Indium-Catalyzed Direct Conversion of Lactones into Thiolactones and Selenolactones in the Presence of Elemental Sulfur and Selenium

Article abstract of DOI:10.1055/s-0036-1591849

The direct conversion of lactones into thiolactones with elemental sulfur (S ₈) catalyzed by InCl ₃ /PhSiH ₃ in a one-pot reaction is described. This catalytic system was successfully applied to the novel preparation of selenolactones from lactones and selenium.

Full text of DOI:10.1055/s-0036-1591849

SYNTHESIS
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
© Georg Thieme Verlag Stuttgart · New York
2017, 49, A–J
paper
A
en
N. Sakai et al.
Paper
Synthesis
Indium-Catalyzed Direct Conversion of Lactones into Thiolactones
and Selenolactones in the Presence of Elemental Sulfur and Selenium
Norio Sakai*
0
0
0
0
0-
0
0
3
0-
7
2
2
4-
8
0
0
thiolactones
O
Z
Ar
O
S8
or
cat. InCl3
Ar
O
Z =
S
8–71%
Shuhei Horikawa
PhSiH3
18 examples
+
n
n
Yohei Ogiwara
0
0
0
0
0-
0
0
3
1-
4
3
8
0-
9
1
6
Δ
selenolactones
Se
Se
43–49%
2 examples
Department of Pure and Applied Chemistry, Faculty of Science
and Technology, Tokyo University of Science (RIKADAI), Noda,
Chiba 278-8510, Japan
sakachem@rs.noda.tus.ac.jp
Received: 06.10.2017
Accepted after revision: 07.11.2017
Published online: 14.12.2017
ther the substrate scope nor the limitations on the selective
conversion of lactones into thiolactones has been studied
systematically.
DOI: 10.1055/s-0036-1591849; Art ID: ss-2017-f0643-op
Abstract The direct conversion of lactones into thiolactones with ele-
mental sulfur (S8) catalyzed by InCl3/PhSiH3 in a one-pot reaction is de-
scribed. This catalytic system was successfully applied to the novel
preparation of selenolactones from lactones and selenium.
S
O
Lawesson reagent
(LR)
O
R
(1)
(2)
O
R
A
Key words thiolactone, selenolactone, lactone, indium, hydrosilane
O
O
O
LR
Sulfur-containing lactones involving
a
thioester
S
[RC(=O)SR] or a thionoester [R(C=S)OR] unit constitute the
main skeleton of natural products, biologically active sub-
stances, and useful intermediates in organic synthesis.1 Al-
so, sulfur atoms have values for ionic radius and electron af-
finity that are larger and higher, respectively, than those of
oxygen atoms. When introduced into a main skeleton, sul-
fur atoms tend to manifest unique and novel chemical char-
acteristics.2 Therefore, development of a facile method for
the preparation of sulfur-containing lactones has continued
to attract our much attention. Thus far, a typical conversion
from lactones into sulfur-containing lactones has been
achieved with Lawesson’s reagent (LR) (Scheme 1, eq 1).3
However, the primary function of this sulfur-introducing
reagent has been limited mainly to the conversion into thi-
onolactones A,4,5 with the exception of one example involv-
ing the conversion from a spiro-type lactone into a spiro-
type thiolactone B (Scheme 1, eq 2).6 Another example of
the use of a sulfur-introducing reagent would be the con-
version of a fused lactone into a fused thiolactone B using
potassium thioacetic acid (AcSK) (Scheme 1, eq 3).7 Another
procedure treats lactones with phosphorus pentasulfide
(P4S10), which results in a low level of selectivity because a
mixture of three compounds are formed: thionolactone A,
thiolactone B, and dithiolactone C (Scheme 1, eq 4).8 Nei-
Et2N
O
NEt2
B
O
O
Bn
Bn
AcSK
O
N
(3)
S
N
O
O
N
N
Bn
Bn
B
O
S
O
S
P4S10
S
R
O
+
+
O
R
S
(4)
(5)
R
R
A
B
C
O
O
In(III)/Si-H
S
+
S8
O
(this work)
Ar
Ar
B
Scheme 1 Conversion of a lactone into thionolactone A, thiolactone
B, or dithiolactone C with a sulfur-introducing reagent
In a previous study, we described how the combination
of an indium(III) compound and a hydrosilane effectively
activated an odorless and economical sulfur reagent, ele-
mental sulfur (S8), which led to the facile sulfidation of aro-
matic carbonyl compounds, such as carboxylic acids and al-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

B
N. Sakai et al.
Paper
Synthesis
dehydes.9,10 Also, we reported that a gallium(III) compound
catalyzed the cyclization of γ-keto acids in the presence of a
hydrosilane to produce the corresponding lactones.11 In a
related study on the activation of elemental sulfur with an
indium catalyst and a hydrosilane, we found that a mixture
of lactones and S8 could be treated with an indium(III) com-
pound and a hydrosilane to produce the corresponding thi-
olactones in a one-pot procedure (Scheme 1, eq 5). We also
described how an indium(III) compound and a hydrosilane
could be applied to convert lactones into selenolactones in
the presence of selenium. In this paper, we report the scope
and limitations of the direct preparation of thiolactones
and selenolactones from lactones.
To determine the optimal conditions, the direct conver-
sion of γ-phenyl-γ-butyrolactone (1a) into γ-butyrothiolac-
tone 2a was carried out with several Lewis acid catalysts
and solvents in the presence of elemental sulfur (S8) and
PhSiH3, and the results are summarized in Table 1.12 Initial-
ly, when lactone 1a was treated with indium acetate at 80
°C for 24 hours in o-dichlorobenzene (o-DCB), the expected
conversion proceeded in a rather low yield, but the forma-
tion of the desired γ-thiolactone 2a was achieved (Table 1,
entry 1). In the 13C NMR spectrum, the carbonyl peak of 2a
appeared at 208 ppm in CDCl3, the peak of which was re-
markably shifted to a lower magnetic field than starting
lactone 1a (δ = 177 in CDCl3), and was in agreement with
that of related γ-thiolactone derivatives. Also, the C=O bond
exhibited a strong IR spectrum absorption at 1702 cm–1
(neat). Thus, to improve the product yield, several indium
compounds were examined. Consequently, InCl3 and
In(OTf)3 were effective in the conversion and produced 2a
in practical yields (entries 2–5), but other metal catalysts,
such as GaCl3, ZnCl2, and CuCl2, were ineffective (entries 6–
8), although such catalysts are often used in the reductive
transformation of some functional groups in the presence
of a hydrosilane.
Although several solvents were then examined, the
yield of 2a was not improved beyond the level achieved
when using o-DCB (Table 1, entries 9–13). Interestingly, the
use of 1,2-dimethoxyethane (DME) produced the ring-
opened carboxylic acid (E)-4-phenylbut-3-enoic acid as a
by-product in an 18% yield. When the reaction was con-
ducted with InCl3 at 120 °C, the yield was slightly improved,
and thiolactone 2a was isolated in a 60% yield (entry 14). In
contrast, when the reaction mixture was similarly treated
with In(OTf)3, the yield of 2a was decreased (entry 15).
With the optimal conditions in hand, the scope and lim-
itations of the substrate were then examined (Table 2). γ-
Lactones with alkyl groups were converted into the corre-
sponding γ-thiolactones 2b–e in relatively good yields (Ta-
ble 2, entries 1–4). A lactone bearing a tetralin ring pro-
duced the γ-thiolactone 2f in a 34% yield (entry 5). For sub-
strates with an electron-donating group, such as a methoxy
or a phenoxy group, the product yields were drastically de-
Table 1 Optimization of the Reaction Conditions
O
O
catalyst (5 mol%)
PhSiH3 (Si-H: 2 equiv)
O
+
S8
S
solvent (0.5 mL)
80 °C, 24 h
(1.1 equiv)
Ph
Ph
1a (0.5 mmol)
2a
Entry
Catalyst
Solvent
Conv. of 1a
(%)
GC yield of 2a
(%)
1
2
In(OAc)3
InCl3
o-DCB
o-DCB
o-DCB
o-DCB
o-DCB
o-DCB
o-DCB
o-DCB
PhCl
7
4
54
16
12
58
0
90
74
52
78
81
9
3
InBr3
4
InI3
5
In(OTf)3
GaCl3
ZnCl2
CuCl2
InCl3
6
7
0
8
3
6
9
86
54
90
6
24
17
20
10
0
10
11
12
13
14b
15b
InCl3
1,2-DCE
toluene
MeCN
DME
InCl3
InCl3
InCl3
48a
97
>99
InCl3
o-DCB
o-DCB
63 (60)c
45
In(OTf)3
a (E)-4-Phenylbut-3-enoic acid (18%) was formed.
b Reaction temperature: 120 °C.
c Isolated yield.
creased, probably due to the fact that an electron-donating
effect promotes a facile cleavage at the benzyl position prior
to an attack of a nucleophile, which leads to a decrease in
the product yield (entries 6–8). This was noted in our relat-
ed studies where reductive transformation was not suc-
cessful when using typical substrates, amides, carboxylic
acids, or nitrobenzenes, with a methoxy group in an indi-
um(III)/Si–H reducing system, which also led to a low
yield.9,13 When using a lactone with a 4-methoxyphenyl
group, however, the ring-opened saturated carboxylic acid
4-(4-methoxyphenyl)butanoic acid was isolated as the ma-
jor product.
That result suggests the occurrence of two consecutive
reactions: cleavage of the benzyl–oxygen bond in the lac-
tone skeleton and a subsequent reduction of the benzyl
moiety. Lactones bearing halogen substituents were con-
verted into thiolactones 2j–l in relatively good yields (Table
2, entries 9–11). The yield was low, however, for a lactone
having a trifluoromethyl group (entry 12). In contrast to
the phenyl group, the conversion of a lactone bearing a
naphthyl ring occurred in a rather low yield (entry 13). The
conversion of a lactone having a thiophene ring was per-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

C
N. Sakai et al.
Paper
Synthesis
Table 2 Scope of thiolactones with γ-aryl-γ-butyrolactones
O
O
InCl3 (5 mol%)
PhSiH3 (Si-H: 2 equiv)
O
O
+
S8
O
S
InCl3 (5 mol%)
o-DCB (0.5 mL)
80 °C, 24 h
n
PhSiH3 (Si-H: 2 equiv)
n
(1.1 equiv)
O
+
S8
S
R
R
o-DCB (0.5 mL)
80 °C, 24 h
3 (0.5 mmol)
4
(1.1 equiv)
Ar
1 (0.5 mmol)
Ar
O
O
2
O
S
Ph
S
S
Entry
Ar
Product 2
Yield (%)a
Ph
4b: 10%
4c: 23%
1
2
3
4
2-MeC6H4
3-MeC6H4
4-MeC6H4
2,5-Me2C6H3
2b
2c
2d
2e
71
55
66
49
4a: 14%
O
O
S
Ph
S
4d: NR
4e: NR
5
2f
34
Scheme 2 Scope of thiolactones with various lactones
6
7
4-MeOC6H4
3-MeOC6H4
4-PhOC6H4
4-FC6H4
2g
2h
2i
7b
16
31
61
60
61
32
24
CMc
When a linear ester benzyl acetate was treated with S8
(1.1 equiv) under the optimal conditions, the corresponding
S-benzyl thioacetate 5 was obtained in a 47% isolated yield
(Scheme 3, eq 1). In contrast, when phenethyl butyrate was
treated with S8 under the same conditions, the desired thio-
ester was not obtained, but the starting ester was recovered
in a 92% yield along with the formation of a trace amount of
butyl phenethyl ether (Scheme 3, eq 2).
8
9
2j
10
11
12
13
14
4-ClC6H4
2k
2l
4-BrC6H4
4-CF3C6H4
1-naphthyl
2-thienyl
2m
2n
2o
InCl3 (5 mol%)
PhSiH3 (Si-H: 2 equiv)
O
O
(1)
a Isolated yield.
+
S8
o-DCB (0.5 mL)
120 °C, 24 h
b 4-(4-Methoxyphenyl)butanoic acid (30%) was formed.
c CM: Complex mixture.
O
Ph
S
Ph
(0.5 mmol)
5: 47%
O
O
as above
(2)
formed under the optimal conditions, unfortunately the re-
action system led to the formation of a complex mixture
(entry 14).
Ph
Ph
n-Pr
O
n-Pr
S
Scheme 3 Direct conversion of linear esters into linear thioesters
The catalytic system was then applied to the direct con-
version of δ-lactones and fused lactones, and the results are
listed in Scheme 2. With δ-lactone, a conversion into δ-thio-
lactone occurred, but the yield of thiolactone 4a was rather
low. In a similar manner, the conversion of fused lactone
derivatives was performed under the optimal conditions,
and the yields of both 4b and 4c were low. For 4a and 4b,
most of the starting materials were consumed, which re-
sulted in the formation of many unidentified side-products.
Also, 3c was recovered in 45% yield. On the other hand,
when the reaction of either γ-lactone with an alkyl group
or a fused γ-lactone without a substituent next to an oxy-
gen atom was examined, the formation of the correspond-
ing thiolactone did not occur, and most of the starting lac-
tone was recovered. These results show that with the ex-
ception of 4e, the oxygen atom adjacent to the benzyl
position in a lactone framework is selectively changed to
the sulfur atom in the present conversion, regardless of
whether the product yield is high or low.
To test the utility of this procedure, the direct prepara-
tion of γ-selenolactones 6 was attempted from lactones
(Scheme 4). For example, when the reaction of lactone 1a
with selenium was conducted with 5 mol% of InCl3 and
PhSiH3 (Si–H: 2 equiv), the expected five-membered sele-
nolactone 5-phenyldihydroselenophen-2(3H)-one (6a) was
directly obtained in a 43% yield following common purifica-
tion.14–16 Interestingly, the carbonyl peak of compound 6a
containing selenium in the 13C NMR spectrum appeared at
211 ppm in CDCl3, thus the peak had shifted to a further
lower magnetic field than that of γ-thiolactone 2a (208
ppm in CDCl3). On the other hand, a strong IR absorption
derived from the carbonyl moiety of 6a appeared at wave-
number of 1712 cm–1 (neat). The wavenumber had shifted
to a slightly higher level than that of thiolactone 2a (1702
cm–1). Also, a lactone bearing a bromine substituent on the
benzene ring produced the corresponding γ-selenolactone
6b in 49% yield.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

D
N. Sakai et al.
Paper
Synthesis
of selenolactones from lactones and selenium. Further in-
vestigation into the substrate scope of linear benzyl esters
and the clarification of the reaction mechanism in this reac-
tion is now in progress.
O
O
InCl3 (5 mol%)
PhSiH3 (Si-H: 2 equiv)
Se
O
+
Se
(1.1 equiv)
Ar
o-DCB (0.5 mL)
120 °C, 24 h
Ar
1
(0.5 mmol)
6a: 43% (Ar = Ph)
6b: 49% (Ar = 4-BrC6H4)
Scheme 4 Application to the preparation of γ-selenolactones 6
All reactions were carried out under a N2 atmosphere, unless other-
wise noted. o-Dichlorobenzene was distilled from CaH2. All indium
compounds and other metal compounds were commercially available
and were used without further purification. Hydrosilanes were used
without further purification. γ-Phenyl-γ-butyrolactone (1a) was
commercially available and purified by recrystallization prior to use.
Reactions were monitored via TLC analysis of the reaction aliquots.
Column chromatography was performed using a silica gel. 1H NMR
spectra were measured at 500 (or 300) MHz using TMS as an internal
standard (0.00 ppm). 13C NMR spectra were measured at 125 (or 75)
MHz using the center peak of CHCl3 (77.0 ppm). High-resolution mass
spectra (HRMS) were measured using NBA (3-nitrobenzyl alcohol) as
a matrix.
We expected the key intermediate in the conversion to
be a disilathiane formed in situ from elemental sulfur and a
hydrosilane.9 Thus, when 1a was treated with hexameth-
yldisilathiane in the presence of InCl3, surprisingly, the cor-
responding thiolactone 2a was obtained in an 82% GC
yield.17 Therefore, on the basis of the results involving the
structure of the by-products obtained in Tables 1 and 2 and
the present control experiment, we predicted that a series
of conversions drive through two plausible paths, as follows
(Scheme 5).18 In path a, the formed disilathiane initially at-
tacks the benzyl position to form linear silyl ester A with a
ring-opening reaction. Then, an intramolecular attack of
the S–Si bond to the silyl ester moiety occurs to produce cy-
clization intermediate B, which finally leads to the thiolac-
tone with a regeneration of the indium catalyst and the lib-
eration of a siloxane. In path b, the disilathiane initially at-
tacks the ester moiety to form monothiol-orthoester
derivative C. A ring-opening reaction of C then occurs to
form linear thioester derivative D. The S–Si moiety in inter-
mediate D intramolecularly attacks the benzyl position to
form the thiolactone ring.19,20 We expect the formation of a
selenolactone from a lactone and selenium to proceed
through the same pathway.
In conclusion, we have demonstrated how an In-
Cl3/PhSiH3 catalytic system activated elemental sulfur to
promote a direct conversion of lactones into thiolactones. A
significant point in this series of transformations is that an
oxygen atom, which was adjacent to a benzyl position, em-
bedded as part of an ester moiety was selectively converted
into a sulfur atom. Another noteworthy point is that an
odorless, economical, and easily-handling elemental sulfur
(S8) functioned as a useful sulfur-introducing reagent. Also,
we used the present protocol to develop a novel preparation
The precursor keto acid derivatives were synthesized using a method
described in the literature and the spectra in this study were in agree-
ment.11,21
Lactone Derivatives 1 and 3; General Procedure
The lactone derivatives were synthesized by either Method A or
Method B described in the corresponding literature, except for 1a.
Method A:11 GaCl3 (8.8 mg, 0.050 mmol), benzene (2 mL), the corre-
sponding keto acid (1.0 mmol), and PhSiH3 (108 mg, 1.00 mmol) were
successively added to a screw-capped tube. After the tube was sealed
with a cap that contained a PTFE septum, the mixture was heated at
60 °C for the reaction time shown for each preparation. After the reac-
tion, H2O (2 mL) was added to the reaction mixture, and the organic
layer was extracted using EtOAc (3 × 5 mL). The combined organic
phases were evaporated under reduced pressure. To remove the silox-
ane residue, the crude material was rinsed with MeOH (15 mL). The
formed precipitate was filtered, and the filtrate was concentrated un-
der reduced pressure. The crude product was purified by silica gel
column chromatography (hexane/EtOAc) to afford the desired lactone
derivative.
Method B:22 NaBH4 (227 mg, 6.00 mmol) was added at 0 °C to a solu-
tion of NaOH (500 mg, 12.5 mmol) and the corresponding keto acid (5
mmol) in H2O (10 mL). The reaction mixture was stirred at r.t. for
more than 2 h. After completion of the reaction, concd HCl was care-
fully added until the pH of the resultant solution reached 2. The solu-
tion was then extracted with CH2Cl2 (3 × 15 mL), and the organic
Si
[In]
Si
S
O
[In]
O
O-Si
O
O-Si
S
[path a]
Ar
Ar
Ar
O
[In]
A
B
O
[In]/Si-H
[In]
Si-O-Si
S
S
S8
Si
Si
Ar
[In]
Ar
[In]
O
[In]
Si
O-Si
S
O-Si
O
S-Si
[path b]
O
Ar
Ar
O
C
D
Scheme 5 Plausible mechanism for the conversion into thiolactones
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

E
N. Sakai et al.
Paper
Synthesis
phases were combined, dried (anhyd Na2SO4), and evaporated under
reduced pressure. The resultant oil or solid was directly dissolved in
CH2Cl2 (18 mL) with trifluoroacetic acid (0.75 mL) and the solution
was stirred at r.t. for more than 24 h. Afterwards, the solution was
cooled and washed with sat. aq Na2CO3 (15 mL). Then, the solution
was extracted with CH2Cl2 (3 × 15mL), and the organic phases were
combined, dried (anhyd Na2SO4) and evaporated under reduced pres-
sure. The crude product was purified by a bulb-to-bulb distillation to
give the corresponding lactone.
5-(5,6,7,8-Tetrahydronaphthalen-2-yl)dihydrofuran-2(3H)-one
(1f)11
Method A; reaction time: 24 h; yield: 210.4 mg (94%); pale yellow oil.
IR (ATR): 1774 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.07–7.09 (m, 1 H, ArH), 7.03–7.04 (m,
2 H, ArH), 5.43–5.46 (m, 1 H, CH), 2.76 (m, 4 H, CH2), 2.58–2.66 (m, 3
H, CH2), 2.15–2.22 (m, 1 H, CH2), 1.78–1.81 (m, 4 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 177.1, 137.6, 136.3, 129.5, 126.0,
122.4, 81.4, 30.9, 29.4, 29.1, 29.0, 23.0.
MS (EI): m/z (%) = 216 (M+, 100).
5-o-Tolyldihydrofuran-2-one (1b)11
Method A; reaction time: 24 h; yield: 151.5 mg (86%); colorless oil.
HRMS (EI): m/z calcd for C14H16O2 [M]+: 216.1150; found: 216.1137.
IR (ATR): 1774 cm–1
.
5-(4-Methoxyphenyl)dihydrofuran-2-one (1g)22
1H NMR (CDCl3, 500 MHz): δ = 7.35 (dd, J = 5.0, 4.5 Hz, 1 H, ArH),
7.23–7.25 (m, 2 H, ArH), 7.18 (dd, J = 4.5, 4.5 Hz, 1 H, ArH), 5.69–5.72
(m, 1 H, CH), 2.64–2.71 (m, 3 H, CH2, CH2), 2.34 (s, 3 H, CH3), 2.06–2.14
(m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 177.1, 137.5, 134.1, 130.7, 128.1,
126.4, 124.1, 78.8, 29.5, 28.6, 18.9.
Method B; yield: 624.7 mg (65%); white solid; mp 52–53 °C.
IR (ATR): 1760 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.27 (d, J = 9.0 Hz, 1 H, ArH), 6.92 (d, J =
9.0 Hz, 2 H, ArH), 5.45–5.47 (m, 1 H, CH), 3.82 (s, 3 H, CH3), 2.58–2.67
(m, 3 H, CH2, CH2), 2.16–2.24 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 176.9, 159.8, 131.2, 126.9, 114.1, 81.3,
55.3, 30.9, 29.2.
MS (EI): m/z (%) = 176 (M+, 100).
HRMS (EI): m/z calcd for C11H12O2 [M]+: 176.0837; found: 176.0844.
MS (EI): m/z (%) = 192 (M+, 62), 137 (100).
HRMS (EI): m/z calcd for C11H12O3 [M]+: 192.0787; found: 192.0789.
5-m-Tolyldihydrofuran-2-one (1c)11
Method B; yield: 731.3 mg (83%); colorless oil.
IR (ATR): 1774 cm–1
.
5-(3-Methoxyphenyl)dihydrofuran-2-one (1h)11
1H NMR (CDCl3, 500 MHz): δ = 7.25–7.29 (m, 1 H, ArH), 7.11–7.15 (m,
3 H, ArH), 5.46–5.49 (m, 1 H, CH), 2.60–2.67 (m, 3 H, CH2, CH2), 2.36
(s, 3 H, CH3), 2.13–2.23 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 176.9, 139.3, 138.5, 129.1, 128.6,
125.8, 122.3, 81.2, 30.9, 28.9, 21.3.
MS (EI): m/z (%) = 176 (M+, 100).
HRMS (EI): m/z calcd for C11H12O2 [M]+: 176.0837; found: 176.0839.
Method B; yield: 884.2 mg (92%); colorless oil.
IR (ATR): 1774 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.28–7.32 (m, 1 H, ArH), 6.86–6.91 (m,
3 H, ArH), 5.47–5.50 (m, 1 H, CH), 3.81 (s, 3 H, OCH3), 2.62–2.68 (m, 3
H, CH2, CH2), 2.16–2.22 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 176.8, 159.8, 141.0, 129.8, 117.3,
113.7, 110.7, 80.9, 55.2, 30.8, 28.8.
MS (EI): m/z (%) = 192 (M+, 100).
HRMS (FAB): m/z calcd for C11H13O3 [M + H]+: 193.0859; found:
5-p-Tolyldihydrofuran-2-one (1d)11
Method B; yield: 837.0 mg (95%); white solid; mp 70–71 °C.
193.0864.
IR (ATR): 1764 cm–1
.
5-(4-Phenoxyphenyl)dihydrofuran-2-one (1i)11
1H NMR (CDCl3, 500 MHz): δ = 7.19–7.24 (m, 4 H, ArH), 5.47–5.50 (m,
1 H, CH), 2.61–2.67 (m, 3 H, CH2, CH2), 2.36 (s, 3 H, CH3), 2.15–2.21 (m,
1 H, CH2).
Method A; reaction time: 24 h; yield: 182.0 mg (72%); white solid;
mp 60–62 °C.
13C NMR (CDCl3, 125 MHz): δ = 177.0, 138.3, 136.2, 129.3, 125.3, 81.3,
IR (ATR): 1753 cm–1
.
30.9, 29.0, 21.1.
MS (EI): m/z (%) = 176 (M+, 87), 121 (100).
HRMS (EI): m/z calcd for C11H12O2 [M]+: 176.0837; found: 176.0839.
1H NMR (CDCl3, 500 MHz): δ = 7.29–7.36 (m, 4 H, ArH), 7.12 (t, J = 7.5
Hz, 1 H, ArH), 7.00–7.02 (m, 4 H, ArH), 5.46–5.49 (m, 1 H, CH), 2.60–
2.68 (m, 3 H, CH2, CH2), 2.16–2.25 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 176.7, 157.5, 156.7, 133.7, 129.8,
127.0, 123.6, 119.1, 118.7, 81.0, 30.9, 29.1.
5-(2,5-Dimethylphenyl)dihydrofuran-2-one (1e)11
Method B; yield: 409.0 mg (43%); pale yellow solid; mp 76–77 °C.
MS (EI): m/z (%) = 254 (M+, 100).
IR (ATR): 1768 cm–1
.
HRMS (EI): m/z calcd for C16H14O3 [M]+: 254.0943; found: 254.0949.
1H NMR (CDCl3, 500 MHz): δ = 7.16 (s, 1 H, ArH), 7.03–7.07 (m, 2 H,
ArH), 5.66–5.68 (m, 1 H, CH), 2.63–2.66 (m, 3 H, CH2, CH2), 2.32 (s, 3
H, CH3), 2.28 (s, 3 H, CH3), 2.07–2.12 (m, 1 H, CH2).
5-(4-Fluorophenyl)dihydrofuran-2-one (1j)11
Method B; yield: 824.7 mg (92%); pale yellow oil.
13C NMR (CDCl3, 125 MHz): δ = 177.1, 137.3, 135.9, 130.8, 130.6,
IR (ATR): 1773 cm–1
.
128.7, 124.7, 78.9, 29.6, 28.6, 21.0, 18.4.
MS (EI) m/z (%) = 190 (M+, 100).
HRMS (EI): m/z calcd for C12H14O2 [M]+: 190.0994; found: 190.0990.
1H NMR (CDCl3, 500 MHz): δ = 7.32 (dd, J = 8.5, 5.5 Hz, 2 H, ArH), 7.08
(t, J = 8.5 Hz, 2 H, ArH), 5.47–5.50 (m, 1 H, CH), 2.62–2.68 (m, 3 H, CH2,
CH2), 2.14–2.22 (m, 1 H, CH2).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

F
N. Sakai et al.
Paper
Synthesis
13C NMR (CDCl3, 125 MHz): δ = 176.6, 162.6 (JC,F = 246.6 Hz), 135.0 (JC,F
3.8 Hz), 127.2 (JC,F = 8.6 Hz), 115.7 (JC,F = 21.1 Hz), 80.6, 31.0, 29.0.
MS (EI): m/z (%) = 180 (M+, 95), 125 (100).
=
IR (ATR): 1774 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.35 (d, J = 5.0 Hz, 1 H, ArH), 7.05 (d, J =
3.5 Hz, 1 H, ArH), 7.01 (dd, J = 5.0, 3.5 Hz, 1 H, ArH), 5.71–5.74 (m, 1 H,
CH), 2.61–2.75 (m, 3 H, CH2, CH2), 2.35–2.43 (m, 1 H, CH2).
HRMS (EI): m/z calcd for C10H9FO2 [M]+: 180.0587; found: 180.0587.
13C NMR (CDCl3, 125 MHz): δ = 176.1, 141.7, 126.9, 126.2, 125.8, 77.3,
5-(4-Chlorophenyl)dihydrofuran-2-one (1k)11
30.7, 28.9.
MS (EI): m/z (%) = 168 (M+, 86), 113 (100).
Method B; yield: 688.2 mg (70%); colorless oil.
HRMS (EI): m/z calcd for C8H8O2S [M]+: 168.0245; found: 168.0245.
IR (ATR): 1776 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.36 (d, J = 9.0 Hz, 2 H, ArH), 7.28 (d, J =
9.0 Hz, 2 H, ArH), 5.46–5.49 (m, 1 H, CH), 2.64–2.69 (m, 3 H, CH2, CH2),
2.13–2.18 (m, 1 H, CH2).
Tetrahydro-6-phenyl-2H-pyran-2-one (3a)23
Method B; yield: 704.9 mg (80%); white solid; mp 55–58 °C.
13C NMR (CDCl3, 125 MHz): δ = 176.5, 137.8, 134.2, 128.9, 126.6, 80.4,
IR (ATR): 1718 cm–1
.
30.9, 28.8.
1H NMR (CDCl3, 500 MHz): δ = 7.31–7.40 (m, 5 H, ArH), 5.34–5.38 (m,
1 H, CH), 2.55–2.74 (m, 1 H, CH2), 2.15–2.19 (m, 1 H, CH2), 1.97–2.02
(m, 2 H, CH2), 1.83–1.91 (m, 1 H, CH2).
MS (EI): m/z (%) = 198 (M+ + 2, 17), 196 (M+, 56), 58 (100).
HRMS (EI): m/z calcd for C10H9ClO2 [M]+: 196.0291; found: 196.0295.
13C NMR (CDCl3, 125 MHz): δ = 171.3, 139.7, 128.6, 128.2, 125.7, 81.6,
5-(4-Bromophenyl)dihydrofuran-2-one (1l)11
30.5, 29.5, 18.6.
MS (EI): m/z (%) = 176 (M+, 40), 104 (100).
Method B; yield: 964.3 mg (80%); white solid; mp 81–82 °C.
IR (ATR): 1760 cm–1
.
3-Phenylisobenzofuran-1-one (3b)11
1H NMR (CDCl3, 500 MHz): δ = 7.52 (d, J = 9.0 Hz, 2 H, ArH), 7.22 (d, J =
9.0 Hz, 2 H, ArH), 5.45–5.48 (m, 1 H, CH), 2.64–2.69 (m, 3 H, CH2, CH2),
2.13–2.18 (m, 1 H, CH2).
Method B; yield: 694.1 mg (66%); white solid; mp 116–117 °C.
IR (ATR): 1746 cm–1
.
13C NMR (CDCl3, 125 MHz): δ = 176.5, 138.4, 131.9, 126.9, 122.4, 80.4,
30.9, 28.8.
MS (EI): m/z (%) = 242 (M+ + 2, 32), 240 (M+, 33), 58 (100).
HRMS (EI): m/z calcd for C10H981BrO2 [M + 2]+: 241.9765; found:
1H NMR (CDCl3, 500 MHz): δ = 7.96 (d, J = 7.5 Hz, 1 H, ArH), 7.65 (t, J =
7.5 Hz, 1 H, ArH), 7.56 (t, J = 7.5 Hz, 1 H, ArH), 7.27–7.39 (m, 6 H, ArH),
6.41 (s, 1 H, CH).
13C NMR (CDCl3, 125 MHz): δ = 170.5, 149.7, 136.4, 134.3, 129.3,
129.3, 128.9, 126.9, 125.6, 125.6, 122.8, 82.7.
241.9757.
MS (EI): m/z (%) = 210 (M+, 85), 105 (100).
5-(4-Trifluoromethylphenyl)dihydrofuran-2-one (1m)11
HRMS (EI): m/z calcd for C14H10O2 [M]+: 210.0681; found: 210.0689.
Method A; reaction time: 24 h; yield: 144.6 mg (63%); pale orange oil.
5-Phenethyldihydrofuran-2(3H)-one (3d)11
IR (ATR): 1782 cm–1
.
Method A; reaction time: 24 h; yield: 181.6 mg (96%); colorless oil.
1H NMR (CDCl3, 500 MHz): δ = 7.66 (d, J = 8.0 Hz, 2 H, ArH), 7.47 (d, J =
8.0 Hz, 2 H, ArH), 5.55–5.58 (m, 1 H, CH), 2.62–2.77 (m, 3 H, CH2, CH2),
2.13–2.21 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 176.4, 143.4, 130.6 (JC,F = 32.6 Hz),
125.7 (JC,F = 3.9 Hz), 125.4, 123.8 (JC,F = 272.0 Hz), 80.1, 30.9, 28.7.
MS (EI): m/z (%) = 230 (M+, 52), 58 (100).
HRMS (FAB): m/z calcd for C11H10F3O2 [M + H]+: 231.0627; found:
IR (ATR): 1770 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.28–7.31 (m, 2 H, ArH), 7.19–7.22 (m,
3 H, ArH), 4.44–4.50 (m, 1 H, CH), 2.80–2.86 (m, 1 H, CH2), 2.70–2.76
(m, 1 H, CH2), 2.52–2.55 (m, 2 H, CH2), 2.27–2.34 (m, 1 H, CH2), 2.01–
2.09 (m, 1 H, CH2), 1.83–1.95 (m, 2 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 177.1, 140.7, 128.5, 128.4, 126.1, 79.8,
37.3, 31.6, 28.8, 27.9.
231.0633.
MS (EI): m/z (%) = 190 (M+, 51), 130 (100).
5-Naphthalen-1-yldihydrofuran-2-one (1n)11
HRMS (EI): m/z calcd for C12H14O2 [M]+: 190.0994; found: 190.0994.
Method A; reaction time: 24 h; yield: 165.5 mg (78%); colorless oil.
IR (ATR): 1774 cm–1
.
Thiolactone Derivatives 2, 4, and 5 and Selenolactone Derivatives
6; General Procedure
1H NMR (CDCl3, 500 MHz): δ = 7.81–7.90 (m, 3 H, ArH), 7.45–7.56 (m,
4 H, ArH), 6.23–6.26 (m, 1 H, CH), 2.83–2.91 (m, 1 H, CH2), 2.60–2.73
(m, 2 H, CH2), 2.23–2.31 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 177.1, 135.0, 133.7, 129.4, 129.1,
128.7, 126.5, 125.9, 125.3, 122.4, 121.5, 78.6, 29.9, 28.2.
MS (EI): m/z (%) = 212 (M+, 100).
HRMS (EI): m/z calcd for C14H12O2 [M]+: 212.0837; found: 212.0835.
To a screw-capped tube were successively added InCl3 (5.5 mg, 0.025
mmol), o-dichlorobenzene (0.5 mL), the appropriate lactone (0.50
mmol), S8 (17.6 mg, 0.550 mmol) or Se (43.4 mg, 0.550 mmol), and
PhSiH3 (36.1 mg, 0.333 mmol). After the tube was sealed with a cap
that contained a PTFE septum, the mixture was heated for 24 h at 120
°C for thiolactones and at 120 °C for selenolactones. After the reaction,
the mixture was evaporated under reduced pressure. The crude prod-
uct was purified by silica gel column chromatography (hexane/EtOAc)
to afford either the desired thiolactone or selenolactone derivative.
Dihydro-5-(3-thienyl)-2(3H)-furanone (1o)22
Method B; yield: 740.2 mg (88%); pale yellow oil.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

G
N. Sakai et al.
Paper
Synthesis
Dihydro-5-phenyl-2(3H)-thiophenone (2a)5a
Dihydro-5-(2,5-dimethylphenyl)-2(3H)-thiophenone (2e)
General procedure was followed with 5-phenyldihydrofuran-2-one
(1a; 81.6 mg) for 24 h. Column chromatography (9:1 hexane/EtOAc)
afforded 2a as a colorless oil; yield: 48.3 mg (60%).
General procedure was followed with 5-(2,5-dimethylphenyl)dihy-
drofuran-2-one (1e; 95.2 mg) for 24 h. Column chromatography (20:1
hexane/EtOAc) afforded 2e as a dark orange oil; yield: 50.9 mg (49%).
IR (ATR): 1702 cm–1
.
IR (ATR): 1704 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.30–7.40 (m, 5 H, ArH), 5.00 (dd, J =
10.5, 5.5 Hz, 1 H, CH), 2.59–2.82 (m, 3 H, CH2, CH2), 2.24–2.32 (m, 1 H,
CH2).
13C NMR (CDCl3, 125 MHz): δ = 208.1, 139.4, 128.9, 128.2, 127.4, 54.3,
42.9, 35.1.
1H NMR (CDCl3, 500 MHz): δ = 7.36 (s, 1 H, ArH), 7.07 (d, J = 7.5 Hz, 1
H, ArH), 7.01 (d, J = 7.5 Hz, 1 H, ArH), 5.22 (dd, J = 10.0, 5.5 Hz, 1 H,
CH), 2.76–2.82 (m, 1 H, CH2), 2.66–2.73 (m, 1 H, CH2), 2.52–2.58 (m, 1
H, CH2), 2.36 (s, 3 H, CH3), 2.33 (s, 3 H, CH3), 2.24–2.31 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 208.1, 136.9, 136.2, 132.5, 130.6,
128.5, 127.1, 50.3, 42.7, 33.5, 21.0, 19.0.
MS (EI): m/z (%) = 206 (M+, 100).
HRMS (EI): m/z calcd for C12H14OS [M]+: 206.0765; found: 206.0763.
MS (EI): m/z (%) = 178 (M+, 100).
HRMS (EI): m/z calcd for C10H10OS [M]+: 178.0452; found: 178.0459.
Dihydro-5-(2-methylphenyl)-2(3H)-thiophenone (2b)
Dihydro-5-(5,6,7,8-tetrahydronaphthalen-2-yl)-2(3H)-thiophe-
none (2f)
General procedure was followed with 5-o-tolyldihydrofuran-2-one
(1b; 89.3 mg) for 24 h. Column chromatography (9:1 hexane/EtOAc)
afforded 2b as a dark red oil; yield: 62.5 mg (71%).
General procedure was followed with 5-(5,6,7,8-tetrahydronaphtha-
len-2-yl)dihydrofuran-2(3H)-one (1f; 106.0 mg) for 24 h. Column
chromatography (10:1 hexane/EtOAc) afforded 2f as a dark orange
oil; yield: 40.0 mg (34%).
IR (ATR): 1702 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.55 (d, J = 7.5 Hz, 1 H, ArH), 7.18–7.27
(m, 3 H, ArH), 5.25 (dd, J = 10.0, 5.5 Hz, 1 H, CH), 2.77–2.83 (m, 1 H,
CH2), 2.66–2.73 (m, 1 H, CH2), 2.54–2.60 (m, 1 H, CH2), 2.42 (s, 3 H,
CH3), 2.25–2.34 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 208.8, 137.2, 135.7, 130.7, 127.8,
126.7, 126.5, 50.3, 42.7, 33.4, 19.5.
IR (ATR): 1703 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.11–7.14 (m, 2 H, ArH), 7.06 (d, J = 8.0
Hz, 1 H, ArH), 4.93 (dd, J = 10.5, 5.5 Hz, 1 H, CH), 2.54–2.79 (m, 7 H,
CH2, CH2), 2.22–2.30 (m, 1 H, CH2), 1.78–1.80 (m, 4 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 208.2, 137.7, 137.2, 136.4, 129.6,
128.0, 124.4, 54.2, 43.0, 35.0, 29.4, 29.1, 23.0, 23.0.
MS (EI): m/z (%) = 192 (M+, 100).
HRMS (EI): m/z calcd for C11H12OS [M]+: 192.0609; found: 192.0608.
MS (EI): m/z (%) = 232 (M+, 100).
HRMS (EI): m/z calcd for C14H16OS [M]+: 232.0922; found: 232.0922.
Dihydro-5-(3-methylphenyl)-2(3H)-thiophenone (2c)
General procedure was followed with 5-m-tolyldihydrofuran-2-one
(1c; 88.1 mg) for 24 h. Column chromatography (9:1 hexane/EtOAc)
afforded 2c as a dark yellow oil; yield: 53.1 mg (55%).
Dihydro-5-(4-methoxyphenyl)-2(3H)-thiophenone (2g)5a
General procedure was followed with 5-(4-methoxyphenyl)dihydro-
furan-2-one (1g; 96.8 mg) for 24 h. Column chromatography (9:1
hexane/EtOAc) afforded 2g as a green solid; 7.8 mg (7%); mp 68–69
°C.
IR (ATR): 1704 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.21–7.28 (m, 3 H, ArH), 7.13 (d, J = 7.5
Hz, 1 H, ArH), 4.97 (dd, J = 10.0, 5.5 Hz, 1 H, CH), 2.57–2.81 (m, 3 H,
CH2, CH2), 2.37 (s, 3 H, CH3), 2.23–2.37 (m, 1 H, CH2).
IR (ATR): 1701 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.35 (d, J = 8.5 Hz, 2 H, ArH), 6.90 (d, J =
8.5 Hz, 2 H, ArH), 4.97 (dd, J = 10.5, 5.5 Hz, 1 H, CH), 3.81 (s, 3 H, CH3),
2.75–2.80 (m, 1 H, CH2), 2.65–2.72 (m, 1 H, CH2), 2.56–2.61 (m, 1 H,
CH2), 2.21–2.29 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 208.1, 139.4, 138.7, 128.9, 128.8,
128.1, 124.5, 54.4, 42.9, 35.0, 21.4.
MS (EI): m/z (%) = 192 (M+, 100).
HRMS (EI): m/z calcd for C11H12OS [M]+: 192.0609; found: 192.0609.
13C NMR (CDCl3, 125 MHz): δ = 208.1, 159.4, 131.3, 128.6, 114.2, 55.3,
54.0, 43.1, 35.2.
MS (EI): m/z (%) = 208 (M+, 98), 147 (100).
HRMS (EI): m/z calcd for C11H12O2S [M]+: 208.0557; found: 208.0558.
Dihydro-5-(4-methylphenyl)-2(3H)-thiophenone (2d)5a
General procedure was followed with 5-p-tolyldihydrofuran-2-one
(1d; 88.1 mg) for 24 h. Column chromatography (10:1 hexane/EtOAc)
afforded 2d as an orange oil; yield: 63.6 mg (66%).
Dihydro-5-(3-methoxyphenyl)-2(3H)-thiophenone (2h)
IR (ATR): 1703 cm–1
.
General procedure was followed with 5-(3-methoxyphenyl)dihydro-
furan-2-one (1h; 97.4 mg) for 24 h. Column chromatography (9:1
hexane/EtOAc) afforded 2h as a dark orange oil; yield: 16.2 mg (16%).
IR (ATR): 1702 cm–1
1H NMR (CDCl3, 500 MHz): δ = 7.29 (t, J = 8.0 Hz, 1 H, ArH), 7.01 (d, J =
8.0 Hz, 1 H, ArH), 6.97 (s, 1 H, ArH), 6.85 (d, J = 8.0 Hz, 1 H, ArH), 4.97
(dd, J = 10.0 Hz, 5.5 Hz, 1 H, CH), 3.82 (s, 3 H, CH3), 2.58–2.81 (m, 3 H,
CH2, CH2), 2.23–2.31 (m, 1 H, CH2).
1H NMR (CDCl3, 500 MHz): δ = 7.31 (d, J = 8.0 Hz, 2 H, ArH), 7.18 (d, J =
8.0 Hz, 2 H, ArH), 4.92 (dd, J = 10.5, 5.5 Hz, 1 H, CH), 2.56–2.80 (m, 3 H,
CH2, CH2), 2.35 (s, 3 H, CH3), 2.22–2.30 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 208.1, 138.0, 136.4, 129.5, 127.3, 54.2,
42.9, 35.1, 21.1.
MS (EI): m/z (%) = 192 (M+, 100).
HRMS (EI): m/z calcd for C10H12OS [M]+: 192.0609; found: 192.0606.
.
13C NMR (CDCl3, 125 MHz): δ = 207.8, 159.9, 141.0, 129.9, 119.7,
113.4, 113.2, 55.3, 54.3, 42.8, 34.9.
MS (EI): m/z (%) = 208 (M+, 100).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

H
N. Sakai et al.
Paper
Synthesis
HRMS (EI): m/z calcd for C11H12O2S [M]+: 208.0558; found: 208.0559.
Dihydro-5-(4-phenoxyphenyl)-2(3H)-thiophenone (2i)
Dihydro-5-(4-trifluoromethylphenyl)-2(3H)-thiophenone (2m)
General procedure was followed with 5-(4-trifluoromethylphenyl)di-
hydrofuran-2-one (1m; 68.9 mg) for 24 h. Column chromatography
(9:1 hexane/EtOAc) afforded 2m as a pale yellow oil; yield: 21.9 mg
(32%).
General procedure was followed with 5-(4-phenoxyphenyl)dihydro-
furan-2-one (1i; 126.5 mg) for 24 h. Column chromatography (9:1
hexane/EtOAc) afforded 2i as a pale yellow solid; yield: 41.7 mg
(31%); mp 84–87 °C.
IR (ATR): 1708 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.64 (d, J = 8.0 Hz, 2 H, ArH), 7.56 (d, J =
8.0 Hz, 2 H, ArH), 5.05 (dd, J = 10.0, 5.0 Hz, 1 H, CH), 2.62–2.83 (m, 3 H,
CH2, CH2), 2.22–2.30 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 206.9, 143.6 (JC,F = 1.4 Hz), 130.4 (JC,F
32.6 Hz), 127.1, 125.9 (JC,F = 3.8 Hz), 123.9 (JC,F = 272.2 Hz), 53.5, 42.5,
IR (ATR): 1702 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.33–7.38 (m, 4 H, ArH), 7.13 (t, J = 7.5
Hz, 1 H, ArH), 6.98–7.01 (m, 4 H, ArH), 4.99 (dd, J = 10.0, 5.5 Hz, 1 H,
CH), 2.58–2.81 (m, 3 H, CH2, CH2), 2.22–2.29 (m, 1 H, CH2).
=
13C NMR (CDCl3, 125 MHz): δ = 207.8, 157.3, 156.7, 133.9, 129.8,
34.8.
MS (EI): m/z (%) = 246 (M+, 100).
128.8, 123.6, 119.1, 118.9, 53.8, 42.9, 35.2.
MS (EI): m/z (%) = 270 (M+, 100).
HRMS (EI): m/z calcd for C11H9F3OS [M]+: 246.0326; found: 246.0326.
HRMS (EI): m/z calcd for C16H14O2S [M]+: 270.0715; found: 270.0714.
Dihydro-5-naphthalen-1-yl-2(3H)-thiophenone (2n)5a
Dihydro-5-(4-fluorophenyl)-2(3H)-thiophenone (2j)
General procedure was followed with 5-naphthalen-1-yldihydrofu-
ran-2-one (1n; 106.1 mg) for 24 h. Column chromatography (9:1 hex-
ane/EtOAc) afforded 2n as a pale yellow oil; yield: 27.8 mg (24%).
General procedure was followed with 5-(4-fluorophenyl)dihydrofu-
ran-2-one (1j; 90.2 mg) for 24 h. Column chromatography (10:1 hex-
ane/EtOAc) afforded 2j as a dark brown oil; yield: 60.3 mg (61%).
IR (ATR): 1702 cm–1
.
IR (ATR): 1703 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 8.11 (d, J = 8.0 Hz, 1 H, ArH), 7.91 (d, J =
8.0 Hz, 1 H, ArH), 7.84 (d, J = 8.0 Hz, 1 H, ArH), 7.76 (d, J = 8.0 Hz, 1 H,
ArH), 7.49–7.61 (m, 3 H, ArH), 5.82 (dd, J = 8.0, 5.0 Hz, 1 H, CH), 2.75–
2.86 (m, 3 H, CH2, CH2), 2.50–2.57 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 207.7, 134.7, 133.9, 131.1, 129.2,
128.7, 126.0, 125.5, 124.1, 122.6, 49.9, 42.3, 33.0.
1H NMR (CDCl3, 500 MHz): δ = 7.40 (dd, J = 8.5, 5.5 Hz, 2 H, ArH), 7.06
(t, J = 8.5 Hz, 2 H, ArH), 4.99 (dd, J = 10.5, 5.5 Hz, 1 H, CH), 2.58–2.81
(m, 3 H, CH2, CH2), 2.19–2.28 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 207.5, 162.3 (JC,F = 247.1 Hz), 135.2 (JC,F
3.3 Hz), 129.1 (JC,F = 8.0 Hz), 115.8 (JC,F = 21.6 Hz), 53.5, 42.8, 35.2.
MS (EI): m/z (%) = 196 (M+, 100).
HRMS (EI): m/z calcd for C10H9FOS [M]+: 196.0358; found: 196.0359.
=
MS (EI): m/z (%) = 228 (M+, 100).
HRMS (EI): m/z calcd for C14H12OS [M]+: 228.0609; found: 228.0609.
Dihydro-5-(4-chlorophenyl)-2(3H)-thiophenone (2k)5a
Tetrahydro-6-phenyl-2H-benzothiopyran-2-one (4a)
General procedure was followed with tetrahydro-6-phenyl-2H-
pyran-2-one (3a; 88.2 mg) for 24 h. Column chromatography (9:1
hexane/EtOAc) afforded 4a as an orange oil; yield: 13.4 mg (14%).
General procedure was followed with 5-(4-chlorophenyl)dihydrofu-
ran-2-one (1k; 98.1 mg) for 24 h. Column chromatography (9:1 hex-
ane/EtOAc) afforded 2k as a blue oil; yield: 63.4 mg (60%).
IR (ATR): 1665 cm–1
.
IR (ATR): 1703 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.34–7.39 (m, 4 H, ArH), 7.28–7.32 (m,
1 H, ArH), 4.64 (dd, J = 11.0, 4.5, 1 H, CH), 2.72–2.78 (m, 1 H, CH2),
2.57–2.64 (m, 1 H, CH2), 2.37–2.41 (m, 1 H, CH2), 2.13–2.19 (m, 1 H,
CH2), 1.94–2.09 (m, 2 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 201.3, 140.4, 128.9, 128.1, 127.7, 50.5,
40.5, 32.4, 22.7.
1H NMR (CDCl3, 500 MHz): δ = 7.33–7.37 (m, 4 H, ArH), 4.97 (dd, J =
10.0, 5.5 Hz, 1 H, CH), 2.59–2.80 (m, 3 H, CH2, CH2), 2.18–2.26 (m, 1 H,
CH2).
13C NMR (CDCl3, 125 MHz): δ = 207.3, 138.0, 133.9, 129.0, 128.8, 53.5,
42.7, 35.0.
MS (EI): m/z (%) = 214 (M+ + 2, 30), 212 (M+, 82), 117 (100).
HRMS (EI): m/z calcd for C10H9ClOS [M]+: 212.0063; found: 212.0054.
MS (EI): m/z (%) = 192 (M+, 79), 104 (100).
HRMS (EI): m/z calcd for C11H12OS [M]+: 192.0609; found: 192.0606.
Dihydro-5-(4-bromophenyl)-2(3H)-thiophenone (2l)24
3-Phenylbenzo[c]thiophen-1(3H)-one (4b)25
General procedure was followed with 5-(4-bromophenyl)dihydrofu-
ran-2-one (1l; 120.7 mg) for 24 h. Column chromatography (10:1
hexane/EtOAc) afforded 2l as a gray solid; yield: 76.8 mg (61%); mp
56–58 °C.
General procedure was followed with 3-phenylisobenzofuran-1-one
(3b; 104.9 mg) for 24 h. Column chromatography (9:1 hexane/EtOAc)
afforded 4b as a pale yellow solid; yield: 11.1 mg (10%); mp 100–102
°C.
IR (ATR): 1704 cm–1
.
IR (ATR): 1672 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.49 (d, J = 8.0 Hz, 2 H, ArH), 7.30 (d, J =
8.0 Hz, 2 H, ArH), 4.95 (dd, J = 10.0, 5.5 Hz, 1 H, CH), 2.58–2.80 (m, 3 H,
CH2, CH2), 2.18–2.26 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 207.2, 138.5, 131.7, 129.1, 121.9, 53.5,
42.7, 34.9.
MS (EI): m/z (%) = 258 (M+ + 2, 89), 256 (M+, 90), 117 (100).
HRMS (EI): m/z calcd for C10H9OS [M]+: 255.9557; found: 255.9558.
1H NMR (CDCl3, 500 MHz): δ = 7.86 (d, J = 7.5 Hz, 1 H, ArH), 7.57 (t, J =
7.5 Hz, 1 H, ArH), 7.48 (t, J = 7.5 Hz, 1 H, ArH), 7.25–7.36 (m, 6 H, ArH),
5.91 (s, 1 H, CH).
13C NMR (CDCl3, 125 MHz): δ = 197.2, 151.2, 138.8, 135.7, 133.6,
129.0, 128.3 (×2, overlap), 128.3, 126.6, 123.6, 54.6.
MS (EI): m/z (%) = 226 (M+, 100).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

I
N. Sakai et al.
Paper
Synthesis
HRMS (EI-Quadrupole): m/z calcd for C14H10OS [M]+: 226.0452;
found: 226.0453.
MS (EI): m/z (%) = 308 (M+ + 4, 6), 307 (M+ + 3, 5), 306 (M+ + 2, 7), 305
(M+ + 1, 4), 304 (M+, 38), 303 (M+ – 1, 2), 302 (M+ – 2, 19), 301 (M+ – 3,
7), 300 (M+ – 4, 7), 116 (100).
1,4-Dihydro-3H-2-benzothiopyran-3-one (4c)26
HRMS (EI): m/z calcd for
C
10H9BrOSe [M]+: 303.9002; found:
303.9007.
General procedure was followed with 1,4-dihydro-3H-2-benzopyran-
3-one (3c; 74.4 mg) for 24 h. Column chromatography (9:1 hex-
ane/EtOAc) afforded 4c as a pale yellow solid; yield: 18.7 mg (23%);
mp 92–93 °C.
Funding Information
IR (ATR): 1651 cm–1
.
This work was partially supported by JSPS KAKENHI grant number
JP25410120.
1H NMR (CDCl3, 500 MHz): δ = 7.20–7.33 (m, 4 H, ArH), 4.22 (s, 2 H,
CH2), 3.79 (s, 2 H, CH2).
a
Jp
a
n
S
o
ecity
o
f
r
hte
Pro
m
o
itn
of
Secince
K
A
K
E
N
H
I
P
J(2
5
4
1
0
1
2
0)
13C NMR (CDCl3, 125 MHz): δ = 202.9, 134.2, 133.7, 128.7, 128.0,
Acknowledgment
127.4, 126.6, 49.2, 34.2.
MS (EI): m/z (%) = 164 (M+, 21), 104 (100).
HRMS (EI): m/z calcd for C9H8OS [M]+: 164.0296; found: 164.0297.
We deeply thank Shin-Etsu Chemical Co., Ltd., for a gift of hydro-
silanes.
S-Benzyl Thioacetate (5)27
Supporting Information
General procedure was followed with benzyl acetate (75.9 mg) for 24
h. Column chromatography (100:1 hexane/EtOAc) afforded 5 as a pale
yellow oil; yield: 39.0 mg (47%).
Supporting information for this article is available online at
https://doi.org/10.1055/s-0036-1591849.
S
u
p
p
o
nrtogI
f
rmoaitn
S
u
p
p
ortiInfogrmoaitn
IR (ATR): 1690 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.28–7.31 (m, 5 H, ArH), 4.12 (s, 2 H,
CH2), 2.35 (s, 3 H, CH2).
References
13C NMR (CDCl3, 125 MHz): δ = 195.1, 137.6, 128.8, 128.6, 127.2, 33.4,
30.3.
MS (EI): m/z (%) = 166 (M+, 60), 91 (100).
HRMS (EI): m/z calcd for C9H10OS [M]+: 166.0452; found: 166.0453.
(1) For example: (a) Jones, B. A.; Bradshaw, J. S. Chem. Rev. 1984, 84,
17. (b) Larik, F. A.; Saeed, A.; Muqadar, U.; El-Seedi, H.; Faisal,
M.; Channar, P. A.; Mehfooz, H. Phosphorus, Sulfur Silicon Relat.
Elem. 2017, 192, 490.
(2) For example: Ertas, E.; Ozturk, T. Tetrahedron Lett. 2004, 45,
3405; and references cited therein.
(3) (a) Scheibye, S.; Kristensen, J.; Lawesson, S. O. Tetrahedron 1979,
35, 1339. (b) Cava, M. P.; Levinson, M. I. Tetrahedron 1985, 41,
5061.
(4) For a selected paper on the conversion of lactones into thiono-
lactones with Lawesson’s reagent, see: Clyne, D. S.; Weiler, L.
Tetrahedron 1999, 55, 13659.
(5) For selected papers on the conversion of lactones (or esters)
into thionolactones (or thionoesters) without Lawesson’s
reagent, see: (a) Rioult, P.; Vialle, J. Bull. Soc. Chim. Fr. 1965,
3312. (b) Nader, R. B.; Kaloustian, M. K. Tetrahedron Lett. 1979,
20, 1477. (c) Kaloustian, M. K.; Khouri, F. Tetrahedron Lett. 1981,
22, 413. (d) Curphey, T. J. J. Org. Chem. 2002, 67, 6461. (e) Cho,
D.; Ahn, J.; De Castro, K. A.; Ahn, H.; Rhee, H. Tetrahedron 2010,
66, 5583. (f) Yang, C.-H.; Li, G.-J.; Gong, C.-J.; Li, Y.-M. Tetrahe-
dron 2015, 71, 637. (g) Ozturk, T.; Ertas, E.; Mert, O. Chem. Rev.
2010, 110, 3419; and references cited therein.
Dihydro-5-phenyl-2(3H)-selenophenone (6a)
General procedure was followed with 5-phenyldihydrofuran-2-one
(1a; 81.1 mg) for 24 h. Column chromatography (10:1 hexane/EtOAc)
afforded 6a as a yellow oil; yield: 48.6 mg (43%).
IR (ATR): 1712 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.45 (d, J = 7.5 Hz, 2 H, ArH), 7.36 (t, J =
7.5 Hz, 2 H, ArH), 7.29 (t, J = 7.5 Hz, 1 H, ArH), 5.20 (dd, J = 10.5, 5.0 Hz,
1 H, CH), 2.81–2.86 (m, 1 H, CH2), 2.50–2.62 (m, 2 H, CH2, CH2), 2.31–
2.40 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz): δ = 211.0, 140.3, 128.8, 127.9, 127.8, 52.4,
48.6, 35.1.
MS (EI): m/z (%) = 228 (M+ + 2, 7), 227 (M+ + 1, 4), 226 (M+, 38), 225
(M+ – 1, 2), 224 (M+ – 2, 19), 223 (M+ – 3, 7), 222 (M+ – 4, 7), 117 (100).
HRMS (EI): m/z calcd for C10H10OSe [M]+: 225.9897; found: 225.9894.
(6) Zhan, X.-Q.; Qian, Z.-H.; Zheng, H.; Su, B.-Y.; Lan, Z.; Xu, J.-G.
Chem. Commun. 2008, 1859.
(7) Gerecke, M.; Zimmermann, J. P.; Aschwanden, W. Helv. Chim.
Acta 1970, 53, 991.
(8) (a) Fries, K.; Mengel, H. Ber. Dtsch. Chem. Ges. 1912, 45, 3408.
(b) For isomerization of thionolactones to thiolactones with a
Lewis acid, see also: Filippi, J.-J.; Fernandez, X.; Duñach, E.
Tetrahedron Lett. 2006, 47, 6067. (c) Oparin, D. A.; Kuznetsova,
A. S. Chem. Heterocycl. Compd. 1991, 27, 139.
(9) For a report on an in situ formation of a disilathiane from S8 and
a hydrosilane in the presence of an In(III) compound, see:
Miyazaki, T.; Nishino, K.; Yoshimoto, S.; Ogiwara, Y.; Sakai, N.
Eur. J. Org. Chem. 2015, 1991.
Dihydro-5-(4-bromophenyl)-2(3H)-selenophenone (6b)
General procedure was followed with 5-(4-bromophenyl)dihydrofu-
ran-2-one (1l; 120.1 mg) for 24 h. Column chromatography (10:1
hexane/EtOAc) afforded 6b as a pale yellow solid; yield: 74.5 mg
(49%); mp 45–47 °C.
IR (ATR): 1715 cm–1
.
1H NMR (CDCl3, 500 MHz): δ = 7.47 (d, J = 8.0 Hz, 2 H, ArH), 7.32 (d, J =
8.0 Hz, 2 H, ArH), 5.14 (dd, J = 11.0, 5.0 Hz, 1 H, CH), 2.81–2.86 (m, 1 H,
CH2), 2.49–2.61 (m, 2 H, CH2, CH2), 2.25–2.33 (m, 1 H, CH2).
13C NMR (CDCl3, 125 MHz) : δ = 210.3, 139.4, 131.9, 129.4, 121.6, 51.5,
48.4, 35.0.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J

J
N. Sakai et al.
Paper
Synthesis
(10) For selected papers on In(III)-catalyzed transformation of car-
bonyl compounds in the presence of hydrosilane, see:
adding lactone 1a to the resultant solution consisting of the
disilathiane, which was prepared from S8 and PhSiH3 in the
presence of 5 mol % of InCl3 under o-DCB reflux conditions (3 h),
thiolactone 2a was obtained in an 84% GC yield. The result
further supported that a disilathiane is a key intermediate in the
series of conversions.
a
(a) Miura, K.; Yamada, Y.; Tomita, M.; Hosomi, A. Synlett 2004,
1985. (b) Sakai, N.; Moriya, T.; Konakahara, T. J. Org. Chem. 2007,
72, 5920. (c) Tsuchimoto, T.; Igarashi, M.; Aoki, K. Chem. Eur. J.
2010, 16, 8975. (d) Pehlivan, L.; Métay, E.; Delbrayelle, D.;
Mignani, G.; Lemaire, M. Eur. J. Org. Chem. 2012, 4689.
(e) Moriya, T.; Yoneda, S.; Kawana, K.; Ikeda, R.; Konakahara, T.;
Sakai, N. J. Org. Chem. 2013, 78, 10642. (f) Inamoto, Y.; Kaga, Y.;
Nishimoto, Y.; Yasuda, M.; Baba, A. Org. Lett. 2013, 15, 3452.
(g) Ogiwara, Y.; Uchiyama, T.; Sakai, N. Angew. Chem. Int. Ed.
2016, 55, 1864. (h) Nomiyama, S.; Hondo, T.; Tsuchimoto, T. Adv.
Synth. Catal. 2016, 358, 1136.
(18) As the control experiment, when a thionolactone, dihydro-5-
phenyl-2(3H)-furanthionone, was treated with only 5 mol% of
InCl3, the quantitative formation of thiolactone 1a was observed
as well as the result reported by Duñach et al.8b Therefore, there
may be a third pathway of the direct conversion of a lactone
into a thiolactone via a thionolactone intermediate, besides to
our proposed pathways shown in Scheme 5. However, during
our investigations we have not found any trace of the corre-
sponding thionolactone intermediate in the cross-over reaction
between a γ-lactone and a disilathiane at all.
(19) For selected papers on the addition or substitution of a thiosi-
lane with electrophiles, see: (a) Degl’Innocenti, A.; Ulivi, P.;
Capperucci, A.; Reginato, G.; Mordini, A.; Ricci, A. Synlett 1992,
883. (b) Nishimoto, Y.; Okita, A.; Yasuda, M.; Baba, A. Org. Lett.
2012, 14, 1846. (c) Nishino, K.; Minato, K.; Miyazaki, T.;
Ogiwara, Y.; Sakai, N. J. Org. Chem. 2017, 82, 3659.
(20) (a) For report on a nucleophilic substitution of a benzyl silyl
ether with either a benzyl silyl thioether or a dithiasilane,
leading to a dibenzyl thioether, see: Miyazaki, T.; Katayama, M.;
Yoshimoto, S.; Ogiwara, Y.; Sakai, N. Tetrahedron Lett. 2016, 57,
676. (b) See also ref. 9.
(21) Sakai, N.; Kobayashi, T.; Ogiwara, Y. Chem. Lett. 2015, 44, 1503.
(22) Grover, H. K.; Emmett, M. R.; Kerr, M. A. Org. Lett. 2013, 15,
4838.
(11) Sakai, N.; Horikawa, S.; Ogiwara, Y. RSC Adv. 2016, 6, 81763.
(12) When γ-butyrolactone (1a) was treated with several hydro-
silanes, such as Ph2MeSiH, Et3SiH, and TMDS (tetramethyldisi-
loxane) in the presence of InCl3, the corresponding γ-butyrothi-
olactone (2a) was obtained in 4, 9, and 25% yields, respectively.
(13) (a) Moriya, T.; Yoneda, S.; Kawana, K.; Ikeda, R.; Konakahara, T.;
Sakai, N. Org. Lett. 2012, 14, 4842. (b) Sakai, N.; Asama, S.; Anai,
S.; Konakahara, T. Tetrahedron 2014, 70, 2027. (c) Sakai, N.;
Takeoka, M.; Kumaki, T.; Asano, H.; Konakahara, T.; Ogiwara, Y.
Tetrahedron Lett. 2015, 56, 6448.
(14) For selected reviews on oraganoselenium chemistry, see:
(a) Freudendahl, D. M.; Shahzad, S. A.; Wirth, T. Eur. J. Org.
Chem. 2009, 1649. (b) Wirth, T. Angew. Chem. Int. Ed. 2000, 39,
3740. (c) Wirth, T. Tetrahedron 1999, 55, 1. (d) Baird, C. P.;
Rayner, C. M. J. Chem. Soc., Perkin Trans. 1 1998, 1973.
(15) For papers on the preparation of selenolactones with NaSeH,
see: (a) Lemaire, C.; Luxen, A.; Christiaens, L.; Guillaume, M.
J. Heterocycl. Chem. 1983, 20, 811. (b) Sashida, H.; Nakayama, A.;
Kaname, M. Synthesis 2008, 3229.
(23) Dohi, T.; Takenaga, N.; Goto, A.; Maruyama, A.; Kita, Y. Org. Lett.
2007, 9, 3129.
(16) For a recent example on the preparation of 2-selenopyrones and
selenocoumarins, see: Murai, T.; Yoshida, A.; Mizutani, T.;
Kubuki, H.; Yamaguchi, K.; Maruyama, T.; Shibahara, F. Chem.
Lett. 2017, 46, 1017.
(17) On the basis of our previous work on in situ generation of a
disilathiane derived from S8 and a hydrosilane in the presence
of InI3,9 we performed the following control experiment. When
(24) Pirkle, W. H.; Spence, P. L. J. Chromatogr. A 1997, 775, 81.
(25) Kobayashi, K.; Shigemura, Y.; Ezaki, K. Heterocycles 2015, 91,
526.
(26) Almena, J.; Foubelo, F.; Yus, M. J. Org. Chem. 1996, 61, 1859.
(27) Baig, N.; Sai Sudhir, R. B. V.; Chandrasekaran, S. Synlett 2008,
2684.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–J