Gold-catalyzed oxidative reactions of propargylic carbonates involving 1,2-carbonate migration: Stereoselective synthesis of functionalized alkenes

Article abstract of DOI:10.1021/jo500573s

A gold-catalyzed oxidative reaction of propargylic carbonates or acetates using 3,5-dichloropyridine as the oxidant has been developed. The reaction provides efficient access to α-functionalized-α,β-unsaturated ketones with excellent regio- and diastereoc

Full text of DOI:10.1021/jo500573s

Article
pubs.acs.org/joc
Gold-Catalyzed Oxidative Reactions of Propargylic Carbonates
Involving 1,2-Carbonate Migration: Stereoselective Synthesis of
Functionalized Alkenes
Ning Sun, Ming Chen, and Yuanhong Liu*
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345
Lingling Lu, Shanghai 200032, People’s Republic of China
S
* Supporting Information
ABSTRACT: A gold-catalyzed oxidative reaction of propargylic carbonates or acetates using 3,5-dichloropyridine as the oxidant
has been developed. The reaction provides efficient access to α-functionalized-α,β-unsaturated ketones with excellent regio- and
diastereocontrol via a regioselective attack of the N-oxide to the gold-activated alkyne followed by a 1,2-carbonate migration. In
addition, the alkene products could be further transformed into the valuable 5-hydroxycyclopent-2-enones via cyclocondensation
with acetone or cyclodimerization under basic conditions.
carbonates, leading to functionalized alkenes.9 In this study, we
report the gold-catalyzed oxidative reaction of propargylic
carbonates using 3,5-dichloropyridine N-oxide as the oxidant,
which provides α-functionalized-α,β-unsaturated ketones with
INTRODUCTION
■
Gold-catalyzed rearrangement reactions of propargylic carbox-
ylates have been proved as useful strategies for rapid access to a
wide range of functionalized structural motifs.1 Two main
competitive processes, namely 1,2-acyloxy migration2 and 3,3-
excellent stereoselectivity. In addition, these alkene products
rearrangement3 via intermediate A, are usually involved, leading
to the formation of vinyl gold-carbenoid B or gold-coordinated
are also applied successfully as diketone equivalents for the
diastereoselective synthesis of cyclopentenones.
carboxyallene C, respectively (Scheme 1). The reaction
RESULTS AND DISCUSSION
patterns are highly dependent on the substituents on either
end of the propargyl moiety. It is widely accepted that terminal
or electron-poor alkynes undergo 1,2-acyloxy migration, while
internal alkynes prefer 3,3-rearrangement, although there are
some exceptions.4 It is noted that compared with the intensive
development of propargyl esters, little attention has been paid
to the gold-catalyzed transformations of propargyl carbonates.5
On the other hand, gold-catalyzed oxidative reactions of alkynes
in the presence of pyridine or quinoline N-oxides provide new
possibilities in the development of novel transformation
reactions.6 During our ongoing project on gold-catalyzed
rearrangement reactions of propargylic carbonates7 and
oxidative reactions of propargylic alcohols,8 we envisioned
that the presence of an oxidant in the reaction system of the
internal propargylic carbonates may hamper the normal 3,3-
rerrangement reaction and trigger a new reaction pathway. That
is, gold catalyzes regioselective generation of α-carbonyl gold
carbenoid E followed by nucleophilic attack of the adjacent
carbonyl group of the carbonate (Scheme 2). This would result
in a formal 1,2-carbonate migration of the internal propargylic
■
To test the feasibility of our hypothesis, methyl (1-phenylhept-
1-yn-3-yl) carbonate 1a was chosen as a model substrate for
optimization of the reaction conditions. The results are shown
in Table 1. In light of the efficient performance of 8-methyl
quinoline N-oxide (2a) in various gold-catalyzed oxidative
reactions,6q−t we first investigated the reaction of 1a with 2a in
the presence of 5 mol % of Johnphos(MeCN)AuSbF6 (A)
(Table 1, entry 1). It was found that α-functionalized-α,β-
unsaturated ketone 3a could be obtained in 70% NMR yield at
50 °C for 4 h in DCE as a mixture of geometric isomers (Z/E =
3.7:1).10 The results indicated that 1,2-carbonate migration
indeed occurred during the reaction process. Switching the
oxidant to 3,5-dichloropyridine N-oxide 2b allowed the
formation of 3a in higher yield of 88% with high Z/E ratio
(28:1, entry 2). Decreasing the amount of 2b to 1.2 equiv
Received: March 11, 2014
Published: April 14, 2014
© 2014 American Chemical Society
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Scheme 1
Scheme 2
Table 1. Optimization Studies for the Formation of Alkene 3a
a
entry
oxidant
catalyst
solvent
temp (°C)
time (h)
yield (%) (Z/E ratio)
1
2a
2b
2b
2c
2d
2e
2b
2b
2b
2b
2b
2b
2b
2b
2b
2b
A
A
A
A
A
A
A
A
A
DCE
DCE
DCE
DCE
DCE
DCE
DCM
THF
Toluene
DCE
DCE
DCE
DCE
DCE
DCE
DCE
50
50
50
50
50
50
50
50
50
50
50
50
50
rt
4
3
70 (3.7:1)
88 (28:1)
2
b
3
5
88 (21:1)
4
10
10
10
5
45 (76:1)
5
29 (>200:1)
14 (>300:1)
6
c
7
93 (22:1)
8
3
93 (46:1)
88 (21:1)
89 (59:1)
89 (52:1)
85 (65:1)
97 (74:1)
9
3
10
11
12
13
14
15
16
PPh3AuCl/AgSbF6
PPh3AuCl/AgOTf
PPh3AuNTf2
2
3
2
IPrAuCl/AgSbF6
IPrAuCl/AgSbF6
PPh3AuCl
2
d
1.5
5
96 (69:1)
e
50
50
−
−
e
AgSbF6
5
a
b
Combined NMR yields. Determined by 1H NMR using CH2Br2 as an internal standard of the crude reaction mixture. A 1.2 equiv of 2b was used.
c
d
e
In a sealed tube. Isolated yield was 95%. Compound 1a was recovered in 99% yield.
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a
Table 2. Synthesis of Functionalized Alkenes 3 through Gold-Catalyzed Oxidative Reactions of 1
a
b
Isolated yields. At 80 °C, 2−5 h.
resulted in a longer reaction time and lower Z/E ratio (entry 3).
Employment of other oxidants such as pyridine N-oxide, 4-
methylpyridine N-oxide, or 4-methoxypyridine N-oxide resulted
in lower yields of 3a (14−45%, entries 4−6), possibly due to
the competitive coordination of the released pyridine
derivatives, which decreased the reactivity of the gold catalyst.11
The solvent effects were also examined. The reactions
proceeded well also in DCM, THF, and toluene, providing
3a in 88−93% yields with the Z/E ratio ranging from 21:1 to
46:1 (entries 7−9). Next, a series of gold catalysts were
screened with the use of 3,5-dichloropyridine N-oxide 2b as the
oxidant. The frequently employed gold(I) complexes such as
Having the optimized reaction conditions in hand, we next
examined the substrate scope using various substituted
propargylic carbonates under the reaction conditions shown
in Table 1, entry 14. The results are shown in Table 2. In all
cases, the desired alkene products 3 were obtained as a single Z-
isomer. We first investigated the effect of the protecting groups
(R) on the carbonate moiety. It was found that in addition to
methyl carbonate, benzyl or tert-butyl carbonates were all
compatible under the catalytic reaction conditions, furnishing
3b and 3c in 80 and 92% yields, respectively. Propargylic
acetate also underwent the reaction smoothly to afford 3d in
97% yield. We next examined the substituent effect (R2) on the
alkyne terminus. Both electron-rich and electron-deficient aryl
substituents (p-OMe, p-Me, p-Cl) were tolerated well during
the reaction, providing the corresponding products 3e−3g in
high yields of 86−90%. A thienyl-substituted alkyne was also
suited, producing 3h in 91% yield. Alkenyl-substituted alkyne
such as a cyclohexenyl-substituted one could also be used in
this reaction, and the desired 3i was obtained in 88% yield. A
range of alkyl-substituted alkynes such as n-butyl, tert-butyl, or
cyclopropyl-substituted ones were efficiently transformed into
alkenes 3j−3l in good yields of 76−84%. It should be noted
PPh3AuCl with different counterions of SbF6 , OTf−, or NTf2
−
−
catalyzed the reaction efficiently to deliver 3a in 85−89% yields
with high stereoselectivity (entries 10−12). To our delight, the
reaction of 1a with IPrAuCl/AgSbF6 [IPr = 1,3-bis(2,6-
diisopropylphenyl)imidazol-2-ylidene] as the catalyst in DCE
led to 97% yield (Z/E = 74:1) at 50 °C or 96% yield (Z/E =
69:1) of 3a at the room temperature (entries 13−14). Control
experiments with PPh3AuCl or AgSbF6 alone did not give the
desired product, and the starting material 1a was recovered in
high yields (entries 15−16).
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Scheme 3
a
Table 3. Cyclocondensation of 3 with Acetone to Cyclopentenones 8
a
b
Isolated yields. A 1.2 equiv of NaOH (10% aq) was used.
that in the cases of n-butyl or tert-butyl-substituted alkynes
higher reaction temperature (80 °C) was required in order to
complete the reaction (for 3j and 3k). We also investigated the
substituent effect at the propargylic position (R1). When R1 is a
methyl group, the reaction proceeded smoothly to give 3m in
93% yield. Sterically more demanding alkyl substitutents such
as isopropyl, cyclohexyl, and even tert-butyl groups at this
position were accommodated well to afford 3n−3p in 60−93%
yields. Benzyl-substituted propargyl carbonate afforded 3q in a
high yield of 93%. Tertiary propargyl carbonate bearing a cyclic
ring at C-1 also participated in this reaction, leading to 3r in
72% yield. When substrate bearing a phenyl group at the
propargylic position such as 1,3-diphenylprop-2-ynyl methyl
carbonate was employed, two major products were isolated in a
high combined yield. However, because these two products
could not be separated from each other by column
chromatography, their exact structures have not been defined
yet. The structure and the geometric configuration of the
functionalized alkenes 3 was unambiguously confirmed by X-
ray crystallographic analysis of 3p.12
A mechanistic proposal for this gold-catalyzed oxidative
reaction of propargylic carbonates is depicted in Scheme 3.
Initially, regioselective attack of 3,5-dichloropyridine N-oxide to
the gold-activated alkyne affords the alkenylgold intermediate 5.
The regioselectivity might be due to the inductive effect of the
carbonate group,9 rendering the β-carbon of the propargylic
carbonate more electrophilic. Fragmentation of 5 gives α-
carbonyl gold carbenoid 6. Subsequent nucleophilic attack of
the carbonyl group on the gold carbenoid13 followed by
elimination of the cationic gold catalyst affords the α-
functionalized-α,β-unsaturated ketone 3.14 In cyclic transition
state 7, R1 and COR2 groups may prefer to be orientated trans
to avoid the large steric effect, while due to the longer Au−
C(sp3) bond,15 the cis orientation of R1 and LAu moiety might
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a
Table 4. Cyclodimerization of 3 Under Basic Conditions
a
b
Isolated yields. A 1.2 equiv of NaOH (10% aq) was used.
Scheme 4
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Scheme 5
Figure 1. Biologically active cyclopentenones with a 5-hydroxy-bearing quaternary stereocenter.
be less steric hindrance, thus leading to the stereoselective
formation of the Z-isomer of 3.
carried out the reaction of 3a with 3.0 equiv of NaOH in
acetone at 0 °C. It was found that 1,2-diketone 10a was formed
in 40% yields, together with 28% of 8a (Scheme 5, eq 1).
Subjection of 10a to the basic conditions in acetone afforded 8a
and 9a in 67 and 10% yields, respectively (Scheme 5, eq 2).
These results well supported our proposed reaction mecha-
nism. 1,2-Diketones are versatile building blocks in organic
synthesis;16 however, the cyclizations of 1,2-diketones to
cyclopentenones are quite rare.17 In an earlier report, upon
acid-promoted reaction of butan-2,3-dione, cyclopentenone of
type 9 via dimerization of butan-2,3-dione was isolated in only a
trace amount.18 In addition, cyclopentenones with a 5-hydroxy-
bearing quaternary stereocenter represent an important
structural motif frequently found in a variety of bioactive
compounds.19 For example, 2-epi-hydroxyisojatrogrossidion
and curcusone D are diterpenoids with carbon skeleton from
Jatropha curcas, which show a potent antiproliferative activity
against L5178Y (mouse lymphoma) cell line.19a 2α-Hydroxyja-
tropholone exhibits an in vitro activity against Plasmodium
falciparum19b (Figure 1). Our method provides an attractive
new route for diverse substituted cyclopentenones in a regio-
and stereoselective manner.
Interestingly, when deprotection of the carbonate group on
functionalized alkene 3 was carried out in acetone using NaOH
as a base, cyclocondensation of 3 with acetone occurred
efficiently to afford 5-hydroxycyclopent-2-enone 812 bearing a
quaternary stereocenter in moderate to good yields. Typical
results are shown in Table 3. Substrates with alkyl groups as R1
and aryl groups as R2 cyclized smoothly, providing 8a−8e in
57−78% yields. Satisfactory results were also obtained when R1
is a normal alkyl group and R2 is a sterically demanding group
such as isopropyl or tert-butyl group, leading to 8f and 8g
regioselectively in 59 and 50% yields, respectively.
To our surprise, when the reaction was carried out in
CH3CN, a cyclodimerization of 3 occurred smoothly to afford
cyclopentenone 9 with an acyl functional group at the C-3
position (Table 4). The reaction is highly stereoselective, as
only trans- diastereomer was obtained in all cases. The
stereochemistry of cyclopentenones 9 was verified unambigu-
ously by X-ray crystallography of 9b.12 The method is
applicable to a range of suitably substituted alkene 3, resulting
in 45−64% yields of 9a−9f.
A possible reaction mechanism for the formation of
cyclopentenones 8 and 9 is shown in Scheme 4. The reaction
starts with hydrolysis of the carbonate moiety of 3 to give 1,2-
diketone 10. Nucleophilic attack of the carboanion derived
from acetone on the COR2 moiety produces the intermediate
11, which can be deprotonated by base to generate a stable
enough carboanion 12 due to the presence of an adjacent
carbonyl group. This is followed by intramolecular nucleophilic
addition and dehydration to afford cyclopentenone 8. Similarly,
in the absence of acetone, attack of carboanion derived from
diketone 10 gives intermediate 14 or its diastereomer 15. Fast
epimerization of 14 to more stable 15 under basic conditions
might occur, which undergoes intramolecular nucleophilic
addition and dehydration leading to cyclopentenone 9 as a
single diastereomer. To isolate the possible intermediate, we
CONCLUSION
■
In summary, we have developed a gold-catalyzed oxidative
reaction of propargylic carbonates or acetates using 3,5-
dichloropyridine N-oxide as the oxidant. The reaction provides
efficient access to α-functionalized-α,β-unsaturated ketones
with excellent regio- and diastereocontrol via a regioselective
attack of the N-oxide followed by a 1,2-carbonate migration. In
addition, the alkene products could be further transformed into
valuable cyclopentenones bearing a quaternary stereocenter via
cyclocondensation with acetone or cyclodimerization under
basic conditions.
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tert-Butyl (1-Phenylhept-1-yn-3-yl) Carbonate (1c). Three equiv-
alent of Et3N and 2 equiv of (Boc)2O were used. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a yellow liquid in 94% (2 mmol
EXPERIMENTAL SECTION
■
General Methods. All reactions were carried out under argon
unless noted. DCM and DCE were distilled from CaH2. Toluene was
distilled from sodium and benzophenone. THF was distilled from
sodium and benzophenone or purified using solvent purification
system (for the synthesis of substrates). MeCN was purified using a
solvent purification system. Unless noted, all commercial reagents
were used without further purification. 1,3-Bis(2,6-di-
isopropylphenyl)imidazole-2-ylidene gold(I) chloride and
(acetonitrile)[(2-biphenyl)di-tert-butylphosphine]gold(I) hexafluor-
oantimonate were purchased from Chemical Company. PPh3PAuCl20
1
scale, 542 mg) isolated yield from 1-phenylhept-1-yn-3-ol. H NMR
(400 MHz, CDCl3, Me4Si) δ 7.44−7.42 (m, 2H), 7.29−7.26 (m, 3H),
5.41 (t, J = 6.8 Hz, 1H), 1.92−1.84 (m, 2H), 1.54−1.47 (m, 11H),
1.43−1.34 (m, 2H), 0.93 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 152.6, 131.7, 128.4, 128.1, 122.3, 86.2, 85.5, 82.3, 67.4, 34.6,
27.6, 27.1, 22.1, 13.8; IR (neat) 2957, 2932, 2864, 2227, 1740, 1490,
1458, 1444, 1394, 1369, 1271, 1251, 1158, 1112, 1083, 1034, 986, 965,
844, 791, 755, 690 cm−1. HRMS (EI) calcd for C18H24O3, 288.1725;
found, 288.1730.
21
and PPh3AuNTf2 were prepared according to the published
methods. 8-Methylquinoline N-oxide was prepared according to the
1-Phenylhept-1-yn-3-yl Acetate (1d). Three equivalent of Et3N
and 2 equiv of (Ac)2O were used. Column chromatography on silica
gel (eluent: petroleum ether/ethyl acetate, 20:1) afforded the title
product as a light yellow liquid in 93% (2 mmol scale, 428 mg)
isolated yield from 1-phenylhept-1-yn-3-ol. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.45−7.42 (m, 2H), 7.30−7.26 (m, 3H), 5.60 (t, J =
6.8 Hz, 1H), 2.10 (s, 3H), 1.88−1.82 (m, 2H), 1.52−1.45 (m, 2H),
1.43−1.34 (m, 2H), 0.93 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 169.9, 131.7, 128.4, 128.1, 122.2, 86.6, 85.0, 64.4, 34.5, 27.1,
22.2, 20.9, 13.8; IR (neat) 3056, 2957, 2863, 2227, 2198, 1741, 1668,
1598, 1490, 1465, 1443, 1370, 1225, 1112, 1070, 1047, 1016, 994, 953,
915, 862, 798, 755, 690 cm−1. HRMS (ESI) calcd for C15H22NO2 [M
+ NH4]+, 248.1645; found, 248.1650. 1d is a known compound.23
1-(4-Methoxyphenyl)hept-1-yn-3-yl Methyl Carbonate (1e). Col-
umn chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 20:1) afforded the title product as a yellow liquid in 91% (5
published method.22
1H NMR spectra were recorded at 400 MHz, and 13C NMR spectra
1
were recorded at 100 MHz, in CDCl3 (containing 0.03% TMS). H
NMR spectra were recorded with tetramethylsilane (δ = 0.00 ppm) as
internal reference; 13C NMR spectra were recorded with CDCl3 (δ =
77.00 ppm) as internal reference. High-resolution mass spectrometry
was performed on a mass spectrometer with a TOF (for EI or ESI)
analyzer. The single crystals of 3p and 8b were obtained after
recrystallization from the mixed solvent of hexane and dichloro-
methane, and the single crystal of 9b was obtained after
recrystallization from the mixed solvent of toluene and hexane.
Synthesis of Propargyl Carbonates 1. Typical Procedure for
the Synthesis of Methyl(1-phenylhept-1-yn-3-yl)carbonate (1a). To
a solution of ethynylbenzene (1.43 mL, 13 mmol) in THF (35.0 mL)
was added n-BuLi (4.8 mL, 12 mmol, 2.5 M in hexanes) at −78 °C.
After the solution stirred at the same temperature for 15 min,
valeraldehyde (1.06 mL, 10 mmol, dissolved in 5 mL THF) was added
at −78 °C. The dry ice/acetone bath was then removed. The reaction
mixture was warmed to room temperature and stirred for 2 h. Then,
the resulting mixture was quenched with saturated ammonium
chloride solution, extracted with ethyl acetate, and dried over
anhydrous Na2SO4. The solvent was evaporated under the reduced
pressure, and the residue was used directly for the next step.
To a solution of the above alcohol in DCM (40 mL) were added
pyridine (8 mL, 100 mmol) and DMAP (122 mg, 1 mmol). Methyl
chloroformate (3.85 mL, 50 mmol) was added to the mixture at 0 °C.
The resulting solution was warmed to room temperature and stirred
for 2 h. Then, the mixture was quenched with saturated ammonium
chloride solution, extracted with dichloromethane, and dried over
anhydrous Na2SO4. The solvent was evaporated under reduced
pressure, and the residue was purified by chromatography on silica gel
(eluent: petroleum ether/ethyl acetate, 20:1) to afford propargyl
carbonate 1a in 90% isolated yield (2.228 g) over two steps as a light
yellow oil.
1
mmol scale, 1.257 g) isolated yield over two steps. H NMR (400
MHz, CDCl3, Me4Si) δ 7.37−7.35 (m, 2H), 6.82−6.79 (m, 2H), 5.44
(t, J = 6.4 Hz, 1H), 3.78 (s, 3H), 3.75 (s, 3H), 1.93−1.83 (m, 2H),
1.53−1.46 (m, 2H), 1.42−1.33 (m, 2H), 0.93 (t, J = 7.2 Hz, 3H); 13C
NMR (100 MHz, CDCl3) δ 159.6, 154.8, 133.0, 113.9, 113.6, 85.7,
84.3, 68.5, 54.8, 54.4, 34.4, 26.8, 21.9, 13.6; IR (neat) 2956, 2863,
2227, 1747, 1606, 1571, 1509, 1441, 1342, 1244, 1172, 1108, 1030,
992, 933, 874, 831, 805, 789 cm−1. HRMS (EI) calcd for C16H20O4,
276.1362; found, 276.1365.
Methyl (1-(p-Tolyl)hept-1-yn-3-yl) Carbonate (1f). Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a yellow liquid in 89% (5 mmol
1
scale, 1.158 g) isolated yield over two steps. H NMR (400 MHz,
CDCl3, Me4Si) δ 7.33 (d, J = 8.0 Hz, 2H), 7.09 (d, J = 8.0 Hz, 2H),
5.45 (t, J = 6.4 Hz, 1H), 3.80 (d, J = 1.2 Hz, 3H), 2.32 (s, 3H), 1.96−
1.83 (m, 2H), 1.54−1.47 (m, 2H), 1.43−1.34 (m, 2H), 0.93 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 155.0, 138.7, 131.6, 128.9,
119.0, 86.1, 85.1, 68.7, 54.7, 34.6, 27.0, 22.1, 21.3, 13.8; IR (neat)
2956, 2864, 2229, 1748, 1510, 1441, 1353, 1254, 1114, 1045, 1021,
994, 946, 933, 882, 816, 789, 735 cm−1. HRMS (EI) calcd for
C16H20O3, 260.1412; found, 260.1413.
Methyl(1-phenylhept-1-yn-3-yl)carbonate (1a). 1H NMR (400
MHz, CDCl3, Me4Si) δ 7.45−7.42 (m, 2H), 7.30−7.27 (m, 3H), 5.46
(t, J = 6.8 Hz, 1H), 3.79 (s, 3H), 1.93−1.87 (m, 2H), 1.53−1.47 (m,
2H), 1.41−1.35 (m, 2H), 0.93 (t, J = 7.2 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 154.9, 131.7, 128.5, 128.1, 122.0, 85.9, 85.7, 68.5,
54.6, 34.5, 26.9, 22.1, 13.7; IR (neat) 2957, 2863, 2231, 2198, 1748,
1490, 1442, 1342, 1254, 1114, 1070, 1027, 1004, 948, 933, 875, 790,
756, 690 cm−1. HRMS (EI) calcd for C15H18O3, 246.1256; found,
246.1257.
1-(4-Chlorophenyl)hept-1-yn-3-yl Methyl Carbonate (1g). Col-
umn chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 20:1) afforded the title product as a yellow liquid in 88% (5
1
mmol scale, 1.235 g) isolated yield over two steps. H NMR (400
MHz, CDCl3, Me4Si) δ 7.37−7.35 (m, 2H), 7.28−7.25 (m, 2H), 5.45
(t, J = 6.8 Hz, 1H), 3.81 (s, 3H), 1.93−1.85 (m, 2H), 1.54−1.46 (m,
2H), 1.42−1.33 (m, 2H), 0.93 (t, J = 7.2 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 154.7, 134.4, 132.8, 128.3, 120.4, 86.7, 84.6, 68.2,
54.5, 34.3, 26.8, 22.0, 13.6; IR (neat) 2957, 2863, 2231, 1899, 1748,
1489, 1441, 1343, 1253, 1114, 1091, 1046, 1015, 993, 948, 933, 882,
827, 789, 763 cm−1. HRMS (EI) calcd for C15H17O3Cl, 280.0866;
found, 280.0864.
Benzyl(1-phenylhept-1-yn-3-yl)carbonate (1b). Three equivalent
of ClCO2Bn was used. Column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 20:1) afforded the title product as a
yellow liquid in 93% (2 mmol scale, 600 mg) isolated yield from 1-
1
phenylhept-1-yn-3-ol. H NMR (400 MHz, CDCl3, Me4Si) δ 7.48−
7.32 (m, 10H), 5.52 (t, J = 6.4 Hz, 1H), 5.23 (s, 2H), 1.98−1.92 (m,
2H), 1.59−1.51 (m, 2H), 1.46−1.37 (m, 2H), 0.97 (t, J = 7.6 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 154.3, 135.0, 131.7, 128.54, 128.45,
128.4, 128.2, 128.1, 122.1, 86.0, 85.8, 69.7, 68.7, 34.5, 27.0, 22.1, 13.8;
IR (neat) 3033, 2956, 2863, 2231, 1952, 1744, 1598, 1490, 1456, 1383,
1235, 1113, 1070, 1027, 1003, 940, 909, 881, 788, 755, 691 cm−1.
HRMS (ESI) calcd for C21H26NO3 [M + NH4]+, 340.1907; found,
340.1908.
Methyl (1-(Thiophen-2-yl)hept-1-yn-3-yl) Carbonate (1h). Col-
umn chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 20:1) afforded the title product as a yellow liquid in 92% (5
mmol scale, 1.16 g) isolated yield over two steps. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.26 (dd, J = 5.2, 1.2 Hz, 1H), 7.22 (dd, J = 3.6, 1.2
Hz, 1H), 6.95 (dd, J = 5.2, 3.6 Hz, 1H), 5.45 (t, J = 6.8 Hz, 1H), 3.81
(s, 3H), 1.95−1.85 (m, 2H), 1.53−1.45 (m, 2H), 1.43−1.34 (m, 2H),
0.93 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 154.9, 132.7,
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1
127.6, 126.8, 121.9, 89.7, 79.3, 68.6, 54.8, 34.4, 26.9, 22.1, 13.8; IR
(neat) 3106, 2956, 2863, 2225, 1747, 1440, 1360, 1340, 1256, 1192,
1113, 1038, 946, 895, 848, 789, 701 cm−1. HRMS (EI) calcd for
C13H16O3S, 252.0820; found, 252.0821.
mmol scale, 1.212 g) isolated yield over two steps. H NMR (400
MHz, CDCl3, Me4Si) δ 7.45−7.42 (m, 2H), 7.31−7.28 (m, 3H), 5.30
(d, J = 5.6 Hz, 1H), 3.80 (s, 3H), 1.95−1.67 (m, 7H), 1.29−1.16 (m,
4H); 13C NMR (100 MHz, CDCl3) δ 155.0, 131.7, 128.4, 128.0,
122.1, 86.6, 84.7, 72.7, 54.7, 42.0, 28.3, 27.9, 26.0, 25.55, 25.49. The
spectroscopic data are in agreement with that previously reported.24
4,4-Dimethyl-1-phenylpent-1-yn-3-yl Methyl Carbonate (1p).
Column chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 20:1) afforded the title product as a light yellow solid in 82%
(5 mmol scale, 1.011 g) isolated yield over two steps; mp 64−66 °C;
1H NMR (400 MHz, CDCl3, Me4Si) δ 7.45−7.43 (m, 2H), 7.30−7.27
(m, 3H), 5.19 (s, 1H), 3.81 (s, 3H), 1.10 (s, 9H); 13C NMR (100
MHz, CDCl3) δ 155.3, 131.7, 128.5, 128.1, 122.2, 86.5, 84.7, 76.5,
54.8, 35.5, 25.4. IR (neat): 2966, 2931, 2866, 2198, 1748, 1664, 1598,
1490, 1476, 1435, 1396, 1367, 1343, 1309, 1254, 1190, 1099, 1072,
1049, 1028, 994, 953, 933, 891, 791, 761, 693 cm−1; HRMS (ESI)
calcd for C15H19O3 [M + H]+, 247.1329; found, 247.1332. 1p is a
known compound.25
1-(Cyclohex-1-en-1-yl)hept-1-yn-3-yl Methyl Carbonate (1i).
Column chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 20:1) afforded the title product as a yellow liquid in 93% (5
1
mmol scale, 1.162 g) isolated yield over two steps. H NMR (400
MHz, CDCl3, Me4Si) δ 6.13−6.11 (m, 1H), 5.33 (t, J = 6.8 Hz, 1H),
3.79 (s, 3H), 2.12−2.06 (m, 4H), 1.88−1.74 (m, 2H), 1.65−1.54 (m,
4H), 1.48−1.41 (m, 2H), 1.38−1.31 (m, 2H), 0.92 (t, J = 7.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 154.9, 135.8, 119.7, 87.7, 83.0, 68.7,
54.6, 34.6, 28.8, 26.9, 25.4, 22.1, 22.0, 21.2, 13.7; IR (neat) 3483, 2934,
2864, 2212, 1748, 1679, 1442, 1345 1259, 1113, 1039, 933, 889, 845,
789 cm−1. HRMS (EI) calcd for C15H22O3, 250.1569; found,
250.1572.
Methyl Undec-6-yn-5-yl Carbonate (1j). Column chromatography
on silica gel (eluent: petroleum ether/ethyl acetate, 20:1) afforded the
title product as a yellow liquid in 91% (5 mmol scale, 1.028 g) isolated
yield over two steps. 1H NMR (400 MHz, CDCl3, Me4Si) δ 5.20 (tt, J
= 6.4, 2.0 Hz, 1H), 3.79 (s, 3H), 2.21 (td, J = 7.2, 2.0 Hz, 2H), 1.85−
1.71 (m, 2H), 1.52−1.30 (m, 8H), 0.93−0.89 (m, 6H); 13C NMR
(100 MHz, CDCl3) δ 155.0, 86.9, 76.9, 68.6, 54.5, 34.7, 30.4, 26.9,
22.1, 21.7, 18.2, 13.7, 13.4; IR (neat) 2957, 2933, 2864, 2238, 1749,
1442, 1343, 1258, 1161, 1108, 1030, 937, 887, 790, 737 cm−1. HRMS
(EI) calcd for C13H22O3, 226.1569; found, 226.1572.
1,4-Diphenylbut-3-yn-2-yl Methyl Carbonate (1q). Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a yellow liquid in 86% (5 mmol
1
scale, 1.211 g) isolated yield over two steps. H NMR (400 MHz,
CDCl3, Me4Si) δ 7.40−7.38 (m, 2H), 7.33−7.26 (m, 8H), 5.62 (t, J =
6.8 Hz, 1H), 3.78 (s, 3H), 3.15−3.26 (m, 2H); 13C NMR (100 MHz,
CDCl3) δ 154.8, 135.6, 131.8, 129.7, 128.7, 128.4, 128.2, 127.0, 122.0,
87.0, 85.3, 69.1, 54.9, 41.3; IR (neat) 3031, 2956, 2854, 2228, 1747,
1598, 1491, 1441, 1355, 1249, 1192, 1104, 1081, 1070, 1028, 1009,
995, 955, 931, 851, 789, 755, 690 cm−1. HRMS (ESI) calcd for
2,2-Dimethylnon-3-yn-5-yl Methyl Carbonate (1k). Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a yellow liquid in 96% (5 mmol
C18H20NO3 [M + NH ]+, 298.1438; found, 298.1437.
1
4
scale, 1.087 g) isolated yield over two steps. H NMR (400 MHz,
Synthesis of Methyl 1-(Phenylethynyl)cyclohexyl Carbonate (1r).
To a solution of ethynylbenzene (0.71 mL, 6.5 mmol) in THF (15.0
mL) was added n-BuLi (2.4 mL, 6 mmol, 2.5 M in hexanes) at −78
°C. After the solution stirred at the same temperature for 15 min,
cyclohexanone (0.52 mL, 5 mmol, dissolved in 5 mL of THF) was
added at −78 °C and stirred at the same temperature for 2 h. Then,
methyl chloroformate (1.15 mL, 15 mmol) was added at −78 °C. The
dry ice/acetone bath was then removed. The reaction mixture was
warmed to room temperature and stirred for 2 h. The resulting
mixture was quenched with saturated ammonium chloride solution at
0 °C, extracted with ethyl acetate, and dried over anhydrous Na2SO4.
The solvent was evaporated under reduced pressure, and the residue
was purified by chromatography on silica gel (eluent: petroleum ether/
ethyl acetate, 30:1) to afford 1r in 81% isolated yield (1.05 g) over two
steps as a yellow oil. 1H NMR (400 MHz, CDCl3, Me4Si) δ 7.46−7.42
(m, 2H), 7.30−7.26 (m, 3H), 3.75 (s, 3H), 2.28−2.25 (m, 2H), 1.97−
1.89 (m, 2H), 1.73−1.52 (m, 5H), 1.39−1.30 (m, 1H); 13C NMR
(100 MHz, CDCl3) δ 153.1, 131.6, 128.2, 128.0, 122.4, 88.2, 86.5,
77.9, 54.0, 36.9, 24.9, 22.6. The spectroscopic data are in agreement
with that previously reported.26
Typical Procedure for the Synthesis of α-Functionalized-α,β-
Unsaturated Ketones 3a. In a glovebox, to a Schlenk tube was
added AgSbF6 (5.2 mg, 0.015 mmol). The Schlenk tube was then
removed from the glovebox, IPrAuCl (9.3 mg, 0.015 mmol) and DCE
(1 mL) were added successively, and the mixture was stirred at room
temperature for 10 min. Then 3,5-dichloropyridine N-oxide 2b (98
mg, 0.6 mmol) was added, followed by the addition of a DCE solution
of 1a (74 mg, 0.3 mmol in 2 mL of DCE). After the reaction mixture
was stirred at room temperature for 1.5 h, the solvent was evaporated
under reduced pressure, and the residue was purified by column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) to afford 3a (74.7 mg, 95%) as a yellow oil.
CDCl3, Me4Si) δ 5.22 (t, J = 6.8 Hz, 1H), 3.79 (s, 3H), 1.83−1.69 (m,
2H), 1.46−1.31 (m, 4H), 1.21 (s, 9H), 0.92 (t, J = 7.2 Hz, 3H); 13C
NMR (100 MHz, CDCl3) δ 154.9, 94.9, 75.3, 68.5, 54.5, 34.8, 30.6,
27.2, 26.9, 22.0, 13.7; IR (neat) 2958, 2866, 2242, 1749, 1442, 1363,
1253, 1117, 1007, 935, 879, 791 cm−1. HRMS (EI) calcd for
C13H22O3, 226.1569; found, 226.1565.
1-Cyclopropylhept-1-yn-3-yl Methyl Carbonate (1l). Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a light yellow liquid in 97% (5 mmol
1
scale, 1.018 g) isolated yield over two steps. H NMR (400 MHz,
CDCl3, Me4Si) δ 5.16 (td, J = 6.8, 2.0 Hz, 1H), 3.78 (s, 3H), 1.82−
1.68 (m, 2H), 1.45−1.31 (m, 4H), 1.29−1.22 (m, 1H), 0.91 (t, J = 7.2
Hz, 3H), 0.80−0.75 (m, 2H), 0.69−0.65 (m, 2H); 13C NMR (100
MHz, CDCl3) δ 154.7, 89.7, 71.9, 68.3, 54.3, 34.5, 26.8, 21.9, 13.5,
7.94, 7.92, −0.9; IR (neat) 3011, 2957, 2864, 2246, 1747, 1441, 1364,
1342, 1256, 1164, 1112, 1054, 1028, 935, 887, 813, 790 cm−1. HRMS
(EI) calcd for C12H18O3, 210.1256; found, 210.1251.
Methyl 4-Phenylbut-3-yn-2-yl Carbonate (1m). Column chroma-
tography on silica gel (eluent: petroleum ether/ethyl acetate, 10:1)
afforded the title product as a light yellow liquid in 99% (10 mmol
1
scale, 2.026 g) isolated yield over two steps. H NMR (400 MHz,
CDCl3, Me4Si) δ 7.45−7.43 (m, 2H), 7.32−7.27 (m, 3H), 5.56 (q, J =
6.8 Hz, 1H), 3.81 (s, 3H), 1.63 (d, J = 6.8 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 154.8, 131.8, 128.6, 128.2, 122.0, 86.5, 85.3, 64.8,
54.8, 21.4; IR (neat) 3057, 2992, 2957, 2236, 1746, 1598, 1490, 1441,
1377, 1346, 1314, 1250, 1108, 1080, 1020, 940, 916, 858, 790, 756,
690 cm−1. HRMS (EI) calcd for C12H12O3, 204.0786; found,
204.0788.
Methyl (4-Methyl-1-phenylpent-1-yn-3-yl) Carbonate (1n). Col-
umn chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 30:1) afforded the title product as a yellow liquid in 91% (5
1
mmol scale, 1.057 g) isolated yield over two steps. H NMR (400
(Z)-Methyl (1-Oxo-1-phenylhept-2-en-2-yl) Carbonate (3a). 1H
NMR (400 MHz, CDCl3, Me4Si) δ 7.77 (d, J = 7.6 Hz, 2H), 7.56 (t, J
= 7.2 Hz, 1H), 7.45 (t, J = 7.6 Hz, 2H), 6.16 (t, J = 7.6 Hz, 1H), 3.85
(s, 3H), 2.34 (q, J = 7.2 Hz, 2H), 1.49−1.41 (m, 2H), 1.40−1.31 (m,
2H), 0.91 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 189.5,
153.3, 145.4, 136.7, 134.8, 132.3, 129.2, 128.2, 55.5, 30.2, 25.7, 22.3,
13.6. IR (neat): 3059, 2958, 2930, 2860, 1760, 1663, 1598, 1579, 1441,
1320, 1250, 1163, 1027, 1001, 940, 799, 781, 746, 698, 660 cm−1;
MHz, CDCl3, Me4Si) δ 7.45−7.43 (m, 2H), 7.31−7.28 (m, 3H), 5.31
(d, J = 5.2 Hz, 1H), 3.81 (d, J = 0.8 Hz, 3H), 2.19−2.10 (m, 1H), 1.10
(dd, J = 12.4, 6.4 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ 155.1,
131.8, 128.5, 128.1, 122.1, 86.6, 84.4, 73.5, 54.8, 32.6, 18.1, 17.4. The
spectroscopic data are in agreement with that previously reported.24
1-Cyclohexyl-3-phenylprop-2-yn-1-yl Methyl Carbonate (1o).
Column chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 30:1) afforded the title product as a yellow liquid in 89% (5
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HRMS (ESI) calcd for C15H19O4 [M + H]+ 263.1278; found,
263.1278.
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 86% (71 mg)
1
Synthesis of the (E)-Isomer of 3a. To a solution of 1a (148 mg, 0.6
mmol) in DCE (6 mL) was added 8-methylquinoline N-oxide (115
mg, 0.72 mmol) and catalyst A (23.2 mg, 0.03 mmol). After the
reaction mixture was stirred at 50 °C for 4 h, the solvent was
evaporated under reduced pressure, and the residue was purified by
column chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 35:1) to afford E-3a (21 mg, 13%) and Z-3a (89 mg, 57%) as a
yellow oil. For the characterization data of E-3a: 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.90−7.87 (m, 2H), 7.56 (t, J = 7.2 Hz, 1H), 7.46 (t,
J = 7.6 Hz, 2H), 6.01 (t, J = 8.4 Hz, 1H), 3.71 (s, 3H), 2.15 (q, J = 7.6
Hz, 2H), 1.42−1.35 (m, 2H), 1.30−1.21 (m, 2H), 0.82 (t, J = 7.2 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 190.0, 153.9, 143.7, 137.0,
133.1, 129.2, 129.0, 128.5, 55.4, 31.2, 26.4, 22.1, 13.7. HRMS (ESI)
calcd for C15H19O4 [M + H]+, 263.1278; found, 263.1276.
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.69 (d, J = 8.0
Hz, 2H), 7.25 (d, J = 8.0 Hz, 2H), 6.14 (t, J = 7.6 Hz, 1H), 3.84 (s,
3H), 2.41 (s, 3H), 2.33 (q, J = 7.2 Hz, 2H), 1.48−1.41 (m, 2H), 1.40−
1.31 (m, 2H), 0.91 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3)
δ 189.2, 153.3, 145.4, 143.2, 134.0, 133.9, 129.4, 128.9, 55.5, 30.2, 25.6,
22.3, 21.5, 13.6; IR (neat) 2958, 2929, 2861, 1761, 1660, 1607, 1441,
1380, 1314, 1251, 1181, 1163, 1114, 1037, 988, 935, 833, 781, 766,
685 cm−1. HRMS (ESI) calcd for C16H21O4 [M + H]+, 277.1434;
found, 277.1435.
(Z)-1-(4-Chlorophenyl)-1-oxohept-2-en-2-yl Methyl Carbonate
(3g). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a light yellow solid in 90% (80 mg)
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.74−7.72 (m,
2H), 7.45−7.42 (m, 2H), 6.13 (t, J = 7.6 Hz, 1H), 3.85 (s, 3H), 2.34
(q, J = 7.2 Hz, 2H), 1.49−1.42 (m, 2H), 1.40−1.31 (m, 2H), 0.91 (t, J
= 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 188.3, 153.3, 145.2,
138.8, 135.0, 134.7, 130.6, 128.6, 55.6, 30.2, 25.7, 22.3, 13.6; IR (neat)
2959, 2931, 2873, 1761, 1667, 1589, 1488, 1441, 1400, 1252, 1165,
1090, 1014, 988, 935, 842, 775, 735, 703, 680 cm−1. HRMS (ESI)
calcd for C15H18ClO4 [M + H]+, 297.0888; found, 297.0887.
(Z)-Methyl (1-Oxo-1-(thiophen-2-yl)hept-2-en-2-yl) Carbonate
(3h). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 91% (73.5 mg)
isolated yield. 1H NMR (400 MHz, CDCl3, Me4Si) δ 7.80 (dd, J = 3.6,
0.8 Hz, 1H), 7.68 (dd, J = 4.8, 0.8 Hz, 1H), 7.14 (dd, J = 4.8 Hz, 4.0
Hz, 1H), 6.44 (t, J = 7.6 Hz, 1H), 3.85 (s, 3H), 2.33 (q, J = 7.6 Hz,
2H), 1.53−1.47 (m, 2H), 1.45−1.34 (m, 2H), 0.93 (t, J = 7.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 180.1, 153.2, 144.9, 141.3, 134.0,
(Z)-Benzyl (1-Oxo-1-phenylhept-2-en-2-yl) Carbonate (3b). Re-
actions were carried out on a 0.3 mmol scale. Column chromatography
on silica gel (eluent: petroleum ether/ethyl acetate, 30:1) afforded the
1
title product as a yellow liquid in 80% (81.6 mg) isolated yield. H
NMR (400 MHz, CDCl3, Me4Si) δ 7.76−7.74 (m, 2H), 7.55−7.52 (m,
1H), 7.44−7.40 (m, 2H), 7.36−7.32 (m, 5H), 6.16 (t, J = 7.6 Hz, 1H),
5.20 (s, 2H), 2.31 (q, J = 7.6 Hz, 2H), 1.46−1.40 (m, 2H), 1.38−1.30
(m, 2H), 0.88 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
189.4, 152.7, 145.6, 136.7, 134.59, 134.56, 132.3, 129.1, 128.53,
128.50, 128.2, 128.1, 70.4, 30.2, 25.7, 22.3, 13.6; IR (neat) 3062, 3033,
2958, 2929, 2872, 1758, 1664, 1598, 1498, 1449, 1380, 1319, 1226,
1165, 1112, 1026, 1001, 937, 908, 779, 745, 696, 662 cm−1. HRMS
(ESI) calcd for C21H26NO4 [M + NH 4]+, 356.1856; found, 356.1854.
(Z)-tert-Butyl (1-Oxo-1-phenylhept-2-en-2-yl) Carbonate (3c).
Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 92% (84 mg)
133.5, 132.3, 127.9, 55.6, 30.2, 25.6, 22.2, 13.6; IR (neat) 2958, 2930,
2860, 1761, 1638, 1514, 1440, 1412, 1356, 1251, 1228, 1158, 1083,
1039, 946, 905, 853, 782, 768, 726, 702, 666 cm−1. HRMS (ESI) calcd
for C13H17O4S [M + H]+, 269.0842; found, 269.0843.
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.79−7.76 (m,
2H), 7.56−7.52 (m, 1H), 7.46−7.42 (m, 2H), 6.11 (t, J = 7.6 Hz, 1H),
2.34 (q, J = 7.2 Hz, 2H), 1.46−1.30 (m, 13H), 0.91 (t, J = 7.2 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 189.9, 150.8, 145.6, 136.9,
133.6, 132.2, 129.1, 128.2, 83.8, 30.3, 27.4, 25.6, 22.3, 13.7; IR (neat)
2960, 2932, 2873, 1753, 1693, 1667, 1599, 1581, 1450, 1396, 1371,
1318, 1270, 1251, 1143, 1070, 1024, 1001, 945, 856, 783, 761, 702
cm−1. HRMS (ESI) calcd for C18H28NO4 [M + NH4]+, 322.2013;
found, 322.2017.
(Z)-1-(Cyclohex-1-en-1-yl)-1-oxohept-2-en-2-yl Methyl Carbo-
nate (3i). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 88% (70.2 mg)
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 6.73−6.71 (m,
1H), 6.07 (t, J = 8.0 Hz, 1H), 3.84 (s, 3H), 2.30−2.24 (m, 6H), 1.70−
1.62 (m, 4H), 1.49−1.42 (m, 2H), 1.41−1.31 (m, 2H), 0.92 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 190.4, 153.4, 145.0, 140.7,
137.4, 131.3, 55.4, 30.3, 25.7, 25.4, 23.8, 22.3, 21.7, 21.4, 13.6; IR
(neat) 3514, 2933, 2872, 1760, 1715, 1652, 1442, 1379, 1251, 1145,
1038, 947, 781 cm−1.; HRMS (ESI) calcd for C15H23O4 [M + H]+,
267.1591; found, 267.1587.
(Z)-1-Oxo-1-phenylhept-2-en-2-yl Acetate (3d). Reactions were
carried out on a 0.3 mmol scale. Column chromatography on silica gel
(eluent: petroleum ether/ethyl acetate, 30:1) afforded the title product
as a yellow liquid in 97% (72 mg) isolated yield. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.77−7.75 (m, 2H), 7.56−7.52 (m, 1H), 7.45−7.42
(m, 2H), 6.15 (t, J = 7.6 Hz, 1H), 2.28 (q, J = 7.6 Hz, 2H), 2.26 (s,
3H), 1.48−1.40 (m, 2H), 1.40−1.31 (m, 2H), 0.91 (t, J = 7.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 189.8, 168.7, 145.6, 136.9, 134.9,
132.2, 129.2, 128.1, 30.2, 25.8, 22.3, 20.2, 13.6; IR (neat) 3055, 2957,
2930, 2861, 1758, 1663, 1598, 1578, 1447, 1370, 1319, 1272, 1199,
1159, 1105, 1076, 1044, 1013, 961, 930, 899, 762, 707, 667 cm−1.
HRMS (ESI) calcd for C15H19O3 [M + H]+, 247.1329; found,
247.1330.
(Z)-Methyl (7-Oxoundec-5-en-6-yl) Carbonate (3j). Reactions
were carried out on a 0.3 mmol scale. The reaction was carried out
at 80 °C. Column chromatography on silica gel (eluent: petroleum
ether/ethyl acetate, 30:1) afforded the title product as a yellow liquid
in 84% (61.3 mg) isolated yield. 1H NMR (400 MHz, CDCl3, Me4Si)
δ 6.45 (t, J = 7.6 Hz, 1H), 3.86 (s, 3H), 2.63 (t, J = 7.2 Hz, 2H), 2.26
(q, J = 7.2 Hz, 2H), 1.66−1.59 (m, 2H), 1.50−1.42 (m, 2H), 1.39−
1.31 (m, 4H), 0.92 (t, J = 7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3)
δ 193.8, 153.3, 145.8, 131.9, 55.5, 36.7, 30.2, 26.2, 25.6, 22.3, 22.2,
13.7, 13.6; IR (neat) 2959, 2933, 2873, 1764, 1688, 1442, 1380, 1250,
1129, 1004, 947, 781 cm−1. HRMS (ESI) calcd for C13H23O4 [M +
H]+, 243.1591; found, 243.1591.
(Z)-1-(4-Methoxyphenyl)-1-oxohept-2-en-2-yl Methyl Carbonate
(3e). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 90% (79.3 mg)
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.82−7.80 (m,
(Z)-2,2-Dimethyl-3-oxonon-4-en-4-yl Methyl Carbonate (3k).
Reactions were carried out on a 0.3 mmol scale. The reaction was
carried out at 80 °C. Column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 30:1) afforded the title product as a
2H), 6.95−6.93 (m, 2H), 6.10 (t, J = 7.6 Hz, 1H), 3.86 (s, 3H), 3.84
(s, 3H), 2.33 (q, J = 7.6 Hz, 2H), 1.50−1.44 (m, 2H), 1.39−1.32 (m,
2H), 0.92 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 188.2,
163.2, 153.3, 145.3, 133.0, 131.6, 129.1, 113.5, 55.5, 55.3, 30.3, 25.5,
22.3, 13.6; IR (neat) 2958, 2930, 2860, 1760, 1655, 1599, 1574, 1509,
1441, 1420, 1306, 1249, 1157, 1114, 1026, 930, 843, 816, 774, 685
cm−1. HRMS (ESI) calcd for C16H21O5 [M + H]+, 293.1384; found,
293.1380.
1
yellow liquid in 76% (55 mg) isolated yield. H NMR (400 MHz,
CDCl3, Me4Si) δ 6.38 (t, J = 7.2 Hz, 1H), 3.86 (s, 3H), 2.22 (q, J = 7.2
Hz, 2H), 1.49−1.42 (m, 2H), 1.40−1.31 (m, 2H), 1.27 (s, 9H), 0.92
(t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 199.5, 153.3,
144.1, 131.4, 55.4, 42.8, 30.2, 27.5, 25.5, 22.3, 13.7; IR (neat) 2960,
2933, 2874, 1763, 1680, 1479, 1442, 1397, 1368, 1250, 1178, 1091,
(Z)-Methyl (1-Oxo-1-(p-tolyl)hept-2-en-2-yl) Carbonate (3f).
Reactions were carried out on a 0.3 mmol scale. Column
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1030, 948, 781 cm−1. HRMS (ESI) calcd for C13H23O4 [M + H]+,
243.1591; found, 243.1592.
1496, 1441, 1320, 1239, 1197, 1178, 1142, 1069, 1028, 1001, 990, 941,
781, 745, 696, 659 cm−1. HRMS (ESI) calcd for C18H17O4 [M + H]+,
297.1121; found, 297.1124.
(Z)-1-Cyclopropyl-1-oxohept-2-en-2-yl Methyl Carbonate (3l).
Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 82% (56 mg)
1-Cyclohexylidene-2-oxo-2-phenylethyl Methyl Carbonate (3r).
Reactions were carried out on a 0.3 mmol scale. The reaction was
carried out at 80 °C. Column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 30:1) afforded the title product as a
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 6.58 (t, J = 7.6
1
Hz, 1H), 3.86 (s, 3H), 2.32−2.25 (m, 3H), 1.51−1.45 (m, 2H), 1.42−
1.33 (m, 2H), 1.15−1.11 (m, 2H), 0.99−0.91 (m, 5H); 13C NMR
(100 MHz, CDCl3) δ 193.5, 153.3, 146.3, 131.6, 55.5, 30.2, 25.6, 22.3,
16.0, 13.6, 11.3; IR (neat) 2959, 2932, 2874, 1765, 1713, 1672, 1442,
1394, 1239, 1086, 1033, 984, 945, 875, 779, 674 cm−1. HRMS (ESI)
calcd for C12H19O4 [M + H]+, 227.1278; found, 227.1276.
yellow liquid in 72% (59 mg) isolated yield. H NMR (400 MHz,
CDCl3, Me4Si) δ 7.90−7.88 (m, 2H), 7.56−7.53 (m, 1H), 7.44 (t, J =
7.6 Hz, 2H), 3.72 (s, 3H), 2.42−2.39 (m, 2H), 2.22−2.19 (m, 2H),
1.72−1.66 (m, 2H), 1.61−1.51 (m, 4H); 13C NMR (100 MHz,
CDCl3) δ 190.7, 154.0, 140.3, 137.8, 137.1, 132.8, 129.1, 128.4, 55.4,
29.7, 28.5, 27.4, 27.2, 25.9; IR (neat) 2931, 2855, 1755, 1660, 1597,
1580, 1441, 1318, 1277, 1248, 1223, 1150, 1059, 1027, 1003, 945, 874,
849, 817, 784, 738, 697 cm−1. HRMS (ESI) calcd for C16H19O4 [M +
H]+, 275.1278; found, 275.1280.
(Z)-Methyl 1-Oxo-1-phenylbut-2-en-2-yl Carbonate (3m). Reac-
tions were carried out on a 0.3 mmol scale. Column chromatography
on silica gel (eluent: petroleum ether/ethyl acetate, 20:1) afforded the
1
General Procedure for the Synthesis of 8. For the synthesis of
8, there is no need to exclude the air. The reactions were carried out
on 0.2 or 0.3 mmol scale. To a solution of 3 (0.3 mmol) in acetone (3
mL) was added 10% sodium hydroxide solution (1.5 mmol, 0.55 mL).
The resulting mixture was stirred at room temperature until the
reaction was complete as monitored by thin-layer chromatography.
Then the mixture was quenched with water, extracted with ethyl
acetate, and dried over anhydrous Na2SO4. The solvent was
evaporated under reduced pressure, and the residue was purified by
column chromatography on silica gel to afford the product 8.
2-Butyl-5-hydroxy-3-methyl-5-phenylcyclopent-2-enone (8a).
Reactions were carried out on a 0.2 mmol scale. A 1.2 equiv 10%
sodium hydroxide solution was used. Column chromatography on
silica gel (eluent: petroleum ether/ethyl acetate, 8:1) afforded the title
title product as a yellow liquid in 93% (61.4 mg) isolated yield. H
NMR (400 MHz, CDCl3, Me4Si) δ 7.78−7.75 (m, 2H), 7.57−7.53 (m,
1H), 7.46−7.42 (m, 2H), 6.25 (q, J = 7.2 Hz, 1H), 3.85 (s, 3H), 1.90
(d, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 189.3, 153.2,
146.4, 136.6, 132.3, 129.9, 129,1, 128.2, 55.5, 11.6; IR (neat) 3061,
2959, 2850, 1759, 1658, 1598, 1579, 1442, 1380, 1334, 1276, 1240,
1164, 1065, 984, 941, 923, 847, 799, 781, 743, 697, 660 cm−1. HRMS
(ESI) calcd for C12H13O4 [M + H]+, 221.0808; found, 221.0808.
(Z)-Methyl (4-Methyl-1-oxo-1-phenylpent-2-en-2-yl) Carbonate
(3n). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 80% (60 mg)
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.78−7.76 (m,
2H), 7.58−7.54 (m, 1H), 7.46 (t, J = 7.6 Hz, 2H), 5.99 (d, J = 10.0 Hz,
1H), 3.85 (s, 3H), 2.96−2.87 (m, 1H), 1.08 (d, J = 6.8 Hz, 6H); 13C
NMR (100 MHz, CDCl3) δ 189.8, 153.4, 143.6, 140.8, 136.7, 132.4,
129.3, 128.3, 55.6, 26.1, 21.8; IR (neat) 2962, 2872, 1760, 1663, 1598,
1578, 1441, 1320, 1270, 1238, 1166, 1119, 1066, 1027, 964, 925, 798,
779, 747, 699, 666 cm−1. HRMS (ESI) calcd for C14H17O4 [M + H]+,
249.1121; found, 249.1121.
1
product in 78% (38 mg) isolated yield as a yellow oil. H NMR (400
MHz, CDCl3, Me4Si) δ 7.33−7.22 (m, 5H), 3.35 (s, 1H), 2.97 (d, J =
18.4 Hz, 1H), 2.87 (d, J = 18.8 Hz, 1H), 2.34−2.20 (m, 2H), 2.12 (s,
3H), 1.46−1.38 (m, 2H), 1.36−1.27 (m, 2H), 0.91 (t, J = 7.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 208.4, 169.5, 143.0, 138.3, 128.4,
127.4, 124.4, 78.4, 49.9, 30.2, 22.9, 22.6, 17.2, 13.8; IR (neat) 3432,
3059, 3022, 2956, 2929, 2858, 1698, 1636, 1600, 1494, 1447, 1385,
1344, 1232, 1185, 1103, 1058, 1033, 967, 928, 876, 769, 729, 697
cm−1. HRMS (ESI) calcd for C16H21O2 [M + H]+, 245.1535; found,
245.1536.
(Z)-1-Cyclohexyl-3-oxo-3-phenylprop-1-en-2-yl Methyl Carbo-
nate (3o). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
30:1) afforded the title product as a yellow liquid in 60% (51.9 mg)
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.77−7.75 (m,
5-Hydroxy-2-isopropyl-3-methyl-5-phenylcyclopent-2-enone
(8b). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
7:1) afforded the title product as a white solid in 59% (41 mg) isolated
yield; mp 115−117 °C. 1H NMR (400 MHz, CDCl3, Me4Si) δ 7.32−
7.22 (m, 5H), 3.32 (s, 1H), 2.95 (d, J = 18.0 Hz, 1H), 2.83 (d, J = 18.0
Hz, 1H), 2.90−2.83 (m, 1H), 2.12 (s, 3H), 1.23−1.20 (m, 6H); 13C
NMR (100 MHz, CDCl3) δ 208.0, 168.1, 143.1, 142.4, 128.4, 127.3,
124.3, 78.2, 49.9, 25.1, 20.4, 19.8, 17.4; IR (neat) 3426, 2956, 2914,
2872, 1688, 1628, 1601, 1490, 1450, 1419, 1386, 1342, 1237, 1102,
1073, 828, 783, 745, 701, 684, 656 cm−1. HRMS (ESI) calcd for
C15H18O2Na [M + Na]+, 253.1199; found, 253.1208.
2-tert-Butyl-5-hydroxy-3-methyl-5-phenylcyclopent-2-enone
(8c). Reactions were carried out on a 0.2 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
7:1) afforded the title product as a white solid in 68% (33 mg) isolated
yield; mp 118−120 °C. 1H NMR (400 MHz, CDCl3, Me4Si) δ 7.31−
7.22 (m, 5H), 3.29 (s, 1H), 2.95 (dd, J = 18.0 Hz, 0.8 Hz, 1H), 2.82
(d, J = 18.0 Hz, 1H), 2.27 (s, 3H), 1.32 (s, 9H); 13C NMR (100 MHz,
CDCl3) δ 208.5, 166.6, 143.4, 143.0, 128.4, 127.4, 124.3, 78.0, 51.3,
33.6, 29.4, 19.6; IR (neat) 3709, 3422, 2956, 2916, 2851, 1687, 1607,
1486, 1449, 1422, 1360, 1327, 1236, 1154, 1119, 1106, 1071, 883, 839,
778, 742, 701, 578, 655 cm−1. HRMS (ESI) calcd for C16H20O2Na [M
+ Na]+, 267.1356; found, 267.1357.
2H), 7.58−7.54 (m, 1H), 7.45 (t, J = 8.0 Hz, 2H), 6.00 (d, J = 9.6 Hz,
1H), 3.86 (s, 3H), 2.67−2.58 (m, 1H), 1.77−1.66 (m, 5H), 1.38−1.26
(m, 2H), 1.23−1.10 (m, 3H); 13C NMR (100 MHz, CDCl3) δ 189.8,
153.4, 143.8, 139.4, 136.8, 132.4, 129.3, 128.2, 55.6, 35.5, 31.7, 25.6,
25.2; IR (neat) 2928, 2854, 1744, 1491, 1441, 1349, 1259, 1185, 965,
926, 891, 790, 756, 691 cm−1. HRMS (ESI) calcd for C17H21O4 [M +
H]+1, 289.1434; found, 289.1438.
(Z)-4,4-Dimethyl-1-oxo-1-phenylpent-2-en-2-yl Methyl Carbo-
nate (3p). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a white solid in 93% (73 mg)
1
isolated yield; mp 86−88 °C. H NMR (400 MHz, CDCl3, Me4Si) δ
7.78−7.76 (m, 2H), 7.57−7.53 (m, 1H), 7.45 (t, J = 7.6 Hz, 2H), 6.06
(s, 1H), 3.84 (s, 3H), 1.22 (s, 9H); 13C NMR (100 MHz, CDCl3) δ
190.6, 153.2, 143.9, 142.2, 136.8, 132.3, 129.3, 128.2, 55.6, 33.1, 29.5;
IR (neat) 2959, 2864, 1761, 1665, 1598, 1441, 1366, 1317, 1249, 1201,
1138, 1072, 1026, 963, 945, 916, 800, 780, 748, 698, 669, 653 cm−1.
HRMS (ESI) calcd for C15H19O4 [M + H]+, 263.1278; found,
263.1281.
(Z)-Methyl (1-Oxo-1,4-diphenylbut-2-en-2-yl) Carbonate (3q).
Reactions were carried out on a 0.5 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
20:1) afforded the title product as a yellow liquid in 93% (138 mg)
1
isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.77 (d, J = 7.6
2-Butyl-5-hydroxy-5-(4-methoxyphenyl)-3-methylcyclopent-2-
enone (8d). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
7:1) afforded the title product as a yellow oil in 62% (51 mg) isolated
Hz, 2H), 7.52−7.48 (m, 1H), 7.41−7.37 (m, 2H), 7.30−7.26 (m, 2H),
7.22−7.18 (m, 3H), 6.28 (t, J = 8.0 Hz, 1H), 3.84 (s, 3H), 3.66 (d, J =
7.6 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ 189.3, 153.2, 145.3,
137.3, 136.3, 132.4, 132.1, 129.1, 128.6, 128.4, 128.20, 128.15, 126.6,
55.6, 32.1; IR (neat) 3053, 3028, 2958, 2850, 1760, 1662, 1598, 1578,
1
yield. H NMR (400 MHz, CDCl3, Me4Si) δ 7.22−7.20 (m, 2H),
6.84−6.82 (m, 2H), 3.77 (s, 3H), 3.31 (s, 1H), 2.96 (d, J = 18.0 Hz,
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1H), 2.86 (d, J = 18.0 Hz, 1H), 2.31−2.19 (m, 2H), 2.11 (s, 3H),
1.41−1.28 (m, 4H), 0.90 (t, J = 6.8 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 208.4, 169.1, 158.8, 138.2, 135.0, 113.7, 78.0, 55.2, 49.7,
30.3, 22.9, 22.6, 17.2, 13.8; IR (neat) 3439, 2955, 2931, 2858, 1699,
1637, 1609, 1582, 1509, 1637, 1609, 1582, 1509, 1464, 1441, 1385,
1344, 1293, 1249, 1178, 1101, 1031, 924, 876, 831, 796, 734 cm−1.
HRMS (ESI) calcd for C17H22O3Na [M + Na]+, 297.1461; found,
297.1465.
24.1, 22.6, 22.3, 13.7, 13.4; IR (neat) 3465, 3062, 2956, 2930, 2860,
1713, 1660, 1596, 1579, 1494, 1448, 1379, 1343, 1315, 1241, 1209,
1176, 1151, 1123, 1073, 1053, 1018, 1001, 923, 890, 804, 721, 697,
673 cm−1. HRMS (ESI) calcd for C26H34NO3 [M + NH4]+, 408.2533;
found, 408.2537.
(4S*, 5R*)-3-Benzoyl-5-hydroxy-2,4-dimethyl-5-phenylcyclopent-
2-enone (9b). Reactions were carried out on a 0.3 mmol scale.
Column chromatography on silica gel (eluent: petroleum ether/ethyl
acetate, 5:1) afforded the title product as a light yellow solid in 59%
(27.0 mg) isolated yield; mp 116−118 °C. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.87−7.85 (m, 2H), 7.67−7.63 (m, 1H), 7.54−7.50
(m, 2H), 7.44−7.40 (m, 2H), 7.39−7.33 (m, 2H), 7.32−7.27 (m, 1H),
3.60−3.54 (m, 1H), 3.47 (s, 1H), 1.71 (d, J = 2.0 Hz, 3H), 1.23 (d, J =
7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 209.0, 196.1, 168.9,
142.4, 136.0, 135.6, 134.5, 129.09, 129.07, 128.6, 127.7, 124.7, 79.9,
49.8, 14.0, 9.7; IR (neat) 3447, 3059, 2976, 2927, 2850, 1714, 1689,
1596, 1579, 1495, 1448, 1377, 1343, 1314, 1265, 1240, 1177, 1119,
1074, 1014, 952, 918, 894, 848, 733, 697 cm−1. HRMS (ESI) calcd for
C20H19O3 [M + H]+, 307.1329; found, 307.1329.
(4S*, 5R*)-2,4-Dibutyl-5-hydroxy-3-(4-methoxybenzoyl)-5-(4-me-
thoxyphenyl) Cyclopent-2-enone (9c). Reactions were carried out on
a 0.3 mmol scale. Column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 10:1) afforded the title product as a
yellow oil in 45% (30.3 mg) isolated yield. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.82−7.80 (m, 2H), 7.37−7.35 (m, 2H), 6.98−6.96
(m, 2H), 6.90−6.88 (m, 2H), 3.90 (s, 3H), 3.81 (s, 3H), 3.48 (dd, J =
7.6, 4.0 Hz, 1H), 3.13 (s, 1H), 2.28−2.23 (m, 1H), 2.07−2.20 (m,
1H), 1.85−1.78 (m, 1H), 1.47−1.43 (m, 2H), 1.33−1.05 (m, 7H),
0.77−0.70 (m, 6H); 13C NMR (100 MHz, CDCl3) δ 209.3, 194.8,
168.8, 164.6, 159.0, 139.9, 135.1, 131.6, 128.7, 126.1, 114.3, 113.9,
80.5, 55.6, 55.25, 55.16, 30.3, 30.0, 29.6, 24.1, 22.7, 22.4, 13.8, 13.5; IR
(neat) 3465, 2956, 2930, 2859, 1712, 1651, 1594, 1572, 1509, 1463,
1442, 1422, 1379, 1313, 1248, 1166, 1111, 1026, 925, 892, 847, 831,
798, 735, 703 cm−1. HRMS (ESI) calcd for C28H34O5Na [M + Na]+,
473.2298; found, 473.2304.
2-Butyl-5-(4-chlorophenyl)-5-hydroxy-3-methylcyclopent-2-
enone (8e). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
7:1) afforded the title product as a white solid in 57% (47.6 mg)
1
isolated yield; mp 76−78 °C. H NMR (400 MHz, CDCl3, Me4Si) δ
7.27−7.25 (m, 2H), 7.21−7.19 (m, 2H), 3.50 (s, 1H), 2.96 (d, J = 18.0
Hz, 1H), 2.82 (s, J = 18.4 Hz, 1H), 2.31−2.21 (m, 2H), 2.13 (s, 3H),
1.43−1.25 (m, 4H), 0.91 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 207.9, 169.7, 141.5, 138.4, 133.2, 128.5, 125.9, 78.0, 49.9,
30.2, 22.9, 22.6, 17.3, 13.8; IR (neat) 3431, 2956, 2929, 2859, 1697,
1635, 1489, 1466, 1433, 1385, 1343, 1233, 1185, 1156, 1091, 1057,
1013, 966, 925, 876, 830, 758, 725 cm−1. HRMS (ESI) calcd for
C16H19O2ClNa [M + Na]+, 301. 0966; found, 301. 0978.
2-Butyl-5-cyclopropyl-5-hydroxy-3-methylcyclopent-2-enone
(8f). Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
8:1) afforded the title product as a yellow oil in 59% (37 mg) isolated
1
yield. H NMR (400 MHz, CDCl3, Me4Si) δ 2.57 (d, J = 17.6 Hz,
1H), 2.45 (d, J = 18.0 Hz, 1H), 2.48 (s, 1H), 2.25−2.12 (m, 2H), 2.04
(s, 3H), 1.39−1.26 (m, 4H), 1.08−1.01 (m, 1H), 0.90 (t, J = 7.2, 3H),
0.49−0.44 (m, 1H), 0.40−0.35 (m, 3H); 13C NMR (100 MHz,
CDCl3) δ 209.1, 167.9, 137.7, 76.2, 45.1, 30.4, 22.7, 22.6, 18.1, 17.1,
13.9, 0.9, 0.1; IR (neat) 3452, 2956, 2928, 2858, 1698, 1639, 1466,
1430, 1386, 1343, 1187, 1098, 1069, 1041, 1020, 984, 946, 918, 893,
869, 831 cm−1. HRMS (ESI) calcd for C13H20O2Na [M + Na]+,
231.1356; found, 231.1356.
5-tert-Butyl-2-butyl-5-hydroxy-3-methylcyclopent-2-enone (8g).
Reactions were carried out on a 0.3 mmol scale. Column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
7:1) afforded the title product as a yellow oil in 50% (33.7 mg)
isolated yield. 1H NMR (400 MHz, CDCl3, Me4Si) δ 2.73 (d, J = 18.0
Hz, 1H), 2.41 (d, J = 18.4 Hz, 1H), 2.56 (s, 1H), 2.23−2.09 (m, 2H),
2.04 (s, 3H), 1.39−1.26 (m, 4H), 0.93 (s, 9H), 0.90 (t, J = 6.8 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 210.2, 167.9, 138.8, 80.7, 43.5,
36.7, 30.3, 24.5, 22.8, 22.7, 16.9, 13.8; IR (neat) 3484, 2956, 2933,
2872, 1697, 1644, 1467, 1386, 1366, 1341, 1215, 1182, 1107, 1067,
1039, 1010, 980, 930, 875, 848, 811, 729 cm−1. HRMS (ESI) calcd for
C14H24O2Na [M + Na]+, 247.1669; found, 247.1670.
General Procedure for the Synthesis of 9. For the synthesis of
9, there is no need to exclude the air. The reactions were carried out
on 0.2 or 0.3 mmol scale. To a solution of 3 (0.3 mmol) in acetonitrile
(3 mL) was added 10% sodium hydroxide solution (1.5 mmol, 0.55
mL). The resulting mixture was stirred at room temperature until the
reaction was complete as monitored by thin-layer chromatography.
Then the mixture was quenched with water, extracted with ethyl
acetate, and dried over anhydrous Na2SO4. The solvent was
evaporated under reduced pressure, and the residue was purified by
column chromatography on silica gel to afford the product 9.
(4S*, 5R*)-3-Benzoyl-2,4-dibutyl-5-hydroxy-5-phenylcyclopent-2-
enone (9a). Column chromatography on silica gel (eluent: petroleum
ether/ethyl acetate, 10:1) afforded the product 9a in 64% isolated yield
(25 mg) as a light yellow oil (0.2 mmol scale, and when 3a and 1.2
equiv of 10% sodium hydroxide solution were used). 9a was obtained
in 64% yield (0.3 mmol scale, 37.5 mg) when 3c was used, or 60%
yield (0.3 mmol scale, 35 mg) when 3d was used. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.85−7.83 (m, 2H), 7.66−7.63 (m, 1H), 7.50 (t, J =
8.0 Hz, 2H), 7.45−7.42 (m, 2H), 7.38−7.34 (m, 2H), 7.31−7.27 (m,
1H), 3.54−3.50 (m, 1H), 3.35 (s, 1H), 2.29−2.22 (m, 1H), 2.08−2.00
(m, 1H), 1.87−1.83 (m, 1H), 1.52−1.43 (m, 2H), 1.35−1.26 (m, 2H),
1.22−1.14 (m, 3H), 1.13−1.05 (m, 2H), 0.77−0.69 (m, 6H); 13C
NMR (100 MHz, CDCl3) δ 209.3, 196.5, 168.5, 143.1, 140.8, 135.7,
134.4, 129.1, 129.0, 128.6, 127.8, 124.7, 80.7, 55.3, 30.2, 29.9, 29.6,
(4S*, 5R*)-2,4-Dibutyl-3-(4-chlorobenzoyl)-5-(4-chlorophenyl)-5-
hydroxycyclopent-2-enone (9d). Reactions were carried out on a 0.3
mmol scale. Column chromatography on silica gel (eluent: petroleum
ether/ethyl acetate, 10:1) afforded the title product as a yellow oil in
1
46% (32 mg) isolated yield. H NMR (400 MHz, CDCl3, Me4Si) δ
7.79−7.77 (m, 2H), 7.52−7.50 (m, 2H), 7.37−7.32 (m, 4H), 3.45 (dd,
J = 8.0, 4.4 Hz, 1H), 3.18 (s, 1H), 2.28−2.21 (m, 1H), 2.04−1.96 (m,
1H), 1.86−1.79 (m, 1H), 1.64 (s, 1H), 1.42−1.07 (m, 8H), 0.77−0.71
(m, 6H); 13C NMR (100 MHz, CDCl3) δ 208.6, 195.1, 167.9, 141.4,
141.3, 140.8, 133.9, 133.7, 130.5, 129.6, 128.8, 126.2, 80.3, 55.2, 30.3,
30.0, 29.6, 24.2, 22.6, 22.4, 13.7, 13.5; IR (neat) 3457, 2957, 2929,
2860, 1713, 1660, 1585, 1570, 1489, 1465, 1401, 1379, 1247, 1209,
1171, 1152, 1091, 1053, 1012, 925, 890, 848, 828, 799, 768, 738, 676
cm−1. HRMS (ESI) calcd for C26H28O3Cl Na [M + Na]+, 481.1292;
2
found, 481.1308.
(4S*,5R*)-2,4-Dibutyl-5-hydroxy-5-(thiophen-2-yl)-3-(thiophene-
2-carbonyl)-cyclopent-2-enone (9e). Reactions were carried out on a
0.3 mmol scale. Column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 10:1) afforded the title product as a
light yellow solid in 53% (32 mg) isolated yield. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 7.82 (d, J = 4.8 Hz, 1H), 7.55 (d, J = 4.0 Hz, 1H),
7.26 (d, J = 4.8 Hz, 1H), 7.18 (t, J = 4.0 Hz, 1H), 7.02−7.01 (m, 1H),
6.98−6.96 (m, 1H), 3.63−3.60 (m, 1H), 3.39 (s, 1H), 2.36−2.29 (m,
1H), 2.24−2.17 (m, 1H), 1.81−1.78 (m, 1H), 1.59−1.13 (m, 9H),
0.81−0.74 (m, 6H); 13C NMR (100 MHz, CDCl3) δ 206.6, 187.7,
166.8, 147.0, 142.8, 140.1, 136.3, 134.7, 128.7, 127.0, 125.2, 123.7,
79.2, 55.5, 30.2, 29.9, 29.6, 24.3, 22.7, 22.4, 13.8, 13.5; IR (neat) 3455,
3105, 2956, 2930, 2861, 1716, 1638, 1512, 1465, 1409, 1353, 1257,
1208, 1164, 1121, 1050, 1013, 1050, 1013, 897, 853, 839, 788, 730,
701, 668 cm−1. HRMS (ESI) calcd for C22H26O3S Na [M + Na]+,
2
425.1216; found, 425.1230.
(4S*, 5S*)-2,4-Dibutyl-3-(cyclopropanecarbonyl)-5-cyclopropyl-
5-hydroxycyclopent-2-enone (9f). Reactions were carried out on a
0.3 mmol scale. Column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 10:1) afforded the title product as a
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Article
yellow oil in 64% (30.4 mg) isolated yield. 1H NMR (400 MHz,
CDCl3, Me4Si) δ 3.10−3.07 (m, 1H), 2.44 (t, J = 7.6 Hz, 2H), 2.36 (s,
1H), 2.27−2.21 (m, 1H), 1.63−1.55 (m, 1H), 1.47−1.40 (m, 3H),
1.38−1.07 (m, 10H), 1.02−0.95 (m, 1H), 0.91−0.84 (m, 6H), 0.53−
0.48 (m, 1H), 0.44−0.37 (m, 3H); 13C NMR (100 MHz, CDCl3) δ
211.1, 204.2, 166.6, 141.1, 78.6, 50.5, 30.5, 30.4, 30.0, 23.9, 22.8, 22.6,
21.2, 19.9, 13.9, 13.7, 13.6, 12.7, 0.8, 0.2; IR (neat) 3478, 3009, 2957,
2929, 2860, 1711, 1671, 1466, 1383, 1338, 1190, 1162, 1050, 1022,
960, 933, 878, 824, 734, 679 cm−1. HRMS (ESI) calcd for
C20H30O3Na [M + Na]+, 341.2087; found, 341.2089.
Chem.Eur. J. 2007, 13, 1350. (c) Wang, S.; Zhang, G.; Zhang, L.
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Isolation of the Intermediate of 1,2-Diketone 10a. To a
solution of 3a (0.2 mmol, 52.5 mg) in acetone (2 mL) was added 10%
sodium hydroxide solution (0.6 mmol, 0.22 mL). The resulting
mixture was stirred at 0 °C until the reaction was complete as
monitored by thin-layer chromatography. Then the mixture was
quenched with water, extracted with ethyl acetate, and dried over
anhydrous Na2SO4. The solvent was evaporated under reduced
pressure, and the residue was purified by column chromatography on
silica gel (eluent: petroleum ether/ethyl acetate, 20:1 to 8:1) to afford
10a in 40% (16.3 mg) yield as a yellow liquid and 8a in 28% (13.7 mg)
yield as a light yellow liquid.
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1-Phenylheptane-1,2-dione (10a). H NMR (400 MHz, CDCl3,
́
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Me4Si) δ 7.97 (d, J = 7.6 Hz, 2H), 7.63 (t, J = 7.2 Hz, 1H), 7.48 (t, J =
7.6 Hz, 2H), 2.87 (t, J = 7.2 Hz, 2H), 1.73−1.66 (m, 2H), 1.35−1.34
(m, 4H), 0.90 (t, J = 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
203.4, 192.4, 134.4, 131.9, 130.0, 128.7, 38.6, 31.2, 22.4, 22.3, 13.8; IR
(neat) 3061, 2957, 2931, 2872, 1710, 1671, 1596, 1580, 1449, 1401,
1378, 1319, 1268, 1235, 1201, 1181, 1159, 1128, 1086, 1001, 935, 911,
881, 845, 786, 689, 658 cm−1. HRMS (ESI) calcd for C13H17O2 [M +
H]+, 205.1223; found, 205.1225. The spectroscopic data are in
agreement with those previously reported.27
Transformation of 1,2-Diketone 10a to Cyclopentenones. To a
solution of 10a (0.2 mmol, 40.9 mg) in acetone (2 mL) was added
10% sodium hydroxide solution (1.0 mmol, 0.36 mL). The resulting
mixture was stirred at room temperature until the reaction was
complete as monitored by thin-layer chromatography. Then the
mixture was quenched with water, extracted with ethyl acetate, and
dried over anhydrous Na2SO4. The solvent was evaporated under
reduced pressure, and the residue was purified by column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate,
10:1) to afford 8a in 67% (33 mg) yield as a light yellow liquid and 9a
in 10% (4 mg) yield as a light yellow liquid.
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ASSOCIATED CONTENT
* Supporting Information
■
S
X-ray crystallography and the crystal data of compounds 3p, 8b,
and 9b, spectroscopic characterization of all substrates and
products, and CIF files giving crystal data. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*Fax: (+86) 021-64166128. E-mail: yhliu@mail.sioc.ac.cn
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the National Natural Science Foundation of China
(Grant Nos. 21125210, 21121062, 21372244), Chinese
Academy of Science, and the Major State Basic Research
Development Program (Grant No. 2011CB808700) for
financial support.
REFERENCES
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