Preparation of 1,5-diketone derivatives containing ferrocenyl by Michael reaction under solvent-free condition

Article abstract of DOI:10.1016/S0022-328X(01)00894-4

This work describes a fast, mild, convenient and simple method for preparing 1,5-diketones by Michael reaction under solvent-free condition. Fourteen new 1,5-diketone compounds containing ferrocenyl were synthesized. The product 1f is discussed from its ¹H-NMR spectrum.

Full text of DOI:10.1016/S0022-328X(01)00894-4

Journal of Organometallic Chemistry 637–639 (2001) 719–722
www.elsevier.com/locate/jorganchem
Note
Preparation of 1,5-diketone derivatives containing ferrocenyl by
Michael reaction under solvent-free condition
Wan-yi Liu a, Qi-hai Xu a, Yong-min Liang a, Bao-hua Chen a, Wei-min Liu b,
Yong-xiang Ma a,*
a National Laboratory of Applied Organic Chemistry, Lanzhou Uni6ersity, Lanzhou 730000, People’s Republic of China
b Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences,
Lanzhou 730000, People’s Republic of China
Received 12 November 2000; received in revised form 20 February 2001; accepted 21 February 2001
Abstract
This work describes a fast, mild, convenient and simple method for preparing 1,5-diketones by Michael reaction under
solvent-free condition. Fourteen new 1,5-diketone compounds containing ferrocenyl were synthesized. The product 1f is discussed
1
from its H-NMR spectrum. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Ferrocene; Ketone; Michael reaction; Solid-state reaction; Solvent-free
(iii) the condensation of ketone enolate and the Man-
nich base derived from methyl ketones [7]; and (iv) the
conjugate addition of the enones to trimethylsilylenol
ethers as donor [8]. These methods can be used for
suitable reactive substrates, but there are some limita-
tions, such as the reaction between aldehyde and ace-
tophenone is only performed in alkaline alcohols and
under refluxing condition. The aldehyde should have a
drawing-electronic group and needs a large amount of
solvent. In addition, these methods need to use more
expensive reagents and have longer synthetic routes.
The fourth method is considered to be a better one, but
it should be carried under moisture- and oxygen-free
conditions.
The solid-state Michael addition has been performed
well recently [9–11]. However, until now this addition
to ferrocene derivatives containing a,b-unsaturated ke-
tones has attracted rather little attention [12–14], the
addition of chalcone using acetophenone as Michael
donor under solvent-free condition has not been re-
ported so far. Herein, we describe this kind of reac-
tions. It is shown that the 1,5-diketones containing
ferrocenyl can be obtained in satisfactory yields by
Michael addition in the dry state. The reaction has a
1. Introduction
1,5-Diketones are extremely important synthetic in-
termediates in their own right and are desirable starting
materials for preparing many heterocyclic [1–3] and
polyfunctional compounds [4–7]. These compounds,
such as a,a-oligopyridines [4], terpyridylferrocene and
bis(terpyridinylferrocene) [5] have potential applications
in coordination chemistry, molecular sensing, catalytic
reactions, the chemical modification of electrodes, and
redox active self-assembly devices. According to the
reports in literatures, there are four procedures for
synthesizing 1,5-diketones: (i) by the aldol–Michael
addition strategy [1,2,4,6]; (ii) the addition of activated
methylene compounds to a,b-unsaturated ketones [3];
Scheme 1.
* Corresponding author. Fax: +86-931-8611688.
E-mail address: mayx@lzu.edu.cn (Y.-x. Ma).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00894-4

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W.-y. Liu et al. / Journal of Organometallic Chemistry 637–639 (2001) 719–722
Table 1
Preparation of compounds 3
Entry
Compound
R1
R2
Time (h)
Yield (%) a
M.p. (°C)
1
2
3
4
5
6
7
8
9
3a
3b
3c
3d
3e
3f
3g
3h
3i
Ph
Fc
Fc
Fc
Fc
Fc
Fc
Fc
Ph
Fc
1.5
1.5
1.5
1
76.2
79
68
87
84
71
73
82
92
105–106
143.5–144
140–141
137.5–138
140–142
129.5–130
93.5–94.5
141–142
3,4-OCH2OꢀC6H3
4-Me2NꢀC6H4
4-ClꢀC6H4
3-O2NꢀC6H4
PhCHꢁCH
2-Furyl
1 b
1.5
1
4-FcꢀC6H4
Fc
1
1.5
119–122
a Isolated yields.
b Carried out at room temperature.
Scheme 2.
series of advantages, such as reduced pollution, low
cost, mild conditions and simplicity in process and
handling.
more reactive than those with an electron-pushing
group. The preparation of 3e was performed at room
temperature, but on heating the mixture soon turned
black and no Michael adduct was obtained. Theoreti-
cally, entry 6 should have two Michael adducts, i.e. one
of 1,4-addition (3f) and the other of 1,6-addition (3f%).
2. Result and discussion
1
But from the H-NMR spectra, we can infer that 3f is
the only product of Michael addition. The chemical
shift of HA is 6.263–6.381 ppm as a double-doublet and
that of HB is 6.447–6.526 ppm as a doublet. If 3f% is
produced, the peak shape of HA% should be a double-
doublet and that of HB% should be a double-triplet.
We prepared a series of ferrocenyl-1,5-diketones (3)
through the Michael addition between a ferrocenylchal-
cone, R1CHꢁCHCOR2 (1), and benzophenone (2), us-
ing NaOH as catalyst in solvent-free and under mild
conditions as shown in Scheme 1. The results are listed
in Table 1.
It is known that the 1,5-dioxo-3,5-diphenylpentyl
ferrocene (3a) is the only reported compound of this
series [8]. It was prepared by conjugate addition to
enones by enolates derived from base-induced cleavage
of the OꢀSi bond of trimethylsily enol ether under
argon atmosphere. That is, 2a with enol silane (1.2
equivalents) in CH2Cl2 with degassed 5% aq. NaOH
and 10 mol% tetrabutylammonium bromide as PTC. It
can be seen that the operation is very tedious and the
reagents are more expensive than those in our process.
From Table 1, we can see that Michael addition can
be performed easily and gives product 3 in satisfactory
yield. Compound 1 could react completely when we
added a large amount of acetopenone (fivefold) and the
yields of 3 increased and its reaction speed became fast.
From entries 2–5, we might infer that enones bearing
an electron-drawing group on the aromatic ring are
We had also carried out the reaction of 1a in differ-
ent conditions, and we can see that higher temperature
and longer reaction time may cut down the yield of the
target product due to formation of some byproducts.
Some of the byproducts have been isolated and charac-
terized. So we can infer 1a can decompose to acetylfer-
rocene (4) and benzaldehyde. Compounds 4 and 1 also
undergo Michael addition to form another 1,5-diketone
(5) under reaction conditions. Compound 1 and
product 3 react to form a triketone. That is, 1 can
undergo reaction in solvent-free condition as shown in
Scheme 2.

W.-y. Liu et al. / Journal of Organometallic Chemistry 637–639 (2001) 719–722
721
In summary, the Michael reaction of acetophenone
with ferrocene-containing chalcones under solvent-free
condition is a fast, mild and simple method to prepare
ferrocenyl-1,5-diketone derivatives.
cm−1): w(CꢁO) 1658, 1688. Anal. Found: C, 69.73; H,
4.73. Calc. for C28H24FeO4: C, 70.01; H, 5.04%.
3c:
1,5-Dioxo-3-(4-N,N-dimethylaminophenyl)-5-
phenylpentyl ferrocene. Yellow solid, m.p. 140–141 °C.
1H-NMR (l, ppm): 2.89 (s, 6H, NMe2); 3.09–3.13 (d,
2H, FcCOCH2, J=7.0 Hz); 3.25–3.54 (dq, 2H,
3
2
3. Experimental
PhCOCH2, J=7.2 Hz, J=23.2 Hz); 3.90–4.03 (m,
1H, ꢀCH); 4.08 (s, 5H, Cp-ring); 4.47 (s, 2H, Cp-ring);
4.77 (s, 2H, Cp-ring); 6.67–6.72 (d, 2H, Ar, J=8.7
Hz); 7.19–7.23 (d, 2H, Ar, J=8.7 Hz); 7.40–7.58 (m,
3H, PhCO); 7.95–7.99 (d, 2H, PhCO, J=8.4Hz). MS;
m/z (%): 479 (73). IR (KBr, cm−1): w(CꢁO) 1670. Anal.
Found: C, 72.55; H, 5.71; N, 2.92. Calc. for
C29H29FeNO2: C, 72.66; H, 6.10; N, 2.92%.
1H-NMR spectra were recorded on a DRX-200 spec-
trometer, except that of 3a, 5b, 3d, 3i and 5i, which
were recorded on a FC-80 spectrometer, using CDCl3
as solvent and TMS as an internal standard. Mass
spectra were obtained on a ZAB-HS mass spectrometer
by fast atom bombardment (FAB, MASPEC II data-
base). IR spectra were recorded in KBr on a Nicolet
1795X FTIR spectrophotometer. The elemental analy-
sis was carried out with an Elementary Vario EL
analyzer. The melting points reported are uncorrected.
3d: 1,5-Dioxo-3-(4-choloro phenyl)-5-phenylpentyl
1
ferrocene. Orange–red solid, m.p. 137.5–138 °C. H-
NMR (l, ppm): 3.11–3.19 (d, 2H, FcCOCH2, J=6.7
Hz); 3.36–3.50 (m, 2H, PhCOCH2); 3.85–3.98 (m, 1H,
ꢀCH); 4.11 (s, 5H, Cp-ring); 4.58 (s, 2H, Cp-ring); 4.79
(s, 2H, Cp-ring); 7.30 (s, 4H, Ar); 7.46–7.60 (br, 3H,
PhCO); 7.92–8.02 (d, 2H, PhCO, J=7.1 Hz). MS; m/z
(%): 473 (27), 470.3 (61). IR (KBr, cm−1): w(CꢁO)
1658, 1688. Anal. Found: C, 68.43; H, 4.65. Calc. for
C27H23ClFeO2: C, 68.88; H, 4.92%.
3.1. Preparation of the materials
All compounds of 1 were synthesized as reported
[15]. Acetophenone is commercially available and used
directly.
3e: 1,5-Dioxo-3-(3-nitro phenyl)-5-phenylpentyl fer-
1
3.2. General procedure for the preparation of 3
rocene. Orange–red solid, m.p. 140–142 °C. H-NMR
3
(l, ppm): 3.10–3.32 (dq, 2H, FcCOCH2, J=7.2 Hz,
3
A mixture of 1 (1 mmol), 2 (4 mmol) and 0.2 g
NaOH (5 mmol) was ground with an agate mortar and
a pestle, and allowed to stand at 45 °C for a specific
time as shown in Table 1. (Note: entry 5 reacted at
room temperature.) The final products were extracted
with CH2Cl2 and the solution dried with MgSO4. After
filtration, the solvent was removed and the diketones
were separated from the residue by column chromatog-
raphy (silica gel, petroleum ether–5% EtOAc as
eluant).
2J=16.4 Hz); 3.35–3.62 (dq, 2H, PhCOCH2, J=7.4
Hz, 2J=16.2 Hz); 4.06 (s, 5H, Cp-ring); 4.10–4.283 (m,
1H, ꢀCH); 4.50 (s, 2H, Cp-ring); 4.81 (s, 2H, Cp-ring);
7.42–7.74 (m, 7H, Ar and PhCO); 7.93–7.96 (d, 2H,
PhCO, J=7.0 Hz), MS; m/z (%): 481 (34). IR (KBr,
cm−1): w(NO2) 1350, 1528, w(CꢁO) 1676. Anal. Found:
C, 66.97; H, 4.56. Calc. for C27H23FeNO4: C, 67.38; H,
4.82; N, 2.91%.
3f: 1,5-Dioxo-5-phenyl-3-(2-phenyl ethenyl)pentyl
ferrocene. Red solid, m.p. 129.5–130 °C. H-NMR (l,
ppm): 2.90–3.16 (dq, 2H, FcCOCH2, J=6.6 Hz, J=
1
3
2
3a: 1,5-Dioxo-3,5-diphenylpentyl ferrocene. Orange–
1
3
yellow needles, m.p. 105–106 °C. H-NMR (l, ppm):
18.0 Hz); 3.12–3.46 (dq, 2H, PhCOCH2, J=6.8 Hz,
3.13–3.22 (d, 2H, FcCOCH2, J=6.7 Hz); 3.40–3.52
2J=16.2 Hz); 3.50–3.69 (m, 1H, ꢀCH); 4.18 (s, 5H,
Cp-ring); 4.50 (s, 2H, Cp-ring); 4.82 (s, 2H, Cp-ring);
6.26–6.38 (dd, 1H, CHAꢁCHBꢀCHCꢂ, JAB=15.8 Hz,
3
2
(dd, 2H, PhCOCH2, J=6.6 Hz, J=3.4 Hz); 3.92–
4.19 (m, 1H, ꢀCH); 4.07 (s, 5H, Cp-ring); 4.49 (s, 2H,
Cp-ring); 4.78 (s, 2H, Cp-ring); 7.25–7.54 (m, 8H, Ph
and PhCO); 7.93–8.04 (dd, 2H, PhCO, Jo=7.7 Hz,
Jm=2.1 Hz). MS; m/z (%): 436.4 (33). IR (KBr,
cm−1): w(CꢁO) 1657, 1683. Anal. Found: C, 72.97; H,
4.96. Calc. for C27H24FeO2: C, 74.32; H, 5.54%.
J
BC=7.8 Hz); 6.45–6.53 (d, 1H, PhCHꢁC, J=15.8
Hz); 7.14–7.34 (m, 5H, Ph); 7.43–7.56 (m, 3H, PhCO);
7.99–8.03 (d, 2H, PhCO, J=7.5 Hz). MS; m/z (%):
462.2 (100). IR (KBr, cm−1): w(CꢁCꢀH) 969, w(CꢁO)
1666. Anal. Found: C, 74.84; H, 5.17. Calc. for
C29H26FeO2: C, 75.33; H, 5.67%.
3b:
1,5-Dioxo-3-(3,4-methylenedioxyphenyl)-5-
phenylpentyl ferrocene. Orange–red solid, m.p. 143.5–
144 °C. 1H-NMR (l, ppm): 3.08–3.11 (d, 2H,
FcCOCH2, J=7.0 Hz); 3.23–3.52 (dd, 2H, PhCOCH2,
3g: 1,5-Dioxo-3-(2-furyl)-5-phenylpentyl ferrocene.
Yellow solid, m.p. 93.5–94.5 °C. H-NMR (l, ppm):
1
3
2
3.23–3.28 (dq, 2H, FcCOCH2, J=6.6 Hz, J=16.4
2
3
2
3J=7.0 Hz, J=16.2 Hz); 3.89–4.05 (m, 1H, ꢀCH);
Hz); 3.34–3.55 (dq, 2H, PhCOCH2, J=6.8 Hz, J=
16.4 Hz); 4.01–4.23 (m, 1H, ꢀCH); 4.13 (s, 5H, Cp-
ring); 4.49 (s, 2H, Cp-ring); 4.79 (s, 2H, Cp-ring); 6.13
(s, 1H, furyl); 6.26 (s, 1H, furyl); 7.30 (s, 1H, furyl);
7.26–7.56 (m, 3H, PhCO); 7.97–8.01 (d, 2H, PhCO,
4.07 (s, 5H, Cp-ring); 4.48 (s, 2H, Cp-ring); 4.77 (s, 2H,
Cp-ring); 5.89 (s, 2H, OꢀCH2ꢀO); 6.70–6.84 (m, 3H,
Ar); 7.41–7.56 (m, 3H, PhCO); 7.94–7.98 (d, 2H,
PhCO, J=7.0 Hz). MS; m/z (%): 480.1 (23). IR (KBr,

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W.-y. Liu et al. / Journal of Organometallic Chemistry 637–639 (2001) 719–722
J=7.6 Hz). MS; m/z (%): 426.2 (100). IR (KBr, cm−1):
w(CꢁO) 1667. Anal. Found: C, 69.73; H, 5.30. Calc. for
C25H22FeO3: C, 70.44; H, 5.20%.
(s, 4H, Cp-ring); 5.91 (s, 2H, OꢀCH2ꢀO); 6.87–6.93 (m,
3H, Ar). MS; m/z (%): 588.1 (69). Anal. Found: C,
64.92; H, 4.68. Calc. for C32H28Fe2O4: C, 65.34; H,
4.80%.
3h: 1,5-Dioxo-1,5-diphenyl-3-(4-ferrocenyl phenyl)
1
5i: 1,5-Dioxo-1,3,5-triferrocenyl pentane. Red solid,
m.p. 183–185 °C; obtained from 3i (entry 9, Table 1)
pentane. Yellow solid, m.p. 141–142 °C. H-NMR (l,
3
2
ppm): 3.37–3.49 (dq, 2H, PhCOCH2, J=6.8 Hz, J=
13.2 Hz); 3.86–4.03 (m, 1H, ꢀCH); 4.10 (s, 5H, Cp-
ring); 4.58 (s, 2H, Cp-ring); 4.81 (s, 2H, Cp-ring);
7.17–7.74 (m, 10H, p-FcꢀC6H4 and PhCO); 7.99–8.03
(d, 4H, PhCO, J=7.8 Hz). MS; m/z (%): 512 (21). IR
(KBr, cm−1): w(CꢁO) 1680. Anal. Found: C, 77.57; H,
5.17. Calc. for C33H28FeO2: C, 77.35; H, 5.51%.
1
as a byproduct in 5% yield. H-NMR (l, ppm): 3.15–
3.22 (d, 4H, FcCOCH2, J=5.6 Hz); 3.76–3.98 (br, 1H,
ꢀCH); 4.19 (s, 15H, Cp-ring); 4.52 (s, 6H, Cp-ring); 4.85
(s, 6H, Cp-ring). MS; m/z (%): 652.2 (84). Anal. Found:
C, 63.58; H, 4.47. Calc. for C35H32Fe3O2: C, 64.46; H,
4.95%.
6g:
1,7-Dioxo-4-benzoyl-1,7-diferrocenyl-3,5-di-(2-
3i: 1,5-Dioxo-3-ferrocenyl-5-phenylpentyl ferrocene.
Yellow solid, m.p. 119–122 °C. 1H-NMR (l, ppm):
3.10–3.18 (d, 2H, FcCOCH2, J=6.0 Hz); 3.40–3.54
(br, 2H, PhCOCH2); 3.74–3.91 (m, 1H, ꢀCH); 4.16 (s,
10H, Cp-ring); 4.51 (s, 4H, Cp-ring); 4.80 (s, 4H,
Cp-ring); 7.49–7.57 (br, 3H, PhCO); 8.01–8.10 (d, 2H,
PhCO, J=7.8 Hz). MS; m/z (%): 544 (81). IR (KBr,
cm−1): w(CꢁO) 1662, 1686. Anal. Found: C, 68.68; H,
4.94. Calc. for C31H28Fe2O2: C, 68.41; H, 5.18%.
5a: 1,5-Dioxo-1,5-diferrocenyl-3-phenyl pentane. Yel-
low solid, m.p. 158–160 °C; obtained from 3a (entry 1,
Table 1) as a byproduct in 3% yield. 1H-NMR (l,
ppm): 3.14–3.18 (d, 4H, FcCOCH2, J=7.0 Hz); 3.81–
4.11 (m, 1H, ꢀCH); 4.05 (s, 10H, Cp-ring); 4.47 (s, 4H,
Cp-ring); 4.77 (s, 4H, Cp-ring); 7.17–7.41 (m, 5H, Ph).
MS; m/z (%): 544.3 (48). Anal. Found: C, 68.01; H,
4.84. Calc. for C31H28Fe2O2: C, 68.41; H, 5.19%.
furyl) heptane. Yellow solid, m.p. 106–107 °C; ob-
tained from 3g (entry 7, Table 1) as a byproduct in 7%
yield. 1H-NMR (l, ppm): 2.860–3.361 (m, 4H,
FcCOCH2); 3.77–4.71 (m, 21H, Cp-ring and ꢀCH);
5.89–6.20 (m, 4H, furyl); 7.10 (s, 1H, furyl); 7.22 (s,
1H, furyl); 7.38–7.83 (m, 5H, Ph). MS; m/z (%): 732.5
(42); Anal. Found: C, 68.50; H, 4.57. Calc. for
C42H36Fe2O5: C, 68.87; H, 4.95%.
References
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6a:
1,7-Dioxo-4-benzoyl-1,7-diferrocenyl-3,5-
diphenyl heptane. Yellowish solid, m.p. 180–183 °C;
obtained from 3a (entry 1, Table 1) as a byproduct in
9% yield. 1H-NMR (l, ppm): 2.96–3.39 (m, 4H,
2FcCOCH2); 3.71–4.73 (m, 21H, Cp-ring and ꢀCH);
7.05–7.94 (m, 15H, Ar). MS; m/z (%): 752.2 (31). Anal.
Found: C, 72.97; H, 4.96. Calc. for C46H40Fe2O3: C,
73.42; H, 5.36%.
[10] S. Annunziata, S. Aldo, R.D. Margherita, G. Manueia, S.
Arrigo, Tetrahedron Lett. 38 (1997) 289.
5b:
1,5-Dioxo-1,5-diferrocenyl-3-(3,4-methyle-
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174.
neoxyphenyl) pentane. Orange–yellow solid, m.p. 167–
169 °C; obtained from 3b (entry 2, Table 1) as a
byproduct in 5% yield. H-NMR (l, ppm): 3.08–3.16
(d, 4H, FcCOCH2, J=6.8 Hz); 3.80–4.09 (br, 1H,
ꢀCH); 4.12 (s, 10H, Cp-ring); 4.51 (s, 4H, Cp-ring); 4.80
1
[14] Z.X. Bian, Y.G. Liu, F.Z. Li, Huaxue Shiji 16 (1994) 175.
[15] W.Y. Liu, Q.H. Xu, Y.X. Ma, Syn. Commun. in press.