Synthesis of Cyclic 3-Aryl-Substituted 1,2-Dicarbonyl Compounds via Suzuki Cross-Coupling Reactions

Article abstract of DOI:10.1055/s-0036-1591543

A method for the synthesis of cyclic 3-aryl and heteroaryl-substituted 1,2-dicarbonyl compounds with different ring sizes by using a Suzuki cross-coupling reaction between 3-halo-1,2-dicarbonyl compounds and arylboronic acids is developed. The 3-halo-1,2-dicarbonyl substrates are easily available from 1,2-dicarbonyl compounds. The method is versatile, affording good to high yields of the target compounds.

Full text of DOI:10.1055/s-0036-1591543

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2018, 50, A–H
paper
A
en
E. Lopušanskaja et al.
Paper
Synthesis
Synthesis of Cyclic 3-Aryl-Substituted 1,2-Dicarbonyl Compounds
via Suzuki Cross-Coupling Reactions
Eleana Lopušanskaja
O
O
Anne Paju
OR1
OR1
Ivar Järving
Margus Lopp*
X
OH
OH
Pd(OAc)2/PPh3
Na2CO3 or Et3N
X
+
Ar
B
(C)
(C)
n
n
Ar
Y
Department of Chemistry, Tallinn University of Technology,
Akadeemia tee 15, Tallinn, Estonia
margus.lopp@ttu.ee
n = 1; X = C, O R1= H, Me, TBS, TBDPS, MOM
n = 2; X = C
23 examples
yields up to 99%
Ar = Ph, p-HOC6H4, p-FC6H4, 2-thienyl,
Y = Cl, Br
o-MeC6H4, p-MeC6H4, o-MeCO2C6H4,
p-O2NC6H4, p-TBSOC6H4
Received: 17.12.2017
Accepted after revision: 19.01.2018
Published online: 12.02.2018
used 3-aryl-substituted 1,2-dicarbonyl compounds in the
synthesis of 2-aryl-γ-lactone acids and 4′-aryl-substituted
nucleoside analogues.10
DOI: 10.1055/s-0036-1591543; Art ID: ss-2017-t0823-op
There are several possible ways of synthesizing 3-aryl-
substituted cyclopentane-1,2-diones (Figure 1) and cyclo-
hexane-1,2-diones. For example, 3-phenyl-1,2-cyclopen-
tanedione was synthesized starting from 3-phenyl-2-cyclo-
penten-1-one by epoxidation and subsequent epoxyketone
rearrangement,11a from 3-phenyl-1,2,4-cyclopentanetrione
by reduction of the 2-phenyl-3,5,5-triethoxy-2-cyclopent-
en-1-one intermediate,11b and by the heterogeneous
platinum catalytic aerobic oxidation of 3-phenylcyclo-
pentane-1,2-diols.11c
Abstract A method for the synthesis of cyclic 3-aryl- and heteroaryl-
substituted 1,2-dicarbonyl compounds with different ring sizes by using
a Suzuki cross-coupling reaction between 3-halo-1,2-dicarbonyl com-
pounds and arylboronic acids is developed. The 3-halo-1,2-dicarbonyl
substrates are easily available from 1,2-dicarbonyl compounds. The
method is versatile, affording good to high yields of the target com-
pounds.
Key words Suzuki cross-coupling, dicarbonyl compounds, halodi-
ketones, arylation, palladium catalysis
O
O
O
Cyclic 3-substituted 1,2-dicarbonyl compounds are sim-
ple multifunctional structures the synthetic potential of
which has not been fully exploited, although there are
many examples of the successful use of these molecules in
organic synthesis. For example, α-alkylation,1a α′-allyla-
tion,1b Michael addition,1c and Claisen rearrangement2 us-
ing this structural unit have been reported. In addition,
there are examples of asymmetric alkylations of these
structural units,3 and asymmetric oxidation to afford γ-
lactone carboxylic acids.4
O
OH
OH
O
O
HOOC
SO2Me
X
WF-3681
3-aryl-1,2 cyclopentanedione
DFP
Figure 1 Examples of cyclic 3-aryl-substituted 1,2-dicarbonyl com-
pounds
Cyclic 3-alkyl-substituted 1,2-dicarbonyl compounds
have been used in the synthesis of natural compounds such
as milbemycin β3, trichodiene, (–)-terpestacin and (+)-con-
fertin.5 The cyclic 3-aryl-substituted 1,2-dicarbonyl struc-
tural motif is present in several biologically active com-
pounds, including the aldose reductase inhibitor WF-36816
and the anti-inflammatory agent DFP (Figure 1).7 Several
butyrolactones exhibit cytotoxic activity against some
tumor cells,8a,8b and antiplasmodial activity.8c In addition,
aryl derivatives of ascorbic acid (vitamin C) show anti-in-
flammatory9a and HIV-1 integrase inhibition.9b We have
Various aryl-substituted cyclopentane-1,2-diones were
synthesized by the Stetter reaction between substituted
benzaldehydes and 1-acetoxy-3-butene-2-one followed by
cyclization. However, for the preparation of 1-acetoxy-3-
butene-2-one, a toxic Hg salt was used10,12 making this ap-
proach unattractive for preparative synthesis. Also, for the
arylation of 1,2-diketones, photolysis of 2-arenesulfonyl-2-
cycloalkenones was used to synthesize 3-aryl/heteroarylcy-
cloalkene-1,2-diones.13 Furthermore, for the synthesis of 3-
phenyl-1,2-cyclohexanedione, methods involving conjugate
addition of lithium dicuprate reagents to the enol tosylate
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H

B
E. Lopušanskaja et al.
Paper
Synthesis
of a 1,2-diketone,14a reaction of 2-phenylcyclohexanone
with iodine/copper(II) acetate14b and Swern oxidation of 2-
hydroxy-5-phenylcyclohexanone14c were used. For differ-
ent 3-aryl-substituted cyclohexanediones an efficient Heck
arylation procedure using aryl bromides in reactions with
1,2-cyclohexanedione15a or 2,3-epoxycyclohexanone15b
were applied.
There are also many synthetic procedures for the syn-
thesis of 4-aryl-substituted 2,3-dihydrofurandiones. Of
these, the more general are the aldol reactions of pyruvic
acid derivatives with aromatic aldehydes using different
catalysts.9a,16 Also, there are examples of using the oxidative
cyclization of α,β-unsaturated methyl ketones,17a the Wittig
rearrangement/alkylative cyclization sequence,17b reactions
of the dianion of 2,4-oxazolidinedione with α-haloke-
tones17c and Suzuki cross-coupling reactions of cyclic 3-
bromoisotetronic acids with substituted arylboronic
acids.18
Considering the increasing need for 3-substituted 1,2-
diones, we previously developed methods for the synthesis
of 3-alkyl- and 3-alkynyl-substituted 1,2-diketones by us-
ing bromodiketones as substrates for Negishi19a and Sono-
gashira19b cross-coupling reactions.
In the present study, we completed our investigations by
synthesizing 3-substituted 1,2-diones via Suzuki cross-cou-
pling reactions20 of halodiketones 1, 2 and 3 with arylbo-
ronic acids 4 to afford 3-aryl- and 3-heteroaryl-substituted
1,2-diketones 5, 6 and 7.
The substrates for the coupling reactions, 3-bromo-1,2-
cyclopentanedione (1-Br), 3-bromo-1,2-cyclohexanedione
(2-Br) and their OTBS-protected derivatives, were prepared
from cyclopentane-1,2-dione and 1,2-cyclohexanedione
using NBS as described in our previous publication.19b 3-
Chloro-1,2-cyclopentanedione (1-Cl) was prepared analo-
gously using NCS. 1-Br, 1-Cl and 2-Br methoxy-protected
derivatives were prepared according to the reported proce-
dure,21 whilst hydroxy-protected 4-bromo-3-hydroxy-2-fu-
ranones 3 were prepared from 3-hydroxyfuran-2(5H)-one22
by bromination with NBS followed by different protecting
group manipulations (see the Supporting Information).
We started our investigations with the more stable Me-
and MOM-protected 3-halo-cyclopentane-1,2-diones 1, 2
and 3 and phenylboronic acids 4 by using standard condi-
tions.18 The obtained results of the Suzuki cross-coupling
reactions yielding the corresponding coupling products 5, 6
and 7 are presented in Table 1.
The reaction of methyl-protected 3-bromocyclo-
pentane-1,2-dione (1-Br-b) with phenylboronic acid (4a)
under standard reaction conditions [Pd(OAc)2 as the cata-
lyst (5 mol%), PPh3 (10 mol%), Na2CO3 as the base in
THF/H2O mixture (4:1) at 60 °C overnight] afforded the cou-
pling product 5a-b in 84% isolated yield (Table 1, entry 1).
Also, the reactions of boronic acids 4b–e with methyl-pro-
tected 3-bromocyclopentane-1,2-dione (1-Br-b) gave good
Table 1 Synthesis of Cyclopentane- and Cyclohexane-3-Aryl-Substi-
tuted 1,2-Diketones by Suzuki Cross-Couplinga
O
O
OR1
OR1
X
OH
OH
Pd(OAc)2/PPh3
Na2CO3
X
+
Ar
B
(C)
(C)
n
n
Ar
Y
1 n = 1; X = C
2 n = 2; X = C
3 n = 1, X = O
R
1 = H (a),
Me (b),
MOM (d)
4 Ar = Ph (a), p-HOC6H4 (b),
p-FC6H4 (c), 2-thienyl (d),
5 n = 1; X = C
6 n = 2; X = C
7 n = 1; X = O
o-MeC6H4 (e), p-MeC6H4 (f),
o-MeCO2C6H4 (g),
Y = Cl, Br
p-O2NC6H4 (h)
Entry
Substrate
R1
ArB(OH)2 Pd(OAc)2(mol %) Product (Yield %)b
5a-b (84)
1
2
1-Br
1-Br
1-Br
1-Br
1-Br
1-Br
1-Cl
1-Cl
1-Br
2-Br
2-Br
2-Br
2-Br
2-Br
3-Br
3-Br
3-Br
3-Br
3-Br
b
4a
4b
4c
4d
4e
4a
4a
4a
4a
4a
4f
5
5
b
b
b
b
a
b
b
b
b
b
b
b
b
b
d
d
d
d
5b-b (70)
5c-b (90)
5d-b (92)
5e-b (79)
5a-a (14)
5a-b (51)
5a-b (96)
5a-b (95)
6a-b (96)
6f-b (82)
6g-b (36)
6g-b (50)
6f-b (88)
7c-b (82)
7d-d (99)
7g-d (25)
7h-d (68)
7d-d (66)
3
5
4
5
5
5
6
5
7
5
8
10
5
9c
10
11
12
13
14c
15
16
17
18
19c
5
5
4g
4g
4f
5
10
5
4c
4d
4g
4h
4d
5
5
5
5
5
a Reagents and conditions: substrate 1, 2 or 3 (0.5 mmol), ArB(OH)2 4 (0.75
mmol), Pd(OAc)2 (6 mg, 5 mol% or 12 mg, 10 mol%), PPh3 (13 mg, 10 mol%
or 26 mg, 20 mol%), Na2CO3 (106 mg, 1.0 mmol), THF/H2O (4:1, 5 mL),
60 °C, overnight.
b Yield of isolated product.
c Reagents and conditions: substrate 1-Br, 2-Br or 3-Br (0.5 mmol), ArB(OH)2
4 (0.75 mmol), Pd(OAc)2 (6 mg, 5 mol%), PPh3 (13 mg, 10 mol%), Et3N (1.5
mmol), H2O (1.5 mL), r.t., under air, overnight.
to excellent yields (70–92%) of the 3-aryl-substituted cyclo-
pentane-1,2-dione coupling products 5b–e (entries 2–5).
Protection of the enol OH in the substrate is recommended
because the reaction of unprotected 1-Br-a with phenylbo-
ronic acid (4a) afforded the coupling product 5a-a in a low
14% yield (entry 6). When we compared the reactivity of
Me-protected 3-chloro-cyclopentanedione (1-Cl-b) and the
corresponding bromo derivative, we found that it was
slightly less reactive than 1-Br-b, affording the coupling
product 5a-b in 51% yield (entry 7). A two-fold amount of
the catalyst (10 mol%) was needed to obtain an excellent
coupling yield (96%) with the 3-chloro-substituted sub-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H

C
E. Lopušanskaja et al.
Paper
Synthesis
Table 2 Optimization of the Conditions for Silyl-Protected Productsa
strate (entry 8). Thus, we continued our studies with 3-bro-
mo-substituted substrates 2-Br and 3-Br. We also checked
the possibility of using water as a solvent for the reaction.23
By slightly changing the reaction conditions—running the
reaction at room temperature and allowing free access of
air—the coupling product 5a-b was obtained in an excellent
95% yield (entry 9).
O
O
OR1
OR1
R2
OH
OH
Pd(OAc)2/PPh3
Na2CO3
X
X
+
B
(C)
(C)
n
n
Br
4
1 n = 1; X = C
2 n = 2; X = C
3 n = 1, X = O
R
1 = H (a),
TBS (c),
TBDPS (c')
R2 = H (a), p-OH (b),
5 n = 1; X = C
6 n = 2; X = C
7 n = 1; X = O
R2
p-F (c), p-O2N (h),
p-TBSO (i)
With cyclohexane substrate 2-Br-b, a similar result to
that of the reaction of 1-Br-b with boronic acid (4a) was ob-
tained, with the yield of 6a-b being 96% (Table 1, entry 10).
The more complex and sterically demanding boronic acid
4g was less reactive (36% yield, entry 12) requiring 10 mol%
of the catalyst to increase the yield to 50% (entry 13). Again,
in aqueous solution, the reaction of boronic acid 4f with 2-
Br-b afforded a slightly higher yield of 6f-b than in the
THF/water mixture (88% vs 82%, entries 14 and 11).
The 4-bromofurandiones 3-Br showed good reactivity
with different boronic acids, affording the coupling prod-
ucts 7 in good to high yields (Table 1, entries 15, 16, 18 and
19). The more labile MOM protecting group was utilized in
the substrate instead of the Me group because of the lower
stability of the furanone ring compared with the carbocy-
cles, and such that removal of the protecting group in later
transformations would be tolerated. Again, the boronic acid
4g was less reactive, resulting in compound 7g with a low
yield of 25% (entry 17), most probably because of steric fac-
tors. However, the furanone substrate 3-Br-d gave a lower
yield in water than in the THF/water solvent (66% vs 99%),
probably because of the tendency of lactone units to hydro-
lyze in water.
Entry Substrate R1 ArB(OH)2 Solvent
Product
(Yield %)b
5a-c (68)
5a-c (65)
1
1-Br
1-Br
1-Br
1-Br
2-Br
2-Br
2-Br
2-Br
2-Br
3-Br
3-Br
c
c
c
c
c
c
c
c
c
c
4a
4a
4b
4i
THF/H2O (4:1)
H2O
2c
3
THF/H2O (4:1)
5b-a (26); 5b-c (23)
4d
5
toluene/H2O (10:1) 5i-c (67)
4a
4c
4h
4h
4h
4a
THF/H2O (4:1)
THF/H2O (4:1)
THF/H2O (4:1)
THF/H2O (10:1)
6a-c (86)
6
6c-c (87)
7
6h-a (60); 6h-c (32)
6h-a (25); 6h-c (33)
8
9d
10
11
toluene/H2O (10:1) 6h-c (69)
THF/H2O (4:1)
THF/H2O (4:1)
7a-a (51)
7a-a (68)
c′ 4a
a Reagents and conditions: substrate 1, 2 or 3 (0.5 mmol), ArB(OH)2 4 (0.75
mmol), Pd(OAc)2 (6 mg, 5 mol%), PPh3 (13 mg, 10 mol%), Na2CO3 (106 mg,
1.0 mmol), solvent (5 mL), 60 °C, overnight.
b Yield of isolated product.
c Reagents and conditions: substrate 1-Br, 2-Br or 3-Br (0.5 mmol), ArB(OH)2
4 (0.75 mmol), Pd(OAc)2 (6 mg, 5 mol%), PPh3 (13 mg, 10 mol%), Et3N (1.5
mmol), H2O (1.5 mL), r.t., under air, overnight.
d Reaction at 100 °C, overnight.
To obtain the coupling products with even more easily
removable protecting groups, we investigated the coupling
of different boronic acids 4 with silyl-protected substrates
1-Br-c, 2-Br-c, 3-Br-c and 3-Br-c′. The results are presented
in Table 2.
The reaction of unsubstituted boronic acid 4a with 1-
Br-c afforded the coupling product 5a-c in good yield,
which, however, was less than that for corresponding Me-
protected substrate 1-Br-b (68% vs 84%, compare Table 2,
entry 1 and Table 1, entry 1).
A more drastic drop in the yield was observed when the
reaction was carried out in water (65% vs 95%; compare Ta-
ble 2, entry 2 and Table 1, entry 9), which may be connected
with the stability of the substrate in water. The problem of
the stability of the silyl-protecting group in the reaction
was clearly seen in the case of the reaction of boronic acid
4b with a free phenolic OH group and substrate 1-Br-c:
both the deprotected and protected coupling products 5b-a
and 5b-c were obtained (Table 2, entry 3). This means that
the phenolic OH was acidic enough to cause partial depro-
tection during the reaction. From our results with the free
enol OH group in compound 1-Br-a (see Table 1, entry 6),
we know that it is a poor substrate for coupling. We suggest
that the deprotection of the substrate during the reaction
might be the reason for the low yield.
Reactions of phenylboronic and p-fluorophenylboronic
acids with the TBS-protected cyclohexane substrate 2-Br-c
afforded the coupling products 6a-c and 6c-c in good yields
of 86% (Table 2, entries 5 and 6). The use of p-nitrophenyl-
boronic acid was more complicated: under the standard re-
action conditions a mixture of deprotected and protected
6h-a and 6h-c (60:32) was obtained (entry 7). Reducing the
amount of water to 10:1 led to a decrease in the yield of the
process, affording deprotected and protected products 6h-a
and 6h-c in a ratio of 25:33, with an overall reduction in the
yield of unprotected 6h-a (entry 8). After changing THF to
toluene and increasing the temperature to 100 °C, finally
only the protected product 6h-c was obtained in 69% yield
(entry 9). Also, under these conditions, by using TBS-pro-
tected 1-Br-c and 4i,24 the disilylated coupling product 5i-c
was obtained in 67% yield (entry 4).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H

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Synthesis
The 4-bromofurandione with a TBS protecting group af-
forded only the deprotected coupling compound 7a-a in
51% yield (Table 2, entry 10). Changing the TBS moiety to
the more stable TBDPS group resulted in an increased yield
of 68% (entry 11). In the reaction of 3-Br-c′ and boronic acid
4a in aqueous medium, the unprotected product 7a-a was
formed in only trace amount. So, in the case of furanones,
silyl protection of the substrate is not tolerated under the
Suzuki cross-coupling reaction conditions.
Yield: 78 mg (84%); mp 45–47 °C.
IR (KBr): 2853, 1695, 1603, 1357, 768 cm–1
1H NMR (400 MHz, CDCl3): δ = 7.95–7.82 (m, 2 H), 7.49–7.34 (m, 3 H),
4.05 (s, 3 H), 2.91–2.80 (m, 2 H), 2.56–2.44 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 203.7, 152.4, 147.9, 134.1, 129.9,
128.6, 127.5, 58.3, 32.7, 23.8.
MS (EI, 70 eV): m/z (%) = 188 (100) [M]+, 145 (46), 129 (23), 115 (63),
103 (82), 89 (40), 77 (33), 63 (23).
.
HRMS (ESI): m/z [M + H]+ calcd for C12H13O2: 189.0910; found:
In conclusion, we have demonstrated that various cyclic
3-aryl-substituted 1,2-dicarbonyl compounds can be easily
obtained by Suzuki cross-coupling reactions of 3-chloro-
and 3-bromo-1,2-diketones 1-Cl, 1-Br, 2-Br and 3-Br with
arylboronic acids 4 possessing different substituents. The
reaction can be carried out in different solvents, including
water, and tolerates a variety of protecting groups. The
present protocol for the preparation of different types of 3-
aryl-substituted 1,2-dicarbonyl compounds 5, 6 and 7 is an
addition to our previously developed procedures for the
synthesis of 3-alkyl- and 3-alkynyl-substituted 1,2-cycloal-
kanediones,19 and completes the series, allowing cross-cou-
pling reactions to be utilized in a simple and general route
for the preparation of a wide range of 3-substituted 1,2-di-
carbonyl compounds.
189.0915.
3-(4-Hydroxyphenyl)-2-methoxycyclopent-2-en-1-one (5b-b)
Following general procedure A gave product 5b-b as a white solid.
Yield: 72 mg (70%); mp 166–170 °C.
IR (KBr): 3095, 1658, 1570, 1243, 817 cm–1
1H NMR (400 MHz, MeOD): δ = 7.82 (d, J = 8.8 Hz, 2 H), 6.84 (d, J = 8.9
Hz, 2 H), 6.61 (s, 1 H), 3.92 (s, 3 H), 2.90–2.80 (m, 2 H), 2.49–2.40 (m, 2
H).
13C NMR (101 MHz, MeOD): δ = 206.1, 160.9, 152.7, 130.7, 126.5,
116.8, 116.4, 58.5, 33.2, 24.7.
MS (EI, 70 eV): m/z (%) = 204 (61) [M]+, 187 (11), 161 (13), 148 (11),
.
133 (22), 119 (100), 105 (22), 91 (23), 77 (27), 65 (18), 51 (21).
HRMS (ESI): m/z [M + H]+ calcd for C12H13O3: 205.0859; found:
205.0865.
3-(4-Fluorophenyl)-2-methoxycyclopent-2-en-1-one (5c-b)
Following general procedure A gave product 5c-b as a yellow solid.
Yield: 106 mg (90%); mp 85–88 °C.
All reactions sensitive to oxygen or moisture were conducted under
an argon atmosphere in oven-dried glassware. Purchased chemicals
and solvents were used as received. THF was degassed before use.
Precoated silica gel 60 F254 plates (TLC Silicagel Merck) were used for
TLC. Column chromatography was performed on a preparative purifi-
cation system with 40–63 μm silica gel (Thomar). Melting points
were obtained using a Boëtius (Nagema) instrument and are uncor-
rected. IR spectra were recorded on a Bruker PMA 50 spectrometer. 1H
and 13C NMR spectra were recorded in deuterated solvents on a
Bruker Avance USLA 400 spectrometer. Deuterated solvent peaks
were used as references. 2D FT methods were used for the full assign-
ment of 1H and 13C NMR chemical shifts. Mass spectra were measured
on a Shimadzu GCMS - QP2010 spectrometer using EI (70 eV). High-
resolution mass spectrometry was performed using an Agilent Tech-
nologies 6540 UHD Accurate-Mass Q-TOF LC/MS spectrometer with
AJ-ESI ionization..
IR (KBr): 3064, 2949, 1703, 1602, 1510, 1447, 1226, 820 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.93–7.86 (m, 2 H), 7.15–7.07 (m, 2 H),
4.05 (s, 3 H), 2.87–2.80 (m, 2 H), 2.54–2.47 (m, 2 H).
13C NMR (101 MHz, CDCl3) δ = 203.5, 163.5 (FCarom d, J = 251.3 Hz),
152.0 (d, J = 1.9 Hz), 146.5, 130.4 (Carom d, J = 3.5 Hz), 129.6 (o-CHarom
d, J = 8.4 Hz), 115.7 (m-CHarom d, J = 21.4 Hz), 58.2, 32.6, 23.8.
MS (EI, 70 eV): m/z (%) = 206 (99) [M]+, 177 (21), 163 (38), 147 (20),
133 (52), 121 (100), 107 (47), 101 (38), 96 (14), 75 (18), 57 (20).
HRMS (ESI): m/z [M + H]+ calcd for C12H12FO2: 207.0816; found:
207.0821.
2-Methoxy-3-(thiophen-2-yl)cyclopent-2-en-1-one (5d-b)
Following general procedure A gave product 5d-b as a greenish solid.
Yield: 90 mg (92%); mp 63–65 °C.
Coupling of Halodiketones 1–3 with Arylboronic Acids 4; General
Procedure A
IR (KBr): 3064, 2923, 1679, 1611, 1441, 1359, 1119, 1059, 960, 818,
The reaction was conducted overnight at 60 °C under an argon atmo-
sphere in THF/H2O (4:1, 5 mL) by using of 1, 2 or 3 (0.5 mmol),
ArB(OH)2 4 (0.75 mmol), Na2CO3 (1.0 mmol), Pd(OAc)2 (5 mol%) and
PPh3 (10 mol%). After cooling to r.t., the mixture was diluted with H2O
and extracted with EtOAc. The combined organic layers were washed
with brine, dried over Na2SO4 or MgSO4, filtered and then evaporated
to dryness. The crude residue was purified by column chromatogra-
phy (generally using petroleum ether/EtOAc) to afford the pure prod-
uct.
730 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.53 (dd, J = 5.1, 1.1 Hz, 1 H), 7.44 (dd,
J = 3.7, 1.1 Hz, 1 H), 7.13 (dd, J = 5.1, 3.7 Hz, 1 H), 4.11 (s, 3 H), 2.94–
2.81 (m, 2 H), 2.59–2.48 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 201.7, 149.7, 143.5, 136.7, 130.0,
127.5, 127.4, 58.1, 33.0, 23.6.
MS (EI, 70 eV): m/z (%) = 194 (89) [M]+, 165 (16), 151 (11), 137 (26),
123 (27), 109 (100), 95 (13), 77 (10).
HRMS (ESI): m/z [M + H]+ calcd for C10H11O2S: 195.0474; found:
195.0476.
2-Methoxy-3-phenylcyclopent-2-en-1-one (5a-b)
Following general procedure A gave product 5a-b as a yellow solid.
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2-Methoxy-3-(o-tolyl)cyclopent-2-en-1-one (5e-b)
Following general procedure A gave product 5e-b as a white solid.
Yield: 80 mg (79%); mp 44–46 °C.
MS (EI, 70 eV): m/z (%) = 216 (37) [M]+, 201 (100), 155 (12), 145 (22),
131 (54), 115 (40), 91 (30), 77 (9).
HRMS (ESI): m/z [M + H]+ calcd for C14H17O2: 217.1223; found:
217.1226.
IR (KBr): 2946, 1701, 1625, 1445, 1348, 1139, 1105, 783 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.32–7.16 (m, 4 H), 3.65 (s, 3 H), 2.77–
2.69 (m, 2 H), 2.58–2.50 (m, 2 H), 2.29 (s, 3 H).
13C NMR (101 MHz, CDCl3): δ = 203.2, 152.3, 148.6, 135.7, 135.5,
130.4, 128.7, 127.4, 125.8, 58.4, 33.2, 27.9, 20.1.
MS (EI, 70 eV): m/z (%) = 202 (51) [M]+, 187 (100), 159 (14), 145 (44),
128 (32), 115 (67), 103 (23), 91 (34), 77 (27).
HRMS (ESI): m/z [M + H]+ calcd for C13H15O2: 203.1067; found:
203.1069.
2-Methoxy-3-(o-methoxycarbonylphenyl)cyclohex-2-en-1-one
(6g-b)
Following general procedure A gave product 6g-b as a yellow solid.
Yield: 65 mg (50%); mp 55–58 °C.
IR (KBr): 2950, 1723, 1681, 1626, 1435, 1351, 1292, 1260, 1136, 1097,
1075, 994, 894, 760, 709 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 8.00 (ddd, J = 7.9, 1.4, 0.5 Hz, 1 H), 7.54
(td, J = 7.6, 1.4 Hz, 1 H), 7.40 (td, J = 7.7, 1.3 Hz, 1 H), 7.20 (ddd, J = 7.7,
1.3, 0.5 Hz, 1 H), 3.85 (s, 3 H), 3.39 (s, 3 H), 2.61 (dt, J = 10.7, 6.4 Hz, 4
H), 2.14 (quin, J = 6.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 195.4, 166.9, 147.6, 147.3, 139.7,
132.3, 130.6, 128.4, 128.2, 127.9, 59.6, 52.2, 38.9, 32.4, 22.9.
2-Hydroxy-3-phenylcyclopent-2-en-1-one (5a-a)
Following general procedure A gave product 5a-a as a white solid.
Yield: 12 mg (14%).
MS (EI, 70 eV): m/z (%) = 260 (73) [M]+, 229 (21), 186 (82), 168 (16),
157 (22), 141 (18), 129 (100), 115 (43), 102 (25), 77 (18), 55 (21).
IR (KBr): 3394, 3282, 2918, 1681, 1633, 1495, 1449, 1391, 1323, 1286,
1218, 1136, 1047, 988, 889, 765, 691, 623 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 9.88 (s, 1 H), 7.99–7.85 (m, 2 H),
7.45 (dd, J = 8.3, 6.8 Hz, 2 H), 7.41–7.31 (m, 1 H), 2.82–2.72 (m, 2 H),
2.48–2.39 (m, 2 H).
HRMS (ESI): m/z [M + H]+ calcd for C15H17O4: 261.1121; found:
261.1126.
13C NMR (101 MHz, DMSO-d6): δ = 202.8, 149.8, 136.9, 134.7, 128.7,
128.5, 127.0, 31.1, 22.7.
MS (EI, 70 eV): m/z (%) = 174 (100) [M]+, 145 (25), 131 (20), 117 (63),
103 (50), 89 (29), 77 (33), 63 (20), 51 (24).
HRMS (ESI): m/z [M + H]+ calcd for C11H11O2: 175.0754; found:
175.0752.
4-(4-Fluorophenyl)-3-methoxyfuran-2(5H)-one (7c-b)
Following general procedure A gave product 7c-b as a white solid.
Yield: 84 mg (82%); mp 164–167 °C.
IR (KBr): 2963, 1739, 1651, 1593, 1513, 1447, 1355, 1229, 1149, 1071,
970, 836 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.86–7.74 (m, 2 H), 7.32–7.19 (m, 2 H),
5.19 (s, 2 H), 4.29 (s, 3 H).
2-Methoxy-3-phenylcyclohex-2-en-1-one (6a-b)
Following general procedure A gave product 6a-b as a yellow liquid.
Yield: 97 mg (96%).
13C NMR (101 MHz, CDCl3): δ = 168.8, 163.4 (FCarom d, J = 251.8 Hz),
139.7 (d, J = 2.2 Hz), 132.8, 128.8 (o-CHarom d, J = 8.2 Hz), 126.3 (Carom
d, J = 3.5 Hz), 116.2 (m-CHarom d, J = 21.7 Hz), 67.2, 58.6.
MS (EI, 70 eV): m/z (%) = 208 (100) [M]+, 179 (29), 162 (21), 151 (23),
136 (79), 121 (95), 109 (89), 75 (27).
IR (KBr): 2934, 2834, 1676, 1603, 1493, 1442, 1351, 1329, 1306, 1278,
1234, 1203, 1140, 1090, 991, 893, 763, 697 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.56–7.46 (m, 2 H), 7.44–7.28 (m, 3 H),
3.52 (s, 3 H), 2.76 (t, J = 6.0 Hz, 2 H), 2.57 (dd, J = 7.4, 6.1 Hz, 2 H), 2.09
(dt, J = 12.4, 6.2 Hz, 2 H).
HRMS (ESI): m/z [M + H]+ calcd for C11H10O3F: 209.0608; found:
209.0609.
13C NMR (101 MHz, CDCl3): δ = 196.0, 149.1, 144.0, 137.5, 128.7,
128.3, 128.0, 60.0, 38.9, 31.0, 22.7.
MS (EI, 70 eV): m/z (%) = 202 (100) [M]+, 187 (21), 156 (21), 145 (31),
129 (50), 117 (73), 103 (81), 91 (45), 77 (60), 63 (22), 51 (36).
HRMS (ESI): m/z [M + H]+ calcd for C13H15O2: 203.1067; found:
203.1075.
3-(Methoxymethoxy)-4-(thiophen-2-yl)furan-2(5H)-one (7d-d)
Following general procedure A gave product 7d-d as a yellow solid.
Yield: 112 mg (99%); mp 54–56 °C.
IR (KBr): 3106, 2936, 1752, 1655, 1516, 1428, 1360, 1162, 1128, 925,
838, 715 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.55 (dd, J = 5.1, 1.1 Hz, 1 H), 7.31–7.22
(m, 1 H), 7.13 (dd, J = 5.1, 3.7 Hz, 1 H), 5.58 (s, 2 H), 5.09 (s, 2 H), 3.53
(s, 3 H).
13C NMR (101 MHz, CDCl3): δ = 168.2, 135.1, 132.4, 131.3, 129.7,
127.6, 126.7, 95.6, 67.3, 57.7.
2-Methoxy-3-(p-tolyl)cyclohex-2-en-1-one (6f-b)
Following general procedure A gave product 6f-b as a brown oil.
Yield: 89 mg (82%); mp 44–46 °C.
MS (EI, 70 eV): m/z (%) = 226 (7) [M]+, 196 (14), 168 (8), 109 (28), 65
(6), 45 (100).
IR (KBr): 2931, 1676, 1604, 1510, 1436, 1350, 1186, 1141, 994, 815
cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.48–7.39 (m, 2 H), 7.23–7.15 (m, 2 H),
3.51 (s, 3 H), 2.75 (t, J = 6.0 Hz, 2 H), 2.61–2.50 (m, 2 H), 2.37 (s, 3 H),
2.07 (dt, J = 12.2, 6.3 Hz, 2 H).
HRMS (ESI): m/z [M + H]+ calcd for C10H11O4S: 227.0373; found:
227.0380.
13C NMR (101 MHz, CDCl3): δ = 196.0, 149.0, 144.0, 138.8, 134.5,
129.0, 128.0, 59.9, 38.8, 30.9, 22.6, 21.4.
3-(Methoxymethoxy)-4-(o-methoxycarbonylphenyl)furan-2(5H)-
one (7g-d)
Following general procedure A gave product 7g-d as a yellow liquid.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H

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Synthesis
Yield: 35 mg (25%).
2-[(tert-Butyldimethylsilyl)oxy]-3-(4-hydroxyphenyl)cyclopent-2-
en-1-one (5b-c)
IR (KBr): 2955, 1730, 1598, 1574, 1436, 1349, 1265, 1159, 1092, 940,
765, 710 cm–1
Following general procedure A gave product 5b-c as a white solid.
Yield: 36 mg (23%); mp 169–171 °C.
.
1H NMR (400 MHz, CDCl3): δ = 8.01 (dd, J = 7.8, 1.4 Hz, 1 H), 7.59 (td,
J = 7.6, 1.4 Hz, 1 H), 7.50 (td, J = 7.7, 1.4 Hz, 1 H), 7.34 (dd, J = 7.6, 1.3
Hz, 1 H), 5.05 (s, 2 H), 4.99 (s, 2 H), 3.86 (s, 3 H), 3.17 (s, 3 H).
13C NMR (101 MHz, CDCl3): δ = 168.8, 166.8, 139.9, 137.7, 132.3,
131.0, 130.9, 130.3, 129.6, 129.5, 95.5, 69.9, 56.7, 52.6.
MS (EI, 70 eV): m/z (%) = 278 (0.3) [M]+, 246 (1), 233 (3), 189 (17), 161
(12), 129 (13), 45 (100).
HRMS (ESI): m/z [M + H]+ calcd for C14H15O6: 279.0863; found:
279.0865.
IR (KBr): 3394, 3283, 2918, 1682, 1632, 1495, 1441, 1392, 1323, 1286,
1218, 1136, 1047, 988, 889, 765, 691, 623 cm–1
.
1H NMR (400 MHz, MeOD): δ = 7.87–7.79 (m, 2 H), 6.86–6.79 (m, 2
H), 2.86–2.80 (m, 2 H), 2.46–2.39 (m, 2 H), 0.97 (s, 9 H), 0.21 (s, 6 H).
13C NMR (101 MHz, MeOD): δ = 205.4, 160.4, 149.2, 148.3, 130.6,
127.0, 116.1, 32.3, 26.4, 24.8, 19.5, –3.4.
MS (EI, 70 eV): m/z (%) = 289 (2) [M]+ = 304, 247 (100), 232 (4), 217
(7), 131 (3), 115 (5), 75 (16).
HRMS (ESI): m/z [M + H]+ calcd for C17H25O3Si: 305.1567; found:
305.1558.
3-(Methoxymethoxy)-4-(4-nitrophenyl)furan-2(5H)-one (7h-d)
Following general procedure A gave product 7h-d as a yellow solid.
Yield: 90 mg (68%); mp 135–137 °C.
2-[(tert-Butyldimethylsilyl)oxy]-3-phenylcyclohex-2-en-1-one
(6a-c)
IR (KBr): 2928, 1753, 1644, 1596, 1513, 1460, 1341, 1153, 1062, 944,
886, 754 cm–1
.
Following general procedure A gave product 6a-c as a white solid.
1H NMR (400 MHz, DMSO-d6): δ = 8.39–8.32 (m, 2 H), 8.05–7.96 (m, 2
Yield: 130 mg (86%); mp 41–43 °C.
IR (KBr): 2928, 1670, 1572, 1415, 1249, 1168, 852, 674 cm–1
.
H), 5.53 (s, 2 H), 5.37 (s, 2 H), 3.37 (s, 3 H).
13C NMR (101 MHz, DMSO-d6): δ = 167.9, 147.5, 138.8, 135.5, 134.6,
128.0, 124.0, 95.3, 67.6, 56.9.
HRMS (ESI): m/z [M + H]+ calcd for C12H12NO6: 266.0659; found:
1H NMR (400 MHz, CDCl3): δ = 7.48–7.41 (m, 2 H), 7.39–7.31 (m, 2 H),
7.31–7.24 (m, 1 H), 2.73 (t, J = 6.0 Hz, 2 H), 2.60–2.50 (m, 2 H), 2.13–
2.02 (m, 2 H), 0.66 (s, 9 H), 0.00 (s, 6 H).
13C NMR (101 MHz, CDCl3): δ = 195.8, 144.2, 138.6, 138.4, 128.6,
266.0659.
128.0, 38.5, 31.2, 25.6, 22.9, 18.7, –4.1.
2-[(tert-Butyldimethylsilyl)oxy]-3-phenylcyclopent-2-en-1-one
(5a-c)
MS (EI, 70 eV): m/z (%) = 245 (100) [M – 57]+, 167 (4), 141 (4), 128 (4),
115 (5), 103 (3), 91 (6), 75 (26), 57 (4).
Following general procedure A gave product 5a-c as a white solid.
HRMS (ESI): m/z [M + H]+ calcd for C18H26O2Si: 303.1775; found:
Yield: 98 mg (68%); mp 84–86 °C.
303.1778.
IR (KBr): 2927, 1702, 1607, 1374, 1247, 1146, 843, 761, 650 cm–1
.
2-[(tert-Butyldimethylsilyl)oxy]-3-(4-fluorophenyl)cyclohex-2-
en-1-one (6c-c)
1H NMR (400 MHz, CDCl3): δ = 7.95–7.90 (m, 2 H), 7.45–7.34 (m, 3 H),
2.89–2.84 (m, 2 H), 2.51–2.46 (m, 2 H), 0.97 (s, 9 H), 0.25 (s, 6 H).
Following general procedure A gave product 6c-c as a white solid.
Yield: 139 mg (87%); mp 36–38 °C.
13C NMR (101 MHz, CDCl3): δ = 203.4, 149.4, 144.9, 134.6, 129.4,
128.4, 127.5, 31.6, 26.0, 23.9, 18.7, –3.4.
MS (EI, 70 eV): m/z (%) = 231 (100) [M – 57]+, 216 (5), 201 (10), 128
(8), 115 (7), 75 (14).
IR (KBr): 2928, 1672, 1600, 1509, 1470, 1537, 1223, 1162, 836, 785
cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.50–7.39 (m, 2 H), 7.08–7.00 (m, 2 H),
2.70 (t, J = 6.0 Hz, 2 H), 2.58–2.51 (m, 2 H), 2.07 (dt, J = 12.2, 6.3 Hz, 2
H), 0.68 (s, 9 H), 0.01 (s, 6 H).
HRMS (ESI): m/z [M + H]+ calcd for C17H25O2Si: 289.1618; found:
289.1624.
2-Hydroxy-3-(4-hydroxyphenyl)cyclopent-2-en-1-one (5b-a)
Following general procedure A gave product 5b-a as a brown solid.
Yield: 25 mg (26%); mp 236–241 °C.
13C NMR (101 MHz, CDCl3): δ = 195.7, 162.4 (FCarom d, J = 247.8 Hz),
144.4, 137.0, 134.5 (Carom d, J = 3.4 Hz), 130.5 (o-CHarom d, J = 8.0 Hz),
115.0 (m-CHarom d, J = 21.4 Hz), 38.4, 31.1, 25.7, 22.8, 18.7, -4.1.
MS (EI, 70 eV): m/z (%) = 263 (100) [M – 57]+, 233 (3), 159 (4), 133 (5),
109 (8), 75 (29).
IR (KBr): 3319, 2923, 2468, 1656, 1598, 1516, 1430, 1386, 1280, 1214,
1175, 1139, 1117, 957, 845, 821, 560 cm–1
.
HRMS (ESI): m/z [M + H]+ calcd for C18H26O2SiF: 321.1681; found:
321.1688.
1H NMR (400 MHz, MeOD): δ = 7.97–7.76 (m, 2 H), 6.91–6.76 (m, 2
H), 2.89–2.74 (m, 2 H), 2.51–2.29 (m, 2 H).
13C NMR (101 MHz, MeOD): δ = 204.8, 159.8, 149.2, 141.4, 130.5,
127.6, 116.2, 32.2, 24.3.
MS (EI, 70 eV): m/z (%) = 190 (100) [M]+,161 (15), 145 (12), 133 (42),
119 (56), 105 (23), 91 (28), 77 (24), 65 (18), 51 (23).
HRMS (ESI): m/z [M + H]+ calcd for C11H11O3: 191.0703; found:
191.0707.
2-Hydroxy-3-(4-nitrophenyl)cyclohex-2-en-1-one (6h-a)
Following general procedure A gave a brown solid (78 mg), from
which 6h-a (70 mg, 60%) and the impurity 4,4′-dinitro-1,1′-biphenyl
(8 mg) were obtained.
IR (KBr): 3406, 3358, 2930, 1647, 1592, 1510, 1494, 1378, 1340, 1289,
1229, 1189, 1163, 1110, 850, 698 cm–1
.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H

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1H NMR (400 MHz, MeOD): δ = 8.22–8.17 (m, 2 H), 7.98–7.91 (m, 2
H), 2.79 (t, J = 5.9 Hz, 2 H), 2.60 (dd, J = 7.3, 6.0 Hz, 2 H), 2.10 (quin, J =
6.4 Hz, 2 H).
13C NMR (101 MHz, MeOD): δ = 197.0, 148.0, 146.8, 146.2, 130.4,
126.2, 124.0, 37.5, 29.6, 23.8.
MS (EI, 70 eV): m/z (%) = 233 (100) [M]+, 216 (52), 205 (35), 186 (55),
158 (21), 129 (24), 115 (63), 102 (37), 91 (38), 77 (47), 63 (27), 51
(33).
HRMS (ESI): m/z [M + H]+ calcd for C12H12O4N: 234.0761; found:
234.0761.
3-(Methoxymethoxy)-4-(thiophen-2-yl)furan-2(5H)-one (7d-d)
Following general procedure B gave 7d-d as a yellow solid.
Yield: 75 mg (66%).
The physical and spectroscopic properties correspond to the data giv-
en above (following general procedure A).
2-[(tert-Butyldimethylsilyl)oxy]-3-phenylcyclopent-2-en-1-one
(5a-c)
Following general procedure B gave 5a-c as a white solid.
Yield: 93 mg (65%).
The physical and spectroscopic properties correspond to the data giv-
en above (following general procedure A).
2-[(tert-Butyldimethylsilyl)oxy]-3-(4-nitrophenyl)cyclohex-2-en-
1-one (6h-c)
Following general procedure A gave a yellow solid (66 mg), from
which 6h-c (55 mg, 32%) and the impurity 4,4′-dinitro-1,1′-biphenyl
(11 mg) were obtained. See below for the physical and spectroscopic
properties of product 6h-c obtained via general procedure C.
Coupling of Halodiketones 1 and 2 with Arylboronic Acids 4 (Silyl-
Protected Compounds); General Procedure C
The reaction was conducted overnight at 100 °C under an argon at-
mosphere in toluene/H2O (10:1, 5 mL) by using of 1 or 2 (0.5 mmol),
ArB(OH)2 (0.75 mmol), Na2CO3 (1.0 mmol), Pd(OAc)2 (5 mol%) and
PPh3 (10 mol%). After cooling to r.t., the mixture was diluted with H2O
and extracted with EtOAc. The combined organic layers were washed
with brine, dried over Na2SO4 or MgSO4, filtered and then evaporated
to dryness. The crude residue was purified by column chromatogra-
phy (generally using petroleum ether/EtOAc) to afford the pure prod-
uct.
3-Hydroxy-4-phenylfuran-2(5H)-one (7a-a)
Following general procedure A gave 7a-a as a white solid.
Yield: 60 mg (68%); mp 202–205 °C.
IR (KBr): 3302, 2939, 2457, 1722, 1499, 1453, 1400, 1324, 1167, 759,
687 cm–1
.
1H NMR (400 MHz, MeOD): δ = 7.78–7.66 (m, 2 H), 7.47–7.37 (m, 2
H), 7.36–7.24 (m, 1 H), 5.09 (s, 2 H).
13C NMR (101 MHz, MeOD): δ = 172.3, 138.8, 132.2, 129.9, 129.7,
127.5, 127.4, 69.2.
MS (EI, 70 eV): m/z (%) = 176 (23) [M]+, 131 (23), 103 (100), 91 (7), 77
2-[(tert-Butyldimethylsilyl)oxy]-3-{4-[(tert-butyldimethylsi-
lyl)oxy]phenyl}cyclopent-2-en-1-one (5i-c)
Following general procedure C gave 5i-c as a white solid.
Yield: 141 mg (67%); mp 117–118 °C.
(18), 65 (5), 63 (6), 51 (15).
IR (KBr): 2957, 2929, 2858, 1707, 1605, 1512, 1373, 1276, 1146, 1108,
HRMS (ESI): m/z [M + H]+ calcd for C10H9O3: 177.0546; found:
177.0544.
916, 845, 782 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.87–7.80 (m, 2 H), 6.92–6.83 (m, 2 H),
2.87–2.78 (m, 2 H), 2.49–2.42 (m, 2 H), 0.99 (s, 9 H), 0.97 (s, 9 H), 0.25
(s, 6 H), 0.22 (s, 6 H).
13C NMR (101 MHz, CDCl3): δ = 203.0, 157.0, 148.3, 145.2, 129.1,
128.0, 120.1, 31.6, 26.1, 25.8, 23.9, 18.7, 18.4, –3.4, –4.2.
MS (EI, 70 eV): m/z (%) = 418 (0.3) [M]+, 403 (2), 387 (1), 361 (100),
289 (3), 152 (8), 73 (21).
HRMS (ESI): m/z [M + H]+ calcd for C23H39O3Si2: 419.2432; found:
419.2425.
Coupling of Halodiketones 1–3 with Arylboronic Acids 4 under
Aqueous Conditions; General Procedure B
The reaction was conducted at r.t. for 3 h under an air atmosphere in
H2O (1.5 mL) by using 1, 2 or 3 (0.5 mmol), ArB(OH)2 ( 0.75 mmol),
Et3N (1.5 mmol), Pd(OAc)2 (5 mol%) and PPh3 (10 mol%). The mixture
was diluted with H2O and extracted with EtOAc. The combined or-
ganic layers were washed with brine, dried over Na2SO4 or MgSO4, fil-
tered and then evaporated to dryness. The crude residue was purified
by column chromatography (generally using petroleum ether/EtOAc)
to afford the pure product.
2-[(tert-Butyldimethylsilyl)oxy]-3-(4-nitrophenyl)cyclohex-2-en-
1-one (6h-c)
2-Methoxy-3-phenylcyclopent-2-en-1-one (5a-b)
Following general procedure C gave a yellow solid (123 mg), from
which 6h-c (119 mg, 69%) and the impurity 4,4′-dinitro-1,1′'-biphe-
nyl (4 mg) were obtained.
Following general procedure B on 0.35 mmol scale gave 5a-b as a yel-
low solid.
Yield: 63 mg (95%).
IR (KBr): 2927, 1679, 1593, 1517, 1470, 1371, 1343, 1249, 842, 782
cm–1
.
The physical and spectroscopic properties correspond to the data giv-
en above (following general procedure A).
1H NMR (400 MHz, CDCl3): δ = 8.25–8.17 (m, 2 H), 7.68–7.58 (m, 2 H),
2.73 (t, J = 5.9 Hz, 2 H), 2.59 (dd, J = 7.4, 5.9 Hz, 2 H), 2.12 (quin, J = 6.2
Hz, 2 H), 0.66 (s, 9 H), 0.04 (s, 6 H).
2-Methoxy-3-(p-tolyl)cyclohex-2-en-1-one (6f-b)
Following general procedure A on 0.37 mmol scale gave 6f-b as a
brown oil.
13C NMR (101 MHz, CDCl3): δ = 195.4, 147.1, 145.5, 145.3, 134.6,
129.6, 123.3, 38.4, 30.6, 25.6, 22.8, 18.7, –3.9.
Yield: 70 mg (88%).
MS (EI, 70 eV): m/z (%) = 290 (100) [M – 57]+, 244 (21), 115 (3), 75
The physical and spectroscopic properties correspond to the data giv-
en above (following general procedure A).
(12).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H

H
E. Lopušanskaja et al.
Paper
Synthesis
HRMS (ESI): m/z [M + H]+ calcd for C18H26O4NSi: 348.1626; found:
348.1613.
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Funding Information
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Kanger, T.; Lopp, M. Synthesis 2006, 3031. (b) Jõgi, A.; Paju, A.;
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2009, 65, 2959.
This work has been supported by the Estonian Ministry of Education
and Research grants IUT 19-32 and IUT23-7 and the Centre of Excel-
lence in Molecular Cell Engineering (No. 2014-2020.4.01.15-0013).
)(
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Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0036-1591543.
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–H