A new one-pot synthetic method for selenium-containing medium-sized α,β-unsaturated cyclic ketones

Article abstract of DOI:10.1055/s-0028-1083153

The reaction of tetrahydroselenopyran-2-one (7) with ethynyllithiums 20a-h, followed by treatment with aqueous 5% H₂SO₄ successfully led to a two-carbon ring expansion to give the 2-substituted 5,6,7,8-tetrahydroselenocin-4-ones 21a-h in 43-95% yields. Seven- to nine-membered γ-selena-α,β-unsaturated cyclic ketones 22-26 and a 5,6,7,8-tetrahydrotellurocin-4-one 27 were also prepared from the corresponding selenolactones or tellurolactone in a one-pot reaction.

Full text of DOI:10.1055/s-0028-1083153

PAPER
3229
A New One-Pot Synthetic Method for Selenium-Containing Medium-Sized
a,b-Unsaturated Cyclic Ketones1
S
ynthesis of Selen
a
ium-Contai
r
ning
a
,
b
u
-Unsaturated
k
Cyclic
K
eto
i
nes Sashida,* Akemi Nakayama, Mamoru Kaname
Faculty of Pharmaceutical Sciences, Hokuriku University, Kanagawa-machi, Kanazawa 920-1181, Japan
Fax +81(76)2292781; E-mail: h-sashida@hokuriku-u.ac.jp
Received 12 June 2008; revised 2 July 2008
O
O
O
1) 33% HBr
AcOH
Abstract: The reaction of tetrahydroselenopyran-2-one (7) with
ethynyllithiums 20a–h, followed by treatment with aqueous 5%
H2SO4 successfully led to a two-carbon ring expansion to give the
2-substituted 5,6,7,8-tetrahydroselenocin-4-ones 21a–h in 43–95%
yields. Seven- to nine-membered g-selena-a,b-unsaturated cyclic
ketones 22–26 and a 5,6,7,8-tetrahydrotellurocin-4-one 27 were
also prepared from the corresponding selenolactones or tellurolac-
tone in a one-pot reaction.
NaSeH
Cl
Se
O
2) SOCl2
(CH2)n
(CH2)n
(CH2)n
Br
1: n = 1
2: n = 0
3: n = 2
7: n = 1
8: n = 0
9: n = 2
4: n = 1
5: n = 0
6: n = 2
for 4
NaTeH
O
Key words: selenolactone, ethynyllithium, ring expansion, seleni-
um , selenoketone
Te
19
Recently, the synthesis of heterocycles containing a sele-
nium element has received increasingly intensive study
and a variety of selenium-containing heterocycles have
been prepared because many of them show interesting
chemical properties2 and potential pharmaceutical activi-
ties.3 However, there are few reports concerning the
syntheses of selenium-containing medium-sized hetero-
cycles. Medium-sized heterocycles are generally difficult
to prepare using standard ring-closure methodologies.
Ring-expansion reactions4 have provided successful strat-
egies for the construction of medium-sized rings. We have
previously disclosed the syntheses of benzene ring fused
seven-membered heterocycles containing a tellurium or
selenium element, that is, 3-benzotellurepines,5 1-benzo-
tellurepines,6 1-benzoselenepines,6 and 1,5-benzo-
telluazepines7 using the intramolecular cyclization of the
tellurol or selenol moiety to a triple bond as the synthetic
strategy.8 In this report, we now describe our novel meth-
od involving the one-pot preparation of selenium-contain-
ing medium-sized heterocycles by the intramolecular ring
closure of the selenols, which were generated in situ from
selenolactones and ethynyllithiums.
O
O
O
O
Cl
1) HBr
NaSeH
Se
2) SOCl2
Br
Me
Me
Me
12
10
11
O
O
O
Me
Me
Me
O
Se
Cl
1) HBr
NaSeH
NaSeH
2) SOCl2
Br
13
14
15
O
O
O
Me
Me
1) HBr
Me
Cl
Br
Se
O
2) SOCl2
18
16
17
Scheme 1
chloride (4) is obtained via ring-opening hydrolysis of
d-valerolactone (1) with 33% hydrogen bromide in acetic
acid followed by chlorination with thionyl chloride.
Overnight treatment of 4 with sodium hydrogen selenide
(NaSeH) in the presence of tetrabutylammonium hydro-
gen sulfate as a phase-transfer catalyst in toluene at room
temperature under argon resulted in ring closure to afford
the teterahydroselenopyran-2-one (7) in 76% yield. Simi-
larly, other selenolactones 8, 9, 12, 15, 18 were synthe-
sized in good yields, and the tellurolactone 19 was also
obtained in 84% yield from 4 using tellurium powder in-
stead of selenium powder.
Preparation of the Starting Selenolactones and
Tellurolactone
The synthetic routes to the selenolactones and a tellurolac-
tone are shown in Scheme 1. All the selenolactones and
the tellurolactone were prepared from the commercially
available lactones via the bromocarboxylic chlorides,
according to the reported method.9 5-Bromopentanoic
SYNTHESIS 2008, No. 20, pp 3229–3236
x
x.
x
x
.
2
0
0
8
Advanced online publication: 25.09.2008
DOI: 10.1055/s-0028-1083153; Art ID: F13208SS
© Georg Thieme Verlag Stuttgart · New York

3230
H. Sashida et al.
PAPER
in high yields (entries 7, 8, and 9). These results imply that
the electron-withdrawing or -donating substituent groups
One-Pot Synthesis of Tetrahydroselenocin-4-ones
At first, the six-membered selenolactone, tetrahydrosele- on the phenyl ring do not significantly exert an influence
nopyran-2-one (7), was lithiated with 1.1 equivalents of on the ring-enlargement reaction. In addition, the treat-
phenylethynyllithium (20a) in anhydrous THF at 0 °C, ment of 7 with an alkylethynyllithium, such as 3,3-di-
followed by the addition of EtOH or appropriate acid as a methyl-1-butynyllithium (20e), and 1-hexynyllithium
proton source at room temperature to afford the desired (20f), also produced the 2-butyl-5,6,7,8-tetrahydroseleno-
two carbon ring enlargement product 21a as shown in cin-4-ones 21e,f in 78 and 54% yields, respectively (en-
Table 1. Examination of the reaction conditions revealed tries 10 and 11). Cyclohex-1-enylethynyllithium (20g)
that this ring-expansion reaction was very clean at –40 °C reacted with 7 to give the corresponding selenocin-4-one
and use of aqueous 5% H2SO4 as a proton source gave the 21g in moderate yield (entry 12). 2-Trimethylsilyl-
best results (Table 1, entry 4). This is in contrast to a re- 5,6,7,8-tetrahydroselenocin-4-one (21h) was also ob-
port that good yields were obtained in the addition of tained by the reaction of 7 with trimethylsilylethynyllithi-
EtOH as a proton source for the preparation of um (20h) (entry 13), however, desilylation of the product
isoselenochromenes10 (prepared from o-ethynylbenzyl using tetrabutylammonium fluoride in THF at 0 °C failed
bromides and NaSeH) (entry 1). THF was found to be bet- to produce the unsubstituted tetrahydroselenocin-4-one
ter than Et2O as a solvent (entry 4 vs. 6).
framework. The nature of the ethynyllthium is not very
critical for the success of the ring-expansion reaction.
Table 1 2-Substituted 5,6,7,8-Tetrahydroselenocin-4-ones Pre-
A possible mechanism for the formation of the ring ex-
panded products 21 from the selenolactones 7 is shown in
Scheme 2. The initial intermediate, 2-ethynyl-2-hydroxy-
selenacycloalkane A, probably generated by nucleophilic
attack of the ethynyllithium 20 at the carbonyl carbon of
7, followed by hydrolysis, undergoes ring opening with
migration of the hydroxyl proton to form the insoluble
alkylselenol B. The regioselective intramolecular cycliza-
tion of the resulting selenol B to a triple bond of the ynone
moiety proceeds via the Michael-type addition in the
endo-dig mode to afford the successful a,b-unsaturated
selenacycloalkanone 21. It is known that the addition of
ethynyllithium to the aldehydes or ketones at low temper-
ature provides the secondary or tertiary alcohols.11 We
have previously reported the successful regioselective
endo-dig mode cyclization of the selenol to a triple bond
of the ynone moiety to produce the selenochromones via
the Michael-type addition.12
pared
O
O
Li
R
1)
20
Se
2) proton source
R
Se
21
7
Entry R
Conditions
Yield (%)
1
2
3
4
5
6
7
8
9
a: Ph
THF, –40 °C; EtOH
THF, –40 °C; H2O
46
74
a: Ph
a: Ph
THF, –40 °C; aq sat. NH4Cl 32
THF, –40 °C; aq 5% H2SO4 95
a: Ph
a: Ph
THF, 0 °C; 5% aq H2SO4
22
a: Ph
Et2O, –40 °C; aq 5% H2SO4 32
THF, –40 °C; aq 5% H2SO4 94
THF, –40 °C; aq 5% H2SO4 86
THF, –40 °C; aq 5% H2SO4 90
THF, –40 °C; aq 5% H2SO4 78
THF, –40 °C; aq 5% H2SO4 54
b: 4-MeC6H4
c: 4-MeOC6H4
d: 4-CF3C6H4
Li
R
1)
20
21
7
2) 5% H2SO4
10 e: t-Bu
11 f: n-Bu
R
12 g: cyclohex-1-enyl THF, –40 °C; aq 5% H2SO4 57
13 h: SiMe3 THF, –40 °C; aq 5% H2SO4 43
R
H
O
O
SeH
Se
B
The results of this ring-expansion reaction of 7 with sev-
eral ethynyllithiums 20a–h are summarized in Table 1.
The reaction of tetrahydroselenopyran-2-one (7) with
phenylethynyllithium (20a), followed by the addition of
aqueous 5% H2SO4 afforded the eight-membered 2-phe-
nyl-5,6,7,8-tetrahydroselenocin-4-one (21a) in 95% yield
(entry 4). A similar reaction of 7 with 2-p-tolylethynyl-
lithium (20b), 2-(4-methoxyphenyl)ethynyllithium (20c),
and 2-(4-trifluoromethylphenyl)ethynyllithium (20d) fur-
nished the corresponding 2-arylselenocin-4-ones 21b–d
A
Scheme 2
Next, the use of this ring-expansion reaction into the six-
membered selenolactones having a methyl group at the
C-3 or C-6 position was carried out (Table 2). 6-Meth-
yltetrahydroselenopyran-2-one (12) was similarly lithiat-
ed with phenylethynyllithium (20a) in anhydrous THF at
–40 °C, followed by the addition of aqueous 5% H2SO4 to
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PAPER
Synthesis of Selenium-Containing a,b-Unsaturated Cyclic Ketones
3231
give the desired 8-methyl-2-phenylselenocin-4-one (22a) Table 2 Selenium-, Tellurium-Containing a,b-Unsaturated Cyclic
Ketones
in 82% yield (entry 1). 2-tert-Butyl 22e and 2-butylsele-
nocin-4-one 22f were also obtained by the one-pot reac-
Entry Selenolactone Product
Tellurolactone
Yield
(%)
tion of 12 and the corresponding ethynyllithium 20e or
20f in good yields (entries 2 and 3). The 8-methyl-2-tri-
metylsilyl derivative 22h was produced from the seleno-
lactone 12 and trimethylsilylethynyllithium (20h) in 32%
yield (entry 4). 3-Methylselenolactone 15, having a meth-
yl group at the a position of carbonyl group, was em-
ployed for evaluating of the influence of steric hindrance.
When 15 reacted with the phenyl- 20a, tert-butyl- 20e, n-
butyl- 20f or trimethylsilylethynyllithium (20h), not only
2-phenyl- 23a and 2-alkylselenocin-4-ons 23e,f, but also
the TMS derivative 23h were obtained in good yields (en-
tries 5–8). In our experiments, the reaction of the six-
membered selenolactones with the several substituted
alkynyllithiums efficiently gave the desired tetrahydrose-
lenocin-4-one in yields ranging from 53 to 95%, except
for the TMS derivative (Table 1, entries 4, 7–12 and
Table 2, entries 1–8). However, no products were ob-
tained by the reaction of the selenolactones 7 with a het-
eroarylethynyllithium, such as 2-thienylethynyllithium
and 2-furylethynyllithium.
O
O
1
a: R = Ph
82
62
53
32
2
3
e: R = t-Bu
f: R = n-Bu
h: R = SiMe3
Se
R
Se
4
Me
Me
12
22
Me
O
O
5
6
7
8
a: R = Ph
73
72
66
63
Me
e: R = t-Bu
f: R = n-Bu
h: R = SiMe3
Se
R
Se
15
23
O
O
9
10
11
12
a: R = Ph
35
b: R = 4-MeC6H4 33
c: R = 4-MeOC6H4 31
Se
R
e: R = t-Bu
30
Se
8
24
O
O
O
13
14
15
16
a: R = Ph
35
34
33
31
Me
e: R = t-Bu
f: R = n-Bu
h: R = SiMe3
Me
Se
R
Se
18
Selenepin-4-ones, Selenonin-4-ones, and Tellurocin-
4-one
25
26
O
17
18
a: R = Ph
14
Se
Ring expansion of the five-membered selenolactones 8
and the 3-methyl derivative 18 into the seven-membered
compounds was examined next. In this case, not only the
alkylethynyllithium, but also the arylethynyllithium react-
ed with dihydroselenophene 8 to afford the corresponding
6,7-dihydro-5H-selenepin-4-ones 24a–c,e in 30–35%
yields together with a complex mixture involving a small
amount of the Claisen-type self-condensation products (as
shown by MS, entries 9–12). When 3-methyldihydrosele-
nophene (18) was treated with phenylethynyllithium
(20a), the 5-methyl-2-phenylselenepine (25a) was formed
in one-pot in 35% yield (entry 13). The 2-alkyl and tri-
methylsilyl substituted seven-membered derivatives
25e,f,h were also produced from 18 and the corresponding
ethynyllithiums 20 in 31–34% yields as the sole product
although no other characterized products were obtained
(entries 14–16).
b: R = 4-MeC6H4 12
R
Se
O
9
O
Te
19
a: R = Ph
42
R
Te
19
27
similarly lithiated with 1.1 equivalents of ethynyllithium
20a in anhydrous THF at –40 °C, followed by the addition
of aqueous 5% H2SO4 and allowed to warm to room tem-
perature to give the desired 2-phenyl-5,6,7,8-tetrahydro-
tellurocin-4-one (27a) in 42% yield together with some
uncharacterized products. While the selenocines 21 are
stable compounds, the starting tellurolactone 19 and the
ring expansion product 27a are somewhat unstable.
Therefore, 27a was gradually decomposed during the iso-
lation or purification.
Unfortunately, the 2-aryl-6,7,8,9-tetrahydro-5H-seleno-
nin-4-ones 26 were obtained from the seven-membered
caprolactone 9 and arylethnyllithium 20a,b in low yields
(entries 17 and 18). This distinction between the six-mem-
bered selenolactones and five- or seven-membered ones
with respect to yields of the ring expansion products has
not yet been clarified. The obtained selenium-containing
products 21–26 are stable and could be stored in a refrig-
erator for more than several weeks.
In conclusion, we have shown that the ring-expansion re-
action of a selenolactone with an ethynyllithium can pro-
vide an easy entry into seven- to nine-membered
selenium-containing a,b-unsaturated carbonyl com-
pounds via one-pot from readily available selenolactones
involving the tellurium analogue.
Finally, the construction of the tellurium analogue, the tel-
lurocin-4-one framework, was successfully attempted us-
Melting points were measured on a Yanagimoto micro melting
point hot stage apparatus and are uncorrected. IR spectra were de-
ing the six-membered tellurolactone instead of the termined with a Hitachi 270-30 spectrometer. Mass spectra and
HRMS were recorded on a Jeol JMS-DX300 instrument. 1H NMR
selenolactone. The tetrahydrotelluropyran-2-one 19 was
Synthesis 2008, No. 20, 3229–3236 © Thieme Stuttgart · New York

3232
H. Sashida et al.
PAPER
spectra were determined with a Jeol PMX-60 SI (60 MHz), Jeol EX-
90A (90 MHz) or Jeol JNM-GSX 400 (400 MHz) spectrometer in
CDCl3 using TMS as an internal standard and J values are given in
Hz. 13C NMR spectra were measured on Jeol JNM-GSX 400
(100MHz) spectrometer.
ing residue was distilled under reduced pressure or recrystallized
from benzene–hexane to give the respective selenolactone.
Tetrahydroselenopyran-2-one (7)
Yield: 76%; pale yellow oil; bp 120–122 °C/30 mmHg.
Lactones 1–3, 10 and 16 are commercially available, compound 13
was prepared by the reported method.13 4-Bromobutyroyl chloride
(5) and 6-bromohexanoyl chloride (6) are also commercially avail-
able, but easily obtained in good yields by the reaction of the corre-
sponding lactones with HBr as described below.
IR (neat): 1678 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 2.0–2.2 (4 H, m, 4-H2, 5-H2), 2.54
(2 H, t, J = 6 Hz, 6-H2), 3.24 (2 H, t, J = 6 Hz, 3-H2).
EI-MS: m/z (%) = 164 (M+, 70), 162 (55), 55 (100).
EI-HRMS: m/z calcd for C5H8O80Se [M+]: 163.9740; found:
w-Bromocarboxylic chlorides; General Procedure
163.9743.
A solution of the appropriate lactone (0.25 mol) in HBr (33% in
AcOH, 250 mL) was maintained at r.t. for 2 h and then heated at 70
°C for 2 h. The mixture was evaporated and SOCl2 (150 mL) was
added to the residue. The mixture was refluxed for 3 h. Excess
SOCl2 was evaporated and the residue was distilled under reduced
pressure to give the respective carboxylic chloride.
Dihydroselenophen-2-one (8)
Yield: 77%; colorless oil; bp 93–95 °C/18 mmHg.
IR (neat): 1708 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 2.1–2.7 (4 H, m, 4-H2, 5-H2), 3.50
(2 H, t, J = 6 Hz, 3-H2).
5-Bromopentanoyl Chloride (4)
EI-MS: m/z (%) = 150 (M+, 100), 148 (47).
EI-HRMS: m/z calcd for C4H6O80Se [M+]: 149.9584; found:
Yield: 94%; colorless oil; bp 116–118 °C/33 mm Hg [Lit.14a bp
103–105 °C/20 mmHg; Lit.14b bp 102–104 °C/15 mmHg].
149.9581.
4-Bromobutyroyl Chloride (5)
Yield: 82%; colorless oil; bp 80–83 °C/18–20 mmHg.
Selenepan-2-one (9)
Yield: 76%; pale yellow prisms; mp 54–56 °C.
IR (neat): 1681 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.3–1.9 (6 H, m, 4-H2, 5-H2, 6-H2),
2.62 (2 H, t, J = 7 Hz, 7-H2), 2.88 (2 H, t, J = 7 Hz, 3-H2).
6-Bromohexanoyl Chloride (6)
Yield: 92%; colorless oil; bp 126 °C/18 mmHg.
5-Bromohexanoyl Chloride (11)
Yield: 89%; colorless oil; bp 120 °C/32 mmHg.
EI-MS: m/z (%) = 178 (M+, 100), 176 (50), 150 (60).
EI-HRMS: m/z calcd for C6H10O80Se [M+]: 177.9897; found:
177.9902.
IR (neat): 1793 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.8–2.2 (4 H, m, 3-H2, 4-H2), 1.67
(3 H, d, J = 7 Hz, 5-CH3), 2.9–3.2 (2 H, m, 2-H2), 3.9–4.4 (1 H, m,
5-H).
EI-MS: m/z (%) = 179, 177 (M+ – Cl, 74, 74), 133 (52), 97 (88), 69
(100).
EI-HRMS: m/z calcd for C6H10BrO [M+ – Cl]: 178.9895, 176.9915;
found: 178.9893, 176.9911.
6-Methyltetrahydroselenopyran-2-one (12)
Yield: 82%; pale yellow oil; bp 132 °C/38 mmHg.
IR (neat): 1678 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.50 (3 H, d, J = 8 Hz, 6-CH3), 1.5–
2.5 (5 H, m, 4-H2, 5-H2, 6-H), 3.6–4.1 (2 H, m, 3-H2).
EI-MS: m/z (%) = 178 (M+, 100), 176 (50), 115 (59).
EI-HRMS: m/z calcd for C6H10O80Se [M+]: 179.9897; found:
179.9895.
5-Bromo-2-methylpentanoyl Chloride (14)
Yield: 85%; colorless oil; bp 100–105 °C/90 mmHg.
IR (neat): 1783 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.28 (3 H, d, J = 7 Hz, 2-CH3), 1.7–
2.1 (4 H, m, 3-H2, 4-H2), 2.7–3.2 (1 H, m, 2-H), 3.3–3.6 (2 H, m,
5-H2).
3-Methyltetrahydroselenopyran-2-one (15)
Yield: 67%; yellow oil; bp 122–125 °C/23–24 mmHg.
IR (neat): 1678 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.17 (3 H, d, J = 8 Hz, 3-CH3), 1.7–
2.7 (4 H, m, 4-H2, 5-H2), 2.8–3.5 (3 H, m, 3-H, 6-H2).
EI-MS: m/z (%) = 179, 177 (M+ – Cl, 97, 100), 151 (35), 149 (37),
69 (76).
EI-MS: m/z (%) = 178 (M+, 100), 176 (50), 149 (82), 69 (88).
EI-HRMS: m/z calcd for C6H10BrO [M+ – Cl]: 178.9895, 176.9915;
EI-HRMS: m/z calcd for C6H10O80Se [M+]: 179.9897; found:
found: 178.9891, 176.9920.
177.9892.
4-Bromo-2-methylbutyroyl Chloride (17)
Yield: 85%; colorless oil; bp 107–113 °C/53 mm Hg [Lit.15 bp 128
°C/15 mmHg].
3-Methyldihydroselenophen-2-one (18)
Yield: 81%; colorless oil; bp 112–115 °C/52 mmHg.
IR (neat): 1697 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.15 (3 H, d, J = 7 Hz, 3-CH3), 1.6–
2.6 (4 H, m, 4-H2, 5-H2), 3.3–3.5 (1 H, m, 3-H).
EI-MS: m/z (%) = 164 (M+, 100), 162 (49), 55 (63).
EI-HRMS: m/z calcd for C5H8O80Se [M+]: 163.9740; found:
Selenolactones; General Procedure
The appropriate acid chloride (0.15 mol) was dissolved in anhyd
toluene (300 mL) and slowly added to a solution of NaSeH [0.15
mol, freshly prepared from Se powder (11.84 g, 0.15 mol) and
NaBH4 (11.49 g, 0.3 mol) at 0 °C in H2O (200 mL)] containing
Bu4NHSO4 (1.92 g). The mixture was vigorously stirred at r.t. for
6–12 h under argon. After washing with aq 5% NaHCO3 (100 mL)
and drying (MgSO4), the toluene was removed in vacuo. The result-
163.9736.
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PAPER
Synthesis of Selenium-Containing a,b-Unsaturated Cyclic Ketones
3233
Tetrahydrotelluropyran-2-one (19)
13C NMR (100 MHz, CDCl3): d = 23.5 (t), 28.4 (t), 28.9 (t), 38.1 (t),
55.4 (q), 113.8 (d), 128.5 (d), 129.9 (d), 133.2 (s), 152.7 (s), 161.3
(s), 205.7 (s).
EI-MS: m/z (%) = 296 (M+, 36), 294 (19), 215 (64), 132 (100).
EI-HRMS: m/z calcd for C17H14O280Se [M+]: 296.0316; found:
Acid chloride 4 (0.15 mol) was treated with NaTeH (0.15 mol), pre-
pared from Te powder and NaBH4, as described above for selenium.
Similar workup as above gave 19; yield: 84%; yellow oil; bp 115–
120 °C/25 mmHg.
IR (neat): 1702 cm–1 (C=O).
1H NMR (90 MHz, CDCl3): d = 1.7–2.6 (6 H, m, 4-H2, 5-H2, 6-H2),
3.23 (2 H, t, J = 7 Hz, 3-H2).
296.0305.
2-(4-Trifluoromethylphenyl)-5,6,7,8-tetrahydroselenocin-4-one
(21d)
EI-MS: m/z (%) = 214 (M+, 100), 212 (92), 55 (86).
EI-HRMS: m/z calcd for C5H8O130Te [M+]: 213.9638; found:
Yellow prisms (MeOH); mp 79–82 °C.
IR (KBr): 1639 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): d = 2.04–2.19 (4 H, m, 6-H2, 7-H2),
2.92–2.99, 3.03–3.09 (each 2 H, m, 5-H2, 8-H2), 6.56 (1 H, s, 3-H),
7.62, 7.67 (each 2 H, d, J = 8.9 Hz, ArH).
213.9634.
5,6,7,8-Tetrahydroselenocin-4-ones; 2-Phenyl-5,6,7,8-tetrahy-
droselenocin-4-one (21a); Typical Procedure
To a solution of 7 (2.0 mmol) in anhyd THF (6 mL) was added phe-
nylethynylithium (20; 2.2 mmol), which was freshly prepared from
phenylacetylene (224 mg) and n-BuLi (1.6 mol in pentane solution,
1.38 mL, 2.2 mmol) in anhyd THF (3 mL) at –40 °C under argon.
The mixture was stirred under these conditions for 1 h and was al-
lowed to rise to r.t. over 2–3 h with stirring. Aq 5% H2SO4 (5 mL)
was added, and the mixture was further stirred for 6–8 h. H2O (25
mL) was added, and the resulting aqueous mixture was extracted
with EtOAc (3 × 30 mL). The combined organic extracts were
washed with brine (2 × 50 mL), dried (MgSO4), and evaporated in
vacuo. The residue was chromatographed on silica gel using ben-
zene–EtOAc (10:0 to 10:1) as eluent to give 21a; yield: 554 mg
(95%); yellow needles (CH2Cl2–hexane); mp 65–66 °C (Table 1).
13C NMR (100 MHz, CDCl3): d = 23.1 (t), 28.2 (t), 29.6 (t), 39.7 (t),
123.9 (d, JC,F = 272.2 Hz), 125.5 (d), 128.4 (d), 129.8 (d), 131.5 (q,
JC,F = 32.6 Hz), 144.7 (s), 148.2 (s), 206.0 (s).
EI-MS: m/z (%) = 334 (M+, 65), 332 (31), 250 (46), 170 (100), 136
(55), 83 (75).
EI-HRMS: m/z calcd for C14H13F3O80Se [M+]: 334.0084; found:
334.0085.
2-tert-Butyl-5,6,7,8-tetrahydroselenocin-4-one (21e)
Yellow oil.
IR (neat): 1651 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 1.24 (9 H, s, t-C4H9), 1.91–2.08
(4 H, m, 6-H2, 7-H2), 2.79–3.00 (4 H, m, 4-H2, 8-H2), 6.41 (1 H, s,
3-H).
13C NMR (100 Hz, CDCl3): d = 23.7 (t), 27.1 (t), 28.9 (t), 30.0 (q),
38.2 (t), 40.1 (s), 126.7 (d), 163.8 (s), 207.9 (s).
IR (KBr): 1650 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): d = 2.01–2.14 (4 H, m, 6-H2, 7-H2),
2.94–3.04 (4 H, m, 5-H2, 8-H2), 6.56 (1 H, s, 3-H), 7.33–7.41, 7.54–
7.58 (3 H, m; 2 H, m, C6H5).
13C NMR (100 MHz, CDCl3): d = 23.2 (t), 29.3 (t), 28.2 (t), 39.1 (t),
128.1 (d), 128.5 (d), 128.7 (d), 129.8 (d), 141.1 (s), 151.0 (s), 206.1
(s).
EI-MS: m/z (%) = 246 (M+, 100), 244 (50), 136 (60), 83 (68).
EI-HRMS: m/z calcd for C11H18O80Se [M+]: 246.0523; found:
246.0516.
EI-MS: m/z (%) = 266 (M+, 57), 264 (28), 185 (30), 136 (36), 102
(100), 83 (63).
2-Butyl-5,6,7,8-tetrahydroselenocin-4-one (21f)
Yellow oil.
IR (neat): 1655 cm–1 (C=O).
EI-HRMS: m/z calcd for C13H14O80Se [M+]: 266.0210; found:
266.0215.
1H NMR (500 Hz, CDCl3): d = 0.92, 1.31–1.40, 1.54–1.61, 1.65–
1.85, 1.92–2.05, 2.31–2.39 (3 H, t, J = 7 Hz; 2 H, m; 2 H, m; 2 H,
m; 2 H, m; 2 H, t, J = 7 Hz, n-Bu and 6-H2, 7-H2), 2.80–2.95 (4 H,
m, 5-H2, 8-H2), 6.21 and 6.31 (total 1 H, intensity ratio 1:2, s, 3-H).
13C NMR (125 Hz, CDCl3): d = 13.9 (q), 22.1 (t), 23.2 (t), 26.9 (t),
29.4 (t), 31.7 (t), 39.5 (t), 41.6(t), 128.3 (d), 152.2 (s), 206.8 (s).
EI-MS: m/z (%) = 246 (M+, 65), 244 (35), 136 (100), 134 (50), 83
(64).
EI-HRMS: m/z calcd for C11H18O80Se [M+]: 246.0523; found:
2-p-Tolyl-5,6,7,8-tetrahydroselenocin-4-one (21b)
Yellow oil.
IR (neat): 1645 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): d = 1.97–2.15 (4 H, m, 6-H2, 7-H2),
2.37 (3 H, s, CH3), 2.95–3.05 (4 H, m, 5-H2, 8-H2), 6.55 (1 H, s,
3-H), 7.17, 7.48 (each 2 H, d, J = 8.1 Hz, ArH).
13C NMR (100 MHz, CDCl3): d = 21.3 (q), 23.4 (t), 28.3 (t), 29.2 (t),
38.7 (t), 128.2 (d), 129.1 (d), 129.2 (d), 138.2 (s), 140.2 (s), 151.9
(s), 206.0 (s).
246.0520.
EI-MS: m/z (%) = 280 (M+, 67), 278 (35), 199 (64), 116 (100), 115
(83), 83 (72).
2-Cyclohex-1-enyl-5,6,7,8-tetrahydroselenocin-4-one (21g)
Yellow oil.
IR (neat): 1641 cm–1 (C=O).
EI-HRMS: m/z calcd for C14H16O80Se [M+]: 280.0367; found:
280.0364.
1H NMR (500 Hz, CDCl3): d = 1.57–1.74, 2.16–2.28, 6.57 (4 H, m;
4 H, m; 1 H, t, J = 4.1 Hz, cyclohexenyl-H), 1.94–2.07 (4 H, m,
6-H2, 7-H2), 2.85 (2 H, t, J = 5.5 Hz, 8-H2), 3.00 (2 H, t, J = 6.0 Hz,
5-H2), 6.41 (1 H, s, 3-H).
13C NMR (125 Hz, CDCl3): d = 21.8 (t), 22.8 (t), 23.7 (t), 26.3 (t),
27.0 (t), 28.0 (t), 28.7 (t), 38.2 (t), 126.2 (d), 133.1 (d), 137.5 (s),
152.2 (s), 206.9 (s).
2-(4-Methoxyphenyl)-5,6,7,8-tetrahydroselenocin-4-one (21c)
Yellow oil.
IR (neat): 1644 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): d = 1.96–2.14 (4 H, m, 6-H2, 7-H2),
2.96–3.05 (4 H, m, 5-H2, 8-H2), 3.82 (3 H, s, OCH3), 6.53 (1 H, s,
3-H), 6.88, 7.56 (each 2 H, d, J = 8.5 Hz, ArH).
Synthesis 2008, No. 20, 3229–3236 © Thieme Stuttgart · New York

3234
H. Sashida et al.
PAPER
EI-MS: m/z (%) = 270 (M+, 100), 268 (50), 189 (28), 136 (38), 106
EI-HRMS: m/z calcd for C12H20O80Se [M+]: 260.0680; found:
(56), 83 (67).
260.0682.
EI-HRMS: m/z calcd for C13H18O80Se [M+]: 270.0523; found:
270.0523.
8-Methyl-2-trimethylsilyl-5,6,7,8-tetrahydroselenocin-4-one
(22h)
Yellow oil.
IR (neat): 1658 cm–1 (C=O).
2-Trimethylsilyl-5,6,7,8-tetrahydroselenocin-4-one (21h)
Pale yellow prisms (CH2Cl2–hexane); mp 166–168 °C.
IR (neat): 1662 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 0.20 [9 H, s, Si(CH3)3], 1.38 (3 H, d,
J = 7.0 Hz, 8-CH3), 1.75–2.00, 2.21–2.23 (3 H, m, 1 H, m, 6-H2,
7-H2), 2.61 (1 H, ddd, J = 14.4, 11.8, 2.6 Hz, 8-H), 2.87–2.95, 3.20–
3.30 (1 H, m; 1 H, m, 5-H2), 6.68 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = –1.51 (q), 23.4 (t), 23.6 (q), 38.5
(d), 38.9 (t), 42.0 (t), 135.8 (d), 149.4 (s), 208.6 (s).
EI-MS: m/z (%) = 276 (M+, 93), 274 (45), 264 (56), 73 (100), 69
(41).
EI-HRMS: m/z calcd for C11H20OSi80Se [M+]: 276.0449; found:
276.0451.
1H NMR (400 Hz, CDCl3): d = 0.26 [9 H, s, Si(CH3)3], 1.78–1.82 (4
H, m, 6-H2, 7-H2), 2.42 (2 H, t, J = 6.6 Hz, 8-H2), 2.85 (2 H, t,
J = 6.8 Hz, 5-H2), 6.66 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = –0.59 (q), 24.4 (t), 25.8 (t), 30.0 (t),
42.8 (t), 129.5 (d), 167.1 (s), 195.2 (s).
EI-MS: m/z (%) = 262 (M+, 83), 260 (42), 136 (67), 83 (100), 73
(93).
EI-HRMS: m/z calcd for C10H18OSi80Se [M+]: 262.0292; found:
262.0290.
5-Methyl-2-phenyl-5,6,7,8-tetrahydroselenocin-4-one (23a)
Yellow prisms (CH2Cl2–hexane); mp 77–79 °C.
IR (neat): 1641 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 1.18 (3 H, d, J = 6.9 Hz, 5-CH3),
1.86–2.20 (4 H, m, 6-H2, 7-H2), 2.82–2.90, 3.07–3.17 (1 H, m; 1 H,
m, 8-H2), 3.34–3.43 (1 H, m, 5-H), 6.53 (1 H, s, 3-H), 7.35–7.40,
7.50–7.58 (3 H, m; 2 H, m, C6H5).
13C NMR (100 Hz, CDCl3): d = 18.8 (q), 26.9 (t), 28.5 (t), 31.3 (t),
44.5 (d), 127.66 (d), 127.69 (d), 127.7 (d), 129.4 (d), 141.3 (s),
146.8 (s), 209.8 (s).
8-Methyl-2-phenyl-5,6,7,8-tetrahydroselenocin-4-one (22a)
Yellow prisms (CH2Cl2–hexane); mp 76–78 °C.
IR (neat): 1630 cm–1 (C=O).
1H NMR (500 Hz, CDCl3): d = 1.54 (3 H, d, J = 7.1 Hz, 8-CH3),
1.86–2.08, 2.20–2.31 (3 H, m; 1 H, m, 6-H2, 7-H2), 2.81–2.89 (1 H,
m, 8-H), 3.07–3.15, 3.34–3.43 (each 1 H, m, 5-H2), 6.63 (1 H, s,
3-H), 7.33–7.42, 7.55–7.61 (3 H, m; 2 H, m, C6H5).
13C NMR (125 Hz, CDCl3): d = 23.7 (t), 24.6 (q), 37.3 (t), 40.0 (t),
40.4 (d), 128.3 (d), 128.4 (d), 129.7 (d), 130.6 (d), 141.6 (s), 149.5
(s), 205.4 (s).
EI-MS: m/z (%) = 276 (M+, 94), 278 (51), 150 (71), 102 (100).
EI-HRMS: m/z calcd for C14H16O80Se [M+]: 280.0367; found:
EI-MS: m/z (%) = 280 (M+, 94), 278 (51), 199 (77), 182 (61), 102
(100).
280.0366.
EI-HRMS: m/z calcd for C14H16O80Se [M+]: 280.0367; found:
280.0360.
2-tert-Butyl-5-methyl-5,6,7,8-tetrahydroselenocin-4-one (23e)
Yellow oil.
IR (neat): 1660 cm–1 (C=O).
2-tert-Butyl-8-methyl-5,6,7,8-tetrahydroselenocin-4-one (22e)
Yellow oil.
IR (neat): 1647 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 1.11, 1.12 (total 3 H, intensity ratio
7:3, d, J = 6.9 Hz, 5-CH3), 1.24 (9 H, s, t-C4H9), 1.74–2.10 (4 H, m,
6-H2, 7-H2), 2.56–2.66, 2.94–3.04 (1 H, m; 1 H, m, 8-H2), 3.28–
3.36, 3.56–3.65 (total 1 H, intensity ratio 3:7, m, 5-H), 6.07, 6.39
(total 1 H, intensity ratio 3:7, m, 3-H).
13C NMR (100 Hz, CDCl3): d = 18.9 and 19.1 (q), 25.8 (t), 28.3 and
28.3 (t), 31.3 and 32.5 (t), 29.9 and 30.1 (q), 39.6 and 40.2 (s), 42.9
and 44.8 (d), 121.7 and 125.6 (d), 159.8 (s), 211.3 and 211.4 (s).
EI-MS: m/z (%) = 260 (M+, 47), 258 (23), 150 (100), 148 (51), 97
(48), 69 (75).
EI-HRMS: m/z calcd for C12H20O80Se [M+]: 260.0680; found:
260.0677.
1H NMR (400 Hz, CDCl3): d = 1.24 (9 H, s, t-C4H9), 1.44 (3 H, d,
J = 7.1 Hz, 8-CH3), 1.78–1.97, 2.04–2.14 (3 H, m; 1 H, m, 6-H2,
7-H2), 2.68–2.77 (1 H, m, 8-H), 2.96–3.06, 3.33–3.38 (each 1 H, m,
5-H2), 6.47 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = 23.9 (t), 25.1 (q), 30.0 (q), 36.7 (t),
38.4 (t), 39.7 (d), 40.3 (s), 128.3 (d), 162.5 (s), 207.2 (s).
EI-MS: m/z (%) = 260 (M+, 100), 258 (49), 217 (38), 97 (39), 69
(49).
EI-HRMS: m/z calcd for C12H20O80Se [M+]: 260.0680; found:
260.0671.
2-Butyl-8-methyl-5,6,7,8-tetrahydroselenocin-4-one (22f)
Yellow oil.
IR (neat): 1651 cm–1 (C=O).
2-Butyl-5-methyl-5,6,7,8-tetrahydroselenocin-4-one (23f)
Yellow oil.
IR (neat): 1666 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 0.92, 1.30–1.41, 1.54–1.63, 1.77–
1.90, 1.90–2.00, 2.13–2.24, 2.36–2.46 (3 H, t, J = 7.1 Hz; 2 H, m; 2
H, m; 2 H, m; 1 H, m; 1 H, m; 2 H, m, n-Bu, 6-H2, 7-H2), 1.44 (3 H,
d, J = 7.1 Hz, 8-CH3), 2.78 (1 H, ddd, J = 13.6, 10.8, 2.9 Hz, 8-H),
3.01–3.08, 3.14–3.21 (each 1 H, m, 5-H2), 6.37 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = 13.8 (q), 22.0 (t), 23.5 (t), 24.2 (q),
31.4 (t), 31.6 (t), 39.1 (d), 39.9 (t), 42.3 (t), 130.1 (d), 151.0 (s),
206.0 (s).
1H NMR (400 Hz, CDCl3): d = 0.93, 1.31–1.42, 1.52–1.62, 2.30–
2.42 (3 H, t, J = 7.3 Hz; 2 H, m; 2 H, m; 2 H, m, n-Bu), 1.11 (3 H,
d, J = 6.9 Hz, 5-CH3), 1.81–2.04 (4 H, m, 6-H2, 7-H2), 2.68–2.78,
2.90–2.99 (each 1 H, m, 8-H2), 3.24–3.33 (1 H, m, 5-H), 6.29 (1 H,
s, 3-H).
13C NMR (100 Hz, CDCl3): d = 13.6 (q), 18.3 (q), 21.8 (t), 25.4 (t),
28.1 (t), 31.1 (t), 31.5 (t), 41.0 (t), 44.3 (d), 126.6 (d), 147.7 (s),
209.8 (s).
EI-MS: m/z (%) = 260 (M+, 100), 258 (50), 179 (61), 137 (82), 69
(60).
EI-MS: m/z (%) = 260 (M+, 100), 258 (56), 150 (83), 148 (44).
Synthesis 2008, No. 20, 3229–3236 © Thieme Stuttgart · New York

PAPER
Synthesis of Selenium-Containing a,b-Unsaturated Cyclic Ketones
3235
EI-HRMS: m/z calcd for C12H20O80Se [M+]: 260.0680; found:
EI-HRMS: m/z calcd for C10H16OSe [M+]: 232.0366; found:
260.0687.
232.0361.
5-Methyl-2-trimethylsilyl-5,6,7,8-tetrahydroselenocin-4-one
(23h)
5-Methyl-2-phenyl-6,7-dihydro-5H-selenepin-4-one (25a)
Yellow prisms; mp 86–90 °C (CH2Cl2–hexane).
Yellow prisms; (from CH2Cl2–hexane); mp 48–52 °C.
IR (KBr): 1670 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 0.22 [9 H, s, Si(CH3)3], 1.44 (3 H,
dd, J = 6.9, 2.5 Hz, 5-CH3), 1.90–2.02, 2.02–2.12 (3 H, m; 1 H, m;
6-H2, 7-H2), 2.72–2.80, 2.92–3.01 (each 1 H, m, 8-H2), 3.01–3.09 (1
H, m, 5-H), 6.65 (1 H, s, 3-H).
IR (KBr): 1633 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 1.21 (3 H, d, J = 6.5 Hz, 5-CH3),
2.05–2.13, 2.24–2.33 (each 1 H, m, 6-H2), 2.93, 3.15 (each 1 H, ddd,
J = 14.1, 14.1, 5.6 Hz; J = 14.1, 5.6, 0.9 Hz, 7-H2), 3.50–3.57 (1 H,
m, 5-H), 6.62 (1 H, s, 3-H), 7.33–7.41, 7.58–7.60 (3 H, m, 2 H,
C6H5).
13C NMR (100 Hz, CDCl3): d = –1.38 (q), 18.0 (q), 25.2 (t), 28.8 (t),
13C NMR (100 Hz, CDCl3) d = 15.4 (q), 31.1 (t), 40.4 (t), 44.4 (d),
127.9 (d), 128.6 (d), 130.1 (d), 130.2 (d), 140.4 (s), 159.9 (s), 204.3
(s).
30.7 (t), 46.1 (d), 133.9 (d), 146.7 (s), 213.0(s).
EI-MS: m/z (%) = 276 (M+, 78), 274 (40), 150 (100), 148 (50), 73
(50).
EI-MS: m/z (%) = 266 (M+, 100), 264 (50), 238 (89), 210 (80), 182
(94), 102 (72).
EI-HRMS: m/z calcd for C11H20O80SeSi [M+]: 276.0449; found:
276.0448.
EI-HRMS: m/z calcd for C13H14OSe [M+]: 266.0210; found:
266.0207.
2-Phenyl-6,7-dihydro-5H-selenepin-4-one (24a)
Colorless prisms; mp 90–93 °C (MeOH).
2-tert-Butyl-5-methyl-6,7-dihydro-5H-selenepin-4-one (25e)
Yellow prisms; mp 54–57 °C (CH2Cl2–hexane).
IR (KBr): 1639 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 1.16 (3 H, d, J = 6.5 Hz, 5-CH3),
1.25 (9 H, s, t-C4H9), 1.88–2.00, 2.10–2.25 (each 1 H, m, 6-H2),
2.61, 3.04 (each 1 H, ddd, J = 14.1, 14.1, 5.6 Hz; J = 13.2, 6.4, 0.7
Hz, 7-H2), 3.39–3.50 (1 H, m, 5-H), 6.45 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = 15.3 (q), 30.0 (t), 30.2 (q), 39.5 (t),
40.4 (s), 44.2 (d), 128.2 (d), 173.7 (s), 205.7 (s).
EI-MS: m/z (%) = 246 (M+, 100), 244 (56), 189 (65).
EI-HRMS: m/z calcd for C11H18OSe [M+]: 246.0523; found:
IR (KBr): 1620 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 2.33–2.40 (2 H, m, 6-H2), 3.00 (2 H,
t, J = 6.6 Hz, 7-H2), 3.12 (2 H, t, J = 6.6 Hz, 5-H2), 6.62 (1 H, s,
3-H), 7.35–7.43, 7.58–7.61 (3 H, m; 2 H, m, C6H5).
13C NMR (100 Hz, CDCl3): d = 31.1 (t), 32.1 (t), 41.7 (t), 128.0 (d),
128.6 (d), 130.3 (d), 130.6 (d), 140.4 (s), 202.2 (s).
EI-MS: m/z (%) = 252 (M+, 100), 250 (48), 182 (53), 102 (79).
EI-HRMS: m/z calcd for C12H12OSe [M+]: 252.0054; found
252.0054.
2-p-Tolyl-6,7-dihydro-5H-selenepin-4-one (24b)
246.0521.
Yellow oil.
2-Butyl-5-methyl-6,7-dihydro-5H-selenepin-4-one (25f)
Yellow oil.
IR (neat): 1639 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 0.92, 1.29–1.40, 1.52–1.62, 2.42–
2.55 (3 H, t, J = 7.3 Hz; 2 H, m; 2 H, m; 2 H, m, n-Bu), 1.15 (3 H,
d, J = 6.5 Hz, 5-CH3), 1.92–2.02, 2.12–2.24 (each 1 H, m, 6-H2),
2.71, 3.04 (each 1 H, ddd, J = 14.1, 14.0, 5.7 Hz; J = 13.2, 6.3, 0.9
Hz, 7-H2), 3.33–3.44 (1 H, m, 5-H), 6.36 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = 13.8 (q), 15.4 (q), 22.1 (t), 30.4 (t),
31.7 (t), 39.5 (t), 41.3 (t), 44.4 (d), 130.8 (d), 162.8 (s), 204.9 (s).
IR (neat): 1645 cm–1 (C=O).
1H NMR (90 Hz, CDCl3): d = 2.2–3.0 (4 H, m, 6-H2, 7-H2), 2.37 (3
H, s, CH3), 3.3–3.5 (2 H, m, 5-H2), 6.60 (1 H, s, 3-H), 7.18, 7.50
(each 2 H, d, J = 8 Hz, ArH).
EI-MS: m/z (%) = 266 (M+, 77), 264 (38), 196 (97), 194 (45), 185
(48), 114 (98), 115 (100).
EI-HRMS: m/z calcd for C13H14OSe [M+]: 266.0210; found:
266.0203.
2-(4-Methoxyphenyl)-6,7-dihydro-5H-selenepin-4-one (24c)
Yellow oil.
EI-MS: m/z (%) = 246 (M+, 100), 244 (50), 162 (93), 148 (61), 84
(67).
IR (neat): 1650 cm–1 (C=O).
EI-HRMS: m/z calcd for C11H18OSe [M+]: 246.0523; found:
246.0520.
1H NMR (90 Hz, CDCl3): d = 2.2–3.0 (4 H, m, 6-H2, 7-H2), 3.84 (3
H, s, OCH3), 3.2–3.6 (2 H, m, 5-H2), 6.57 (1 H, s, 3-H), 6.90, 7.58
(each 2 H, d, J = 9 Hz, ArH).
EI-MS: m/z (%) = 282 (M+, 65), 280 (31), 201 (29), 132 (100), 87
(77).
EI-HRMS: m/z calcd for C13H14O2Se [M+]: 282.0159; found:
282.0159.
5-Methyl-2-trimethylsilyl-6,7-dihydro-5H-selenepin-4-one
(25h)
Yellow oil.
IR (neat): 1660 cm–1 (C=O).
1H NMR 400 Hz, CDCl3): d = 0.26 [9 H, s, Si(CH3)3], 1.20 (3 H, d,
J = 6.5 Hz, 5-CH3), 2.00–2.04, 2.18–2.30 (each 1 H, m, 6-H2), 2.65,
3.10 (each 1 H, ddd, J = 13.7, 13.7, 5.7 Hz; J = 13.1, 6.3, 1.3 Hz,
7-H2), 3.35–3.45 (1 H, m, 5-H), 6.82 (1 H, s, 3-H).
13C NMR (100 Hz, CDCl3): d = –1.59 (q), 15.4 (q), 30.9 (t), 40.2 (t),
44.6 (d), 138.3 (d), 162.4 (s), 205.1 (s).
2-tert-Butyl-6,7-dihydro-5H-selenepin-4-one (24e)
Yellow oil.
IR (neat): 1652 cm–1 (C=O).
1H NMR (90 Hz, CDCl3): d = 1.26 (9 H, s, t-C4H9), 2.20–2.51 (2 H,
m, 6-H2), 2.89 (2 H, t, J = 7.0 Hz, 7-H2), 2.91 (2 H, t, J = 7.0 Hz,
5-H2), 6.46 (1 H, s, 3-H).
EI-MS: m/z (%) = 262 (M+, 89), 260 (45), 83 (41), 73 (100).
EI-HRMS: m/z calcd for C10H18OSiSe [M+]: 262.0292; found:
EI-MS: m/z (%) = 232 (M+, 100), 230 (49), 175 (66).
262.0295.
Synthesis 2008, No. 20, 3229–3236 © Thieme Stuttgart · New York

3236
H. Sashida et al.
PAPER
2-Phenyl-6,7,8,9-tetrahydro-5H-selenonin-4-one (26a)
Yellow oil.
IR (KBr): 1665 cm–1 (C=O).
ty (2007). The authors wish to express to Mrs. A. Nozyo, T. Koh-
mura and Miss M. Ohtake (Hokuriku University) for their technical
support.
1H NMR (90 Hz, CDCl3): d = 1.3–2.2 (8 H, m, 6-H2, 7-H2, 8-H2,
9-H2), 2.6–3.1 (2 H, m, 5-H2), 6.63 (1 H, s, 3-H), 7.1-7.6 (5 H, m,
C6H5).
EI-MS: m/z (%) = 280 (M+, 85), 278 (42), 237 (66), 231 (61), 102
(95), 97 (100), 69 (70).
EI-HRMS: m/z calcd for C14H16OSe [M+]: 280.0367; found:
280.0370.
References
(1) This paper constitutes Part 26 in the ‘Studies on Tellurium-
Containing Heterocycles’. For Part 25, see: Ohyanagi, K.;
Sashida, H. Heterocycles 2006, 68, 505.
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(d) Organoselenium Chemistry, A Practical Approach;
Back, T. G., Ed.; Oxford University Press: Oxford, 1999.
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Weinheim, 1991.
2-p-Tolyl-6,7,8,9-tetrahydro-5H-selenonin-4-one (26b)
Yellow oil.
IR (KBr): 1664 cm–1 (C=O).
1H NMR (90 Hz, CDCl3): d = 1.3–2.2 (8 H, m, 6-H2, 7-H2, 8-H2,
9-H2), 2.30 (3 H, s, CH3), 2.8–3.2 (2 H, m, 5-H2), 6.58 (1 H, s, 3-H),
7.0–7.5 (4 H, m, ArH).
EI-MS: m/z (%) = 294 (M+, 85), 292 (42), 251 (50), 213 (50), 115
(100), 97 (51).
EI-HRMS: m/z calcd for C15H18OSe [M+]: 294.0523; found:
294.0521.
(5) Sashida, H.; Kurahashi, H.; Tsuchiya, T. J. Chem. Soc.,
Chem. Commun. 1991, 802.
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2-Phenyl-5,6,7,8-tetrahydrotellurocin-4-one (27a)
Red needles (CH2Cl2–hexane); mp 66–68 °C.
IR (KBr): 1610 cm–1 (C=O).
1H NMR (400 Hz, CDCl3): d = 2.02–2.12, 2.24–2.34 (each 2 H, m,
6-H2, 7-H2), 2.85–3.10 (4 H, m, 5-H2, 8-H2), 6.79 (1 H, s, 3-H),
7.30–7.38, 7.44–7.52 (3 H, m, 2 H, m, C6H5).
13C NMR (100 Hz, CDCl3): d = 8.1 (t), 24.4 (t), 29.5 (t), 37.6 (t),
127.7 (d), 128.5 (d), 129.2 (d), 135.6 (d), 136.5 (s), 143.8 (s), 206.1
(s).
EI-MS: m/z (%) = 316 (M+, 90), 314 (82), 312 (51), 185 (71), 102
(100), 55 (55).
EI-HRMS: m/z calcd for C13H14OTe [M+]: 316.0107; found:
316.0105.
(11) Blum, A.; Hess, W.; Studer, A. Synthesis 2004, 226.
(12) Sashida, H. Synthesis 1998, 745.
(13) Oikawa, M.; Oikawa, H.; Ichihara, A. Tetrahedron 1995, 51,
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(b) Marchant, R.; Wickeert, J. W.; Marvel, C. S. J. Am.
Chem. Soc. 1927, 49, 1828.
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Chem. Abstr. 1928, 22, 3227.
Acknowledgment
This work was supported in part by a Grant-in Aid for Scientific Re-
search from The Ministry of Education, Science and Culture, Japan
(19590022), and the Specific Research Fund of Hokuriku Universi-
Synthesis 2008, No. 20, 3229–3236 © Thieme Stuttgart · New York