Bi(OTf)3-catalyzed tandem Meyer-Schuster rearrangement and 1,4-addition to the resulting vinyl ketone

Article abstract of DOI:10.1021/jo5017663

Bi(OTf)₃-catalyzed Meyer-Schuster rearrangement of electron-rich propargyl alcohols, followed by 1,4-addition of the resulting vinyl ketone, proceeded smoothly though Meyer-Schuster rearrangement of primary propargyl alcohols is rare. This tandem reaction can be extended to an intramolecular version, featuring a one-pot dihydroquinolone synthesis. (Chemical Equation Presented).

Full text of DOI:10.1021/jo5017663

Note
pubs.acs.org/joc
Bi(OTf)3‑Catalyzed Tandem Meyer−Schuster Rearrangement and 1,4-
Addition to the Resulting Vinyl Ketone
Noriko Okamoto, Takuya Sueda, and Reiko Yanada*
Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1 Hirokoshingai, Kure, Hiroshima 737-0112, Japan
S
* Supporting Information
ABSTRACT: Bi(OTf)3-catalyzed Meyer−Schuster rearrange-
ment of electron-rich propargyl alcohols, followed by 1,4-
addition of the resulting vinyl ketone, proceeded smoothly
though Meyer−Schuster rearrangement of primary propargyl
alcohols is rare. This tandem reaction can be extended to an
intramolecular version, featuring a one-pot dihydroquinolone
synthesis.
lkynes are among the most fundamental and important
functional groups. Because of their useful reactivity, many
7). Bismuth compounds are relatively low in toxicity in contrast
to other Group 15 elements and the closely located heavy
metals. Since bismuth(III) compounds exhibit Lewis acidity
and are easy to handle and stable, the application of these
compounds in organic synthesis has attracted recent
attention.10
A
investigations have focused on their synthetic applications.1−4
We have recently been interested in the reaction of alkynes,
especially electron-donating group (EDG) activated alkynes.5
For example, an electron-rich alkyne is cleaved into two nitriles
by treatment with N-iodosuccinimide and trimethylsilylazide
under metal-free conditions.5b This reaction encouraged us to
explore a new type of transformation of electron-rich alkynes.
The Meyer−Schuster rearrangement6 is the acid-catalyzed
isomerization of secondary and tertiary propargyl alcohols to
α,β-unsaturated ketones. Classical Meyer−Schuster rearrange-
ment has been carried out in the presence of stoichiometric
protonic acids. Catalytic methods have been reported recently,7
but the examples with primary propargyl alcohols are
particularly rare.8 We envisioned that the Meyer−Schuster
rearrangement of primary propargyl alcohols could provide
highly reactive vinyl ketones, which might then be successively
subjected to 1,4-addition. We report herein the tandem
Meyer−Schuster rearrangement of primary propargyl alcohol/
1,4-addition of nucleophile and its application for dihydroqui-
nolone synthesis (Scheme 1).
The plausible mechanism is shown in Scheme 2. α,β-
Unsaturated ketone 2 was formed via Bi(OTf)3-catalyzed
Meyer−Schuster rearrangement of 1, followed by 1,4-addition
of EtOH, to give β-alkoxyketone 3. Michael addition of allenol
5, which was an intermediate of rearrangement, to 2 afforded
dimeric diketone 4. The structure of 4 was confirmed by X-ray
crystallographic analysis.11 To the best of our knowledge, this is
the first Bi(OTf)3-catalyzed Meyer−Schuster rearrangement.
Next, we examined the effect of substitution of the aromatic
ring in 6, which alters the electron density of the triple bond
(Table 2). The reaction of an alkyne with a strong EDG on the
aromatic ring proceeded smoothly to give β-alkoxyketone 7a in
good yield (entry 1). A moderate EDG showed low reactivity
(entry 2). Substrates that did not have an EDG resulted in
complex mixtures containing only trace amounts of product
(entries 3 and 4). meta-Methoxyl-substituted 6e did not
proceed in the reaction, resulting in the recovery of starting
material (entry 5). Decreasing the electron density of the
alkynes decelerated the transformation, indicating that an EDG
might facilitate the Meyer−Schuster rearrangement of primary
propargyl alcohol rather than affect the 1,4-addition of EtOH.
The reactions of 1 with various alcohols as the nucleophile
were examined (Table 3). Although water was not suitable for
this reaction, other primary alcohols gave β-alkoxyketone 8 in
good to excellent yields (entries 1−5). 2,2,2-Trifluoroethanol
gave a poor yield because of low nucleophilicity (entry 6).
When ethylene glycol was used, the Meyer−Schuster rearrange-
First, we examined Meyer−Schuster rearrangement of
electron-rich primary propargyl alcohol 1 as a substrate.
Propargyl alcohol 1 was treated with 5 mol % of Lewis acid
in 1,2-dichloroethane (DCE) in the presence of 3 equiv of
EtOH as a nucleophile at 70 °C. A brief survey of several Lewis
acids indicated that metal triflates showed catalytic activity for
Meyer−Schuster rearrangement, and the results are listed in
9
Table 1. Among these metal triflates, Bi(OTf)3 showed the
best catalytic activity, yielding the desired β-alkoxyketone 3
together with two byproducts, α,β-unsaturated ketone 2 and
dimeric diketone 4 (vide infra) (entries 1−5). The formation of
4 was increased when the yield of 3 was lower (entry 3 vs 5). A
decrease of EtOH reduced the yield of 3 (entry 6). Ten
equivalents of EtOH greatly improved the yield to 94% (entry
Received: August 1, 2014
© XXXX American Chemical Society
A
dx.doi.org/10.1021/jo5017663 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
Scheme 1. Tandem Meyer−Schuster Rearrangement/1,4-Addition to the Resulting Vinyl Ketone
Using PhOH resulted in a complex mixture of products (entry
12).
Table 1. Optimization of Reaction Conditions
This reaction was also carried out using secondary and
tertiary propargyl alcohols (Table 4). Such substituted
propargyl alcohols can undergo Meyer−Schuster rearrange-
ment more easily, but 1,4-addition to the resulting α,β-
unsaturated ketone is rather difficult. Secondary propargyl
alcohol 9a gave 63% of 10a and 30% of 11a regardless of
reaction time (entries 1 and 2). The reactions of the more
sterically hindered secondary propargyl alcohols afforded α,β-
unsaturated ketone 11 as a major product (entries 3 and 4).
Although the major product from tertiary propargyl alcohol 9d
was α,β-unsaturated ketone 11d after 5 h, methyl ketone 12
and enyne 13 were formed as byproducts (entry 5). Enyne 13
could be a product of Bi(OTf)3-catalyzed dehydration of 9d,
presumably by an E1 mechanism via a tertiary carbocation.
Prolonging the reaction time to 10 h led to the increase of
methyl ketone 12, which was formed by addition of water to
enone 11d, followed by a retro-aldol reaction (entry 6).
Tertiary propargyl alcohol 9e only afforded α,β-unsaturated
ketone 11e in high yield (entry 7).
entry
Lewis acid
EtOH (equiv) time (h) 2 (%) 3 (%) 4 (%)
1
2
3
4
5
6
7
Cu(OTf)2
Al(OTf)3
Sc(OTf)3
AgOTf
3
2
2
3
3
1
1
3
6.6
10
69
65
48
73
77
52
94
5.9
11
23
8.2
6.8
14
1.8
3
3
6.2
8.3
6.4
7.9
2.0
3
Bi(OTf)3
Bi(OTf)3
Bi(OTf)3
3
1.3
10
Scheme 2. Plausible Reaction Mechanism
Finally, we applied this reaction to intramolecular cyclization,
in which the nucleophilic moiety installed at the ortho-position
of the benzene ring could add to the α,β-unsaturated ketone
moiety to give a cyclic product (Table 5). Substrate 14a had the
methoxymethyl (MOM)-protected hydroxy substituent at the
ortho-position, and MOM deprotection would be expected to
occur under the reaction conditions. Intramolecular 1,4-
addition of an oxygen atom of 15a would be expected to give
chroman-4-one 16a. Unfortunately, this attempt failed to give
any cyclized product regardless of addition of ethanol (entries
1−3).
Then, we tried tandem cyclization using substrate 14b, which
had the more nucleophilic carbamate substituent. When 14b
was treated with Bi(OTf)3, dihydroquinolone 16b was obtained
together with α,β-unsaturated ketone 15b (entry 4). Addition
of EtOH improved the yield, and the best results were obtained
with 5 equiv of ethanol (entries 5−7). Fortunately, in contrast
to the results obtained from Table 4, secondary and tertiary
propargyl alcohols 14c−f could be employed for this reaction
(entries 8−11), but 14g afforded 16g in low yield (entry 12)
In conclusion, we have demonstrated that electron-rich
primary propargyl alcohols undergo Bi(OTf)3-catalyzed
Meyer−Schuster rearrangement and successive 1,4-addition of
alcohol to give β-alkoxyketones. We were also able to extend
this tandem reaction to an intramolecular version, featuring a
one-pot dihydroquinolone synthesis.
Table 2. Effect of Aromatic Substituent
entry
6
R
time
6 h
7
yield (%)
1
2
3
4
5
6a
6b
6c
6d
6e
p-NHCO2Et
p-Me
7a
7b
7c
7d
91
47
2 days
3 days
2 days
2 days
p-H
trace
trace
p-F
m-OMe
recovery of sm
EXPERIMENTAL SECTION
ment did not proceed (entry 7). Protected ethylene glycols
afforded 3 in good to moderate yields (entries 8 and 9). A
secondary alcohol could be used as the nucleophile (entry 10).
As expected, bulky t-BuOH showed poor reactivity (entry 11).
■
1
General. H NMR and 13C NMR spectra were recorded on a 600
MHz spectrometer. Chemical shifts were reported in δ (ppm) from
tetramethylsilane as an internal standard. Data were reported as
B
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The Journal of Organic Chemistry
Note
Table 3. Scope of the Alcohols
entry
ROH
time (h)
8
yield (%)
2 (%)
4 (%)
1
2
H2O
2
26
22
MeOH
2
8a
8b
8c
8d
8e
94
81
86
55
5.2
0.9
0.9
a
3
PhCH2OH
1
4
allyl alcohol
1
5
propargyl alcohol
CF3CH2OH
1
12
6
1
23
23
a
7
ethylene glycol
1 day
trace
7.4
4.2
8.8
26
trace
8.2
a
8
2-methoxyethanol
2
2
6
6
1
8f
77
40
77
27
a
9
2-hydroxyethyl acetate
i-PrOH
8g
8h
8i
20
10
11
12
trace
trace
trace
t-BuOH
a
PhOH
a
5 equiv of ROH was used.
Table 4. Scope of the Substrates
entry
9
R
R′
time (h)
10
yield (%)
11
yield (%)
others
1
2
3
4
5
6
7
9a
9a
9b
9c
9d
9d
9e
Me
Me
i-Bu
Ph
H
5
10
6
10a
10a
10b
63
53
11a
11a
11b
11c
11d
11d
11e
30
32
70
63
73
37
94
H
H
H
6.6
6
Me
Me
Ph
Me
Me
Ph
5
12 (2.5), 13 (18)
12 (40)
10
5
Table 5. Application in the Synthesis of Heterocyclic Compounds
entry
14
EDG
R
R′
EtOH (equiv)
time (h)
16
X
yield (%)
others
1
14a
14a
14a
14b
14b
14b
14b
14c
14d
14e
14f
OMOM
H
H
H
H
H
H
H
H
H
H
H
Me
24
24
24
5
16a
16a
16a
16b
16b
16b
16b
16c
16d
16e
16f
O
O
O
2
OMOM
H
1.3
5
15a (7.8), 17a (13)
15a (8.8), 17a (36)
15b (26)
3
OMOM
H
4
NHCO2Et
NHCO2Et
NHCO2Et
NHCO2Et
NHCO2Et
NHCO2Et
NHCO2Et
NHCO2Et
NHCO2Et
H
NCO2Et
NCO2Et
NCO2Et
NCO2Et
NCO2Et
NCO2Et
NCO2Et
NCO2Et
NCO2Et
28
67
86
83
87
84
79
80
30
5
H
1.3
5
5
15b (7.3), 17b (13)
6
H
24
48
24
24
24
24
24
7
H
10
5
8
Me
i-Bu
Ph
Me
9
5
10
11
12
5
5
14g
−(CH2)5−
−(CH2)5−
5
16g
C
dx.doi.org/10.1021/jo5017663 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
follows: chemical shifts, relative integration value, multiplicity (s =
singlet, d = doublet, t = triplet, q = quartet, br = broad, m = multiplet),
coupling constants (Hz). Infrared spectra were obtained using an FT
spectrometer. Analytical thin-layer chromatography was performed on
Merck silica gel 60 F254 TLC plates.
General Procedure for the Preparation of Propargyl
Alcohol. To a solution of aryl iodide (1 mmol) in Et3N (5 mL)
was added Pd(OAc)2 (11.2 mg, 0.05 mmol), PPh3 (26 mg, 0.1 mmol),
CuI (9.5 mg, 0.05 mmol), and alkyne (1.3 mmol), and the mixture was
stirred at room temperature under nitrogen. The reaction was
monitored by TLC to establish completion. Saturated aqueous
NH4Cl solution was added to the reaction mixture and extracted
with EtOAc (three times). The combined organic solution was washed
with brine, dried over anhydrous MgSO4, and concentrated at the
reduced pressure. Column chromatography on silica gel using hexane/
ethyl acetate as an eluent afforded propargyl alcohols (see the
Supporting Information).
s), 2.06 (2H, d, J = 12.4 Hz), 1.81−1.58 (8H, m), 1.32 (3H, t, J = 6.8
Hz). 13C NMR (CDCl3) δ: 153.3, 139.1, 131.6, 129.6, 122.3, 117.6,
111.0, 100.1, 79.6, 69.3, 61.3, 40.0, 25.1, 23.5, 14.5. IR (CHCl3, cm−1)
3594, 3402, 2940, 2860, 1734, 1583, 1522, 1454, 1308, 1238, 1197,
1063, 962. MS (EI): m/z = 287 (M+). HRMS (EI): m/z calcd for
C17H21NO3: 287.1521; found: 287.1520.
General Procedure for Tandem Meyer−Schuster Rearrange-
ment/1,4-Addition. To a solution of propargyl alcohol 1 (0.4 mmol)
in 1,2-dichloroethane (2 mL) was added EtOH (4 mmol) and
Bi(OTf)3 (0.02 mmol), and the mixture was stirred at 70 °C. After
filtration over a short pad of silica gel, the solvent was removed under
reduced pressure. The crude product was purified by column
chromatography on silica gel (hexane/ethyl acetate as an eluent) to
give the product.
1,5-Bis(4-methoxyphenyl)-2-methylenepentane-1,5-dione (4).
Yield: 15 mg, 23%; colorless plate; mp 73−74 °C. 1H NMR
(CDCl3) δ: 7.96 (2H, d, J = 8.9 Hz), 7.79 (2H, d, J = 8.9 Hz), 6.92
(4H, d, J = 8.9 Hz), 5.85 (1H, s), 5.58 (1H, s), 3.87 (3H, s), 3.86 (3H,
s), 3.17 (2H, t, J = 7.4 Hz), 2.89 (2H, t, J = 7.4 Hz). 13C NMR
(CDCl3) δ: 197.9, 197.0, 163.5, 163.2, 147.0, 132.0, 130.4, 130.2,
129.9, 124.8, 113.7, 113.5, 55.5, 36.8, 28.1. IR (CHCl3, cm−1) 2967,
2938, 2842, 1675, 1649, 1601, 1576, 1510, 1464, 1442, 1420, 1308,
1259, 1170, 1032, 989, 977 844. MS (EI): m/z = 324 (M+). HRMS
(EI): m/z calcd for C20H20O4: 324.1362; found: 324.1363. Crystals for
X-ray diffraction analysis were obtained by recrystallization from
CHCl3−hexane. Crystal data for 4a (CCDC 1015377): C20H20O4, M
= 324.38, monoclinic, space group P21/c, colorless block, a =
18.637(4) Å, b = 7.6745(16) Å, c = 11.725(3) Å, β = 101.421(16)°, V
= 1643.9(7) Å, Z = 4, and Dc = 1.311 g cm−3. The reflection data of
2791 reflections with 0 < θ < 30° were collected on a Rigaku RAXIS-
RAPID diffractometer using monochromated CuKα radiation and an
ω-2θ scan technique (−22 ≤ h ≤ 21, −9 ≤ k ≤ 9, −12 ≤ l ≤ 11). The
structure was solved by the direct method and refined by the full-
matrix least-squares method. The final R value was 0.0421 for 2791
observed reflections (wR = 0.0717, Chebychev polynomial with 3
parameters, 66.6594, 85.0929, 19.0744).
Ethyl (4-(3-Hydroxyprop-1-yn-1-yl)phenyl)carbamate (6a). Yield:
1
166.3 mg, 76%; yellow solid; mp 125−127 °C. H NMR (CDCl3) δ:
7.38−7.35 (4H, m), 6.64 (1H, br s), 4.49 (2H, s), 4.23 (2H, q, J = 7.2
Hz), 1.69 (1H, br s), 1.31 (3H, t, J = 7.2 Hz). 13C NMR (CDCl3) δ:
153.3, 138.2, 132.6, 118.1, 117.1, 86.5, 85.5, 61.5, 51.7, 14.5. IR
(CHCl3, cm−1) 3608, 3434, 1734, 1609, 1581, 1521, 1506, 1411, 1379,
1313, 1237, 1197, 1065, 1023, 839. MS (EI): m/z = 219 (M+). HRMS
(EI): m/z calcd for C12H13NO3: 219.0895; found: 219.0901.
1-(4-Methoxyphenyl)-5-methylhex-1-yn-3-ol (9b). Yield: 205.2
1
mg, 94%; brown oil. H NMR (CDCl3) δ: 7.36 (2H, d, J = 8.9 Hz),
6.83 (2H, d, J = 8.9 Hz), 4.63 (1H, q, J = 6.6 Hz), 3.81 (3H, s), 1.95−
1.88 (1H, m), 1.80 (1H, d, J = 5.5 Hz), 1.75−1.70 (1H, m), 1.67−1.63
(1H, m), 0.98 (3H, d, J = 6.2 Hz), 0.97 (3H, d, J = 6.2 Hz). 13C NMR
(CDCl3) δ: 159.6, 133.1, 114.7, 113.9, 89.0, 84.6, 61.5, 55.2, 47.0, 24.8,
22.6, 22.5. IR (CHCl3, cm−1) 3601, 2961, 2936, 2225, 1608, 1510,
1467, 1442, 1387, 1290, 1249, 1237, 1174, 1107, 1174, 834, 810. MS
(EI): m/z = 218 (M+). HRMS (EI): m/z calcd for C14H18O2:
218.1307; found: 218.1302.
Ethyl (2-(3-Hydroxybut-1-yn-1-yl)phenyl)carbamate (14c). Yield:
212.3 mg, 91%; pale yellow oil. 1H NMR (CDCl3) δ: 8.13 (1H, br s),
7.36−7.31 (3H, m), 6.97 (1H, t, J = 7.6 Hz), 4.83 (1H, q, J = 6.8 Hz),
4.25 (2H, q, J = 7.2 Hz), 2.43 (1H, br s), 1.60 (3H, d, J = 6.8 Hz), 1.33
(3H, t, J = 7.2 Hz). 13C NMR (CDCl3) δ: 153.3, 139.1, 131.9, 129.8,
122.4, 117.7, 110.6, 98.0, 79.2, 61.4, 58.8, 24.4, 14.5. IR (CHCl3, cm−1)
3691, 3601, 3405, 2988, 2224, 2197, 1734, 1602, 1582, 1523, 1450,
1378, 1307, 1240, 1196, 1097, 1062, 933, 810. MS (EI): m/z = 233
(M+). HRMS (EI): m/z calcd for C13H15NO3: 233.1052; found:
233.1045.
Ethyl (4-(3-Ethoxypropanoyl)phenyl)carbamate (7a). Yield: 96.6
1
mg, 91%; white solid; mp 103−105 °C. H NMR (CDCl3) δ: 7.95
(2H, d, J = 8.9 Hz), 7.47 (2H, d, J = 8.2 Hz), 6.76 (1H, br s), 4.25
(2H, q, J = 7.0 Hz), 3.85 (2H, t, J = 6.7 Hz), 3.53 (2H, q, J = 7.2 Hz),
3.22 (2H, t, J = 6.7 Hz), 1.33 (3H, t, J = 7.0 Hz), 1.20 (3H, t, J = 7.2
Hz). 13C NMR (CDCl3) δ: 197.1, 153.1, 142.5, 131.8, 129.7, 117.5,
66.5, 65.8, 61.6, 38.6, 15.1, 14.4. IR (CHCl3, cm−1) 3432, 2981, 2874,
1738, 1676, 1605, 1587, 1528, 1524, 1503, 1412, 1380, 1323, 1312,
11239, 1180, 1107, 1063, 988, 849. MS (EI): m/z = 265 (M+). HRMS
(EI): m/z calcd for C14H19NO4: 265.1314; found: 265.1317.
Ethyl (2-(3-Hydroxy-5-methylhex-1-yn-1-yl)phenyl)carbamate
1
3-Ethoxy-1-(p-tolyl)propan-1-one (7b). Yield: 36 mg, 47%;
(14d). Yield: 242.3 mg, 88%; pale yellow oil. H NMR (CDCl3) δ:
1
colorless oil. H NMR (CDCl3) δ: 7.87 (2H, d, J = 7.8 Hz), 7.26
8.14 (1H, br s), 7.37 (1H, d, J = 8.2 Hz), 7.34−7.31 (2H, m), 6.98
(1H, t, J = 7.6 Hz), 4.72 (1H, q, J = 6.6 Hz), 4.25 (2H, q, J = 7.2 Hz),
1.95−1.93 (2H, m), 1.81−1.69 (2H, m), 1.33 (3H, t, J = 7.2 Hz), 1.01
(3H, d, J = 6.2 Hz), 0.99 (3H, d, J = 6.9 Hz). 13C NMR (CDCl3) δ:
153.3, 139.1, 131.8, 129.8, 122.4, 117.6, 110.7, 97.5, 80.0, 61.5, 61.4,
46.8, 25.0, 22.6, 22.5, 14.5. IR (CHCl3, cm−1) 3601, 3404, 2962, 1734,
1582, 1521, 1451, 1388, 1307, 1240, 1063, 1042. MS (EI): m/z = 275
(M+). HRMS (EI): m/z calcd for C16H21NO3: 275.1521; found:
275.1516.
(2H, d, J = 7.8 Hz), 3.86 (2H, td, J = 6.9, 1.4 Hz), 3.54 (2H, q, J = 6.8
Hz), 3.24 (2H, t, J = 6.9 Hz), 2.41 (3H, s), 1.20 (3H, td, J = 6.8, 1.4
Hz). 13C NMR (CDCl3) δ: 198.0, 143.9, 134.5, 129.2, 128.2, 66.5,
65.8, 38.7, 21.6, 15.1. IR (CHCl3, cm−1) 2979, 2874, 1680, 1607, 1380,
1362, 1328, 1236, 1197, 1181, 1107, 979. MS (EI): m/z = 192 (M+).
HRMS (EI): m/z calcd for C12H16O2: 192.1150; found: 192.1151.
3-(Benzyloxy)-1-(4-methoxyphenyl)propan-1-one (8b). Yield:
1
87.2 mg, 81%; colorless oil. H NMR (CDCl3) δ: 7.95 (2H, d, J =
8.6 Hz), 7.33−7.33 (4H, m), 7.29−7.26 (1H, m), 6.93 (2H, d, J = 8.6
Hz), 4.56 (2H, s), 3.92 (2H, t, J = 6.5 Hz), 3.87 (3H, s), 3.25 (2H, t, J
= 6.5 Hz). 13C NMR (CDCl3) δ: 196.9, 163.5, 138.2, 130.4, 130.1,
128.4, 127.7, 127.6, 113.7, 73.3, 65.9, 55.5, 38.6. IR (CHCl3, cm−1)
2869, 1674, 1601, 1576, 1511, 1455, 1421, 1367, 1316, 1261, 1171,
1101, 1030, 985. MS (EI): m/z = 270 (M+). HRMS (EI): m/z calcd
for C17H18O3: 270.1256; found: 270.1257.
Ethyl (2-(3-Hydroxy-3-phenylprop-1-yn-1-yl)phenyl)carbamate
1
(14e). Yield: 268.7 mg, 91%; pale yellow solid; mp 55−56 °C. H
NMR (CDCl3) δ: 8.14 (1H, br s), 7.63 (2H, d, J = 7.6 Hz), 7.45−7.31
(6H, m), 6.99 (1H, t, J = 7.6 Hz), 5.77 (1H, d, J = 6.2 Hz), 4.23 (2H,
q, J = 7.0 Hz), 2.45 (1H, br s), 1.32 (3H, t, J = 7.0 Hz). 13C NMR
(CDCl3) δ: 153.3, 140.4, 139.4, 131.9, 130.0, 128.8, 128.6, 126.5,
122.4, 117.8, 110.5, 95.9, 81.8, 65.1, 61.4, 14.5. IR (CHCl3, cm−1)
3689, 3590, 3405, 2216, 1734, 1583, 1523, 1451, 1377, 1307, 1240,
1196, 1063, 1043, 960, 832. MS (EI): m/z = 295 (M+). HRMS (EI):
m/z calcd for C18H17NO3: 295.1208; found: 295.1210.
Ethyl (2-((1-Hydroxycyclohexyl)ethynyl)phenyl)carbamate (14g).
Yield: 250 mg, 87%; brown solid; mp 84−86 °C. 1H NMR (CDCl3) δ:
8.13 (1H, br s), 7.37 (1H, d, J = 7.6 Hz), 7.36 (1H, br s), 7.32 (1H, t, J
= 7.9 Hz), 6.98 (1H, t, J = 7.6 Hz), 4.24 (2H, q, J = 6.8 Hz), 2.14 (1H,
3-(Allyloxy)-1-(4-methoxyphenyl)propan-1-one (8c). Yield: 76
1
mg, 86%; colorless oil. H NMR (CDCl3) δ: 7.96 (2H, d, J = 8.6
Hz), 6.94 (2H, d, J = 8.6 Hz), 5.93−5.89 (1H, m), 5.28 (1H, dd, J =
17.2, 2.1 Hz), 5.18 (1H, dd, J = 10.3, 1.4 Hz), 4.02 (2H, d, J = 6.2 Hz),
3.88−3.87 (5H, m), 3.23 (2H, t, J = 6.9 Hz). 13C NMR (CDCl3) δ:
196.8, 163.5, 134.6, 130.4, 130.1, 117.1, 113.7, 72.1, 65.7, 55.4, 38.5. IR
(CHCl3, cm−1) 2912, 2873, 1675, 1601, 1577, 1511, 1464, 1421, 1364,
D
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Note
1316, 1261, 1171, 1100, 1033, 988, 933. MS (EI): m/z = 220 (M+).
HRMS (EI): m/z calcd for C13H16O3: 220.1099; found: 220.1095.
1-(4-Methoxyphenyl)-3-(prop-2-yn-1-yloxy)propan-1-one (8d).
0.96 (6H, d, J = 6.2 Hz). 13C NMR (CDCl3) δ: 189.0, 163.2, 147.8,
130.8, 130.8, 126.5, 113.7, 55.4, 42.1, 28.0, 22.4. IR (CHCl3, cm−1)
3524, 2961, 2871, 2842, 1664, 1617, 1600, 1575, 1511, 1465, 1420,
1351, 1307, 1260, 1171, 1031, 1003, 982, 893, 843. MS (EI): m/z =
218 (M+). HRMS (EI): m/z calcd for C14H18O2: 218.1307; found:
218.1306.
General Procedure for Heterocyclic Compound Synthesis.
To a solution of propargyl alcohol 1 (0.3 mmol) in 1,2-dichloroethane
(1.5 mL) was added EtOH (1.5 mmol) and Bi(OTf)3 (0.015 mmol),
and the mixture was stirred at 70 °C. After filtration over a short pad of
silica gel, the solvent was removed under reduced pressure. The crude
product was purified by column chromatography on silica gel (hexane/
ethyl acetate as an eluent) to give the product.
1
Yield: 48.2 mg, 55%; colorless oil. H NMR (CDCl3) δ: 7.95 (2H,
d, J = 8.9 Hz), 6.94 (2H, d, J = 8.9 Hz), 4.19 (2H, d, J = 2.3 Hz), 3.97
(2H, t, J = 6.5 Hz), 3.88 (3H, s), 3.24 (2H, t, J = 6.5 Hz), 2.44 (1H, t, J
= 2.3 Hz). 13C NMR (CDCl3) δ: 196.5, 163.6, 130.4, 130.0, 113.7,
79.7, 74.5, 65.5, 58.4, 55.5, 38.2. IR (CHCl3, cm−1) 3308, 2912, 1675,
1601, 1577, 1511, 1465, 1443, 1421, 1363, 1333, 1316, 1260, 1170,
1103, 1033, 986, 846. MS (EI): m/z = 218 (M+). HRMS (EI): m/z
calcd for C13H14O3: 218.0943; found: 218.0941.
1-(4-Methoxyphenyl)-3-(2,2,2-trifluoroethoxy)propan-1-one (8e).
Yield: 5.5 mg, 5.2%; colorless oil. 1H NMR (CDCl3) δ: 7.95 (2H, d, J
= 8.9 Hz), 6.95 (2H, d, J = 8.9 Hz), 4.06 (2H, t, J = 6.4 Hz), 3.89 (2H,
q, J = 8.7 Hz), 3.88 (3H, s), 3.25 (2H, t, J = 6.4 Hz). 13C NMR
(CDCl3) δ: 196.0, 163.7, 130.4, 129.8, 124.9, 123.0, 121.2, 113.8, 69.1,
68.9, 68.7, 68.5, 68.1, 55.5, 38.3. IR (CHCl3, cm−1) 3691, 2938, 1676,
1601, 1576, 1512, 1465, 1420, 1309, 1280, 1262, 1170, 1032, 990. MS
(EI): m/z = 262 (M+). HRMS (EI): m/z calcd for C12H13F3O3:
262.0817; found: 262.0826.
Ethyl (2-Acryloylphenyl)carbamate (15b). Yield: 16.8 mg, 26%;
1
pale yellow oil. H NMR (CDCl3) δ: 10.92 (1H, s), 8.47 (1H, d, J =
8.1 Hz), 7.86 (1H, dd, J = 7.8, 1.7 Hz), 7.56 (1H, t, J = 8.1 Hz), 7.22
(1H, dd, J = 16.8, 10.9 Hz), 7.08 (1H, t, J = 7.8 Hz), 6.44 (1H, dd, J =
16.8, 1.6 Hz), 5.94 (1H, dd, J = 10.9, 1.6 Hz), 4.23 (2H, q, J = 7.1 Hz),
1.33 (3H, t, J = 6.9 Hz). 13C NMR (CDCl3) δ: 193.6, 153.9, 141.7,
134.9, 133.1, 131.0, 130.4, 121.9, 121.3, 119.5, 61.2, 14.5. IR (CHCl3,
cm−1) 3292, 2984, 1729, 1653, 1605, 1583, 1525, 1453, 1307, 1239,
1197, 1166, 1095, 1065, 994. MS (EI): m/z = 219 (M+). HRMS (EI):
m/z calcd for C12H13NO3: 219.0895; found: 219.0900.
Ethyl 4-Oxo-3,4-dihydroquinoline-1(2H)-carboxylate (16b). Yield:
56.2 mg, 86%; pale yellow oil. 1H NMR (CDCl3) δ: 8.00 (1H, dd, J =
7.9, 1.8 Hz), 7.81 (1H, d, J = 8.2 Hz), 7.52 (1H, td, J = 7.9, 1.8 Hz),
7.19 (1H, t, J = 7.6 Hz), 4.31 (2H, q, J = 7.2 Hz), 4.22 (2H, t, J = 6.5
Hz), 2.79 (2H, t, J = 6.5 Hz), 1.36 (3H, t, J = 7.2 Hz). 13C NMR
(CDCl3) δ: 193.9, 153.8, 143.7, 134.1, 127.3, 124.9, 124.1, 123.4, 62.6,
44.4, 38.9, 14.4. IR (CHCl3, cm−1) 2986, 1684, 1602, 1575, 1480,
1466, 1458, 1405, 1380, 1352, 1330, 1318, 1305, 1239, 1196, 1135,
1095, 1057, 1029, 963, 861. MS (EI): m/z = 219 (M+). HRMS (EI):
m/z calcd for C12H13NO3: 219.0895; found: 219.0894.
3-(2-Methoxyethoxy)-1-(4-methoxyphenyl)propan-1-one (8f).
1
Yield: 73.6 mg, 77%; colorless oil. H NMR (CDCl3) δ: 7.95 (2H,
d, J = 8.9 Hz), 6.93 (2H, d, J = 8.9 Hz), 3.91 (2H, t, J = 6.5 Hz), 3.87
(3H, s), 3.65 (2H, dd, J = 3.1, 1.6 Hz), 3.54 (2H, dd, J = 3.2, 1.6 Hz),
3.38 (3H, s), 3.26 (2H, t, J = 6.5 Hz). 13C NMR (CDCl3) δ: 196.8,
163.5, 130.3, 130.0, 113.7, 71.8, 70.4, 66.6, 59.0, 55.4, 38.4. IR (CHCl3,
cm−1) 2895, 1675, 1601, 1577, 1511, 1465, 1420, 1363, 1261, 1171,
1032, 987, 844. MS (EI): m/z = 238 (M+). HRMS (EI): m/z calcd for
C13H18O4: 238.1205; found: 238.1205.
2-(3-(4-Methoxyphenyl)-3-oxopropoxy)ethyl Acetate (8g). Yield:
42.6 mg, 40%; colorless oil. 1H NMR (CDCl3) δ: 7.95 (2H, d, J = 8.6
Hz), 6.94 (2H, d, J = 8.6 Hz), 4.21 (2H, t, J = 4.5 Hz), 3.92 (2H, t, J =
6.5 Hz), 3.88 (3H, s), 3.71−3.69 (2H, m), 3.24 (2H, t, J = 6.5 Hz),
2.07 (3H, s). 13C NMR (CDCl3) δ: 196.6, 171.0, 163.5, 130.3, 130.0,
113.7, 69.0, 66.6, 63.5, 55.4, 38.3, 20.9. IR (CHCl3, cm−1) 2965, 1733,
1674, 1601, 1576, 1511, 1464, 1421, 1258, 1238, 1171, 1126, 1049,
987. MS (EI): m/z = 266 (M+). HRMS (EI): m/z calcd for C14H18O5:
266.1154; found: 266.1154.
3-Isopropoxy-1-(4-methoxyphenyl)propan-1-one (8h). Yield: 68.2
mg, 77%; colorless oil. 1H NMR (CDCl3) δ: 7.96 (2H, d, J = 8.9 Hz),
6.93 (2H, d, J = 8.9 Hz), 3.87 (3H, s), 3.84 (2H, t, J = 6.9 Hz), 3.65−
3.61 (1H, m), 3.20 (2H, t, J = 6.9 Hz), 1.16 (6H, d, J = 6.2 Hz). 13C
NMR (CDCl3) δ: 197.1, 163.4, 130.4, 130.2, 113.6, 71.8, 63.5, 55.4,
38.9, 22.0. IR (CHCl3, cm−1) 2974, 1675, 1601, 1511, 1465, 1420,
1346, 1261, 1170, 1126, 1077, 1032, 987, 841. MS (EI): m/z = 222
(M+). HRMS (EI): m/z calcd for C13H18O3: 222.1256; found:
222.1261.
Ethyl 2-Methyl-4-oxo-3,4-dihydroquinoline-1(2H)-carboxylate
1
(16c). Yield: 62.1 mg, 87%; yellow oil. H NMR (CDCl3) δ: 8.00
(1H, dd, J = 7.9, 1.8 Hz), 7.82 (1H, d, J = 8.2 Hz), 7.53 (1H, td, J =
7.9, 1.8 Hz), 7.16 (1H, t, J = 7.6 Hz), 5.19−5.14 (1H, m), 4.37−4.27
(2H, m), 3.06 (1H, dd, J = 17.2, 5.5 Hz), 2.58 (1H, dd, J = 17.2, 2.1
Hz), 1.37 (3H, t, J = 7.2 Hz), 1.24 (3H, d, J = 6.9 Hz). 13C NMR
(CDCl3) δ: 193.3, 153.8, 141.0, 134.4, 126.7, 124.2, 124.1, 123.7, 62.5,
49.7, 44.3, 17.7, 14.4. IR (CHCl3, cm−1) 2985, 1684, 1602, 1577, 1481,
1462, 1398, 1387, 1372, 1326, 1305, 1277, 1129, 1107, 1063, 1052,
1029. MS (EI): m/z = 233 (M+). HRMS (EI): m/z calcd for
C13H15NO3: 233.1052; found: 233.1054.
Ethyl 2-Isobutyl-4-oxo-3,4-dihydroquinoline-1(2H)-carboxylate
1
(16d). Yield: 69.5 mg, 84%; pale yellow oil. H NMR (CDCl3) δ:
7.98 (1H, dd, J = 7.9, 1.7 Hz), 7.73 (1H, br s), 7.53 (1H, td, J = 7.7, 1.6
Hz), 7.18 (1H, t, J = 7.6 Hz), 5.08−5.07 (1H, m), 4.31 (2H, q, J = 7.2
Hz), 3.06 (1H, dd, J = 17.2, 5.5 Hz), 2.59 (1H, dd, J = 17.5, 1.7 Hz),
1.57−1.55 (2H, m), 1.36 (3H, t, J = 7.2 Hz), 1.26−1.22 (1H, m), 0.95
(3H, d, J = 6.2 Hz), 0.81 (3H, d, J = 6.2 Hz). 13C NMR (CDCl3) δ:
193.5, 154.1, 141.0, 134.2, 126.6, 124.9, 124.9, 124.0, 62.4, 52.0, 43.5,
40.4, 25.0, 22.7, 22.0, 14.3. IR (CHCl3, cm−1) 2962, 2915, 1684, 1602,
1577, 1480, 1462, 1400, 1388, 1373, 1340, 1323, 1291, 1268, 1237,
1132, 1053, 971. MS (EI): m/z = 275 (M+). HRMS (EI): m/z calcd
for C16H21NO3: 275.1521; found: 275.1525.
Ethyl 4-Oxo-2-phenyl-3,4-dihydroquinoline-1(2H)-carboxylate
(16e). Yield: 70 mg, 79%; yellow solid; mp 91−93 °C. 1H NMR
(CDCl3) δ: 7.89 (1H, dd, J = 7.9, 1.7 Hz), 7.80 (1H, d, J = 8.2 Hz),
7.47 (1H, t, J = 7.9 Hz), 7.22−7.21 (4H, m), 7.17−7.16 (1H, m), 7.08
(1H, t, J = 7.6 Hz), 6.22 (1H, t, J = 3.8 Hz), 4.43−4.35 (2H, m), 3.32−
3.31 (2H, m), 1.39 (3H, t, J = 7.2 Hz). 13C NMR (CDCl3) δ: 192.8,
154.4, 141.6, 138.1, 134.4, 128.5, 127.4, 126.8, 126.5, 124.9, 124.3,
123.9, 62.9, 55.9, 42.3, 14.4. IR (CHCl3, cm−1) 2986, 1684, 1603,
1481, 1461, 1397, 1380, 1322, 1303, 1237, 1133, 1051, 1042, 953. MS
(EI): m/z = 295 (M+). HRMS (EI): m/z calcd for C18H17NO3:
295.1208; found: 295.1207.
3-(tert-Butoxy)-1-(4-methoxyphenyl)propan-1-one (8i). Yield:
1
25.8 mg, 27%; colorless oil. H NMR (CDCl3) δ: 7.96 (2H, d, J =
8.9 Hz), 6.93 (2H, d, J = 8.9 Hz), 3.87 (3H, s), 3.79 (2H, t, J = 7.2
Hz), 3.17 (2H, t, J = 7.2 Hz), 1.20 (9H, s). 13C NMR (CDCl3) δ:
197.5, 163.4, 130.4, 130.3, 113.6, 73.1, 57.5, 55.4, 39.4, 27.5. IR
(CHCl3, cm−1) 3689, 2977, 1674, 1601, 1511, 1464, 1420, 1396, 1366,
1331, 1259, 1170, 1075, 1033, 987, 845. MS (EI): m/z = 236 (M+).
HRMS (EI): m/z calcd for C14H20O3: 236.1412; found: 236.1408.
3-Ethoxy-1-(4-methoxyphenyl)-5-methylhexan-1-one (10b).
1
Yield: 7 mg, 6.6%; pale yellow oil. H NMR (CDCl3) δ: 7.96 (2H,
d, J = 8.6 Hz), 6.94 (2H, d, J = 8.6 Hz), 4.03−3.99 (1H, m), 3.88 (3H,
s), 3.56−3.45 (2H, m), 3.24 (1H, dd, J = 15.8, 5.9 Hz), 2.87 (1H, dd, J
= 15.8, 5.9 Hz), 1.82−1.75 (1H, m), 1.56−1.51 (1H, m), 1.32−1.27
(1H, m), 1.12 (3H, t, J = 6.9 Hz), 0.94 (3H, d, J = 6.9 Hz), 0.92 (3H,
d, J = 6.9 Hz). 13C NMR (CDCl3) δ: 197.9, 163.5, 130.6, 130.5, 113.7,
74.7, 65.1, 55.5, 44.9, 44.0, 24.7, 23.3, 22.3, 15.6. IR (CHCl3, cm−1)
2969, 1672, 1576, 1511, 1457, 1420, 1311, 1262, 1171, 1085, 1031,
835. MS (EI): m/z = 264 (M+). HRMS (EI): m/z calcd for C16H24O3:
264.1725; found: 264.1728.
(E)-1-(4-Methoxyphenyl)-5-methylhex-2-en-1-one (11b). Yield:
1
61.7 mg, 70%; pale yellow oil. H NMR (CDCl3) δ: 7.96 (2H, d, J
Ethyl 2,2-Dimethyl-4-oxo-3,4-dihydroquinoline-1(2H)-carbox-
ylate (16f). Yield: 59.7 mg, 80%; white solid; mp 45−46 °C. 1H
NMR (CDCl3) δ: 7.95 (1H, d, J = 7.6 Hz), 7.45 (1H, td, J = 7.9, 1.4
= 8.7 Hz), 7.06−7.01 (1H, m), 6.95 (2H, d, J = 8.7 Hz), 6.88 (1H, d, J
= 15.1 Hz), 3.88 (3H, s), 2.20 (2H, t, J = 7.2 Hz), 1.86−1.80 (1H, m),
E
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Note
Hz), 7.29 (1H, d, J = 8.2 Hz), 7.08 (1H, t, J = 7.6 Hz), 4.30 (2H, q, J =
7.2 Hz), 2.76 (2H, s), 1.52 (6H, s), 1.35 (3H, t, J = 7.2 Hz). 13C NMR
(CDCl3) δ: 193.7, 155.0, 144.4, 134.4, 126.6, 123.5, 122.6, 122.5, 62.3,
59.1, 53.0, 26.9, 14.2. IR (CHCl3, cm−1) 2983, 1716, 1685, 1604, 1480,
1461, 1372, 1341, 1318, 1286, 1237, 1168, 1125, 1074, 1023. MS (EI):
m/z = 247 (M+). HRMS (EI): m/z calcd for C14H17NO3: 247.1208;
found: 247.1214.
Chem. Soc. Rev. 2007, 36, 55−66. (c) Furstner, A.; Davies, P. W. Chem.
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ACS Catal. 2014, 4, 1911−1925.
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27−38. (b) Okamoto, N.; Ishikura, M.; Yanada, R. Org. Lett. 2013, 15,
2571−2573. (c) Okamoto, N.; Yanada, R. J. Org. Chem. 2012, 77,
3944−3951. (d) Okamoto, N.; Miwa, Y.; Minami, H.; Takeda, K.;
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Takeda, K.; Ishikura, M.; Yanada, R. J. Org. Chem. 2011, 76, 9139−
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7615−7625. (g) Okamoto, N.; Miwa, Y.; Minami, H.; Takeda, K.;
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Ethyl 4′-Oxo-3′,4′-dihydro-1′H-spiro[cyclohexane-1,2′-quino-
line]-1′-carboxylate (16g). Yield: 26.2 mg, 30%; white solid; mp
1
83−85 °C. H NMR (CDCl3) δ: 7.91 (1H, dd, J = 7.6, 1.4 Hz), 7.50
(1H, t, J = 6.9 Hz), 7.34 (1H, d, J = 7.6 Hz), 7.24 (1H, t, J = 7.6 Hz),
4.13 (2H, q, J = 7.2 Hz), 2.82 (2H, s), 2.39 (2H, br s), 1.65−1.39 (8H,
m), 1.21 (3H, t, J = 7.2 Hz). 13C NMR (CDCl3) δ: 195.2, 154.6, 144.2,
133.5, 127.8, 126.1, 125.2, 62.1, 61.8, 50.5, 35.9, 25.4, 22.2, 14.2. IR
(CHCl3, cm−1) 2940, 1712, 1684, 1603, 1478, 1460, 1397, 1371, 1308,
1275, 1117, 1099, 1089, 1038, 1027. MS (EI): m/z = 287 (M+).
HRMS (EI): m/z calcd for C17H21NO3: 287.1521; found: 287.1525.
3-Ethoxy-1-(2-hydroxyphenyl)propan-1-one (17a). Yield: 20.8
mg, 36%; colorless oil. 1H NMR (CDCl3) δ: 12.24 (1H, s), 7.78
(1H, d, J = 8.2 Hz), 7.47 (1H, t, J = 7.6 Hz), 6.98 (1H, d, J = 8.9 Hz),
6.91 (1H, t, J = 7.6 Hz), 3.86 (2H, t, J = 6.5 Hz), 3.54 (2H, q, J = 7.1
Hz), 3.29 (2H, t, J = 6.5 Hz), 1.20 (3H, t, J = 7.1 Hz). 13C NMR
(CDCl3) δ: 204.5, 162.5, 136.5, 130.1, 119.6, 119.0, 118.5, 66.6, 65.3,
38.6, 15.1. IR (CHCl3, cm−1) 3689, 2875, 1640, 1616, 1488, 1449,
1382, 1355, 1289, 1269, 1158, 1107, 988. MS (EI): m/z = 194 (M+).
HRMS (EI): m/z calcd for C11H14O3: 194.0943; found: 194.0937.
Ethyl (2-(3-Ethoxypropanoyl)phenyl)carbamate (17b). Yield: 10.1
mg, 13%; white solid; mp 43−44 °C. 1H NMR (CDCl3) δ: 11.12 (1H,
br s), 8.48 (1H, d, J = 8.2 Hz), 7.91 (1H, d, J = 7.6 Hz), 7.54 (1H, t, J
= 7.2 Hz), 7.06 (1H, t, J = 7.2 Hz), 4.22 (2H, q, J = 7.2 Hz), 3.84 (2H,
t, J = 6.5 Hz), 3.54 (2H, q, J = 7.0 Hz), 3.30 (2H, t, J = 6.5 Hz), 1.32
(3H, t, J = 7.2 Hz), 1.21 (3H, t, J = 7.0 Hz). 13C NMR (CDCl3) δ:
202.3, 153.9, 141.5, 134.9, 130.9, 121.3, 121.3, 119.2, 66.6, 65.6, 61.1,
40.0, 15.1, 14.5. IR (CHCl3, cm−1) 3269, 2981, 2874, 1729, 1653,
1584, 1526, 1454, 1380, 1361, 1306, 1241, 1167, 1107, 1064, 981. MS
(EI): m/z = 265 (M+). HRMS (EI): m/z calcd for C14H19NO4:
265.1314; found: 265.1314.
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■
S
* Supporting Information
1H and 13C NMR spectra for all new compounds. This material
is available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: ryanada@ps.hirokoku-u.ac.jp (R.Y.).
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(11) CCDC 1015377 (4) contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge
from the Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful to Prof. Y. Miwa and Mr. H. Minami at
Hiroshima International University for the X-ray single-crystal
structural analysis. We gratefully acknowledge a Grant-in-Aid
for Scientific Research (C) from JSPS KAKENHI (23590032 to
R.Y.) and a Grant-in-Aid for Young Scientist (B) from JSPS
KAKENHI (25870983 to N.O.).
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