Coupling of ferrocenyl chromium carbene complex with cyclobutenediones

Article abstract of DOI:10.1016/S0022-328X(02)01403-1

The coupling of ferrocenyl chromium carbene complex with cyclobutenediones leads to ferrocenyl-substituted 5-alkylidenefuranones and 4-cyclopentene- 1,3-diones, methyl ferrocenoate and acetylferrocene in varying amounts. The scope and limitations of these

Full text of DOI:10.1016/S0022-328X(02)01403-1

Journal of Organometallic Chemistry 656 (2002) 11Á17
/
www.elsevier.com/locate/jorganchem
Coupling of ferrocenyl chromium carbene complex with
cyclobutenediones
Metin Zora *, Baris Yucel, N. Bekir Peynircioglu
Department of Chemistry, Middle East Technical University, ODTU, Kimya Bolumu, 06531 Ankara, Turkey
Received 17 January 2002; received in revised form 18 March 2002; accepted 20 March 2002
Abstract
The coupling of ferrocenyl chromium carbene complex with cyclobutenediones leads to ferrocenyl-substituted 5-alkylidenefur-
anones and 4-cyclopentene-1,3-diones, methyl ferrocenoate and acetylferrocene in varying amounts. The scope and limitations of
these processes are investigated. In comparison with the phenyl analog, ferrocenyl chromium carbene complex has been found to be
less reactive. This is also supported by PM3 calculations. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Fischer carbene; Ferrocenyl carbene; Ferrocene; Cyclobutenedione; Alkylidenefuranone; Cyclopentenedione; Coupling
1. Introduction
ferrocene derivatives; particularly their ferrocenium salt
forms could be potential antitumor substances [5].
The biological importance of alkylidenefuranones is
well known [6]. In particular, alkylidenefuranone deri-
vatives possess antiviral, antibiotic and anticancerous
activities. This, together with the finding that ferroce-
nium salts are active against various animal and human
tumors [3,4], suggests that the incorporation of the
essential structural features of alkylidenefuranones with
a ferrocene moiety could provide compounds with
enhanced antitumor activities. Although, since its dis-
covery, ferrocene and its derivatives are among the most
thoroughly studied compounds [7], we were surprised
that there has been limited study of the ferrocenyl-
substituted alkylidenefuranones, particularly, 5-ferroce-
nyl-methylene-5H-furan-2-ones.
Fischer type metal carbene complexes have emerged
as valuable reagents for organic synthesis [8]. It has been
reported that phenols, cyclopentenones, indenes, furans,
furanones, cyclobutenones, vinylketenes and cyclohex-
adienones have resulted from their reactions under
appropriate conditions [9]. An ever-continuing aspect
of these studies has been the use of a structurally diverse
set of Fischer carbene complexes in these reactions to
afford a diverse array of compounds. Although ferro-
cenylcarbene complexes are known for a long time [10],
they have not been utilized extensively in organic
synthesis [8b,11]. We have recently reported that the
After the successful application of the pioneer ‘cispla-
tin’, i.e. cis-[PtCl2(NH3)2], as antitumor agent [1],
interest in the use of transition metal complexes in
medicine and other biological areas has grown rapidly
[2]. Among these derivatives, ferrocenium salts,
Cp2Fe(III)X (Xꢀ
/
PF6, FeCl4, 2,4,6-(NO2)3C6H2O,
Cl3CCO2×2Cl3CCO2H), have proved to be particularly
/
active against a number of tumors [3]. Unsubstituted
ferrocene does not display any tumor inhibiting activity
even if it is solubilized in water using heptakis(2,6-di-O-
methyl)-b-cyclodextrin (dmb-CD) [4], but its oxidized
form, i.e. ferrocenium salt, exhibits inhibitory activity
[3,4]. Although the excellent solubility of salts in water,
caused by their ionic character, proves to be propitious
for applications in biological systems, the inhibitory
activity of ferrocenium salts is independent of the water
solubility. The antitumor effect is related to the oxida-
tion state of the central iron atom, in that only the
oxidation state ꢁ3 (in ferrocenium cations) exhibits
/
inhibitory effects [4]. Thus, in recent years, considerable
interest has been devoted to the synthesis of new
ferrocene derivatives since the properly functionalized
* Corresponding author. Tel.: ꢁ
2101280
E-mail address: zora@metu.edu.tr (M. Zora).
/
90-312-2103213; fax: ꢁ90-312-
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 4 0 3 - 1

12
M. Zora et al. / Journal of Organometallic Chemistry 656 (2002) 11Á17
/
ferrocenylcarbene complexes of Cr, Mo and W react
with alkynes to produce ferrocenyl-substituted cyclobu-
tenones, furans and/or ketoesters [12]. Our results in
that report have shown that, under appropriate condi-
tions with the proper substrates, ferrocenylcarbene
complexes can follow the other reactivity patterns of
metal carbene complexes, as well. It is known that metal
carbene complexes, when treated with cyclobutene-
diones, afford the corresponding cyclopentenediones
and/or alkylidenefuranones via a net insertion of the
Table 1
Coupling of cyclobutenediones 1 with ferrocenylcarbene complex 2
a
b
Entry R1
R2
Cyclobutenedione Products (% yield)
c
1
2
Me
Ph
i-
1A
1B
3A (14)ꢁ4A (6)ꢁ5A
(8)ꢁ8 (15)
5B (8)ꢁ7 (12)
PrO
i-
c
PrO
Me
Ph
i-
3
4
5
Me
Ph
i-
1C
1D
1E
5C (9)ꢁ7 (18)ꢁ8 (9)
5D (8)ꢁ6D (11)
5E (5)
c
PrO PrO
carbene unit into the Cꢀ
/
C bond of the cyclobutenedione
a
b
c
[13]. As part of a program to synthesize new ferrocene
derivatives, we have investigated the reaction of cyclo-
butenediones with ferrocenylcarbene complexes, leading
to ferrocenyl-substituted 5-alkylidenefuranones and/or
4-cyclopentene-1,3-diones (Scheme 1). These alkylidene-
furanones and 4-cyclopentene-1,3-diones are the first
examples of these kind, containing a ferrocene moiety.
We herein report the preliminary results of this study.
All reactions were carried out in dioxane at 100 8C.
Isolated yields.
Configuration of exocyclic double bond was assigned as E.
led to varying amounts of cyclopentenediones 3 and 4,
alkylidenefuranones 5 and 6, methyl ferrocenoate (7)
and acetylferrocene (8). Compared with the phenyl
analog [13], ferrocenylcarbene complex 2 was noticeably
less reactive and afforded the products in lower yields.
The reactions carried out at relatively higher tempera-
tures, such as in p-xylene at 138 8C, led to complex
reaction mixtures and did not improve the yields of the
products significantly. Due to low yields, rationalization
for the product distribution has not been advanced.
Cyclopentenediones and alkylidenefuranones are the
expected insertion products of the reactions between
Fischer carbene complexes and cyclobutenediones [13].
The mechanism proposed for the formation of cyclo-
pentenediones 3 and 4, and alkylidenefuranones 5 and 6
is depicted in Scheme 2. CO dissociation from the
Fischer carbene complex 2 produces the coordinatively
unsaturated Fischer carbene complex 9 [13], which gives
2. Results and discussion
2.1. Synthesis of starting materials
Cyclobutenediones 1 used in this study were synthe-
sized from squaric acid by using well-documented
literature procedures [14,15]. Ferrocenylcarbene com-
plex of chromium (2) was prepared according to a
modified literature procedure [10].
2.2. Coupling of cyclobutenediones 1 with ferrocenyl
chromium carbene complex 2
oxidative addition into acylꢀ/acyl bond of cyclobutene-
dione 1 to afford chromacyclopentenedione 10. Migra-
tion of the more electron deficient acyl group in 10
yields chromacyclohexenedione 11, which affords cyclo-
pentenedione 3 upon reductive elimination (Scheme 2).
The formation of deoxygenated cyclopentenedione 4 is a
secondary reaction and occurs via a chromium-induced
reduction of initially formed cyclopentenedione 3.
For the coupling reactions, cyclobutenediones 1 were
heated to reflux with a slight excess of ferrocenylcarbene
complex 2 (1.5 equivalents) in dioxane for 6 h. The
results of this study are summarized in Scheme 1 and
Table 1.
As indicated in Table 1, the coupling of a variety of
cyclobutenediones 1 with ferrocenylcarbene complex 2
Scheme 1. Compounds 1, 3Á
/
6: (A) R1ꢀ
/
Me, R2ꢀ
/
i-PrO; (B) R1ꢀ
/
Ph, R2ꢀ
/
i-PrO; (C) R1ꢀ
/
R2ꢀ
/
Me; (D) R1ꢀ
/
R2ꢀ
/
Ph; (E) R1ꢀ
/
R2ꢀi-PrO.
/

M. Zora et al. / Journal of Organometallic Chemistry 656 (2002) 11Á
/17
13
Scheme 2.
Secondary deoxygenation processes have often been
observed in the reactions of chromium carbene com-
plexes [13,16]. In all reactions of Table 1, alkylidenefur-
anones 5 were observed, which is consistent with the
findings of Herndon and coworkers [13] using phenyl
chromium carbene complex. Although the interconver-
sion of cyclopentenediones and alkylidenefuranones is
well known [17], alkylidenefuranone 5 is the primary
product of the coupling reactions and does not result
from the rearrangement of initially formed cyclopente-
nedione 3 under the reaction conditions. Cyclopentene-
dione, such as 3 with a phenyl instead of a ferrocenyl
group, does not convert into corresponding alkylidene-
furanone when heated to 100 8C in dioxane, in the
absence or presence of chromium hexacarbonyl, or
when it is additive in the coupling reaction of other
carbene complexes, as shown before [13]. As illustrated
in Scheme 2, elimination of chromium gives enolate-
acylium intermediate 12, which undergoes intramolecu-
lar O-acylation to afford alkylidenefuranone 5 [13].
Deoxygenated alkylidenefuranone 6 results from the
reduction of initially formed 5 by chromium byproducts
during the course of the reaction, as in the formation of
cyclopentenediones 4 from 3 [13]. Although such a
reduction was not previously reported from similar
studies [13], treatment of alkylidenefuranone 5A with
chromium hexacarbonyl in refluxing dioxane led to a
slow reduction to 6A.
Interestingly, from some reactions (entries 1 and 3),
acetylferrocene (8) was isolated [20]. Formation of
ketones from reactions of Fischer carbene complexes is
very rare and has only few precedents [21,22]. The
mechanism proposed for the formation of 8 is outlined
in Scheme 3. Following CO dissociation from carbene
complex 2, the resulting coordinatively unsaturated
carbene complex 9 experiences a 1,3-methyl shift to
afford complex 13, which gives acetylferrocene (8) upon
reductive elimination. A similar mechanism was pre-
viously proposed by Sarkar for the ketone formation
from thermolysis of Fischer carbene complexes
[21a,21b].
2.3. Structural assignments of alkylidenefuranones
The indicated regiochemistry of alkylidenefuranones
5A and 5B has been assigned on the basis of comparison
of 13C-NMR spectra in similar systems [13,23]. In a 4-
alkoxyfuranone, i.e. 5A,B, the b-carbonyl carbon is
unusually downfield while a-carbonyl carbon is upfield.
However, in a 3-alkoxyfuranone, i.e. 5A,B if R1 and R2
are reversed, considerably less polarization is observed.
In 5A and 5B, a-carbonyl carbons appear at d 146.9 and
149.1, respectively, and b-carbonyl carbons at d 162.4
and 162.2, which are more consistent with the indicated
4-alkoxyfuranone structures.
Configurational assignment of g,d-unsaturated dou-
ble bond in alkylidenefuranones 5A,B,E has been based
primarily on the severe chemical shift differences of the
isopropyl methyls and methines in the 1H-NMR spectra.
In similar compounds, i.e. 5A,B if Fc is replaced by Ph,
the chemical shift of the isopropyl methyls in the Z
isomers is below d 0.90, while the same protons in the E
Formation of ester 7 in some reactions (entries 2 and
3) can be attributed to the oxidation of ferrocenylcar-
bene complex 2 by means of low-valent chromium
species generated during the reaction [18,19]. Although
metal carbene complexes can be oxidized efficiently to
corresponding esters by using a variety of reagents [19],
Fischer carbene complexes thermally decompose slowly
in refluxing solvents such as dioxane to produce esters.
isomers occur at d 1.40Á
isopropyl methines of those compounds appear at d
4.39Á4.51 in the Z isomers and d 4.83Á4.88 in the E
/1.42 [13]. Similarly, the
/
/

14
M. Zora et al. / Journal of Organometallic Chemistry 656 (2002) 11Á
/17
Scheme 3.
isomers. This large effect has been attributed to strong
anisotropic interaction of the aromatic rings and the
isopropoxy groups [13]. In the light of these observa-
tions and with the expectation of similar anisotropic
interaction between ferrocenyl and isopropoxy groups,
the configuration of g,d-unsaturated double bond in
alkylidenefuranones 5A,B,E has been assigned as E
acetylferrocene. In the coupling reactions studied, as
supported with the PM3 calculations, ferrocenyl chro-
mium carbene complex has been found to be less
reactive than the phenyl chromium carbene complex
and afforded products in lower yields. Acetylferrocene
results from the intramolecular rearrangement of car-
bene complex itself, a rare occurrence for metal carbene
complexes. We are continuing to improve the yields of
products, as well as to explore the further reactivity of
ferrocenylcarbene complexes.
since the isopropyl methyls appear at d 1.19Á
/1.41, while
the isopropyl methines at d 4.57Á5.26. Similar config-
/
urational assignment could not be made for furanones
5C,D and 6D due to the absence of such isopropoxy
groups. It should be noted that the methoxy groups in
5C,D could not be utilized for assignment purposes since
they resonate in a narrow chemical shift range.
4. Experimental
4.1. General consideration
2.4. Reactivity of ferrocenyl chromium carbene complex
2
Nuclear magnetic resonance (1H and 13C) spectra
were recorded on a Bruker AM 400 spectrometer (400.1
1
MHz for H and 100.6 for 13C). Chemical shifts are
More insight into the reactivity of ferrocenylcarbene
complex 2 can be achieved by means of isodesmic Eq.
(1). The reaction energies of isodesmic equations have
been successfully used for the estimation of relative
reactivities (or stabilities) of compounds [24]. The
reaction enthalpy of Eq. (1) was calculated at the
reported in parts per million (d) downfield from an
internal Me4Si reference. Coupling constants (J values)
are reported in hertz (Hz), and spin multiplicities are
indicated by the following symbols: s (singlet), d
(doublet), t (triplet), q (quartet), m (multiplet). DEPT
13C-NMR information is given in parenthesis as C, CH,
semi-emprical PM3 level [25] using PC SPARTAN
program [26].
PRO
CH2 and CH3. IR spectra were recorded on a PerkinÁ
/
Elmer 1600 Series FT-IR spectrometer. Band positions
are reported in reciprocal centimetres (cmꢂ1). Band
intensities are reported relative to the most intense band
and are listed as: br (broad), vs (very strong), s (strong),
m (medium), w (weak), vw (very weak). Mass spectra
(MS) were obtained on a Micromass UK Platform-II
spectrometer using electron impact (EI); m/e values are
reported, followed by the relative intensity in parenth-
esis. High resolution mass spectra (HRMS) were ob-
tained on a VG ZabSpec spectrometer with double
focusing magnetic sector using EI. Flash column
chromatography was performed using thick-walled glass
columns and ‘flash grade’ silica gel (Merck 230-400
mesh). Routine thin layer chromatography (TLC) was
affected by using precoated 0.25 mm silica gel plates
purchased from Merck. The relative proportion of
solvents in mixed chromatography solvents refers to
(CO)5CrꢁC(Fc)(OCH3)ꢁPhꢀCHꢁCH2
2
0 (CO)5CrꢁC(Ph)(OCH3)ꢁFcꢀCHꢁCH2
(1)
13
DH ꢀ4:9 kcal molꢂ1
DH value for isodesmic reaction of Eq. (1) has been
found to be positive. In the light of this result, ferrocenyl
group stabilizes the carbene complex more compared to
the phenyl group. Thus, in practice, ferrocenylcarbene
complex 2 is expected to be more stable and less reactive,
which is consistent with the experimental results. The
relative stability of carbene complex 2 is attributed to
the p-donor ability of cyclopentadienyl moiety to
stabilize the electropositive carbene carbon.
3. Conclusion
the volumeÁvolume ratio.
/
Chromium hexacarbonyl was purchased from Strem
Company and ferrocene from Aldrich Chemical Com-
pany and they were used as received. Diethyl ether, THF
and dioxane were distilled from Na-benzophenone ketyl
prior to use. All reactions were performed in an inert
In summary, we have investigated the reaction of
ferrocenylcarbene complex of chromium with cyclobu-
tenediones, producing 4-cyclopentene-1,3-diones, 5-al-
kylidenefuranones,
methyl
ferocenoate
and

M. Zora et al. / Journal of Organometallic Chemistry 656 (2002) 11Á
/17
15
atmosphere created by slight positive pressure (ca. 0.1
psi) of Ar. The preparation of ferrocenylcarbene com-
plex 2 was accomplished according to the modification
of Connor’s procedure [10], as given below.
(d, 3H, Jꢀ
6.1 Hz); 13C-NMR (CDCl3): d 197.7 (C),
/
192.5 (C), 166.1 (C), 132.8 (C), 78.5 (C), 75.5 (CH), 71.6
(CH), 70.5 (CH), 70.1 (CH), 68.8 (CH), 57.6 (C), 51.9
(CH3), 23.9 (CH3), 23.7 (CH3), 7.0 (CH3); IR (CH2Cl2):
3097 (vw), 2954 (w), 1709 (vs), 1624 (m), 1463 (m), 1387
(m), 1326 (m), 1275 (vs), 1190 (w), 1143 (s), 1104 (m),
825 (m) cmꢂ1; MS (EI): 382 ([M]ꢁ, 100), 340 (64), 325
(28), 311 (17), 296 (11), 258 (17), 244 (46), 230 (13), 213
(26), 185 (16), 159 (12), 129 (14), 121 (20); HRMS (EI):
Calc. for C20H2256FeO4: 382.0867. Found: 382.0879.
4.2. Pentacarbonyl[(ferrocenyl)methoxymethyl-
ene]chromium (2)
To a solution of ferrocene (3.00 g, 16.10 mmol) in
Et2O (50 ml) at 0 8C under Ar was added via syringe
tert-butyllithium (9.5 ml of a 1.7 M of C6H12Áether
/
solution, 16.10 mmol) over a period of 20 min. The
resulting solution was stirred for 2 h at this temperature
and transferred via cannula to a suspension of chro-
mium hexacarbonyl (2.96 g, 13.40 mmol) in Et2O (50
ml) at 0 8C under Ar. The mixture was stirred for 2 h at
0 8C and methyl trifluoromethanesulfonate (2.0 ml,
20.16 mmol) was added. After stirring at room tem-
perature (r.t.) for 20 min, the mixture was poured into
saturated aq. NaHCO3 solution in a separatory funnel,
4.4.2. 2-Ferrocenyl-4-isopropoxy-5-methyl-4-
cyclopentene-1,3-dione (4A)
Dark red oil, Rfꢀ
NMR (CDCl3): d 5.45 (septet, 1H, Jꢀ
3H), 4.00 (s, 1H), 3.93 (s, 1H), 3.76 (s, 5H), 1.83 (s, 3H),
1.32 (d, 3H, Jꢀ6.1 Hz), 1.30 (d, 3H, Jꢀ
6.1 Hz); 13C-
/
0.33 in 9:1 C6H14Á
/
EtOAc: 1H-
/
6.1 Hz), 4.07 (s,
/
/
NMR (CDCl3): d 195.6 (C), 194.2 (C), 164.2 (C), 135.4
(C), 77.8 (C), 75.0 (CH), 71.5 (CH), 70.6 (CH), 69.2
(CH), 69.1 (CH), 68.6 (CH), 23.7 (CH3), 7.4 (CH3); IR
(CH2Cl2): 3096 (vw), 2979 (w), 2871 (w), 1689 (vs), 1628
(s), 1448 (vw), 1388 (s), 1326 (s), 1152 (m), 1104 (s)
cmꢂ1; MS (EI): 352 ([M]ꢁ, 100), 351 (75), 311 (18), 310
(94), 309 (97), 243 (47), 226 (32), 224 (23), 199 (10), 159
(13), 121 (36), 115 (12); HRMS (EI): Calc. for
C19H2056FeO3: 352.0761. Found: 352.0745.
and then extracted with C6H14 (3ꢃ150 ml). Combined
/
C6H14 layers were washed with water and saturated aq.
NaCl solution, respectively. After drying over Na2SO4,
the solvent was removed on a rotary evaporator. The
crude oil obtained was purified by flash chromatogra-
phy on silica gel using C6H14 as the eluent. The dark
brown fraction (Rfꢀ0.37 in C6H14) was collected to
/
give carbene complex 2 (4.05 g, 72%). 1H-NMR
(CDCl3): d 4.99 (s, 2H), 4.79 (s, 2H), 4.69 (s, 3H),
4.25 (s, 5H); IR (CH2Cl2): 2054 (vw), 1933 (vs), 1272
(vs), 1269 (vs), 1264 (vs), 1223 (vw), 980 (vw), 783 (vw),
752 (vs), 743 (vs), 709 (vs), 508 (m) cmꢂ1. The spectral
data are in agreement with those reported previously for
this compound [10].
4.4.3. 4-Isopropoxy-5-
((ferrocenyl)(methoxy)methylene)-3-methyl-2(5H)-
furanone (5A)
Dark red oil, Rfꢀ
/
0.20 in 9:1 C6H14Á
EtOAc: 1H-
NMR (CDCl3): d 4.80 (m, 1H), 4.78 (s, 2H), 4.43 (s,
/
2H), 4.10 (s, 5H), 3.72 (s, 3H), 1.90 (s, 3H), 1.34 (d, 6H,
Jꢀ
6.0 Hz); 13C-NMR (CDCl3): d 170.7 (C), 162.4 (C),
/
146.9 (C), 135.8 (C), 102.2 (C), 77.1 (C), 75.2 (CH), 71.0
(CH), 70.5 (CH), 69.2 (CH), 63.6 (CH3), 23.0 (CH3), 9.3
(CH3); IR (CH2Cl2): 2981 (w), 2933 (w), 1739 (vs), 1621
(s), 1515 (m), 1456 (m), 1405 (m), 1265 (m), 1188 (m),
1146 (w), 1104 (w) cmꢂ1; MS (EI): 382 ([M]ꢁ, 100), 340
(30), 325 (7), 309 (7), 275 (5), 243 (8), 224 (16), 213 (19),
185 (11), 129 (10), 121 (8); HRMS (EI): Calc. for
C20H2256FeO4: 382.0867. Found: 382.0864.
4.3. General procedure for the reaction of ferrocenyl
carbene complex 2 with cyclobutenediones 1 (Table 1)
A solution of carbene complex 2 (1.00 mmol) and
cyclobutenedione 1 (1.50 mmol) in dioxane (10.00 ml)
was heated to reflux under Ar for a period of 6 h. The
mixture was allowed to cool to r.t. and the solvent was
removed on a rotary evaporator. Final purification was
achieved by flash chromatography on silica gel using
4.4.4. 4-Isopropoxy-5-
((ferrocenyl)(methoxy)methylene)-3-phenyl-2(5H)-
furanone (5B)
19:1 C6H14Á
/
EtOAc followed by 9:1 C6H14Á/EtOAc as
the eluent. The products indicated in Table 1 were
isolated.
Dark red oil, Rfꢀ
NMR (CDCl3): d 7.73 (m, 2H), 7.35 (m, 2H), 7.26 (m,
1H), 4.87 (t, 2H, Jꢀ1.8 Hz), 4.57 (septet, 1H, Jꢀ6.1
Hz), 4.41 (t, 2H, Jꢀ1.8 Hz), 4.14 (s, 5H), 3.81 (s, 3H),
1.19 (d, 6H, Jꢀ
6.1 Hz); 13C-NMR (CDCl3): d 168.3
/
0.32 in 9:1 C6H14Á
/
EtOAc: 1H-
4.4. Spectral data for products
/
/
/
4.4.1. 2-Ferrocenyl-4-isopropoxy-2-methoxy-5-methyl-4-
cyclopentene-1,3-dione (3A)
/
(C), 162.2 (C), 149.1 (C), 135.8 (C), 130.8 (C), 129.2
(CH), 128.7 (CH), 128.4 (CH), 109.0 (C), 77.6 (CH),
76.5 (C), 71.3 (CH), 70.7 (CH), 70.5 (CH), 69.4 (CH),
63.9 (CH3), 22.6 (CH3), 22.6 (CH3); IR (CH2Cl2): 3054
(vw), 2979 (w), 2934 (w), 1739 (vs), 1616 (s), 1541 (vw),
Dark red oil, Rfꢀ
NMR (CDCl3): d 5.66 (septet, 1H, Jꢀ
1H), 4.32 (s, 1H), 4.13 (s, 3H), 4.11 (s, 1H), 4.02 (s, 1H),
3.74 (s, 5H), 1.80 (s, 3H), 1.43 (d, 3H, Jꢀ6.1 Hz), 1.35
/
0.42 in 9:1 C6H14Á
/
EtOAc: 1H-
/6.1 Hz), 4.73 (s,
/

16
M. Zora et al. / Journal of Organometallic Chemistry 656 (2002) 11Á17
/
1493 (w), 1457 (w), 1404 (m), 1320 (w), 1137 (m), 1099
(w), 1052 (w) cmꢂ1; MS (EI): 444 ([M]ꢁ, 100), 403 (10),
402 (37), 382 (6), 352 (7), 305 (10), 286 (16), 213 (21), 185
(15), 129 (11), 121 (9); HRMS (EI): Calc. for
C25H2456FeO4: 444.1024. Found: 444.1036.
4.4.8. 5-(Ferrocenylmethylene)-3,4-diphenyl-2(5H)-
furanone (6D)
Dark red oil, Rfꢀ
/
0.39 in 9:1 C6H14Á
EtOAc: 1H-
/
NMR (CDCl3): d 7.40 (m, 3H), 7.36 (m, 2H), 7.26 (m,
2H), 7.19 (m, 3H), 5.80 (s, 1H), 4.73 (s, 2H), 4.40 (s, 2H),
4.10 (s, 5H); 13C-NMR (CDCl3): d 169.3 (C), 149.5 (C),
146.8 (C), 131.3 (C), 130.3 (C), 129.8 (CH), 129.5 (CH),
129.4 (CH), 129.4 (CH), 128.7 (CH), 128.7 (CH), 123.4
(C), 115.5 (CH), 77.6 (C), 71.6 (CH), 71.2 (CH), 70.2
(CH); IR (CH2Cl2): 3054 (w), 2928 (w), 1745 (vs), 1645
(m), 1456 (w), 1266 (w) cmꢂ1; MS (EI): 432 ([M]ꢁ, 100),
430 (6), 367 (5), 310 (3), 253 (4), 252 (3), 121 (4); HRMS
(EI): Calc. for C27H2056FeO2: 432.0813. Found:
432.0829.
4.4.5. 5-((Ferrocenyl)(methoxy)methylene)-3,4-
dimethyl-2(5H)-furanone (5C)
Dark red oil, Rfꢀ
/
0.21 in 9:1 C6H14Á
EtOAc: 1H-
/
NMR (CDCl3): d 4.86 (s, 2H), 4.44 (s, 2H), 4.18 (s, 5H),
3.77 (s, 3H), 2.30 (s, 3H), 1.91 (s, 3H); 13C-NMR
(CDCl3): d 171.0 (C), 147.3 (C), 147.0 (C), 141.1 (C),
121.8 (C), 76.3 (C), 70.7 (CH), 70.5 (CH), 69.4 (CH),
62.4 (CH3), 12.8 (CH3), 9.0 (CH3); IR (CH2Cl2): 2935
(w), 1740 (vs), 1612 (m), 1454 (w), 1269 (w), 1195 (w),
1142 (w), 1113 (w), 1054 (m) cmꢂ1; MS (EI): 338 ([M]ꢁ,
100), 323 (15), 295 (20), 243 (5), 213 (19), 185 (15), 129
(10), 121 (11); HRMS (EI): Calc. for C18H1856FeO3:
338.0605. Found: 338.0602.
Acknowledgements
We thank the Scientific and Technical Research
Council of Turkey (TBAG-1892), the State Planning
Organization of Turkey (DPT-2000K120390), and the
Research Board of Middle East Technical University
(AFP-98-01-03-06) for support of this research.
4.4.6. 5-((Ferrocenyl)(methoxy)methylene)-3,4-
diphenyl-2(5H)-furanone (5D)
Dark red oil, Rfꢀ
NMR (CDCl3): d 7.37Á
/
0.33 in 9:1 C6H14Á
/
EtOAc: 1H-
7.10 (m,
/
7.22 (m, 6H), 7.20Á
/
References
4H), 4.86 (s, 2H), 4.45 (s, 2H), 4.18 (s, 5H), 3.05 (s, 3H);
13C-NMR (C3H6O-d6): d 168.5 (C), 151.0 (C), 149.7 (C),
140.0 (C), 134.1 (C), 131.6 (C), 130.0 (CH), 129.8 (CH),
129.2 (CH), 129.0 (CH), 128.8 (CH), 123.7 (C), 77.1 (C),
71.8 (CH), 71.0 (CH), 70.0 (C), 63.0 (CH3); IR
(CH2Cl2): 2956 (vs), 2928 (vs), 2865 (s), 1738 (s), 1646
(w), 1601 (vw), 1458 (m), 1377 (w), 1254 (w), 1133 (vw)
cmꢂ1; MS (EI): 462 ([M]ꢁ, 100), 460(6), 419 (4), 367
(10), 213 (22), 185 (11), 129 (7), 121 (6); HRMS (EI):
Calc. for C28H2256FeO3: 462.0918. Found: 462.0909.
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