Reaction of seleno- or thiofenchone with propiolic acid: Wagner-meerwein rearrangement

Article abstract of DOI:10.1002/hc.21181

A reaction of selenofenchone with propiolic acid in refluxing chloroform produced 1,3-oxaselenin-6-one, which further reacted with acid to afford the ring-opened product. A reaction of 1,3-oxathiin-6-one prepared from thiofenchone with trifluoroacetic acid gave a Wagner-Meerwein rearranged product. In the presence of AlCl3, thiofenchone reacted with methyl propiolate to afford the corresponding rearranged ester.

Full text of DOI:10.1002/hc.21181

Heteroatom Chemistry
Volume 25, Number 6, 2014
Reaction of Seleno- or Thiofenchone with
Propiolic Acid: Wagner–Meerwein
Rearrangement
Kentaro Okuma, Hiroyuki Matsui, and Yuichi Mori
Department of Chemistry, Fukuoka University, Jonan-Ku, Fukuoka 814-0180, Japan
Received 26 February 2014; revised 28 April 2014
action of thiofenchone 1 or thiocamphor 2 with
ABSTRACT: A reaction of selenofenchone with pro-
piolic acid in refluxing chloroform produced 1,3-
oxaselenin-6-one, which further reacted with acid to
afford the ring-opened product. A reaction of 1,3-
oxathiin-6-one prepared from thiofenchone with tri-
fluoroacetic acid gave a Wagner–Meerwein rearranged
product. In the presence of AlCl3, thiofenchone re-
acted with methyl propiolate to afford the corre-
propiolic acid gave the corresponding 1,3-oxathiin-
6-ones (exo-5, exo-6), the reactivity of these com-
pounds was still remained unclear [4]. These results
prompted us to investigate the possibility of the for-
mation of Wagner–Meerwein rearranged products
in the reaction of thio- and selenofenchone with pro-
piolate or the reaction of 1,3-oxathiin-6-ones (5, 6)
with acid. Herein, we report the full details of the
Wagner–Meerwein rearrangement in the reaction of
selone 3 and thiones 1 and 2 with propiolic acid
derivatives (see Fig. 1).
ꢀC
sponding rearranged ester.
2014 Wiley Periodi-
cals, Inc. Heteroatom Chem. 25:578–583, 2014; View
this article online at wileyonlinelibrary.com. DOI
10.1002/hc.21181
RESULTS AND DISCUSSION
We first tried the reaction of selenofenchone 3
with propiolic acid (Scheme 1). A treatment of se-
lenofenchone 3 with propiolic acid (2 equiv) in re-
fluxing chloroform gave 1,3-oxaselenin-6-one 4 and
Wagner–Meerwein rearranged product 7 in 45% and
13% yields, respectively (Table 1, entry 1). When
equivalent amount of propiolic acid was used, oxase-
lenin 4 was obtained in 35% yield, while the reaction
proceeded very slowly (entry 2). When the reaction
was carried out in refluxing toluene, compound 4
was obtained in 42% along with 7 (15%). No reaction
proceeded in a polar protic solvent such as MeOH or
MeCN (entry 4). Finally, rearranged product 7 was
obtained in high yield without any solvent (entry 5).
The structures of 4 and Z-7 were determined by
their spectroscopic analysis. The interesting feature
INTRODUCTION
The Wagner–Meerwein rearrangement is a popu-
lar acid-catalyzed reaction, in which 2-methylene-
1-borneols were synthesized from camphor or fen-
chone. The obtained norbornane-type alcohols are
useful starting materials or intermediates for chiral
auxiliaries and natural products [1]. The reaction
of thiofenchone (1) or thiocamphor (2) with alka-
nesulfenyl halide afforded Wagner–Meerwein rear-
ranged sulfides [2]. We have communicated the re-
action of selenofenchone (3) with propiolic acid,
which gave 1,3-oxaselenin-6-one (4) and Wagner–
Meerwein rearranged product [3]. Although the re-
1
Correspondence to: Kentaro Okuma; e-mail: kokuma@
fukuoka-u.ac.jp.
of 4 in its H NMR spectrum was olefinic protons
at 6.32 (doublet; J = 11 Hz) and 7.82 ppm (doublet;
J = 11 Hz), which show the existence of a vicinal
Z-alkene. Compound 7 shows four olefinic protons
Dedicated to Professor Renji Okazaki on the occasion of his
77th birthday.
ꢀC
2014 Wiley Periodicals, Inc.
578

Reaction of Seleno- or Thiofenchone with Propiolic Acid: Wagner–Meerwein Rearrangement 579
H
H
C
C
O
3
+
O
C
C
CHCl3
reflux
Se
CO2H
CO2H
O
4
O
X
X
1: X=S
4: X= Se
3: X= Se
5: X= S
H
Z-7
H
C
Se
CO2H
CO2H
Se
C
SCHEME 2 Reaction mechanism of selone 3 with propiolic
acid.
CO2H
O
S
O
S
2
CO2H
C
6
FIGURE 1 Reaction of thiones with propiolic acid.
C
CO2H
H
C
8
O
+
S
O
CO2H
MeCN
reflux
S
O
S
C
1
CO2H
O
CO2H
O
exo-9
endo-9
+
O
Se
CO2H
Se
Se
SCHEME 3 Synthesis of 1,3-oxathiin-6-one 9.
Z-7
4
3
SCHEME 1 Reaction of selone 3 with propiolic acid.
fluxing chloroform for 14 h gave almost recovery
of starting thione 1. When acid 8 was treated with
thiofenchone 1 in refluxing acetonitrile, a mixture of
exo- and endo-1,3-oxathiin-6-ones 9 (exo:endo = 5:1)
was obtained in 83% yield (Scheme 3). The struc-
tures of exo- and endo-9 were determined by anal-
ogy of the reaction of 1 with propiolic acid, which
gave exo-5 exclusively. The reaction of thiocamphor
2 with acid 8 was also tried, while an unidentified
complex mixture was formed.
We then tried the reaction of exo-1,3-oxathiin-
6-one 5 with acid whether the corresponding rear-
ranged product would be formed (Scheme 4). When
a CH2Cl2 solution of exo-5 was treated with triflu-
oroacetic acid (0.5 equiv) at room temperature, no
reaction occurred (Table 2, entry 1). However, when
the reaction was carried out in refluxing chloroform,
a Wagner–Meerwein rearranged product 10 (E: Z =
1:1) was obtained in 66% yield (entry 2). Similarly,
the reaction of 5 with AlCl3 in refluxing chloroform
TABLE 1 Reaction of Selenofenchone 3 with Propiolic Acid
Propiolic
Acid
Temperature Time
Yield
(%) 7
Entry (equiv) Solvent
(°C)
(h)
4
1
2
3
4
5
2
1
2
2
2
CHCl3
CHCl3
Toluene
MeOH
None
Reflux
Reflux
Reflux
Reflux
60
24 45
90 35
36 42
13
8
15
0
24
10
0
0
95
at 4.94, 5.03, 6.35 (doublet; J = 10 Hz), and 7.82
ppm (doublet; J = 10 Hz), indicating that one of three
methyl protons of 3 converted to exo-methylene pro-
tons and the structure has a vicinal Z-alkene. The
treatment of isolated 1,3-oxaselenin-6-one 4 with tri-
fluoroacetic acid (1 equiv) resulted in the formation
of rearranged product Z-7 in 72% yield. Although
trace amount of E-7 was found in the reaction mix-
ture, the reaction initially formed cycloadduct 4
predominantly, which rearranged via the Wagner–
Meerwein manner to give the rearranged product
Z-7 (Scheme 2).
Since 1,3-oxathiin-6-ones 5 and 6 were synthe-
sized by the reaction of thiofenchone 1 or thio-
camphor 2 with propiolic acid [4], the reaction of
1 with acetylenedicarboxylic acid (8) was carried
out. The reaction of thione 1 with acid 8 in re-
CF3CO2H
or AlCl3
+
O
O
CO2H
S
S
S
CO2H
5
Z-10
E-10
SCHEME 4 Reaction of exo-5 with acids.
Heteroatom Chemistry DOI 10.1002/hc

580 Okuma, Matsui, and Mori
TABLE 2 Reaction of Oxathiin-6-ones 5 with Acid or Lewis Acid.
Product 10 Yield
(%) (E:Z)
Entry
Acid
Solvent
Temperature (°C)
Time (h)
1
2
3
4
CF3COOH
CF3COOH
AlCl3
CH2Cl2
CHCl3
CHCl3
MeOH
Room temperature
Reflux
14
6
6
0
66 (1:1)
74 (1:1)
Reflux
Reflux
a
H2SO4
6
–
aFenchone was obtained in 62% yield.
CF3CO2H
H
CF3CO2H
MeOH
O
5
6
O
O
S
CO2Me
S
OH
S
CF3COO
CF3COO
11 (E:Z = 1:3)
SCHEME 7 Reaction of 6 with trifluoroacetic acid.
OH
E- and Z-10
S
OH
The treatment of adduct 6 with trifluoroacetic
acid (1 equiv) in refluxing MeOH for 5 h resulted
in the formation of α-hydrogen abstracted product
Z-11 in 54% yield (Scheme 7). Additional heating of
this solution for 24 h resulted in a complex mix-
ture of unidentified products, suggesting that not
only Wagner–Meerwein product 12 but also methyl
migration products (Nametkin rearrangement) were
formed under these conditions. Actually, Martinez
et al. showed the Nametkin rearrangement in the
reaction of camphor with triflic anhydride in the
presence of MeCN [5]. This result was quite dif-
ferent from that of thiofenchone adduct 5. Proba-
bly, α-hydrogen abstraction might be easier than the
Wagner–Meerwein rearrangement.
Since 1,3-oxaselenin-6-one 4 and oxathiin-6-one
5 rearranged via the Wagner–Meerwein manner by
using acid or Lewis acid, we finally tried the reac-
tion of thiofenchone 1 or thiocamphor 2 with methyl
propiolate in the presence of AlCl3 whether the cor-
responding Wagner–Meerwein rearranged products
would be formed. The treatment of thiofenchone 1
with methyl propiolate in the presence of AlCl3 (1
equiv) in refluxing chloroform resulted in the for-
mation of rearranged product (13) (1:1 mixture of
E- and Z-isomers) in 65% yield, whereas thiocam-
phor 2 reacted with methyl propiolate in the pres-
ence of AlCl3 to afford the proton-abstracted adduct
11 (1:1 mixture of E- and Z-isomers) in 75% yield
(Scheme 8). When concentrated H2SO4 was used as
an acid in CD3CN, no rearranged products but fen-
chone and camphor were formed exclusively. The
present results are quite different from those ob-
tained in the reaction of sterically congested selones
CF3COO
SCHEME 5 Wagner–Meerwein rearrangement of 5.
O
O
CO2Me
S
S
6
11
Route a
H
MeOH
W. M.
OMe
C
rearrangement
O
CO2Me
Route b
S
S
12
SCHEME 6 Probable reaction mechanism.
afforded a mixture of Z- and E-10 in 74% yield (entry
3). However, when 5 was treated with concentrated
H2SO4 in refluxing methanol for 8 h, fenchone was
formed (entry 4).
Presumably, initially formed carbocation rear-
ranged to give Z-form, which equilibrated by acid
or AlCl3 to afford a mixture of Z- and E-form
(Scheme 5).
In the reaction of thiocamphor-propiolic acid
adduct 6 with acid, two pathways are possible: One
is α-hydrogen abstraction (Scheme 6, route a), and
the other is the route via the Wagner Meerwein re-
arrangement (route b).
Heteroatom Chemistry DOI 10.1002/hc

Reaction of Seleno- or Thiofenchone with Propiolic Acid: Wagner–Meerwein Rearrangement 581
and rearranged product 7 (74 mg, 0.26 mmol). Com-
pound 4: yellow plates: mp 134.5–135.8°C. 1H NMR
(CDCl3) δ = 1.22 (s, 6H, 2 Me), 1.29 (s, 3H, Me), 1.20–
H
C
AlCl3
+
C
CO2Me
CHCl3
reflux
S
1.66 (m, 5H, CH2), 1.77 (br, 1H, CH), 2.20 (br d, 1H,
J = 11 Hz, CHH), 6.32 (d, 1H, J = 10 Hz, = CH),
7.82 (d, 1H, J = 10 Hz, = CH). 13C NMR (CDCl3)
δ = 19.00 (Me), 25.27 (CH2), 28.45 (Me), 29.69 (Me),
32.04 (CH2), 40.32 (CH2), 49.73 (CH), 51.79 (q-C),
55.76 (q-C), 106.46 (q-C), 118.20 ( CH), 140.20 ( C),
164.12 (C O). IR: νC O = 1687 cm−1. Anal. Calcd for
C13H18O2Se: C; 54.74; H, 6.36. Found: C, 54.53; H,
6.28. Compound 7: yellow plates: mp 156–158oC; 1H
NMR (CDCl3) δ = 0.93 (s, 3H, Me), 1.12 (s, 3H, Me),
1.35–1.39 (m, 1H, CHH), 1.70–1.75 (m, 1H, CHH),
1.85–1.97 (m, 2H, CH, and CHH), 2.00–2.12 (m, 2H,
CHH), 2.56 (br d, 1H, J = 16 Hz, CHH), 4.94 (dd, 1H,
J = 1 and 2 Hz, CH2), 5.03 (dd, 1H, J = 1 and 2 Hz,
CH2), 6.35 (d, 1H, J = 10 Hz, CH2) 7.82 (d, 1H,
J = 10 Hz, CH). 13C NMR (CDCl3) δ = 20.16 (Me),
20.97 (Me), 28.62 (CH2), 35.51 (CH2), 37.36 (CH2),
43.79 (CH), 50.70 (q-C), 63.08 (q-C, JSe-C = 43 Hz),
S
CO2Me
1
13 (E:Z = 1:1)
H
C
AlCl3
+
CO2Me
CHCl3
reflux
C
S
S
CO2Me
2
11 (E:Z = 1:1)
SCHEME 8 Reaction of 1 or 2 with methyl propiolate.
with benzyne, which gave methyl-migrated products
along with [2+2] cycloadducts [6].
In summary, we have synthesized Wagner–
Meerwein rearranged products by reacting se-
lenofenchone 3, thiofenchone 1, or thiocamphor 2
with propiolic acid derivatives. Previously, many
workers reported the enantioselective reduction,
substitution, epoxidation, and protonation by using
camphor-derived hydroxyl sulfides [1,7]. The present
reaction provides a new access to another type of
chiral auxiliary bicyclic sulfides.
107.33 ( CH2), 116.11 ( CH), 149.84 ( CH, JSe-C
=
80 Hz), 154.08 ( C), 172.49 (C O). Anal. Calcd for
C13H18O2Se: C; 54.74; H, 6.36. Found: C, 55.04; H,
6.41.
Reaction of 1,3-Oxaselenin-6-one 4 with Triflu-
oroacetic Acid. To a solution of 4 (143 mg, 0.50
mmol) in chloroform (6 mL), trifluoroacetic acid (57
mg, 0.50 mmol) was added in chloroform (5 mL).
After refluxing for 6 h, the reaction mixture was
evaporated to give a colorless oil, which was chro-
matographed over silica gel by elution with CH2Cl2–
ethyl acetate (3:1) to afford the rearranged product
7 (103 mg, 0.36 mmol).
EXPERIMENTAL
General
All solvents were distilled. Analytical TLC was car-
ried out on precoated plates (Merck silica gel 60,
F254), and flash column chromatography was per-
formed with silica (Merck, 70–230 mesh). NMR spec-
tra (1H at 400 MHz; 13C at 100 MHz) were recorded
in CDCl3, and chemical shifts are expressed in ppm
relative to internal TMS (δ = 0.00) and CDCl3 (δ =
77.00) for 1H- and 13C-NMR.
Reaction of Thiofenchone 1 with Acetylenedicar-
boxylic Acid 8. Table 2, entry 2: To a solution of 1
(370 mg, 2.2 mmol) in MeCN (10 mL), acetylenedi-
carboxylic acid (228 mg, 2.0 mmol) was added. After
refluxing for 4 h, the reaction mixture was evapo-
rated to afford a pale yellow solid, which was chro-
matographed over silica gel by elution with CH2Cl2–
ethyl acetate (1:1) to afford a mixture of exo- and
endo-1,3-oxathiin-6-one 9 (5:1) (469 mg, 1.66 mmol).
Recrystallization from ethanol gave pure exo-9. Exo-
9: pale yellow fine crystals; mp 218–219°C. 1H NMR
(CDCl3) δ = 0.99 (s, 3H, Me), 1.05 (s, 3H, Me), 1.11
(s, 3H, Me), 1.36 (d, 1H, J = 10 Hz, CHH), 1.42–1.56
(m, 3H, CH2), 1.69 (m, 1H, CHH), 1.93 (br s, 1H, CH),
Materials
Selenofenchone was synthesized by the reaction of
fenchone hydrazone with diselenium dibromide in
the presence of triethylamine [8]. 1,3-Oxathiin-6-
ones 5 and 6 were synthesized by the reaction of
thiofenchone or thiocamphor with propiolic acid [4].
Reaction of Selenofenchone 3 with Propiolic Acid.
Table 1, entry 1: To a solution of 3 (430 mg, 2.0
mmol) in chloroform propiolic acid (280 mg, 4.0
mmol) was added. After refluxing for 24 h, the reac-
tion mixture was evaporated to afford a pale yellow
oil, which was chromatographed over silica gel by
elution with hexane and CH2Cl2–ethyl acetate (3:1)
to afford 1,3-oxaselenin-3-one 4 (273 mg, 0.96 mmol)
2.04 (d, 1H, J = 10 Hz, CHH), 6.79 (s, 1H, CH). 13
C
NMR (CDCl3) δ = 15.29 (Me), 25.41 (Me), 25.83 (Me),
27.03 (CH2), 31.05 (CH2), 41.59 (CH2), 47.59 (q-C),
48.24 (CH), 55.37 (q-C), 106.15 (q-C), 114.26 ( CH),
146.09 ( C), 166.10 (COO), 171.71 (COOH). HRMS
Heteroatom Chemistry DOI 10.1002/hc

582 Okuma, Matsui, and Mori
(m/zfor C ): MS was determined by its trimethylsi-
lyl ester. Calcd17H26O4354.1321 (M: SSi+). Found
354.1328 (M+). Endo-9 could not be isolated.
(Me), 25.77 (CH2), 31.64 (CH2), 51.59 (OMe), 52.63
(CH), 56.73 (q-C), 57.23 (q-C), 113.49 ( CH), 133.31
( CH), 142.28 ( C), 147.85 ( CH), 167.19 (COO).
Anal. Calcd for C14H20O2S: C; 66.63; H, 7.99. Found:
C, 66.26; H, 7.98. Compound E-11 could not be
isolated.
Reaction of Thiofenchone Adduct 5 with Triflu-
oroacetic Acid in Refluxing Chloroform. To a solu-
tion of 5 (95 mg, 0.40 mmol) in chloroform (7 mL),
trifluoroacetic acid (22 mg, 0.2 mmol) was added.
After refluxing for 6 h, the reaction mixture was
washed with water, dried over magnesium sulfate,
filtered, and evaporated to give colorless solid, which
was chromatographed over silica gel by elution with
hexane: EtOAc (2:1) to afford a mixture of Z- and
E-10 (63 mg, 0.26 mmol). E-10: pale yellow oily solid.
1H NMR (CDCl3) δ = 0.93 (s, 3H, Me), 1.03 (s, 3H,
Me), 1.39 (m, 1H, CHH), 1.78 (m, 1H, CHH), 1.91
(m, 1H, CH), 1.93–2.05 (m, 2H, CH2), 2.08 (d, 1H,
J = 16 Hz, CHH), 2.57 (d, 1H, J = 16 Hz, CHH),
4.93 (s, 1H, = CHH), 5.04 (s, 1H, CHH), 5.97 (d,
1H, J = 16 Hz, = CH), 7.96 (d, 1H, J = 16 Hz, =
CH). 13C NMR (CDCl3) δ = 19.74 (Me), 20.72 (Me),
28.46 (CH2), 35.41 (CH2), 37.15 (CH2), 44.15 (CH),
50.88 (q-C), 64.81 (q-C), 106.67 ( CH2), 114.52 ( C),
150.17 (SCH ), 152.78 ( C), 170.82 (COO). HRMS
(m/z): Calcd for C13H18O2S; 238.1028 (M+). Found:
Reaction of Thiofenchone 1 with Methyl Propi-
olate in Refluxing Chloroform. To a solution of 1
(84 mg, 0.5 mmol) and methyl propiolate (59 mg,
0.7 mmol) in chloroform (6 mL), AlCl3 (53 mg,
0.4 mmol) was added. After refluxing for 5 h, the
reaction mixture was poured into water (10 mL),
extracted with CH2Cl2 (10 mL × 2), separated, and
dried over magnesium sulfate. The filtered solution
was evaporated to give a colorless oil, which was
chromatographed over silica gel by elution with hex-
ane: CH2Cl2 (3:1) to give colorless oil of a mix-
ture of E- and Z-13 (57 mg, 0.34 mmol). Careful
chromatographic separation by using long column
packed with silica gel gave pure E- and Z-13 (elu-
1
ant: hexane: CH2Cl2 = 3:1). E-13: colorless oil. H
NMR (CDCl3) δ = 0.92 (s, 3H, Me), 1.01 (s, 3H, Me),
1.37 (m, 1H, CHH), 1.73 (m, 1H, CHH), 1.84–2.11
(m, 4H, CH2 and CH), 2.55 (br d, 1H, J = 8 Hz,
CHH), 3.75 (s, 3H, OMe), 4.91 (br s, = CHH), 5.05
(br s, = CHH), 5.98 (d, 1H, J = 16 Hz, = CH), 7.82
(d, 1H, J = 16 Hz, = CH). 13C NMR (CDCl3) δ =
19.46 (Me), 20.43 (Me), 28.19 (CH2), 35.15 (CH2),
36.89 (CH2), 43.92 (CH), 50.62 (q-C), 51.54 (OMe),
64.41 (S-C), 106.49 ( CH2), 115.05 ( CH), 146.92
(S CH ), 157.97 (q-C), 166.01 (COO). Anal. Calcd
for C14H20O2S: C, 66.63; H, 7.99. Found: C, 66.96;
H, 7.99. HRMS (m/z): Calcd for C14H20O2S 252.1184
1
238.1043 (M+). Z-10: colorless oily solid. H NMR
(CDCl3) δ = 0.95 (s, 3H, Me), 1.02 (s, 3H, Me), 1.39
(m, 1H, CHH), 1.76 (m, 1H, CHH), 1.88 (m, 1H, CH),
1.93–2.05 (m, 2H, CH2), 2.08 (d, 1H, J = 16 Hz, CHH),
2.57 (d, 1H, J = 16 Hz, CHH), 4.93 (s, 1H, CHH),
5.01 (s, 1H, CHH), 5.86 (d, 1H, J = 10 Hz, CH), 7.43
(d, 1H, J = 10 Hz, CH). 13C NMR (CDCl3) δ = 19.76
(Me), 20.89 (Me), 28.46 (CH2), 35.76 (CH2), 37.24
(CH2), 44.44 (CH), 50.83 (q-C), 64.55 (q-C), 106.66
( CH2), 111.92 ( C), 150.77 (SCH ), 153.10 ( C),
171.84 (COO). HRMS (m/z): Calcd for C13H18O2S;
238.1028 (M+). Found: 238.1048 (M+).
1
(M+). Found: 252.1183 (M+). Z-13: colorless oil. H
NMR (CDCl3) δ = 0.94 (s, 3H, Me), 1.03 (s, 3H, Me),
1.37 (m, 1H, CHH), 1.75 (m, 1H, CHH), 1.84–2.06
(m, 4H, CH2 and CH), 2.56 (br d, 1H, J = 8.4 Hz,
CHH), 3.75 (s, 3H, OMe), 4.91 (br s, = CHH), 5.02
(br s, = CHH), 5.84 (d, 1H, J = 10.4 Hz, = CH), 7.31
(d, 1H, J = 10.4 Hz, = CH). 13C NMR (CDCl3) δ =
19.59 (Me), 20.70 (Me), 28.31 (CH2), 35.59 (CH2),
37.08 (CH2), 44.30 (CH), 50.64 (q-C), 51.42 (OMe),
64.16 (S-C), 106.37 ( CH2), 111.99 ( CH), 147.92
(S CH ), 153.07 (q-C), 167.20 (COO). Anal. Calcd
for C14H20O2S: C, 66.63; H, 7.99. Found, C, 66.26; H,
7.98. HRMS (m/z): Calcd for C14H20O2S; 252.1184
(M+). Found: 252.1188 (M+).
Reaction of Thiocamphor Adduct 6 with Trifluo-
roacetic Acid in MeOH. To a solution of 6 (71 mg,
0.30 mmol) in MeOH (6 mL), trifluoroacetic acid
(34 mg, 0.30 mmol) was added. After refluxing for
5 h, the reaction mixture was poured into water,
extracted with CH2Cl2 (5 mL × 3). The combined
extract was dried over magnesium sulfate, filtered,
and evaporated to afford a colorless oil, which was
chromatographed over silica gel by elution with hex-
ane: EtOAc (3:1) gave colorless oil of Z-11. (38 mg,
0.16 mmol). Compound Z-11: colorless oil. 1H NMR
(CDCl3) δ = 0.81 (s, 3H, Me), 0.83 (s, 3H, Me), 1.06
(s, 3H, Me), 1.00–1.13 (m, 2H, CH2), 1.56 (m,1H,
CHH), 1.93 (m, 1H, CHH), 2.43 (m, 1H, CH), 3.75 (s,
3H, OMe), 5.89 (d, 1H, J = 10 Hz, = CH), 6.25 (d,
1H, J = 2 Hz, CH), 7.19 (d, 1H, J = 10 Hz, CH).
13C NMR (CDCl3) δ = 11.85 (Me), 19.55 (Me), 19.83
Reaction of Thiocamphor 2 with Methyl Pro-
piolate. To a solution of thiocamphor 2 (84 mg,
0.50 mmol) and methyl propiolate (84 mg, 1.0 mmol)
in MeOH (5 mL), AlCl3 (53 mg, 0.4 mmol) was
added. After refluxing for 2 h, the reaction mix-
ture was poured into water (10 mL), extracted with
Heteroatom Chemistry DOI 10.1002/hc

Reaction of Seleno- or Thiofenchone with Propiolic Acid: Wagner–Meerwein Rearrangement 583
Frailem, A. G.; Franco, C. R.; Alvador, J. S.; Subra-
jmanian, L. R.; Hanack, M. Synthesis 1987, 321; (c)
Martinez, A. G.; Vilar, E. T.; Fraile, A. G.; Cerero, S.
de la M.; Maroto, B. L. Tetrahedron Lett. 2001, 42,
6539; (d) Martinez, A. G.; Vilar, E. T.; Fraile, A. G.;
Cerero, S. de la M.; Morillo, C. D. Tetrahedron 2005,
61, 599; (d) Paquette, L. A.; Zhao, M.; Montgomery, F.;
Zeng, Q.; Wang, T. Z.; Elmore, S.; Combink, K.; Wang,
H.-L.; Bailey, S.; Zhuang, S. Pure Appl. Chem. 1998,
70, 1449.
CH2Cl2, separated, and dried over magnesium sul-
fate. The filtered solution was evaporated to give a
colorless oil, which was chromatographed over sil-
ica gel by elution with hexane: CH2Cl2 (3:1) to give
a colorless oil of a mixture of E- and Z-11 (95 mg,
0.37 mmol). Careful separation of the mixture by
using long column packed with silica gel gave pure
E-11 and Z-11. Compound E-11: colorless oil. 1H
NMR (CDCl3) δ = 0.81 (s, 3H, Me), 0.86 (s, 3H, Me),
1.02 (s, 3H, Me), 1.00–1.13 (m, 2H, CH2), 1.56 (m,1H,
CHH), 1.93 (m, 1H, CHH), 2.46 (m, 1H, CH), 3.72
(s, 3H, OMe), 6.02 (d, 1H, J = 15 Hz, = CH), 6.14
(d, 1H, J = 3 Hz, CH), 7.65 (d, 1H, J = 15 Hz,
CH). 13C NMR (CDCl3) δ = 11.97 (Me), 19.76 (Me),
20.02 (Me), 25.88 (CH2), 31.82 (CH2), 51.83 (CH),
52.95 (OMe), 56.69 (q-C), 57.41 (q-C), 116.34 ( CH),
135.91 ( CH), 138.85 ( C), 146.17 (S CH ), 165.79
(COO). Anal. Calcd for C14H20O2S: C, 66.63; H, 7.99.
Anal. Calcd for C14H20O2S: C; 66.63; H, 7.99. Found:
[2] (a) Majchrzak, A.; Mloston, G.; Linden, A.; Heimgart-
ner, H. Helv Chim Acta 2004, 87, 790; (b) Huisgen,
R.; Mloston, G.; Proebstl, A. Tetrahedron Lett 1985,
26, 4431; (c) Huisgen, R.; Mloston, G.; Probstl, A. Het-
eroatom Chem 2001, 12, 136.
[3] Okuma, K.; Mori, Y.; Shigetomi, T.; Tabuchi, M.;
Shioji, K.; Yokomori, Y. Tetrahedron Lett 2007, 48,
8311.
[4] (a) Okuma, K.; Koda, M.; Maekawa, S.; Shioji, K.; In-
oue, T.; Kurisaki, T.; Wakita, H.; Yokomori, Y. Org
Biomol Chem 2006, 4, 2745; (b) Okuma, K.; Maekawa,
S.; Shibata, S.; Shioji, K.; Inoue, T.; Kurisaki, T.;
Wakita, H.; Yokomori, Y. Eur J Org Chem 2003,
3727.
1
C, 66.96; H, 7.99. Compound Z-11: colorless oil. H
[5] Martinez, A. G.; Vilar, E. T.; Fraile, A. G.; Fernandez, A.
H.; Moya Cerero, A. de la; Jimenez, F. M. Tetrahedron
1998, 54, 4607.
[6] Okuma, K.; Okada, A.; Koga, Y.; Yokomori, Y. J. Am
Chem Soc 2001, 123, 7166.
NMR (CDCl3) δ = 0.81 (s, 3H, Me), 0.84 (s, 3H, Me),
1.06 (s, 3H, Me), 0.96–1.13 (m, 2H, CH2), 1.56 (m,1H,
CHH), 1.93 (m, 1H, CHH), 2.45 (m, 1H, CH), 3.75
(s, 3H, OMe), 5.89 (d, 1H, J = 10 Hz, = CH), 6.06
(d, 1H, J = 3 Hz, CH), 7.18 (d, 1H, J = 10 Hz,
CH). 13C NMR (CDCl3) δ = 11.85 (Me), 19.55 (Me),
19.82 (Me), 25.77 (CH2), 31.64 (CH2), 51.59 (CH),
52.63 (OMe), 56.72 (q-C), 57.23 (q-C), 113.48 ( CH),
133.30 ( CH), 142.28 ( C), 147.85 (S CH ),
167.18 (COO). Anal. Calcd for C14H20O2S: C, 66.63;
H, 7.99. Anal. Calcd for C14H20O2S: C; 66.26; H, 7.98.
Found: C, 66.96; H, 7.99.
[7] (a) Hiroi, K.; Watanabe, K. Tetrahedron: Asymmetry
2001, 12, 3067; (b) Bradshaw, D.; Prior, T. J.; Cussen,
E. J.; Claridge, J. B.; Rosseinsky, M. J. J Am Chem
Soc 2004, 126, 6106; (c) Hanyu, N.; Aoki, T.; Mino,
T.; Sakamoto, M.; Fujita, T. Tetrahedron: Asymmetry
2000, 11, 4127; (d) Node, M.; Nishide, K.; Shigeta, Y.;
Shiraki, H.; Obata, K. J Am Chem Soc 2000, 122, 1927;
(e) Nakano, H.; Okuyama, Y.; Yanagida, M.; Hongo, H.
J Org Chem 2001, 66, 620; (f) Aggarwal, V. K.; Ford, J.
G.; Fouquerna, S.; Adams, H.; Jones, R. V. H.; Field-
house, R. J Am Chem Soc 1998, 120, 8328; (g) Taka-
hashi, T.; Naoki, N.; Koizumi, T. Tetrahedron: Asym-
metry 1997, 8, 3293.
REFERENCES
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Heteroatom Chemistry DOI 10.1002/hc