A new, three-component cobalt-catalysed domino reaction leading to ferrocenyl-tetrahydro-4(1H)-pyrimidinone derivatives

Article abstract of DOI:10.1016/j.jorganchem.2012.08.009

The use of N-(alkyl/arylmethyl)-ferrocenylimines as ketene scavengers in the cobalt-catalysed carbonylation of ethyl diazoacetate resulted in the formation of tetrahydro-4(1H)-pyrimidinones as the main products. The structures of the new compounds were determined by various NMR techniques including 2D measurements. In some cases, the stereochemistry was proved by X-ray crystallography.

Full text of DOI:10.1016/j.jorganchem.2012.08.009

Journal of Organometallic Chemistry 718 (2012) 131e138
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Journal of Organometallic Chemistry
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A new, three-component cobalt-catalysed domino reaction leading to
ferrocenyl-tetrahydro-4(1H)-pyrimidinone derivatives
,
János Balogh a, Zsolt Csók b, László Párkányi c, Ferenc Ungváry a, László Kollár b, Rita Skoda-Földes a
*
a University of Veszprém, Institute of Chemistry, Department of Organic Chemistry, Egyetem u. 10, P.O. Box 158, H-8200 Veszprém, Hungary
b University of Pécs, Department of Inorganic Chemistry, H-7624 Pécs, P.O. Box 266, Hungary
c X-ray Diffraction Laboratory, Structural Chemistry Department, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences,
1525 Budapest, P.O. Box 17, Hungary
a r t i c l e i n f o
a b s t r a c t
Article history:
The use of N-(alkyl/arylmethyl)-ferrocenylimines as ketene scavengers in the cobalt-catalysed carbon-
ylation of ethyl diazoacetate resulted in the formation of tetrahydro-4(1H)-pyrimidinones as the main
products. The structures of the new compounds were determined by various NMR techniques including
2D measurements. In some cases, the stereochemistry was proved by X-ray crystallography.
Ó 2012 Elsevier B.V. All rights reserved.
Received 21 May 2012
Received in revised form
31 July 2012
Accepted 2 August 2012
Keywords:
Cobalt
Carbonylation
Domino reactions
Ferrocenes
Schiff bases
1. Introduction
The pyrimidine ring is the main structural element of a great
variety of natural products and biologically active synthetic
Recently, a new domino reaction, comprising the cobalt-
catalysed carbonylation of ethyl diazoacetate in the presence of
nucleophilic reagents leading to various malonic acid derivatives,
has been developed [1e3]. Under carbonylation conditions, octa-
carbonyl dicobalt can be used for the catalytic transformation of
diazo-compounds into ketene derivatives (Scheme 1) [4]. The
highly reactive ketene intermediate (2) was shown to react with
alcohols, phenols, and amines to give the corresponding malonates
(3) [1,2]. The use of N-alkylbenzaldehydimines led to the formation
compounds [7]. 2-Substituted pyrimidin-4-one-5-carboxylic acid
benzylamides were shown to exhibit antitumour activity against
LoVo, a human colon carcinoma cell line, and Hep3B cells, a human
hepatoma cell line [8]. Tetrahydro-4(1H)-pyrimidinones are useful
precursors in the synthesis of b-amino acids [9]. Alkaloids with the
tetrahydro-4(1H)-pyrimidinone moiety were isolated from Aconi-
tum taipeicum, used in Chinese folk medicine, and were shown to
be potential antileukaemia agents [10].
The combination of a ferrocenyl moiety with structures of
pharmacological importance may increase their biological activity
[11], so we decided to explore the scope of the new domino reaction
leading to specifically substituted tetrahydropyrimidin-4-ones. In
the present paper, an investigation of the effect of the reaction
conditions on the formation of the products, as well as full char-
acterisation of the new compounds, are presented.
of
b
-lactams 5 [3] as a result of a 2 þ 2 cycloaddition reaction. At the
same time, in the presence of some N-substituted ferrocenylimines,
the main products were 2-(1-ferrocenylmethylidene)malonic acid
derivatives 6 and 7, probably produced via the N(1)eC(4) cleavage
of the initially formed b-lactams [5]. In some cases, b-lactams were
synthesised in appreciable yields in the presence of an excess of
ethyl diazoacetate even in the reaction of ferrocenylimines [6]. In
the present work, we report on the formation of a new type of
products, tetrahydro-4(1H)-pyrimidinones with two ferrocene
moieties (8), using N-(alkyl/arylmethyl)ferrocenylimines as ketene
scavengers.
2. Results and discussion
2.1. Catalytic experiments
Ethyl diazoacetate (1, Scheme 2) was carbonylated in the pres-
ence of Co2(CO)8 as catalyst and ferrocenylimine (4a) as ketene
scavenger. Our previous results showed [5,6] that both CO pressure
* Corresponding author. Tel.: þ36 88 624 719; fax: þ36 88 624 469.
E-mail address: skodane@almos.uni-pannon.hu (R. Skoda-Földes).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.08.009

132
J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
Scheme 1. Cobalt-catalysed carbonylation of ethyl diazoacetate (1) in the presence of various nucleophiles.
and ethyl diazoacetate/imine ratio had a decisive effect on the
outcome of the reaction. At 80 bar CO pressure, 2-(1-
ferrocenylmethylidene)malonic acid derivatives could be isolated
in good yields [5]. At lower CO pressures (40e50 bar), when other
imines (N-cyclohexyl-, N-isopropyl-, N-tert-butyl-, N-(2-pentyl)-,
N-(4-methoxyphenyl)-, N-(4-methylphenyl)-, N-((1-phenyl)-ethyl)
ferrocenylidenamines) were used as ketene scavengers, formation
Based on these findings, carbonylation was carried out in the
presence of other ferrocenylimines 4bee as ketene scavengers. In
accordance with the previous experiments discussed above,
carbonylations at 40 bar CO pressure using equimolar amounts of
ethyl diazoacetate and imines 4bee led to tetrahydro-4(1H)-pyr-
imidinones 8bee in 41e62% yields as the main products (Table 2,
entries 1e4).
of
b
-lactams was also observed [6]. Accordingly, carbonylation was
Isomeric 2-(1-ferrocenylmethylidene)malonic acid derivatives 6
and 7 were isolated from reaction mixtures obtained at 80 bar CO
pressure (Table 2, entries 5e8), and were characterised by 1H- and
13C NMR, MS and IR. Similarly to the reaction of other imines [5,6],
the main products were the E isomers 6bee in each case.
In the reaction mixtures of 4aec and 4e, obtained at 40 bar, the
presence of other tetrahydropyrimidinones could also be observed.
Interestingly, a decrease in the CO pressure during the course of the
reaction (8 h at 80 bar CO pressure, then 16 h at 40 bar CO) and the
use of a slight excess of ethyl diazoacetate (1.25 eq) led to an
increase in the yield of these side products which made their
isolation and full characterisation possible. Based on X-ray crys-
tallographic data and two dimensional NMR measurements, these
minor components correspond to structures 9aec and 10e (Fig. 1).
Similar tetrahydro-4(1H)-pyrimidinones were previously ob-
tained only as side products in the reactions of cyclic imines with an
carried out under different reaction conditions (Table 1). The
reactions were followed by GC and TLC, and the products were
isolated by column chromatography.
When the reaction was carried out at 40 bar CO pressure, a new
compound was isolated in 52% yield (entry 1). Upon full character-
isation of this compound (see below) it was proved to be a tetrahy-
dropyrimidin-4-one derivative with two ferrocene moieties (8a).
An increase in the CO pressure led to a decrease in the yield of 8a
(entries 2e4). Carbonylation at 80 bar CO pressure led to a mixture
of 2-(1-ferrocenylmethylidine)malonic acid derivatives 6a and 7a
(entry 4) [5]. It is worth noting that the prevailed formation of the
E-isomer (6a) was observed under all the reaction conditions. No
b-lactam formation could be detected by GCeMS. A decrease in the
1/4a ratio (the use of less than one equivalent of 1) led to lower
conversions of 4a, probably due to a decreased rate of ketene
formation. Interestingly, almost total lack of tetrahydropyr-
imidinone 8a was observed in the reaction mixtures (entries 5e8)
in spite of the fact that 4a was in excess of 1. On the contrary, the
use of a slight excess of 1 led to the excellent conversion of 4a and to
the formation of 8a with good selectivity (entries 9e10). It should
be mentioned, however, that in the presence of a high, e.g. threefold
excess of 1, the isolation of the products became very difficult due
to the formation of a considerable amount of several unidentified
side products derived probably from ethyl diazoacetate. Conse-
quently, product yields were lower than before (entry 11).
a-haloenol acetate [12] and an a-diazoketone [13] under thermal
and photochemical conditions, respectively. The photochemical
reaction was proposed to be a [2 þ 2 þ 2] cycloaddition [13], but no
mechanism was suggested for the thermal reaction.
A possible explanation for the formation of the tetrahydropyr-
imidinone derivatives could be based on a [4 þ 2] cycloaddition of an
azadiene, obtained by the tautomerisation of 2-(1-ferrocenyl-
methylidene)malonic acid derivatives 6 and/or 7, with the imine.
However, no cycloaddition of isolated 6a or 7a with imine 4a was
observed either in the absence or in the presence of the cobalt
Scheme 2. Cobalt-catalysed carbonylation of ethyl diazoacetate (1) in the presence of N-(alkyl/arylmethyl)ferrocenylimines 4aee. (Compounds 8aee are obtained as racemic
mixtures, solid and hatched lines represent only the relative positions of the substituents).

J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
133
Table 1
catalyst. Similarly, only 8b, 9b and 6e were detected in the reaction
mixture when ethyl diazoacetatewascarbonylated in thepresence of
a mixture of imine 4b and 2-(1-ferrocenylmethylidene)malonic acid
derivative 6e. If 6e could undergo a cycloaddition under carbonyla-
tion conditions, a tetrahydro-4(1H)-pyrimidinone derivative with
one N-cyclohexylmethyl and one N-(4-methoxyphenyl)methyl
moiety should have also been formed (Scheme 3).
Cobalt-catalysed carbonylation of ethyl diazoacetate (1) in the presence of imine 4a.a
Entry CO pressure [bar] 1/4a [mol/mol] Conv. of 4a [%]b Yield of products [%]c
8a
6a
7a
1
2
3
4
5
6
7
8
40
50
60
80
40
50
40
50
40
50
50
1.0
1.0
1.0
1.0
0.8
0.8
0.66
0.66
1.25
1.25
3.0
89
88
81
76
56
58
50
47
94
94
100
52
48
40
Traces
Traces
Traces
Traces
Traces
53
15
16
20
46
23
29
24
22
6
4
2
3
8
6
6
5
4
4
4
6
The formation of the six-membered ring products may be
explained by the reaction of the zwitterionic intermediate of the
Staudinger [2 þ 2] cycloaddition with the imine (Scheme 4). A
similar reaction was observed for a ketene and an a,b-unsaturated
9
10
11
imine, but in that case, the zwitterionic intermediate reacted with
the C]C double bond of the unsaturated imine leading to a piper-
idinone derivative [14].1
53
29
6
13
a
Reaction conditions: 4a (0.3 mmol), 1 (as indicated), Co2(CO)8 (0.015 mmol) in
2 mL CH2Cl2, rt, 24 h under CO pressure.
2.2. Characterisation of the new compounds
b
Determined by GC, using ferrocene as internal standard.
c
After isolation by column chromatography.
Various NMR techniques (1H- and 13C NMR, 1He1H COSY, HSQC
and HMBC) were used for the characterisation of tetrahydro-4(1H)-
pyrimidinone derivatives 8e10. The structures of 8a (Fig. 2), 9a
(Fig. 3) and 10e (Fig. 4) were confirmed by X-ray crystallography.
For these compounds, a complete assignation of NMR signals
was carried out using 2D NMR measurements. Some characteristic
differences in the spectra of the three compounds are discussed in
the Supporting Information.
The exact structures of pyrimidinones 8bee and 9bec were
determined by comparing their 1H- and 13C NMR spectra with those
of 8a and 9a, respectively. The X-ray structure of the product ob-
tained from imine 4d also supported the structure of 8d (Fig. 5).
EtO2C
Fc
O
H
Co2(CO)8
N
H
H
N
Ph
CO2Et
CO
Fc
H
Fc
N
O
5a
+
Cox(CO)n
N
H
H
Ph
Fc
Ph
H
N
H
Fc
H
H
N
Fc
H
CO2Et
Fc
O
N
N
Ph
H
Ph Fc
H
Cox(CO)nH
CO2Et
CO2Et
Fc
O
Fc
O
Cox(CO)n
+
H
N
N
H
H
N
Ph Fc
N
Ph
Ph
H
H
Ph Fc
H
H
8a, 9a
2-(1-Ferrocenylmethylidene)malonic acid derivatives 6aee and
7aee were characterised by 1H- and 13C NMR, MS, IR and elemental
analysis.
1
One of the referees suggested another interesting mechanistic explanation for
The E stereochemistry of 6a was proved unequivocally by the X-
ray diffraction measurement of a single crystal obtained from the
major product (Fig. 6). The stereochemistry of the other 2-(1-
ferrocenylmethylidene)malonic acid derivatives 6bee and 7bee
were determined by comparing the signals of amide protons in
the 1H NMR spectra. The triplets of these protons have lower
chemical shifts in the spectra of 6aee (between 5.76 ppm and
6.13 ppm) than in those of 7aee (between 7.39 ppm and 7.81 ppm).
the formation of tetrahydro-4(1H)-pyrimidinone derivatives. According to this
suggestion, the products may be obtained by a radical mechanism involving a CoeH
species (see the Scheme above). The stabilised radical could attack the strained b-
lactam ending up with another stabilised benzyl radical and a less strained 6-
membered ring. In the absence of a starter or stable imino radical the reversion
of 5 to 6 and 7 may take place. This assumption is supported by the fact that high
CO pressure retards the reaction. Of course, in the presence of the Co2(CO)8 catalyst,
the formation of radicals cannot be ruled out, but it should be mentioned that in
these reactions, the presence of no b-lactam could be detected by GGeMS.

134
J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
Table 2
Cobalt-catalysed carbonylation of ethyl diazoacetate (1) in the presence of imines
4bee.a
Entry Imine CO pressure [bar] Conv. of 4 [%]b Yield of products [%]c
8
6
7
1
2
3
4
5
6
7
8
4b
4c
4d
4e
4b
4c
4d
4e
40
40
40
40
80
80
80
80
91
91
74
98
67
65
76
75
62
41
53
53
e
7
24
6
14
46
39
38
41
e
6
e
e
10
9
12
13
e
e
e
a
Reaction conditions: 1 (0.3 mmol), 4 (0.3 mmol), Co2(CO)8 (0.015 mmol) in 2 mL
CH2Cl2, rt, 24 h under CO pressure.
b
Determined by GC, using ferrocene as internal standard.
After isolation by column chromatography.
c
Scheme 4. Possible mechanism for the formation of isomeric tetrahydro-4(1H)-pyr-
imidinones 8e10 through the zwitterionic intermediate of the Staudinger reaction.
involves the reaction of the zwitterionic intermediate of the Stau-
dinger [2 þ 2] cycloaddition with the imine.
4. Experimental
1H and 13C NMR spectra were recorded in CDCl3 on a Varian
Inova 400 spectrometer at 400.13 MHz and 100.62 MHz, respec-
tively. Chemical shifts d are reported in ppm relative to CHCl3 (7.26
and 77.00 ppm for 1H and 13C, respectively). GLC analyses were
carried out with a HP-5890/II gas chromatograph using a 15 m HP-5
column. Infrared (IR) spectra were recorded in KBr pellets using an
Avatar330 FT-IR instrument. Elemental analyses were measured on
a 1108 Carlo Erba apparatus. GCeMS measurements were carried
out with a HP-5971A MSD connected to a HP-5890/II gas chro-
matograph. MS spectra were obtained on an Autoflex II TOF/TOF
(Bruker Daltonics, Bremen, Germany) spectrometer in a 2,5-
dihydroxybenzoic acid matrix. The MS spectrum of 8d was
measured on a Waters Micromass Quattro micro API spectrometer
using electrospray ionisation.
Fig. 1. Tetrahydro-4(1H)-pyrimidinones 9aec and 10e, obtained as side products.
3. Conclusion
Cobalt-catalysed domino reaction of ethyl diazoacetate, carbon
monoxide and imines 4aee leads to tetrahydro-4(1H)-pyr-
imidinone derivatives 8aee in good yields (41e62%). Two further
diastereomers were isolated from the reaction mixtures and were
characterised. Comparing these results with our previous findings,
the presence of the N-methylene moiety in the imines is a prereq-
uisite for the formation of the pyrimidinone derivatives. According
to our results, the most probable pathway towards these products
X-ray diffraction intensity data were collected on a Rigaku
RAPID diffractometer at low temperature (6a, 8a, 8d) and room
temperature (9a, 10e). Absorption corrections were applied to the
data. The structures were solved by direct methods and refined by
Scheme 3. Cobalt-catalysed carbonylation of ethyl diazoacetate (1) in the presence of imine 4b and 2-(1-ferrocenylmethylidene)-malonic acid derivatives 6e.

J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
135
Fig. 4. Molecular diagram of 10e. Hydrogen atoms, except those of the pyrimidone ring
are omitted for clarity. Displacement ellipsoids are drawn at the 50% probability level.
4e are new compounds and these were characterised by usual
Fig. 2. Molecular diagram of 8a. Hydrogen atoms, except those of the pyrimidone ring
are omitted for clarity. Displacement ellipsoids are drawn at the 50% probability level.
spectroscopic methods.
4.1.1. N-(Prop-2-ynyl)ferrocenylidenamine (4d)
1H NMR (400 MHz, CDCl3):
d
¼ 8.41 (s, 1H), 4.67 (br s, 2H), 4.39
full-matrix least-squares against intensities [18]. Restraints were
applied to 8d (ISOR and SIMU to the C1c atom) and to 9a (nine
distance restraints) [DFIX] applied to bonds in the cyclopentadienyl
rings. Details on crystal data, data collection and refinement
parameters are shown in the Supporting Information (Table S1).
(br s, 2H), 4.30 (br s, 2H), 4.18 (s, 5H), 2.48 (t, 2.3 Hz, 1H). IR (KBr,
cmꢀ1): 2110, 1643. MS: m/z 251 (Mþ)/100, 211/66, 185/24, 121/38,
56/21. Anal. Calcd. for C14H13FeN (251.10): C 66.96; H 5.22; N 5.58;
found C 66.89; H 5.31; N 5.49. Red-brown solid, Rf (hexane/
EtOAc ¼ 3/1) 0.52; m.p. 63e67 ꢁC. Yield 78%.
4.1. General procedure for the synthesis of ferrocenylimines
4.1.2. N-(Cyclohexylmethyl)ferrocenylidenamine (4e)
1H NMR (400 MHz, CDCl3):
d
¼ 7.98 (s, 1H), 4.56 (t, J ¼ 1.8 Hz,
Ferrocencarboxaldehyde (1.07 g, 5 mmol) was reacted with the
corresponding amine (5 mmol) in methanol (22 mL) in the pres-
ence of molecular sieves (4 Å) under argon at room temperature.
The reaction was followed by GC. On the completion of the reaction,
the solvent was removed in vacuo and the imines were recrystal-
lised from diethyl ether. Imines were obtained in good yields (4a:
80%, 4b: 95%, 4c: 82%, 4d: 78%, 4e: 86%). Their spectra corre-
sponded well to the literature data (4a [15], 4b [16], 4c [17]). 4d and
2H), 4.27 (t, J ¼ 1.8 Hz, 2H), 4.11 (s, 5H), 3.22 (dd, J ¼ 6.5, 1 Hz, 2H),
1.58e1.72 (m, 4H), 1.08e1.26 (m, 5H), 0.82e0.94 (m, 2H). IR (CaF2,
cmꢀ1): 1648 cmꢀ1. MS: m/z 309 (Mþ)/100, 226/25, 199/20, 121/33,
56/10. Anal. Calcd. for C18H23FeN (309.23): C 69.91; H 7.50; N 4.53;
Fig. 3. Molecular diagram of 9a. Hydrogen atoms, except those of the pyrimidone ring
Fig. 5. Molecular diagram of 8d. Hydrogen atoms, except those of the pyrimidone ring
are omitted for clarity. Displacement ellipsoids are drawn at the 50% probability level.
are omitted for clarity. Displacement ellipsoids are drawn at the 50% probability level.

136
J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
CDCl3):
d
¼ 164.3; 163.4; 143.3; 120.7; 77.2; 73.6; 70.2; 70.1; 69.3;
68.1; 59.4; 27.5; 12.4. IR (KBr, cmꢀ1): 3311; 1725; 1634; 1261; 1097.
MS: m/z 365 (Mþ)/100, 320/4, 300/23, 254/12, 216/14, 173/20, 121/
17, 56/9. Anal. Calcd. for C19H19FeNO3 (365.21): C 62.49, H 5.24, N
3.84; found C 62.35, H 5.11, N 3.66. Red solid, Rf ¼ 0.15 (hexane/
EtOAc, 3:1); m.p. 117e122 ꢁC. Yield 38%.
4.2.4. (E)-N-(Cyclohexylmethyl)-2-ethoxycarbonyl-3-ferrocenyl-2-
propenamide (6e)
1H NMR (400 MHz, CDCl3):
d
¼ 7.49 (s, 1H), 5.79 (t, J ¼ 6.8 Hz,
1H), 4.51 (t, J ¼ 1.8 Hz, 2H), 4.37 (t, J ¼ 1.8 Hz, 2H), 4.18 (q, J ¼ 7.1 Hz,
2H), 4.14 (s, 5H), 3.15 (t, J ¼ 6.5 Hz, 2H), 1.70e1.62 (m, 4H), 1.25 (t,
J ¼ 7.1 Hz, 3H), 1.12e1.20 (m, 5H), 0.86e0.90 (m, 2H). 13C NMR
(100.62 MHz, CDCl3):
d
¼ 166.9, 165.7, 143.9, 124.3, 76.1, 71.9, 71.0,
70.1, 61.4, 46.2, 37.9, 31.0, 26.6, 26.0, 14.4. IR (KBr, cmꢀ1): 3323;
1707; 1621; 1243; 1048. MS: m/z 423 (Mþ)/100, 358/46, 314/15,
209/9,121/9. Anal. Calcd. for C23H29FeNO3 (423.33): C 65.26, H 6.90,
N 3.31; found C 64.97, H 7.12, N 3.23. Red solid, Rf ¼ 0.24 (hexane/
EtOAc, 3:1); m.p. 133e137 ꢁC. Yield 41%.
Fig. 6. Molecular diagram of 6a. Displacement ellipsoids are drawn at the 50% prob-
ability level.
foundC 69.98; H 7.61; N 4.48. Red-brownoil, Rf (hexane/EtOAc¼ 3/1)
4.2.5. (Z)-N-Benzyl-2-ethoxycarbonyl-3-ferrocenyl-2-propenamide
0.54. Yield 86%.
(7a)
1H NMR (400 MHz, CDCl3):
d
¼ 8.04 (s, 1H), 7.81 (t, J ¼ 5.6 Hz,
4.2. General procedurefor thesynthesisof 2-ethoxycarbonyl-3-ferro-
cenyl-2-propenamide derivatives
1H), 7.32e7.34 (m, 2H), 7.31e7.32 (m, 2H), 7.24e7.28 (m, 1H), 4.54
(d, J ¼ 5.6 Hz, 2H), 4.50 (t, J ¼ 1.9 Hz, 2H), 4.47 (t, J ¼ 1.9 Hz, 2H), 4.25
(q, J ¼ 7.2 Hz, 2H), 4.18 (s, 5H), 1.26 (t, J ¼ 7.2 Hz, 3H). 13C NMR
In a typical reaction ferrocenylimine (4aee) (0.300 mmol), ethyl
(100.62 MHz, CDCl3):
d
¼ 168.0, 163.7, 147.9, 138.4, 128.7, 127.8,
diazoacetate (1) (32
m
l, 0.300 mmol), Co2(CO)8 (5.1 mg, 0.015 mmol)
127.4, 120.0, 77.5, 71.7, 71.5, 69.9, 61.3, 44.1, 13.9. IR (KBr, cmꢀ1):
3304; 1694; 1623; 1243, 1045. MS: m/z 417 (Mþ)/100, 352/40, 121/
16, 91/26. Anal. Calcd. for C23H23FeNO3 (417.29): C 66.20, H 5.56, N
3.36; found C 66.38, H 5.68, N 3.47. Red oil, Rf ¼ 0.22 (hexane/EtOAc,
3:1). Yield 8%.
and CH2Cl2 (2 mL) were transferred under an inert atmosphere into
a 30 mL stainless steel autoclave. It was charged with carbon
monoxide (80 bar at room temperature) and stirred at room
temperature for 24 h. The evaporation of the solvent and column
chromatography (silica, hexane/EtOAc ¼ 3/1) led to the products.
Spectroscopic data for 6c and 7c have been reported previously
[5].
4.2.6. (Z)-N-((4-Methoxyphenyl)methyl)-2-ethoxycarbonyl-3-
ferrocenyl-2-propenamide (7b)
1H NMR (400 MHz, CDCl3):
d
¼ 7.97 (s,1H), 7.68 (t, J ¼ 5.6 Hz,1H),
4.2.1. (E)-N-Benzyl-2-ethoxycarbonyl-3-ferrocenyl-2-propenamide (6a)
7.19 (d, J ¼ 8.7 Hz, 2H), 6.81 (d, J ¼ 8.7 Hz, 2H), 4.40e4.46 (m, 6H), 4.23
1H NMR (400 MHz, CDCl3):
d
¼ 7.58 (s, 1H), 7.33e7.25 (m, 5H),
(q, J ¼ 7.1 Hz, 2H), 4.13 (s, 5H), 3.74 (s, 3H), 1.20 (t, J ¼ 7.1 Hz, 3H). 13C
5.97 (t, J ¼ 5.8 Hz, 1H), 4.58 (d, J ¼ 5.8 Hz, 2H), 4.56 (t J ¼ 1.8 Hz, 2H),
NMR (100.62 MHz, CDCl3):
d
¼ 168.5,163.1,159.3, 147.7,130.4, 129.5,
4.43 (t, J ¼ 1.8 Hz, 2H), 4.24 (q, J ¼ 7.1 Hz, 2H), 4.18 (s, 5H), 1.31 (t,
129.1,120.0, 77.1, 71.8, 71.5, 70.0, 61.5, 55.2, 43.6,13.9. IR (KBr, cmꢀ1):
3260; 1711; 1639; 1253, 1029. MS: m/z 447 (Mþ)/100, 401/10, 382/
55, 207/11, 121/95, 77/5. Anal. Calcd. for C24H25FeNO4 (447.31): C
64.44, H 5.63, N 3.13; found C 64.51, H 5.76, N 3.29. Red solid, Rf ¼ 0.16
(hexane/EtOAc, 3:1); m.p. 117e122 ꢁC. Yield 10%.
J ¼ 7.1 Hz, 3H). 13C NMR (100.62 MHz, CDCl3):
d
¼ 166.5, 165.3,
144.2,137.7,128.6,127.9,127.5,123.6, 75.7, 71.8, 70.8, 69.9, 61.2, 43.7,
14.2. IR (KBr, cmꢀ1): 3308; 1698; 1619; 1246, 1048. MS: m/z 417
(Mþ)/100, 352/44, 121/14, 91/25. Anal. Calcd. for C23H23FeNO3
(417.29): C 66.20, H 5.56, N 3.36; found C 66.49, H 5.67, N 3.41. Red
needles, Rf ¼ 0.13 (hexane/EtOAc, 3:1); m.p. 154e158 ꢁC. Yield 46%.
4.2.7. (Z)-N-(Prop-2-ynyl)-2-ethoxycarbonyl-3-ferrocenyl-2-
propenamide (7d)
4.2.2. (E)-N-(4-Methoxyphenyl-methyl)-2-ethoxycarbonyl-3-ferro-
cenyl-2-propenamide (6b)
1H NMR (400 MHz, CDCl3):
d
¼ 8.03 (s, 1H), 7.75e7.79 (m, 1H),
4.50 (d, J ¼ 7.8 Hz, 2H), 4.28 (q, J ¼ 7.1 Hz, 2H), 4.17 (s, 5H), 4.13e4.16
(m, 4H), 2.23 (s, 1H), 1.29 (t, J ¼ 7.1 Hz, 3H). IR (KBr, cmꢀ1): 3292;
1693; 1646; 1260; 1097. MS: m/z 365 (Mþ)/100, 320/6, 300/28, 254/
13, 216/14, 173/18, 121/15, 56/9. Anal. Calcd. for C19H19FeNO3
(365.21): C 62.49, H 5.24, N 3.84; found C 62.65, H 5.31, N 3.70. Red
solid, Rf ¼ 0.26 (hexane/EtOAc, 3:1); m.p. 82e86 ꢁC. Yield 12%.
1H NMR (400 MHz, CDCl3):
d
¼ 7.51 (s, 1H), 7.20 (d, J ¼ 8.8 Hz,
2H), 6.78 (d, J ¼ 8.8 Hz, 2H), 5.98 (t, J ¼ 5.3 Hz,1H), 4.49 (t, J ¼ 1.8 Hz,
2H), 4.45 (d, J ¼ 5.3 Hz, 2H), 4.37 (t, J ¼ 1.8 Hz, 2H), 4.18 (q, J ¼ 7.1 Hz,
2H), 4.12 (s, 5H), 3.73 (s, 3H), 1.25 (t, J ¼ 7.1 Hz, 3H). 13C NMR
(100.62 MHz, CDCl3):
d
¼ 166.6, 165.5, 159.3, 144.3, 130.1, 129.5,
123.9, 114.3, 76.0, 72.0, 71.0, 70.0, 61.4, 55.5, 43.5, 14.4. IR (KBr,
cmꢀ1): 3310; 1701; 1637; 1243, 1024. MS: m/z 447 (Mþ)/100, 401/8,
382/58, 207/8, 121/98, 77/5. Anal. Calcd. for C24H25FeNO4 (447.31):
C 64.44, H 5.63, N 3.13; found C 64.61, H, 5.96, N 3.38. Red solid,
Rf ¼ 0.09 (hexane/EtOAc, 3:1); m.p. 139e143 ꢁC. Yield 46%.
4.2.8. (Z)-N-(Cyclohexylmethyl)-2-ethoxycarbonyl-3-ferrocenyl-2-
propenamide (7e)
1H NMR (400 MHz, CDCl3):
d
¼ 7.99 (s, 1H), 7.53e7.58 (m, 1H),
4.49e4.52 (m, 2H), 4.46e4.48 (m, 2H), 4.30 (q, J ¼ 7.1 Hz, 2H), 4.20
(s, 5H), 3.21e3.25 (m, 2H), 1.72e1.80 (m, 4H), 1.31 (t, J ¼ 7.1 Hz, 3H),
1.20e1.26 (m, 5H), 0.80e1.00 (m, 2H). IR (KBr, cmꢀ1): 3329; 1724;
1639; 1229 cmꢀ1. MS: m/z 423 (Mþ)/100, 358/42, 314/11, 209/13,
121/10. Anal. Calcd. for C23H29FeNO3 (423.33): C 65.26, H 6.90, N
3.31; found C 65.01, H 7.17, N 3.19. Red oil, Rf ¼ 0.32 (hexane/EtOAc,
3:1). Yield 13%.
4.2.3. (E)-N-(Prop-2-ynyl)-2-ethoxycarbonyl-3-ferrocenyl-2-propen-
amide (6d)
1H NMR (400 MHz, CDCl3):
d
¼ 7.60 (s, 1H), 6.16 (t, J ¼ 3.8 Hz,
1H), 4.58e4.60 (m, 2H), 4.46 (t, J ¼ 1.8 Hz, 2H), 4.15e4.21 (m, 9H),
2.24 (t, J ¼ 2.5 Hz, 1H), 1.31 (t, J ¼ 7.1 Hz, 3H). 13C NMR (100.62 MHz,

J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
137
4.3. General procedure for the synthesis of ethyl 4-oxo-2,6-
4.3.4. Ethyl 2,6-diferrocenyl-1,3-di(prop-2-ynyl)-tetrahydro-4(1H)-
diferrocenyl-hexahydropyrimidine-5-carboxylate derivatives 8aee
pyrimidinone-5-carboxylate, racemic mixture of (2R,5S,6R) and
(2S,5R,6S) isomers (8d)
In a typical reaction ferrocenylimine (4aee) (0.300 mmol), ethyl
1H NMR (400 MHz, CDCl3):
d
¼ 5.94 (s, 1H), 5.31 (d, J ¼ 15.6 Hz,
diazoacetate (1) (32
ml, 0.300 mmol), Co2(CO)8 (5.1 mg, 0.015 mmol)
1H), 4.60 (d, J ¼ 11.5 Hz, 1H), 4.47 (m, 1H), 4.29 (m, 1H), 4.25 (s,
5H), 4.17e4.22 (m, 6H), 4.06e4.16 (m, 3H), 3.92 (s, 5H), 3.48 (d,
J ¼ 11.5 Hz, 1H), 3.33 (d, J ¼ 16.0 Hz, 1H), 3.07 (d, J ¼ 15.6 Hz, 1H),
2.35 (s, 1H), 2.24 (s, 1H), 1.31 (t, J ¼ 7.1 Hz, 3H). 13C NMR
and CH2Cl2 (2 mL) were transferred under an inert atmosphere into
a 30 mL stainless steel autoclave. It was charged with carbon
monoxide (40 bar at room temperature) and stirred at room
temperature for 24 h. The evaporation of the solvent and column
chromatography (silica, hexane/EtOAc ¼ 3/1) led to the products.
Crystals suitable for X-ray analysis were grown by recrystallisation
from n-hexane/EtOAc ¼ 3/1.
(100.62 MHz, CDCl3):
d
¼ 169.4, 164.1, 86.3, 85.4, 80.8, 78.3, 73.3,
73.0, 72.2, 69.2, 69.1, 69.0; 68.7, 68.2, 68.0, 67.4, 67.1, 66.7, 66.4,
61.6, 53.1, 50.3, 34.8, 34.1, 14.1. IR (KBr, cmꢀ1): 1741; 1650. MS: m/z
1255 ((2M þ Na)þ)/35, 639 ((M þ Na)þ)/100, 617 ((M þ H)þ)/70,
616 (Mþ)/52, 311/50. Anal. Calcd. for C33H32Fe2N2O3 (616.32): C
64.31, H 5.23, N 4.55; found C 64.53, H 5.01, N 4.44. Orange
chunks, Rf ¼ 0.31 (hexane/EtOAc, 3:1); m.p. 186e190 ꢁC. Yield
53%.
4.3.1. Ethyl 1,3-dibenzyl-2,6-diferrocenyl-tetrahydro-4(1H)-
pyrimidinone-5-carboxylate, racemic mixture of (2R,5S,6R) and
(2S,5R,6S) isomers (8a)
1H NMR (400 MHz, CDCl3):
d
¼ 7.27e7.30 (m, 5H), 7.03e7.11 (m,
3H), 6.57 (dd, J ¼ 6.5, 1.5 Hz, 2H), 5.67 (d, J ¼ 14.3 Hz, 1H); 5.00 (s,
1H); 4.83 (d, J ¼ 11.8 Hz, 1H); 4.37e4.38 (m, 1H); 4.35e4.37 (m, 1H);
4.29e4.30 (m,1H); 4.26 (d, J ¼ 7.1 Hz, 2H); 4.17e4.22 (m, 3H); 4.08e
4.09 (m, 1H); 4.03e4.00 (m, 2H); 3.97 (s, 5H); 3.86 (s, 5H); 3.51 (d,
J ¼ 11.8 Hz, 1H); 3.40 (d, J ¼ 13.4 Hz, 1H); 2.68 (d, J ¼ 13.4 Hz, 1H);
4.3.5. Ethyl 1,3-bis(cyclohexylmethyl)-2,6-diferrocenyl-tetrahydro-
4(1H)-pyrimidinone-5-carboxylate, racemic mixture of (2R,5S,6R)
and (2S,5R,6S) isomers (8e)
1H NMR (400 MHz, CDCl3):
d
¼ 5.36 (s, 1H), 4.57 (d, J ¼ 11.9 Hz,
1H); 4.38e4.41 (m, 1H), 4.16e4.23 (m, 8H), 4.10 (s, 5H), 4.00e4.02
(m,1H), 3.96e3.98 (m,1H), 3.78 (s, 5H), 3.37 (d, J ¼ 11.9 Hz,1H), 3.12
(dd, J ¼ 13.6, 5.6 Hz,1H), 2.12 (dd, J ¼ 12.9, 3.6 Hz,1H),1.89e1.99 (m,
1H), 0.95e1.74 (m, 20 H), 1.28 (t, J ¼ 7.1 Hz, 3H), 0.65e0.77 (m, 1H),
1.33 (t, J ¼ 7.1 Hz, 3H). 13C NMR (100.62 MHz, CDCl3):
d
¼ 169.9,
164.9, 138.2, 137.5, 129.1, 128.8, 128.4, 128.0, 127.9, 126.9, 87.6, 86.3,
72.3, 69.1, 69.0, 68.7, 68.6, 68.5, 67.8, 67.4, 67.1, 66.7, 66.6, 61.5, 53.5,
50.1, 48.3, 47.4, 14.1. IR (KBr, cmꢀ1): 1740; 1638. MS: m/z 720 (Mþ)/
84, 418/100, 285/32, 177/21, 137/32. Anal. Calcd. for C41H40Fe2N2O3
(720.47): C 68.35, H 5.60, N 3.89; found C 68.51, H 5.70, N 3.72.
Amber blocks, Rf ¼ 0.36 (hexane/EtOAc, 3:1); m.p. 205e209 ꢁC.
Yield 52%.
0.54e0.65 (m, 1H). 13C NMR (100.62 MHz, CDCl3):
d
¼ 168.6, 163.8,
86.7, 84.9, 72.2, 67.6, 67.5, 67.4, 67.1, 67.0, 66.4, 65.6, 65.3, 65.1, 64.7,
59.7, 51.9, 49.4, 48.1 (2C), 35.5, 34.6, 30.0, 29.8, 29.7, 29.6, 25.2, 24.9,
24.7, 24.5, 24.4, 24.3, 12.6 IR (KBr, cmꢀ1): 1733; 1650. MS: m/z 733
((M þ H)þ)/4, 547/14, 518/4, 451/4, 430/14, 386/21, 311/100, 285/14,
239/25, 219/14, 186/14, 137/7. Anal. Calcd. for C41H52Fe2N2O3
(732.57): C 67.22, H 7.15, N 3.82; found C 66.89, H 7.37, N 3.96.
Yellow solid, Rf ¼ 0.48 (hexane/EtOAc, 3:1); m.p. 175e179 ꢁC.
Yield 53%.
4.3.2. Ethyl 2,6-diferrocenyl-1,3-bis(4-methoxybenzyl)-tetrahydro-
4(1H)-pyrimidinone-5-carboxylate, racemic mixture of (2R,5S,6R)
and (2S,5R,6S) isomers (8b)
1H NMR (400 MHz, CDCl3):
d
¼ 7.22 (d, J ¼ 8.7 Hz, 2H), 6.81 (d,
J ¼ 8.7 Hz, 2H), 6.61 (d, J ¼ 8.7 Hz, 2H), 6.51 (d, J ¼ 8.7 Hz, 2H), 5.60
(d, J ¼ 14.2 Hz, 1H), 5.00 (s, 1H), 4.80 (d, J ¼ 11.8 Hz, 1H), 4.34e4.38
(m, 2H), 4.16e4.31 (m, 6H), 4.04e4.07 (m, 1H), 3.98e4.01 (m, 1H),
4.00 (s, 5H), 3.92 (d, J ¼ 14.2 Hz, 1H), 3.86 (s, 5H), 3.79 (s, 3H), 3.71
(s, 3H), 3.48 (d, J ¼ 11.8 Hz, 1H), 3.32 (d, J ¼ 13.1 Hz, 1H), 2.60 (d,
J ¼ 13.1 Hz, 1H), 1.33 (t, J ¼ 7.1 Hz, 3H). 13C NMR (100.62 MHz,
4.4. General procedure for the synthesis of ethyl 4-oxo-2,6-
diferrocenyl-hexahydropyrimidine-5-carboxylate derivatives 9aec
and 10e
In a typical reaction ferrocenylimine (4aee) (0.300 mmol), ethyl
diazoacetate (1) (40 ml, 0.375 mmol), Co2(CO)8 (5.1 mg, 0.015 mmol)
CDCl3):
d
¼ 170.2, 165.1, 159.6, 158.8; 130.7, 130.5, 129.9, 129.7, 114.4,
and CH2Cl2 (2 mL) were transferred under an inert atmosphere into
a 30 mL stainless steel autoclave. It was charged with carbon
monoxide (80 bar at room temperature) and stirred at room
temperature for 8 h. Then the pressure was decreased to 40 bar and
the reaction mixture was stirred at room temperature for 16 h. The
evaporation of the solvent and column chromatography
(silica, hexane/EtOAc ¼ 3/1) led to the products. Crystals suitable
for X-ray analysis were grown by recrystallisation from n-hexane/
EtOAc ¼ 3/1.
113.6, 88.0, 86.7, 72.1, 69.4, 69.2, 68.9. 68.8. 68.7, 68.0, 67.6, 67.3,
67.0, 66.8, 61.7, 55.6, 55.5, 53.7, 50.3, 47.9, 46.9, 14.3. IR (KBr, cmꢀ1):
1736; 1643. MS: m/z 780 (Mþ)/21, 595/14, 448/36, 334/95, 285/100.
Anal. Calcd. for C43H44Fe2N2O5 (780.52): C 66.17, H 5.68, N 3.59;
found C 65.85, H 5.81, N 3.42. Yellow solid, Rf ¼ 0.21 (hexane/EtOAc,
3:1); m.p. 186e191 ꢁC. Yield 62%.
4.3.3. Ethyl 1,3-dibutyl-2,6-diferrocenyl-tetrahydro-4(1H)-
pyrimidinone-5-carboxylate, racemic mixture of (2R,5S,6R) and
(2S,5R,6S) isomers (8c)
4.4.1. Ethyl 1,3-dibenzyl-2,6-diferrocenyl-tetrahydro-4(1H)-
pyrimidinone-5-carboxylate, racemic mixture of (2S,5S,6R) and
(2R,5R,6S) isomers (9a)
1H NMR (400 MHz, CDCl3):
d
¼ 5.28 (s, 1H), 4.58 (d, J ¼ 11.8 Hz,
1H), 4.37e4.40 (m,1H), 4.22e4.25 (m, 2H), 4.20e4.22 (m, 2H), 4.19e
4.20 (m,1H), 4.16e4.19 (m, 3H), 4.10 (s, 5H), 3.99e4.01 (m,1H), 3.95e
3.97 (m,1H), 3.78 (s, 5H), 3.33 (d, J ¼ 11.8 Hz,1H), 3.16e3.25 (m,1H),
2.18e2.25 (m, 1H), 2.05e2.12 (m, 1H), 1.10e1.68 (m, 8H), 1.28 (t,
J ¼ 7.1 Hz, 3H), 0.92 (t, J ¼ 7.3 Hz, 3H); 0.79 (t, J ¼ 7.1 Hz, 3H).13C NMR
1H NMR (400 MHz, CDCl3):
d
¼ 7.39e7.50 (m, 5H), 7.25e7.32
(m, 3H), 6.86e6.92 (m, 2H), 5.70 (d, J ¼ 14.7 Hz, 1H), 5.27 (s, 1H),
3.83e4.47 (m, 12H), 3.95 (s, 5H), 3.85 (d, J ¼ 12.8 Hz, 1H), 3.78 (s,
5H), 3.46 (d, J ¼ 10.0 Hz, 1H), 3.31 (d, J ¼ 12.8 Hz, 1H), 1.38 (t,
(100.62 MHz, CDCl3):
d
¼ 170.1,164.7, 88.0, 86.6, 73.2, 70.1, 69.9, 69.0,
J ¼ 7.2 Hz, 3H). 13C NMR (100.62 MHz, CDCl3):
¼ 170.0, 167.1, 138.6,
d
68.7, 68.1, 68.0, 67.0, 66.8, 66.5, 66.3, 61.3, 53.6, 49.8, 45.0, 42.8, 30.6,
29.4, 20.3, 20.0, 14.1, 14.0, 13.9. IR (KBr, cmꢀ1): 1738; 1642. MS: m/z
653 ((M þ H)þ)/36, 476/32, 384/36, 346/58, 285/100, 219/37,186/23,
150/10, 39/5. Anal. Calcd. for C35H44Fe2N2O3 (652.44): C 64.43, H
6.80, N 4.29; found C 64.64, H 6.97, N 4.13. Orange solid, Rf ¼ 0.37
(hexane/EtOAc, 3:1); m.p. 174e178 ꢁC. Yield 41%.
137.2, 129.5, 129.1, 128.9, 128.2, 128.1, 127.5, 91.1, 87.4, 72.3, 69.7,
68.8, 68.7, 68.1, 67.8, 67.5, 67.0, 66.6, 66.5, 66.3, 61.5, 60.0, 59.4, 53.5,
48.9, 14.2. MS: m/z 720 (Mþ)/26, 681/16, 535/26, 418/68, 304/100,
239/21, 151/68. Anal. Calcd. for C41H40Fe2N2O3 (720.47): C 68.35, H
5.60, N 3.89; found C 68.12, H 5.41, N 4.03. Yellow blocks, Rf ¼ 0.45
(hexane/EtOAc, 3:1); m.p. 208e212 ꢁC. Yield 24%.

138
J. Balogh et al. / Journal of Organometallic Chemistry 718 (2012) 131e138
4.4.2. Ethyl 2,6-diferrocenyl-1,3-bis(4-methoxybenzyl)-tetrahydro-
4(1H)-pyrimidinone-5-carboxylate, racemic mixture of (2S,5S,6R)
and (2R,5R,6S) isomers (9b)
Gömöry in the measurement of mass spectrum of 8d is also
acknowledged. Z.C. thanks the Bolyai Grant of the Hungarian
Academy of Sciences. The support of the project TÁMOP-4.2.2/B-10/
1-2010-0025, realised with the support of the Hungarian Govern-
ment and the European Union, with the co-funding of the European
Social Fund, is also acknowledged.
1H NMR (400 MHz, CDCl3):
d
¼ 7.27 (d, J ¼ 8.5 Hz, 2H), 6.91 (d,
J ¼ 8.5 Hz, 2H), 6.74e6.82 (m, 4H), 5.55 (d, J ¼ 14.4 Hz, 1H), 5.23 (s,
1H), 4.40e3.94 (m, 12H), 3.91 (s, 5H), 3.84 (s, 3H), 3.80 (s, 5H), 3.77
(s, 3H), 3.69 (d, J ¼ 12.7 Hz, 1H), 3.36 (d, J ¼ 9.6 Hz, 1H), 3.16 (d,
J ¼ 12.7 Hz, 1H), 1.29 (t, J ¼ 7.2 Hz, 3H). 13C NMR (100.62 MHz,
Appendix A. Supplementary material
CDCl3):
d
¼ 170.1, 167.0, 159.6, 159.1, 130.7, 130.6, 130.4, 129.3, 114.2,
113.5, 91.2, 87.5, 72.1, 69.7, 69.1, 68.9, 68.6, 68.1, 67.7, 67.5, 67.0, 66.5,
66.4, 61.5, 59.1, 59.0, 55.4, 55.3, 53.4, 48.3, 14.2. MS: m/z 780 (Mþ)/
57, 595/10, 448/19, 334/100, 285/41. Anal. Calcd. for C43H44Fe2N2O5
(780.52): C 66.17, H 5.68, N 3.59; found C 65.85, H 5.72, N 3.42.
Yellow oil, Rf ¼ 0.25 (hexane/EtOAc, 3:1). Yield 16%.
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication nos.
CCDC 847368e847372. Copies of the data can be obtained, free of
charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK, (fax: þ44-(0)1223-336033 or e-mail: deposit@ccdc.cam.ac.
Uk).
4.4.3. Ethyl 1,3-dibutyl-2,6-diferrocenyl-tetrahydro-4(1H)-
pyrimidinone-5-carboxylate, racemic mixture of (2S,5S,6R) and
(2R,5R,6S) isomers (9c)
Appendix B. Supplementary material
1H NMR (400 MHz, CDCl3):
d
¼ 5.43 (s, 1H), 3.92e4.39 (m, 9H),
4.02 (s, 5H), 4.00 (s, 5H), 3.86e3.91 (m, 1H), 3.78e3.82 (m, 1H),
3.55e3.60 (m, 1H), 3.41 (d, J ¼ 8.8 Hz, 1H), 3.25e3.33 (m, 1H), 2.70e
2.80 (m, 2H), 1.41e1.84 (m, 8H), 1.36 (t, J ¼ 6.8 Hz, 3H), 1.05 (t,
J ¼ 7.1 Hz, 3H), 1.01 (t, J ¼ 7.1 Hz, 3H), 13C NMR (100.62 MHz, CDCl3):
Supplementary material related to this article can be found at
http://dx.doi.org/10.1016/j.jorganchem.2012.08.009.
References
d
¼ 170.6, 166.3, 91.1, 86.9, 76.0, 69.6, 69.4, 68.8, 68.5, 68.3, 68.0,
67.7, 67.1, 66.6, 66.0, 61.5, 59.3, 56.5, 52.3, 46.3, 31.6, 30.2, 20.4, 20.3,
14.2, 14.1, 13.9. MS: m/z 653 ((M þ H)þ)/31, 504/17, 383/64, 270/100,
239/22, 150/25, 121/17. Anal. Calcd. for C35H44Fe2N2O3 (652.44): C
64.43, H 6.80, N 4.29; found C 64.57, H 7.01, N 4.23. Orange oil,
Rf ¼ 0.45 (hexane/EtOAc, 3:1). Yield 15%.
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tetrahydro-4(1H)-pyrimidinone-5-carboxylate, racemic mixture of
(2S,5S,6S) and (2R,5R,6R) isomers (10e)
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1H NMR (400 MHz, CDCl3):
d
¼ 5.58 (s, 1H), 4.50 (d, J ¼ 6.7 Hz,
1H), 4.42e4.48 (m, 1H), 4.11e4.31 (m, 7H), 4.05e4.11 (m, 2H), 4.16
(s, 5H), 3.98 (s, 5H), 3.86e3.90 (m, 1H), 3.51 (d, J ¼ 6.7 Hz, 1H), 3.17
(dd, J ¼ 13.5, 5.7 Hz, 1H), 2.78 (dd, J ¼ 13.8, 3.6 Hz, 1H), 2.49 (dd,
J ¼ 13.8, 10.1 Hz, 1H), 1.02e1.99 (m, 20 H), 1.27 (t, J ¼ 7.1 Hz, 3H),
0.86e0.98 (m, 1H), 0.62e0.73 (m, 1H). 13C NMR (100.62 MHz,
[7] I.M. Lagoja, Chem. Biodiversity 2 (2005) 1e50.
[8] W. Chen, J. Feng, H. Tu, Front. Chem. China 2 (2007) 127e130.
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(b) K.S. Chu, G.R. Negrete, J.P. Konopelski, F.J. Lakner, N.T. Woo,
M.M. Olmstead, J. Am. Chem. Soc. 114 (1992) 1800e1812;
ꢀ
(c) M. Nahrwold, A. Stroncius, A. Penner, B. Neumann, H.G. Stammler,
CDCl3):
d
¼ 166.6, 165.2, 88.2, 84.3, 75.0, 71.7, 70.8, 69.6, 69.2, 69.1,
N. Sewald, Beilstein J. Org. Chem. 5 (43) (2009). doi:103762/bjoc.5.43.
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met. Chem. 21 (2007) 613e625.
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101e107.
[13] Y. Liang, L. Jiao, S. Zhang, J. Xu, J. Org. Chem. 70 (2005) 334e337.
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F.P. Cossío, J. Org. Chem. 61 (1996) 3070e3079.
69.0, 68.5, 67.4, 67.3, 66.8, 61.2, 53.2, 52.5, 51.1, 51.0, 37.3, 36.1, 31.3,
31.2, 30.9, 30.8, 26.4, 26.3, 26.1, 26.0, 25.9, 25.8, 14.1. MS. m/z 733
(M þ Hþ)/19, 632/12, 544/25, 386/37, 285/100, 239/31, 199/19. Anal.
Calcd. for C41H52Fe2N2O3 (732.55): C 67.22, H 7.15, N 3.82; found C
67.15, H 7.22, N 3.98. Yellow blocks, Rf ¼ 0.38 (hexane/EtOAc, 3:1);
m.p. 180e184 ꢁC. Yield 24%.
ꢁ
ꢁ
[15] J. Lewkowski, M. Rzezniczak, R. Skowronski, J. Zakrevski, J. Organomet. Chem.
631 (2001) 105e109.
Acknowledgements
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[18] G.M. Sheldrick, Acta Crystallogr. D64 (2008) 112e122.
The authors thank the Hungarian National Science Foundation
for the financial support (OTKA NK71906). The help of Ágnes