBr): 3463, 2931, 1654, 1446, 1209 cm–1.
Rearrangement Reactions of a-Hydroxy 1,3-Dithianes 1a–k;
General Procedure
1H NMR (200 MHz, CDCl3): d = 1.59–1.68 (m, 4 H), 1.83–2.14 (m,
4 H), 2.33–2.39 (m, 2 H), 2.61–2.69 (m, 1 H), 2.88–3.02 (m, 4 H),
4.62 (s, 1 H), 7.18–7.33 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 25.6, 30.2, 30.3, 35.7, 42.4, 54.7,
73.9, 126.1, 126.8, 128.3, 145.7.
MS (EI): m/z (%) = 294 (10, [M]+), 276 (20), 175 (75), 157 (85),
119 (90), 104 (65), 91 (100), 77 (20), 41 (50).
A solution of a-hydroxy 1,3-dithianes 1a–k (1 mmol) in MeCN (10
mL) was treated with aq 6 N HCl (0.5 mL) and the mixture was re-
fluxed until the starting material was consumed (TLC monitoring).
The solution was then poured into H2O (20 mL) and extracted with
CH2Cl2 (3 × 10 mL). The combined organic layers were washed
with brine (20 mL) and dried (Na2SO4). The solvent was evaporated
at reduced pressure and the residue purified by silica gel column
chromatography using gradients of PE and EtOAc as the eluents.
HRMS: m/z calcd for C16H22OS2: 294.11147; found: 294.14925.
1-Phenyl-2-[(3-sulfanylpropyl)sulfanyl]ethan-1-one (2a)
Yield: 48%.
1H NMR (200 MHz, CDCl3): d = 1.94–2.01 (m, 2 H), 2.64–2.75 (m,
4 H), 3.79 (s, 2 H), 7.44–7.59 (m, 3 H), 7.94–7.98 (m, 2 H).
13C NMR (50 MHz, CDCl3): d = 28.1, 30.8, 37.0, 37.1, 128.6,
128.7, 133.3, 135.2, 194.4
MS (EI): m/z (%) = 226 (10, [M]+), 119 (30), 105 (100), 77 (70), 57
(35), 41 (50).
trans-2-(1,3-Dithian-2-yl)-4-phenylbut-3-en-2-ol (1h)
Yield: 71%.
IR (KBr): 3444, 2900, 1706, 1446, 1272 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.55 (s, 3 H), 1.87–1.90 (m, 1 H),
2.04–2.09 (m, 1 H), 2.79–2.93 (m, 4 H), 4.22 (s, 1 H), 6.41 (d,
J = 15.2 Hz, 1 H), 6.75 (d, J = 15.2 Hz, 1 H), 7.21–7.43 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 25.5, 26.2, 29.9, 30.3, 59.2, 75.4,
126.6, 126.9, 127.6, 128.5, 128.9, 133.1, 136.1, 146.5.
HRMS: m/z calcd for C11H14OS2: 226.04851; found: 226.10547.
MS (EI): m/z (%) = 266 (10, [M]+), 248 (25), 147 (80), 119 (100),
91 (30), 43 (65).
1-(2-Naphthyl)-2-[(3-sulfanylpropyl)sulfanyl]ethan-1-one (2b)
Yield: 53%.
HRMS: m/z calcd for C14H18OS2: 266.07983; found: 266.08016.
1H NMR (200 MHz, CDCl3): d = 1.97–2.05 (m, 2 H), 2.67–2.76 (m,
4 H), 3.91 (s, 2 H), 7.52–7.61 (m, 2 H), 7.85–7.91 (m, 3 H), 8.00 (d,
J = 8.0 Hz, 1 H), 8.49 (s, 1 H).
13C NMR (50 MHz, CDCl3): d = 28.1, 30.8, 37.1, 37.2, 124.3,
126.8, 127.7, 128.5, 128.6, 1287.7, 129.6, 130.5, 132.5, 135.7.
MS (EI): m/z (%) = 276 (5, [M]+), 170 (30), 155 (100), 127 (85),
106 (25), 77 (10), 41 (10).
1-(1,3-Dithian-2-yl)but-2-en-1-ol (1i)
Yield: 66%.
IR (KBr): 3426, 2896, 1671, 1421, 1276 cm–1.
1H NMR (500 MHz, CDCl3): d = 1.67 (d, J = 6.5 Hz, 3 H), 1.78–
2.17 (m, 2 H), 2.67–2.96 (m, 4 H), 3.93 (d, J = 6.5 Hz, 1 H), 4.21 (t,
J = 6.4 Hz, 1 H), 5.51 (dd, J = 15.3, 6.4 Hz, 1 H), 5.73 (m, 1 H).
13C NMR (50 MHz, CDCl3): d = 18.1, 26.0, 28.8, 29.1, 52.9, 74.0,
130.0, 130.2.
HRMS: m/z calcd for C15H16OS2: 276.06426; found: 276.06534.
MS (EI): m/z (%) = 190 (15, [M]+), 119 (100), 106 (15), 91 (30), 75
(65), 41 (80).
4-Phenyl-1-[(3-sulfanylpropyl)sulfanyl]butan-2-one (2c)
Yield: 45%.
IR (KBr): 2925, 2360, 1704, 1454 cm–1.
HRMS: m/z calcd for C8H14OS2: 190.04857; found: 190.05057.
1H NMR (200 MHz, CDCl3): d = 1.78–1.84 (m, 2 H), 2.49–2.60 (m,
2-(1,3-Dithian-2-yl)-3,3-dimethylbutan-2-ol (1j)
Yield: 70%.
IR (KBr): 3505, 2956, 1689, 1421, 1276 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.05 (s, 9 H), 1.30 (s, 3 H), 1.71–
2.14 (m, 2 H), 2.78–3.04 (m, 4 H), 4.37 (s, 1 H).
13C NMR (50 MHz, CDCl3): d = 20.8, 26.2, 26.7, 32.0, 32.1, 39.3,
60.0, 78.2.
4 H), 2.92–2.96 (m, 4 H), 3.16 (s, 2 H), 7.17–7.31 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 23.2, 29.9, 30.3, 32.6, 41.0, 41.6,
126.1, 128.3, 128.4, 140.7, 204.7.
MS (EI): m/z (%) = 254 (60, [M]+), 236 (10), 133 (20), 106 (100),
91 (90).
HRMS: m/z calcd for C13H18OS2: 254.08001; found: 254.08721.
MS (EI): m/z (%) = 220 (20, [M]+), 163 (40), 120 (100), 101 (55),
83 (40).
2-(9H-Fluoren-9-ylidene)-1,3-dithiane (2d)
Yield: 88%.
IR (KBr): 2923, 1685, 1560, 1448 cm–1.
HRMS: m/z calcd for C10H20OS2: 220.09568; found: 220.13583.
1H NMR (200 MHz, CDCl3): d = 2.15–2.22 (m, 2 H), 2.18–3.12 (m,
2-(1,3-Dithian-2-yl)-1-phenylbutan-2-ol (1k)
Yield: 75%.
IR (KBr): 3463, 2931, 1654, 1446, 1209 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.01 (t, J = 7.2 Hz, 3 H), 1.59 (q,
J = 7.3 Hz, 2 H), 1.97–2.13 (m, 2 H), 2.77–2.96 (m, 4 H), 2.91 (d,
J = 14.1 Hz, 1 H), 3.07 (d, J = 14.1 Hz, 1 H), 4.13 (s, 1 H), 7.19–
7.36 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 7.4, 25.9, 29.7, 31.1, 31.2, 41.8,
58.4, 76.4, 126.5, 128.1, 130.8, 136.7.
4 H), 7.26–7.79 (m, 8 H).
13C NMR (50 MHz, CDCl3): d = 29.5, 34.4, 36.4, 119.7 125.2,
126.8, 126.9, 127.1, 127.4, 128.4, 130.3, 132.3, 137.0, 138.2, 140.0,
141.1.
MS (EI): m/z (%) = 282 (10, [M]+), 181 (90), 152 (100), 118 (20),
105 (20), 76 (60), 57 (15), 41 (25).
HRMS: m/z calcd for C17H14S2: 282.05393; found: 282.05439.
Synthesis 2010, No. 8, 1344–1348 © Thieme Stuttgart · New York

1348
K. Krohn, S. Cludius-Brandt
PAPER
3-[(2,2-Diphenylvinyl)sulfanyl]propane-1-thiol (2e)
IR (KBr): 2921, 2360, 1694, 1444 cm–1.
Yield: 64%.
1H NMR (200 MHz, CDCl3): d = 0.99 (s, 9 H), 1.12 (d, J = 7.9 Hz,
3 H), 1.62 (m, 1 H), 1.75–1.85 (m, 1 H), 2.03–2.11 (m, 1 H), 2.75–
3.09 (m, 4 H), 4.42 (d, J = 2.1 Hz, 1 H).
1H NMR (200 MHz, CDCl3): d = 2.03–2.13 (m, 2 H), 2.74–2.91 (m,
4 H), 6.56 (s, 1 H), 7.17–7.44 (m, 10 H).
13C NMR (50 MHz, CDCl3): d = 29.3, 32.2, 36.8, 125.4, 126.9,
127.5, 128.3, 129.9, 139.5, 141.8.
13C NMR (50 MHz, CDCl3): d = 11.5, 26.0, 28.3, 30.7, 32.2, 48.9,
52.3.
MS (EI): m/z (%) = 286 (10, [M]+), 178 (30), 165 (60), 149 (75),
MS (EI): m/z (%) = 204 (20, [M]+), 167 (60), 149 (90), 119 (50), 85
118 (100), 105 (80), 77 (45), 57 (30), 41 (25).
(50), 57 (100).
HRMS: m/z calcd for C17H18S2: 286.08514; found: 286.08598.
HRMS: m/z calcd for C14H18OS2: 204.10076; found: 204.10549.
3-{[2,2-Bis(4-chlorophenyl)vinyl]sulfanyl}propane-1-thiol (2f)
Yield: 71%.
2-(1-Phenylbutan-2-yl)-1,3-dithiane (2k)
Yield: 76%.
1H NMR (200 MHz, CDCl3): d = 2.02–2.09 (m, 2 H), 2.74–2.09 (m,
IR (KBr): 2929, 2358, 1600, 1454, 1274 cm–1.
4 H), 6.55 (s, 1 H), 7.07–7.37 (m, 8 H).
1H NMR (200 MHz, CDCl3): d = 0.95 (t, J = 7.5 Hz, 3 H), 1.36–1.46
(m, 1 H), 1.64–1.74 (m, 1 H), 1.80–1.97 (m, 2 H), 2.06–2.13 (m, 1
H), 2.63–2.95 (m, 6 H), 4.15 (d, J = 3.6 Hz, 1 H), 7.18–7.31 (m,
5 H).
13C NMR (50 MHz, CDCl3): d = 12.0, 23.5, 26.4, 31.0, 31.2, 37.0,
47.7, 52.9, 125.9, 128.3, 129.2, 140.6.
13C NMR (50 MHz, CDCl3): d = 29.2, 33.1, 36.6, 126.7, 128.1,
128.2, 128.5, 131.0, 133.0, 133.5, 136.8, 137.4, 139.8.
MS (EI): m/z (%) = 354 (30, [M]+), 280 (20), 244 (30), 165 (25),
119 (85), 106 (100).
HRMS: m/z calcd for C17H16Cl2S2: 354.00696; found: 354.00882.
MS (EI): m/z (%) = 252 (30, [M]+), 240 (20), 156 (35), 141 (45),
2-(4-Phenylcyclohex-1-en-1-yl)-1,3-dithiane (2g)
119 (100), 91 (65), 57 (50), 41 (25).
Yield: 53%.
IR (KBr): 2921, 1688, 1446, 1272 cm–1.
HRMS: m/z calcd for C14H20S2: 252.10056; found: 251.99349.
1H NMR (200 MHz, CDCl3): d = 1.78–3.03 (m, 13 H), 4.61 (s, 1 H),
6.04 (m, 1 H), 7.17–7.32 (m, 5 H).
References
(1) (a) Wuts, P. G. M.; Greene, T. W. Greene’s Protective
Groups in Organic Synthesis, 4th ed.; Wiley: New York,
2006. (b) Kocienski, P. J. Protecting Groups, 3rd ed.; Georg
Thieme Verlag: Stuttgart, 2004.
(2) (a) Smith, A. B. III; Adams, C. Acc. Chem. Res. 2004, 37,
365. (b) Schaumann, E.; Kirschning, A. Synlett 2007, 177.
(c) Page, P. C. B.; van Niel, M. B.; Prodger, J. C.
Tetrahedron 1989, 45, 7643. (d) Gröbel, B.-T.; Seebach, D.
Synthesis 1977, 357. (e) Seebach, D. Synthesis 1969, 17.
(3) Krohn, K.; Cludius-Brandt, S. Synthesis 2008, 1369.
(4) (a) Kuhn, R.; Baschang-Bister, W.; Dafeldecker, W. Liebigs
Ann. Chem. 1961, 641, 160. (b) Kuhn, R.; Neugebauer, A.
Chem. Ber. 1961, 94, 2629.
(5) (a) Behr, S.; Hegemann, K.; Schimanski, H.; Fröhlich, R.;
Haufe, G. Eur. J. Org. Chem. 2004, 3884. (b) Ong, C. W.;
Yu, C. Y. Tetrahedron 2003, 59, 9677. (c) Wan, Y.;
Barnhurst, L. A.; Kutateladze, A. G. Org. Lett. 1999, 1, 937.
(d) Afonso, C. A. M.; Barros, M. T.; Godinho, L. S.;
Maycock, C. D. Synthesis 1991, 575. (e) Nickon, A.;
Rodriguez, A. D.; Shirhatti, V.; Ganguly, R. J Org. Chem.
1985, 50, 4218. (f) Marshall, J. A.; Roebke, H. J. Org.
Chem. 1969, 34, 4188. (g) Angibeaud, P.; Bosso, C.;
Defaye, J.; Horton, D. J. Chem. Soc., Perkin Trans. 1 1979,
1583. (h) Stork, G.; Cheung, H. T. J. Am. Chem. Soc. 1965,
87, 3783.
13C NMR (50 MHz, CDCl3): d = 25.7, 27.7, 29.8, 30.6, 31.6, 33.9,
39.6, 53.3, 126.1, 126.8, 128.4, 135.8, 146.5.
MS (EI): m/z (%) = 276 (90, [M]+), 202 (30), 169 (70), 119 (100),
91 (85), 77 (20), 41 (25).
HRMS: m/z calcd for C16H20S2: 276.10092; found: 276.10143.
S-(3-Sulfanylpropyl) (E)-2-Methyl-4-phenylbut-3-enethioate
(2h)
Yield: 80%.
IR (KBr): 2980, 2254, 1687, 1421, 1265 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.39 (d, J = 7.6 Hz, 3 H), 1.85–
2.01 (m, 2 H), 2.58–2.69 (m, 2 H), 2.94–3.05 (m, 2 H), 3.41–3.52
(m, 1 H), 6.22 (dd, J = 14.9, 7.6 Hz, 1 H), 6.53 (d, J = 14.9 Hz, 1 H),
7.29–7.42 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 17.1, 23.4, 27.5, 29.7, 52.2, 126.4,
127.8, 128.4, 128.6, 132.5, 136.7, 200.8.
MS (EI): m/z (%) = 266 (5, [M]+), 176 (20), 159 (20), 131 (100),
107 (80), 91 (75), 77 (60), 57 (70), 41 (75).
HRMS: m/z calcd for C14H18OS2: 266.07983; found: 266.08591.
S-(3-Sulfanylpropyl) (E)-Pent-3-enethioate (2i)
Yield: 43%.
(6) Seebach, D.; Corey, E. J. J. Org. Chem. 1975, 40, 231.
(7) (a) We thank the referee for drawing our attention to this
mechanism. (b) For an analogous reaction of vinyl sulfides
to give a-thiolated ketones, see: Braun, M. Tetrahedron Lett.
1978, 19, 3695.
(8) Arad-Yellin, R.; Eaton, D. F. J. Am. Chem. Soc. 1982, 104,
6147.
(9) Iranpoor, N.; Firouzabadi, H.; Shaterian, H. R. J. Org. Chem.
IR (KBr): 2923, 2360, 1681, 1427 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.75 (d, J = 6.4 Hz, 3 H), 2.04–
2.11 (m, 2 H), 2.64–2.85 (m, 6 H), 5.37–5.75 (m, 2 H).
13C NMR (50 MHz, CDCl3): d = 17.6, 25.4, 29.0, 31.0, 47.1, 128.5,
129.2, 207.3.
MS (EI): m/z (%) = 190 (30, [M]+), 132 (100), 106 (25), 83 (20), 55
(15).
2002, 67, 2826.
(10) (a) Okuyama, T.; Fueno, T. J. Am. Chem. Soc. 1980, 102,
6590. (b) Okuyama, T.; Kawao, S.; Fujiwara, W.; Fueno, T.
J. Org. Chem. 1984, 49, 89.
HRMS: m/z calcd for C8H14OS2: 190.04857; found: 190.09946.
2-(3,3-Dimethylbutan-2-yl)-1,3-dithiane (2j)
(11) Carrey, F.; Neergaard, J. E. J. Org. Chem. 1971, 36, 2731.
Yield: 85%.
Synthesis 2010, No. 8, 1344–1348 © Thieme Stuttgart · New York