Magnesium-promoted one-pot double C-acylation and cycloaddition of anthracene and double C-acylation of benzyl acrylates

Article abstract of DOI:10.1055/s-2007-970780

Treatment of anthracene or benzyl acrylate with magnesium turnings for Grignard reaction in the presence of various acid chlorides in N,N-dimethylformamide at room temperature brought about one-pot reductive double C-acylation or tandem intermolecular cyc

Full text of DOI:10.1055/s-2007-970780

LETTER
769
Magnesium-Promoted One-Pot Double C-Acylation and Cycloaddition of
Anthracene and Double C-Acylation of Benzyl Acrylates
D
ouble C-Acylation an
a
dCycloadd
s
itionof
A
a
nthracene to Matsunami, Nobuyasu Sakai, Tomotaka Morimoto, Hirofumi Maekawa, Ikuzo Nishiguchi*
Department of Chemistry, Nagaoka University of Technology, 1603-1, Kamitomioka-cho, Nagaoka, Niigata 940-2188, Japan
Fax +81(258)479300; E-mail: nishiiku@vos.nagaokaut.ac.jp
Received 20 December 2006
Optimization of the reaction conditions for the present
Mg-promoted one-pot double C-acylation of anthracene
with acid chlorides has been accomplished by changing
the solvent, the equivalent of acylating agent and magne-
Abstract: Treatment of anthracene or benzyl acrylate with magne-
sium turnings for Grignard reaction in the presence of various acid
chlorides in N,N-dimethylformamide at room temperature brought
about one-pot reductive double C-acylation or tandem intermolecu-
lar cycloaddition to give the corresponding C-diacylated products in sium on the basis of anthracene (1) to find that the desired
satisfactory yields.
double C-acylation products were obtained most effi-
ciently by using 10 equivalents of acid chloride and 10
equivalents of Mg turnings for Grignard reaction in anhy-
drous N,N-dimethylformamide (DMF) at 15–20 °C under
a nitrogen atmosphere.
Key words: magnesium, anthracene, double acylation, cycloaddi-
tion, benzyl acrylate
Introduction of an acyl group to the carbon–carbon double
bond of activated olefins may be one of the most attrac-
tive, important and useful techniques for carbon–carbon
bond formation.1 We have already reported electro-
chemical2 or Mg-promoted3 C-acylation of a,b-unsaturat-
ed carbonyl compounds to afford the corresponding C-
acylated 1,4-dicarbonyl compounds in the stereo- and
Under the optimized conditions, the reaction proceeded
with a variety of acid chlorides (2a–d) very smoothly in
DMF at room temperature to give the mixtures of the
corresponding two stereoisomers, 9,10-diacylated 9,10-
dihydroanthracenes (3Aa–d, and 3Ba–d), in moderate to
good yields, as shown in Table 1.6,7
regioselective manners. Furthermore, monoacylation of Table 1 Double C-Acylation of Anthracene in the Presence of
Various Acid Chloridesa
stilbenes had also been demonstrated by our group.4 How-
ever, in these reactions, the corresponding double C-acy-
lated products were not detected in the product mixtures,
but only the C-monoacylated products were exclusively
obtained.
R
O
O
Mg
+
DMF
R
Cl
On the other hand, we have recently developed electro-
reductive one-pot vicinal double C-acylation of styrenes
and methacryl esters with acid anhydrides or N-acylimi-
dazole derivatives.5
O
R
1
2
3
Entry
R
Product (%)b
73 (3a)
Isomeric ratio
In this study, we wish to present the first Mg-promoted
one-pot double C-acylation and unique tandem intermo-
lecular cycloaddition of anthracene (1) and benzyl
acrylate (6) with a variety of acid chlorides 2 to give
the corresponding novel 9,10-diacyl-9,10-dihydro-
anthracenes 3 and 1,4-diketones 7, respectively, as the
predominant products in good yields (Scheme 1).
1
2
3
4
Me (2a)
Et (2b)
n-Pr (2c)
i-Pr (2d)
68 (3Aa):32(3Ba)
78 (3Ab):22 (3Bb)
82 (3Ac):18 (3Bc)
>99 (3Ad):<1 (3Bd)
78 (3b)
88 (3c)
59 (3d)
a Reaction conditions: anthracene (5 mmol), acid chloride (10 equiv),
Mg (10 equiv), DMF (40 mL), 15–25 °C, 15 h reaction time, under
O
R
N2 atmosphere.
b GC yield.
Mg
+
2 RCOCl
DMF
The stereoisomeric ratios became larger with the increase
in bulkiness of the alkyl groups of acid chlorides 2a–d. It
may be quite interesting that these two stereoisomers may
be characterized as the cis-exo- and cis-endo-isomers by
their same chemical shifts in 9- and 10-protons of each
isomer of 9,10-diacylated anthracene, in which these cis-
exo- and cis-endo-isomers were found to appear as one
singlet at d = 5.10–5.23 ppm for the major stereoisomers
1
2
3
R
O
R = Me, Et, n-Pr, i-Pr
Scheme 1 Mg-promoted one-pot double C-acylation of anthracene
SYNLETT 2007, No. 5, pp 0769–0774
Advanced online publication: 08.03.2007
DOI: 10.1055/s-2007-970780; Art ID: U15506ST
© Georg Thieme Verlag Stuttgart · New York
1
6.
0
3.
2
0
0
7

770
M. Matsunami et al.
LETTER
3Aa–d and at d = 4.87–4.89 ppm for the minor isomers were used in diluted solution (35 mM) of DMF at room
3Ba–d, respectively, as shown in Scheme 2. The cis-exo- temperature under nitrogen atmosphere.
isomers 3Aa–d are presumably more stable than the cis-
endo-isomers 3Ba–d because of steric hindrance between
The absolute structure of the product 5a formed from
cycloaddition of anthracene with succinyl dichloride was
two acyl groups and two benzene rings. The low-field
confirmed by X-ray analysis of the single crystal, as
shift in the chemical shift of the exo-isomers 3Aa–d may
shown Figure 1, and the bridgehead methine protons of 5a
be attributed to a diamagnetic anisotropy effect induced
by the ring current of their two phenyl rings.
were found to appear at d = 5.14 ppm as the singlet in its
1H NMR spectrum, which shows good consistence with
the chemical shift of the 9,10-bridgehead protons of exo-
stereoisomers 3Aa–f, the major products among 9,10-di-
acylated products of anthracene (1), as mentioned before.
R
O
H
O
R
H
H
R
O
O
H
R
cis-exo-isomer (3Aa–d)
cis-endo-isomer (3Ba–d)
δ value:
5.10–5.23 ppm
4.87–4.89 ppm
Scheme 2 Chemical shift of H-9 and H-10 (one singlet) in 1H NMR
Similarly, employment of more sterically bulky acid chlo-
rides such as ethyl succinyl chloride (2e) and 4-chloro-
butyryl chloride (2f) as the acylating agents in the present
reaction brought about formation of only the correspond-
ing exo-stereoisomers, 9,10-di(3-carboethoxy propionyl)-
9,10-dihydroanthracene (3Ae: 60% yield) and 9,10-di(4-
chlorobutyryl)-9,10-anthracene (3Af: 67% yield), respec-
tively, as shown in Scheme 3.
Figure 1 X-ray crystal structure of 5a
Furthermore, similar one-pot double C-acylation was also
observed in Mg-promoted reduction of benzyl acrylate (6)
with acid chlorides in DMF. Thus, treatment of benzyl
acrylate with Mg turnings at room temperature (15–
25 °C) in the presence of various acid chlorides in DMF
brought about one-pot vicinal double C-acylation to give
the corresponding diketoesters 7a–d in moderate to good
yields, accompanying formation of monoacylated prod-
ucts 8a–d in small amounts as by-products (Table 2).
The present Mg-promoted carbon–carbon bond formation
was successfully applied to novel cycloaddition of
anthracene with a,w-dicarboxylic acid dichlorides 4a,b
such as succinyl and glycolyl dichlorides to give the cor-
responding dibenzobicyclic compounds 5a,b, as shown in
Scheme 4. The optimum results of these Mg-promoted
cycloaddition were obtained to give the corresponding ad-
ducts 5a,b as almost single products in 63% and 34%
yields when each five equivalents of Mg turnings for
Grignard reaction and acid dichloride based on anthracene
In order to obtain some information for reaction mecha-
nism of the present one-pot Mg-promoted double C-
acylation, reduction potential of starting substrates, an-
O
O
OEt
O
Mg
OEt
+
Cl
DMF
60%
OEt
O
O
O
2e
3Ae
O
Cl
O
Mg
+
Cl
Cl
DMF
67%
Cl
O
2f
3Af
Scheme 3 Double C-acylation of anthracene in the presence of ethyl succinyl chloride or 4-chlorobutyryl chloride
Synlett 2007, No. 5, 769–774 © Thieme Stuttgart · New York

LETTER
Double C-Acylation and Cycloaddition of Anthracene
771
O
O
Mg
+
O
Cl
Cl
DMF
O
63%a,b
1
4a
5a
O
O
Mg
O
O
O
+
O
DMF
Cl
Cl
34%a,c
1
4b
5b
Scheme 4 Cycloaddition of anthracene in the presence of various acid dichlorides. Reaction conditions: substrate (5 mmol), acid chloride (5
equiv), Mg (5 equiv), 15–25 °C, reaction time 15 h, under N2 atmosphere; a GC yield; b DMF (100 mL); c TMSCl (0.5 equiv), DMF (140 mL).
acylation of anthracene with acid chlorides, although the
detailed mechanism has not been clear as yet. The first
electron transfer from Mg metal to anthracene (1) may
generate the corresponding anion radicals 9 which may be
delocalized predominantly at the 9- and the 10-positions
and the Mg cation may coordinate at these positions. Sub-
sequently, the first electrophilic attack of an acylating
agent takes place at either of the 9- and 10-positions of an-
thracene (1) from the opposite side of Mg cation, followed
by the fast second electron transfer, giving more stable
benzylic anions 10, which may still coordinate with Mg
cation. The second electrophilic attack of another acylat-
ing agent to benzylic anion from the opposite side of Mg
cation may give a stereoisomeric mixture of the cis-exo-
and/or the cis-endo-9,10-diacylated 9,10-dihydroan-
thracenes 3a–f, in which the cis-exo-isomer may be steri-
cally more favorable as a major component, as shown in
Scheme 5.
Table 2 Double C-Acylation of Benzyl Acrylates in the Presence of
Various Acid Chloridesa
O
O
R
O
Mg
O
+
+
COOBn
R
COOBn
DMF
Cl
R
R
COOBn
6
2
7
8
Entry
R
GC yield (%)
7
8
1
2
3
4
Et (2b)
76 (7a)
61 (7b)
43 (7c)
44 (7d)
24 (8a)
8 (8b)
14 (8c)
8 (8d)
n-Pr (2c)
i-Pr (2d)
i-Bu (2g)
a Reaction conditions: substrate (10 mmol), acid chloride (7 equiv),
Mg (6 equiv), DMF (60 mL), 15–25 °C, 16 h reaction time, under N2
atmosphere.
In the case of benzyl acrylate (6), similarly the first elec-
tron transfer from Mg metal to the benzyl acrylate may
generate the corresponding anion radical 11, which may
be subjected to the first electrophilic attack of acid
chloride to the b-carbon of the activated olefin to give
more stable a-ester anion 13 rather than the less stable
terminal methylene anion 12 after the fast second electron
transfer preferentially rather than less stable methylene
anions 12. Subsequently, the second electrophilic acyla-
tion and protonation took place toward benzylic anions 13
to give vicinal double C-acylation products 7.
thracene and benzyl acrylate, and acid chlorides were
analyzed by cyclic voltammetry, as shown in Table 3.
No reduction wave of acid chloride was observed in the
range of 0 V to –3.00 V. On the other hand, clear reduction
wave of anthracene and benzyl acrylate was obtained at
–1.77 V and –2.20 V, respectively, which may be accessi-
ble by Mg-promoted reduction. The following reaction
scheme may be proposed as one of the most plausible
reaction mechanisms for the present one-pot double C-
Table 3 Reduction Potentials of Active Olefines and Acid Chloridesa
Substrate
Reduction potential (V vs. Ag/
AgCl)
Substrate
Reduction potential (V vs. Ag/
AgCl)
O
Cl
O
–2.20
No wave (0 to –3.00)
COOBn
–1.77
No wave (0 to –3.00)
Cl
Cl
O
a Working electrode: Pt, counter electrode: Pt, reference electrode: Ag/AgCl, solvent: DMF (15 mL), supporting electrolyte: 1% n-Bu4NClO4,
scan rate: 200 mV/s.
Synlett 2007, No. 5, 769–774 © Thieme Stuttgart · New York

772
M. Matsunami et al.
LETTER
Anthracene
RCOCl
R
O
+ e (Mg)
+ e (Mg)
RCOCl
1
Mg
9
Mg
RCOCl
R
O
O
10
RCOCl
R
3
Benzyl acrylate
O
R
COOBn
O
COOBn
6
COOBn
R
RCOCl
12
H+
+ e–
8
+ e–
less stable
O
O
R
RCOCl
+ e–
RCOCl
O
COOBn
R
R
COOBn
COOBn
11
13
7
Scheme 5 Proposed reaction mechanism of double C-acylation by anthracene and benzyl acrylate
According to the hitherto known reaction by Mg–an- electroreduction of anthracene in DMF containing succi-
thracene·3THF complex,8 it might be postulated that this nyl chloride using a Pt-plate as the cathode and a carbon-
reaction might proceed through Mg–anthracene com- rod as the anode, and Et4NOTs as supporting electrolyte
plex.9 However, many attempts from reactions of com- (Scheme 6). These experimental facts may clearly indi-
mercially available Mg–anthracene·3THF10 complex with cate that the present reaction may take place through an
propionyl or succinyl chloride in various solvent systems electron-transfer mechanism from Mg metal, and Mg–an-
such as only DMF, only THF, and a 1:1 mixture of DMF thracene complex may not be involved or may not play
and THF at various temperatures from 60 °C to 15 °C un- any important role.
der the conditions similar to those of the present Mg-pro-
In conclusion, novel one-pot double C-acylation and
moted reaction have never given any of the corresponding
cycloaddition of anthracene or benzyl acrylate by electron
diacylated products, but just a mixture of 9,10-dihydroan-
transfer from easily available Mg metal was successfully
thracene and anthracene.11 Furthermore, the cycloaddition
achieved to obtain the useful 9,10-diacyl-9,10-dihydro-
product 5a was obtained yet in low yield (4%)12 from
3THF
Mg
O
O
ClCOCH2CH2COCl
+
DMF
4a
5a
(or THF, or DMF–THF)
O
+ 2e
O
C
– Pt
+
ClCOCH2CH2COCl
DMF
4%
1
4a
5a
Scheme 6
Synlett 2007, No. 5, 769–774 © Thieme Stuttgart · New York

LETTER
Double C-Acylation and Cycloaddition of Anthracene
773
9,10-Dipropionyl-9,10-dihydroanthracene (3b).
Diastereomeric ratio = 78:22. Mp 134–135 °C (major
anthracene derivatives or related bicyclic compounds.
The reaction is characterized by a simple procedure, satis-
factory yield, mild conditions, a unique reaction type,
environmental preference and much usefulness of the
products.
isomer), 106–108 °C (minor isomer). 1H NMR (400 MHz,
CDCl3): d (major isomer) = 0.82 (t, J = 7.2 Hz, 6 H), 1.99 (q,
J = 7.2 Hz, 4 H), 5.16 (s, 2 H), 7.27–7.35 (m, 8 H) ppm; d
(minor isomer) = 0.95 (t, J = 7.0 Hz, 6 H), 2.54 (q, J = 7.0
Hz, 4 H), 4.88 (s, 2 H), 7.29–7.35 (m, 8 H) ppm. 13C NMR
(100 MHz, CDCl3): d (major isomer) = 8.32, 31.18, 58.36,
128.09, 128.63, 131.23, 209.11 ppm; d (minor isomer) =
7.78, 33.95, 60.00, 127.23, 129.18, 134.17, 207.25 ppm. IR
(KBr): 3030, 2980, 2940, 2890, 1700, 1480 cm–1. MS (EI):
m/z = 292 [M+]. Anal. Calcd for C20H20O2: C, 82.16; H, 6.89.
Found: C, 82.23; H, 7.03.
Acknowledgment
The authors wish to express sincere gratitude for partial support of
this research through the 21st Century COE Program and Grant-in
Aid for Scientific Research (No. 14655333) from the Ministry of
Education, Sports, Culture, Science and Technology, Japan.
9,10-Di(n-butyryl)-9,10-dihydroanthracene (3c).
Diastereomeric ratio = 82:18. Mp 113–114 °C (major
isomer), 91–93 °C (minor isomer). 1H NMR (400 MHz,
CDCl3): d (major isomer) = 0.60 (t, J = 7.3 Hz, 6 H), 1.35
(sext, J = 7.3 Hz, 4 H), 1.92 (t, J = 7.3 Hz, 4 H), 5.14 (s, 2
H), 7.27–7.36 (m, 8 H) ppm; d (minor isomer) = 0.82 (t,
J = 7.4 Hz, 6 H), 1.50 (sext, J = 7.4 Hz, 4 H), 2.48 (t, J = 7.4
Hz, 4 H), 4.87 (s, 2 H), 7.30–7.39 (m, 8 H) ppm. 13C NMR
(100 MHz, CDCl3): d (major isomer) = 13.47, 17.35, 39.68,
58.53, 128.09, 128.73, 131.01, 208.26 ppm; d (minor
isomer) = 13.65, 17.14, 42.37, 60.30, 127.28, 129.22,
134.03, 206.59 ppm. IR (KBr): 3030, 2960, 2930, 2870,
1710, 1480 cm–1. MS (EI): m/z = 320 [M+]. Anal. Calcd for
C22H24O2: C, 82.46; H, 7.55. Found: C, 82.20; H, 7.57.
9,10-Di(isobutyryl)-9,10-dihydroanthracene (3d).
Mp 131–133 °C. 1H NMR (400 MHz, CDCl3): d = 0.69 (d,
J = 6.8 Hz, 12 H), 2.39 (sept, J = 6.8 Hz, 2 H), 5.23 (s, 2 H),
7.26–7.36 (m, 8 H) ppm. 13C NMR (100 MHz, CDCl3):
d = 20.70, 37.22, 58.36, 127.88, 129.17, 130.86, 212.44
ppm. IR (KBr): 3060, 3020, 2970, 2930, 2870, 1710, 1490
cm–1. MS (EI): m/z = 320 [M+]. Anal. Calcd for C22H24O2: C,
82.46; H, 7.55. Found: C, 82.39; H, 7.53.
References and Notes
(1) (a) Hiiro, T.; Morita, Y.; Inoue, T.; Kambe, N.; Ogawa, A.;
Ryu, I.; Sonoda, N. J. Am. Chem. Soc. 1990, 112, 455.
(b) Hiiro, T.; Mogami, T.; Kambe, N.; Fujiwara, S.; Sonoda,
N. Synth. Commun. 1990, 20, 703. (c) Kanbe, N.; Inoue, T.;
Sonoda, N. Org. Synth. 1995, 72, 154. (d) Seyferth, D.;
Wang, W.-L.; Hui, R. C. Tetrahedron Lett. 1984, 25, 1651.
(2) (a) Shono, T.; Nishiguchi, I.; Ohmizu, H. J. Am. Chem. Soc.
1977, 99, 7396. (b) Shono, T.; Nishiguchi, I.; Ohmizu, H.
Chem. Lett. 1977, 1021. (c) Kyoda, M.; Yokoyama, T.;
Maekawa, H.; Ohno, T.; Nishiguchi, I. Synlett 2001, 1535.
(3) (a) Ohno, T.; Ishino, Y.; Tsumagari, Y.; Nishiguchi, I. J.
Org. Chem. 1995, 60, 458. (b) Ohno, T.; Aramaki, H.;
Nakahiro, H.; Nishiguchi, I. Tetrahedron 1996, 52, 1943.
(c) Ohno, T.; Sakai, M.; Ishino, Y.; Shibata, T.; Maekawa,
H.; Nishiguchi, I. Org. Lett. 2001, 3, 3439.
(4) Nishiguchi, I.; Yamamoto, Y.; Sakai, M.; Ohno, T.; Ishino,
Y.; Maekawa, H. Synlett 2002, 759.
(5) Yoshimasa, Y.; Maekawa, H.; Goda, S.; Nishiguchi, I. Org.
Lett. 2003, 5, 2755.
(6) Typical Procedure for Mg-Promoted One-Pot Double
Acylation of Anthracene
Diethyl 2,3,5,6-Dibenzocyclohexane-1,4-bis(1¢,1¢¢-di-
oxa)dibutanoate (3e).
Mp 110–111 °C. 1H NMR (400 MHz, CDCl3): d = 1.18 (t,
J = 7.2 Hz, 6 H), 2.32–2.39 (m, 8 H), 4.04 (q, J = 7.2 Hz, 4
H), 5.20 (s, 2 H), 7.29–7.37 (m, 8 H) ppm. 13C NMR (100
MHz, CDCl3): d = 14.14, 28.10, 32.74, 57.74, 60.50, 128.30,
128.70, 130.95, 172.16, 206.59 ppm. IR (KBr): 2980, 2920,
1730, 1710, 1490 cm–1. LCMS (APCI): m/z = 437 [M + H].
Anal. Calcd for C26H28O6: C, 71.54; H, 6.47. Found: C,
71.33; H, 6.44.
In a 50-mL three-necked flask of nitrogen atmosphere were
introduced 30 mL of anhyd DMF as solvent, anthracene (5
mmol) as starting material and magnesium metal (10 equiv).
Acid chloride (10 equiv) dissolved in 10 mL of DMF was
slowly added at 0–5 °C over 20 min. The reaction mixture
was stirred at 20–25 °C for 15 h. After reaction, the mixture
was poured into sat. NaHCO3 solution. Organic materials
were extracted with three 100-mL portions of EtOAc. The
organic layer was washed with sat. NaCl solution and dried
over anhyd MgSO4. After removal of MgSO4 by filtration
and evaporation of the solvent, the isolation by column
chromatography gave diacylated compounds in satisfactory
yields.
9,10-Di(4-chlorobutyryl)-9,10-dihydroanthracene (3f).
Mp 116 °C. 1H NMR (400 MHz, CDCl3): d = 1.80 (quin,
J = 6.8 Hz, 4 H), 2.13 (t, J = 6.8 Hz, 4 H), 3.28 (t, J = 6.8 Hz,
4 H), 5.18 (s, 2 H), 7.28–7.38 (m, 8 H) ppm. 13C NMR (100
MHz, CDCl3): d = 26.77, 34.60, 43.91, 58.27, 128.39,
128.70, 130.74, 207.02 ppm. IR (KBr): 3070, 3020, 2960,
2950, 2930, 2900, 1700, 1490 cm–1. LCMS (APCI): m/z =
390 [M + H]. Anal. Calcd for C22H22Cl2O2: C, 67.87; H,
5.70. Found: C, 67.78, H, 5.71.
(7) All the products obtained in this study were characterized by
spectroscopic methods (1H NMR, 13C NMR, IR, mass
spectra) and elemental analysis, or by comparison of
spectroscopic and chromatographic behaviors with those of
authentic samples.
7,8,9,10-Dibenzobicyclo[4.2.2]deca-2,5-dione (5a).
Mp 145–147 °C. 1H NMR (400 MHz, CDCl3): d = 2.22 (s, 4
H), 5.14 (s, 2 H), 7.33–7.45 (m, 8 H) ppm. 13C NMR (100
MHz, CDCl3): d = 36.64, 62.82, 128.16, 128.54, 132.72,
206.48 ppm. IR (KBr): 3060, 3030, 3020, 2950, 2910, 1690,
1470 cm–1. MS (EI): m/z = 262 [M+]. Anal. Calcd for
C18H14O2: C, 82.42; H, 5.38. Found: C, 82.03; H, 5.65.
8,9,10,11-Dibenzobicyclo[5.2.2]4-oxaundeca-2,5-dione
(5b).
9,10-Diacetyl-9,10-dihydroanthracene (3a)
Diastereomeric ratio = 68:32. Mp 151–152 °C (major
isomer), 137 °C (minor isomer). 1H NMR (400 MHz,
CDCl3): d (major isomer) = 1.71 (s, 6 H), 5.11 (s, 2 H), 7.27–
7.35 (m, 8 H) ppm; d (minor isomer) = 2.19 (s, 6 H), 4.89 (s,
2 H), 7.32–7.41 (m, 8 H) ppm. 13C NMR (100 MHz, CDCl3):
d (major isomer) = 25.50, 58.75, 128.32, 128.68, 130.84,
205.95 ppm; d (minor isomer) = 28.28, 60.83, 127.47,
129.24, 134.00, 204.74 ppm. IR (KBr): 3070, 3020, 3010,
2960, 2920, 1700, 1490 cm–1. MS (EI): m/z = 264 [M+].
Anal. Calcd for C18H16O2: C, 81.79; H, 6.10. Found: C,
81.93; H, 6.23.
Mp 175–176 °C. 1H NMR (400 MHz, CDCl3): d = 3.93 (s, 4
H), 5.19 (s, 2 H), 7.34–7.43 (m, 8 H) ppm. 13C NMR (100
MHz, CDCl3): d = 60.48, 79.70, 128.32, 128.42, 131.29,
204.78 ppm. IR (KBr): 3060, 3050, 2950, 2920, 1710, 1480
Synlett 2007, No. 5, 769–774 © Thieme Stuttgart · New York

774
M. Matsunami et al.
LETTER
C13H16O3: C, 70.89; H, 7.32. Found: C, 70.63; H, 7.09.
cm–1. MS (EI): m/z = 278 [M+]. Anal. Calcd for C18H14O3: C,
77.68; H, 5.07. Found: C, 77.95; H, 5.20.
Benzyl 4-Oxoheptanoate (8b).
Benzyl 2-(1-Oxopropyl)-4-oxohexanoate (7a).
1H NMR (400 MHz, CDCl3): d = 0.91 (t, J = 7.4 Hz, 3 H),
1.61 (sext, J = 7.4 Hz, 2 H), 2.42 (t, J = 7.4 Hz, 2 H), 2.64 (t,
J = 6.3 Hz, 2 H), 2.72 (t, J = 6.3 Hz, 2 H), 5.14 (s, 2 H),
7.30–7.38 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3):
d = 13.63, 17.19, 27.90, 36.93, 44.61, 66.39, 128.12, 128.16,
128.48, 135.80, 172.60, 208.86 ppm. IR (neat): 3034, 2962,
2939, 1735, 1715, 1648, 1608, 1498 1456, 1383 cm–1. MS
(EI): m/z = 234 [M+]. Anal. Calcd for C14H18O3: C, 71.77; H,
7.74. Found: C, 72.01, H, 8.01.
1H NMR (400 MHz, CDCl3): d = 1.02 (t, J = 7.3 Hz, 3 H),
1.03 (t, J = 7.3 Hz, 3 H), 2.46 (q, J = 7.3 Hz, 2 H), 2.59–2.74
(m, 2 H), 2.93 (dd, J = 5.6, 18.3 Hz, 1 H), 3.15 (dd, J = 8.4,
18.3 Hz, 1 H), 4.07 (dd, J = 5.6, 8.4 Hz, 1 H), 5.12 (d,
J = 12.5 Hz, 1 H), 5.16 (d, J = 12.5 Hz, 1 H), 7.30–7.38 (m,
5 H) ppm. 13C NMR (100 MHz, CDCl3): d = 7.56, 7.63,
35.63, 36.24, 40.38, 52.73, 67.25, 128.04, 128.34, 128.48,
134.98, 168.65, 204.73, 208, 25 ppm. IR (neat): 3034, 2979,
2940, 2882, 1743, 1715, 1655, 1608, 1498, 1457, 1377 cm–1.
MS (EI): m/z = 276 [M+]. Anal. Calcd for C28H28N8O10 [di-
(2,4-dinitrophenylhydrazone)]: C, 52.83; H, 4.43; N, 17.60.
Found: C, 52.78; H, 4.69; N, 17.31.
Benzyl 5-Methyl-4-oxohexanoate (8c).
1H NMR (400 MHz, CDCl3): d = 1.11 (d, J = 6.8 Hz, 6 H),
2.59–2.65 (m, 3 H), 2.78 (t, J = 6.5 Hz, 2 H), 5.11 (s, 2 H),
7.31–7.36 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3):
d = 18.15, 27.94, 34.65, 40.72, 66.36, 128.13 (× 2), 128.47,
135.82, 172.65, 212.52 ppm. IR (neat): 3034, 2971, 2934,
2876, 1735, 1712, 1608, 1498, 1456, 1384 cm–1. MS (EI):
m/z = 234 [M+]. Anal. Calcd for C14H18O3: C, 71.77; H, 7.74.
Found: C, 71.84, H, 7.95.
Benzyl 2-(1-Oxobutyl)-4-oxoheptanoate (7b).
1H NMR (400 MHz, CDCl3): d = 0.84 (t, J = 7.4 Hz, 3 H),
0.89 (t, J = 7.4 Hz, 3 H), 1.57 (sext, J = 7.4 Hz, 4 H), 2.41 (t,
J = 7.4 Hz, 2 H), 2.54–2.67 (m, 2 H), 2.91 (dd, J = 5.8, 18.3
Hz, 1 H), 3.12 (dd, J = 8.3, 18.3 Hz, 1 H), 4.06 (dd, J = 5.8,
8.3 Hz, 1 H), 5.12 (d, J = 12.2 Hz, 1 H), 5.16 (d, J = 12.2 Hz,
1 H), 7.30–7.37 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3):
d = 13.42, 13.61, 16.80, 17.18, 40.65, 44.38, 44.68, 53.03,
67.23, 128.14, 128.34, 128.46, 135.01, 168.63, 203.97,
207.76 ppm. IR (neat): 3036, 2966, 2936, 2877, 1742, 1713,
1648, 1609, 1498, 1456, 1407, 1377cm–1. MS (EI): m/z =
304 [M+]. Anal. Calcd for C18H24O4: C, 71.03; H, 7.95.
Found: C, 71.15; H, 8.11.
Benzyl 6-Methyl-4oxoheptanoate (8d).
1H NMR (400 MHz, CDCl3): d = 0.91 (d, J = 6.7 Hz, 6 H),
2.10–2.20 (m, 1 H), 2.32 (d, J = 6.7 Hz, 2 H), 2.63 (t, J = 6.2
Hz, 2 H), 2.71 (t, J = 6.2 Hz, 2 H), 5.11 (s, 2 H), 7.33–7.35
(m, 5 H) ppm. 13C NMR (100 MHz, CDCl3): d = 22.50,
24.62, 27.87, 37.51, 51.69, 66.39, 128.14, 128.17, 128.50,
135.82, 172.61, 208.57 ppm. IR (neat): 3034, 2972, 2957,
2935, 2872, 1735, 1718, 1606, 1497, 1466, 1385 cm–1. MS
(EI): m/z = 248 [M+]. Anal. Calcd for C15H20O3: C, 72.55; H,
8.12. Found: C, 72.56; H, 8.29.
Benzyl 2-(2-Methyl-1-oxopropyl)-5-methyl-4-oxo-
hexanoate (7c).
1H NMR (400 MHz, CDCl3): d = 1.03 (d, J = 6.8 Hz, 3 H),
1.09 (d, J = 7.1 Hz, 3 H), 1.10 (d, J = 7.1 Hz, 3 H), 1.13 (d,
J = 7.1 Hz, 3 H), 2.63 (sept, J = 6.8 Hz, 1 H), 2.83–2.98 (m,
2 H), 3.15 (dd, J = 8.2, 18.3 Hz, 1 H), 4.24 (dd, J = 5.6, 8.2
Hz, 1 H), 5.12 (d, J = 12.2 Hz, 1 H), 5.16 (d, J = 12.2 Hz, 1
H), 7.26–7.38 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3):
d = 17.76, 18.12, 18.17, 18.66, 38.62, 40.68, 40.79, 51.39,
67.29, 128.17, 128.35, 128.48, 135.03, 168.89, 207.90,
211.25 ppm. IR (neat): 3035, 2972, 2935, 2875, 1743, 1713,
1648, 1609, 1498, 1456, 1384 cm–1. MS (EI): m/z = 304
[M+]. Anal. Calcd for C30H32N8O10 [di(2,4-dinitrophenyl-
hydrazone)]: C, 54.21; H, 4.85; N,16.86. Found: C, 53.94; H,
5.05; N, 16.68.
(8) (a) Bogdanovic, B.; Liao, S.; Mynott, R.; Schlichte, K.;
Westeppe, U. Chem. Ber. 1984, 117, 1378. (b) Bartmann,
E.; Bogdanovic, B.; Janke, N.; Liao, S.; Schlichte, K.;
Shliethoff, B.; Treber, J.; Westeppe, U.; Wilczok, U. Chem.
Ber. 1990, 123, 1517. (c) Bogdanovic, B.; Janke, N.;
Kinzelmann, H. G.; Seevogel, K.; Treber, J. Chem. Ber.
1990, 123, 1529.
(9) (a) Freeman, P. K.; Hutchinson, L. L. J. Org. Chem. 1983,
48, 879. (b) Bogdanovic, B. Acc. Chem. Res. 1988, 21, 261.
(10) Mg–anthracene·3THF complex can be available from
Sigma-Aldrich Co. Ltd.
(11) Treatment of anthracene(1) with isobutyryl chloride and
succinyl dichloride in the presence of 5 equiv of THF (based
on 1) in DMF under the similar conditions as mentioned
above, gave the corresponding adducts 2d and 5a in 56–59%
and 61–63% yields, respectively.
Benzyl 2-(3-Methyl-1-oxobutyl)-6-methyl-4-oxo-
heptanoate (7d).
1H NMR (400 MHz, CDCl3): d = 0.81 (d, J = 6.6 Hz, 3 H),
0.87 (d, J = 6.6 Hz, 3 H), 0.89 (d, J = 6.6 Hz, 3 H), 0.91 (d,
J = 6.6 Hz, 3 H), 2.07–2.17 (m, 2 H), 2.31 (d, J = 7.1 Hz, 2
H), 2.48 (d, J = 6.8 Hz, 2 H), 2.88 (dd, J = 5.8, 18.4 Hz, 1 H),
3.10 (dd, J = 8.3, 18.4 Hz, 1 H), 4.03 (dd, J = 5.8, 8.3 Hz, 1
H), 5.12 (d, J = 12.1 Hz, 1 H), 5.17 (d, J = 12.1 Hz, 1 H),
7.26–7.38 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3):
d = 22.18, 22.46, 22.50, 22.52, 23.92, 24.72, 41.16, 51.45,
51.61, 53.35, 67.29, 128.29, 128.41, 128.50, 134.99, 168.62,
203.49, 207.56 ppm. IR (neat): 3034, 2959, 2935, 2872,
1743, 1715, 1649, 1610, 1499, 1457, 1368 cm–1. MS (EI):
m/z = 332 [M+]. Anal. Calcd for C32H36N8O10 [di(2,4-dinitro-
phenylhydrazone)]: C, 55.49; H, 5.24; N,16.18. Found: C,
55.51; H, 5.14; N, 16.18.
(12) Typical Procedure for Electroreductive Double C-
Acylation of Anthracene Derivatives.
Into a 100-mL beaker-type undivided cell equipped with
platinum plates [20 × 30 × 0.5 mm, Nacalai Tesque (Kyoto,
Japan), 99%] as the cathode and a carbon bar as the anode
were introduced 60 mL of anhyd DMF as a solvent, n-
Et4NOTs (15 mmol) as a supporting electrolyte, acid
dichloride (25 mmol) and anthracene (5 mmol). The
electrolysis was carried out under constant current
conditions (current density: 7 mA/cm2) at –5 °C to 5 °C with
magnetic stirring until 8 F/mol of electricity was passed.
After the reaction, the reaction mixture was poured into sat.
NaHCO3 solution when acid dichloride was used as the
acylating agent. Organic materials were extracted with three
100 mL portions of Et2O. The combined ethereal solution
was washed with sat. NaCl solution and dried over anhyd
MgSO4. After removal of MgSO4 by filtration and
evaporation of the solvent, the isolation by column
chromatography gave diacylated compounds in low yields
(4%).
Benzyl 4-Oxohexanoate (8a).
1H NMR (400 MHz, CDCl3): d = 1.06 (t, J = 7.3 Hz, 3 H),
2.47 (q, J = 7.3 Hz, 2 H), 2.65 (t, J = 6.2 Hz, 2 H), 2.73 (t,
J = 6.2 Hz, 2 H), 5.14 (s, 2 H), 7.34–7.35 (m, 5 H) ppm. 13
NMR (100 MHz, CDCl3): d = 7.70, 27.97, 35.85, 36.52,
C
66.42, 128.14, 128.18, 128.50, 135.80, 172.65, 209.33 ppm.
IR (neat): 3034, 2977, 2939, 2882, 1735, 1719, 1648, 1608,
1498, 1379 cm–1. MS (EI): m/z = 220 [M+]. Anal. Calcd for
Synlett 2007, No. 5, 769–774 © Thieme Stuttgart · New York

Copyright of Synlett is the property of Georg Thieme Verlag Stuttgart and its content may not
be copied or emailed to multiple sites or posted to a listserv without the copyright holder's
express written permission. However, users may print, download, or email articles for
individual use.