Intramolecular friedel-crafts acylation of acyclic (η4-diene)fe(co)3 complexes

Article abstract of DOI:10.1016/S0022-328X(99)00747-0

Intramolecular cyclization of (η⁴-diene)Fe(CO)₃ complexes bearing a carboxylic acid chloride functionality at the terminal side chain of the diene ligand produces (σ, η³-allyl)Fe(CO)₃ complexes, whereas treatment of the acid cholride complexes with Et₃N and A1C1₃ provides (η⁴-diene)Fe(CO)₃ complexes containing a cyclopentanone moiety.

Full text of DOI:10.1016/S0022-328X(99)00747-0

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 599 (2000) 128–134
Intramolecular Friedel–Crafts acylation of acyclic
(h4-diene)Fe(CO)3 complexes
Ming-Chang P. Yeh *, Suen-Chi Chang, Ching-Ju Chang
Department of Chemistry, National Taiwan Normal Uni6ersity, 88, Ding-Jou Road, Section 4, Taipei 117, Taiwan, ROC
Received 24 September 1999; received in revised form 22 November 1999; accepted 6 December 1999
Abstract
Intramolecular cyclization of (h4-diene)Fe(CO)3 complexes bearing a carboxylic acid chloride functionality at the terminal side
chain of the diene ligand produces (s, h3-allyl)Fe(CO)3 complexes, whereas treatment of the acid chloride complexes with Et3N
and AlCl3 provides (h4-diene)Fe(CO)3 complexes containing a cyclopentanone moiety. © 2000 Elsevier Science S.A. All rights
reserved.
Keywords: Iron; Diene; Friedel–Crafts acylation; Intramolecular; Cyclopentanone
carbon center to produce hydrofuran derivatives in fair
yields [5]. Only one example of intramolecular cycliza-
tion of a cyclic (h4-diene)Fe(CO)3 complexes, for exam-
ple 1, afforded the bicyclic ketone 2 upon treating 1
with oxalyl chloride, Et3N and AlCl3 in methylene
chloride. Complex 1 presumably underwent double
bond migration in the presence of AlCl3 to give 3.
Intramolecular Friedel–Crafts acylation of 3 provided
2 [5]. In this paper, we report in full detail that in-
tramolecular cyclization of acyclic (h4-diene)Fe(CO)3
complexes bearing an acid chloride at the terminal
position of the diene ligand using AlCl3 and Et3N
generates iron–diene complexes containing a cyclopen-
tanone ring.
1. Introduction
The chemistry of (h4-diene)Fe(CO)3 complexes is a
subject of continuing interest. Numerous synthetically
useful carbonꢀcarbon forming reactions using the com-
plexes are based on the fact that diene ligands bonded
to the electrophilic irontricarbonyl moiety are activated
toward addition by reactive carbon nucleophiles [1] and
ketyl anion radicals [2]. However, activation of dienes
toward electrophilic attack by complexation with iron-
tricarbonyl has been limited to intermolecular Friedel–
Crafts acylation [3]. Only limited examples of
intramolecular nucleophilic reactions of the tricar-
bonylmyrceneiron(0) complex with carbon electrophiles
have been reported [4]. The reactions involved protona-
tion or acylation of the pendant free double bond of the
tricarbonylmyrceneiron(0) complex to generate the car-
bonium ion or the acyl chloride intermediate. In-
tramolecular nucleophilic addition of the diene ligand
to the electron-deficient carbon centers gave cyclized
products. Recently, we have found that the diene ligand
of acyclic (h4-butadiene)Fe(CO)3 complexes is also ca-
pable of addition at the pendant chromium carbene
* Corresponding author. Fax: +886-2-29324249.
E-mail address: cheyeh@scc.ntnu.edu.tw (M.-C.P. Yeh)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00747-0

M.-C.P. Yeh et al. / Journal of Organometallic Chemistry 599 (2000) 128–134
129
2. Results and discussion
instead to a new iron complex. Thus, the reaction was
quenched with an excess of ethanol to give an iron
complex, identified as (s, h3-allyl)Fe(CO)3 complex (9)
(Scheme 2). Complex 9 was isolated as the only
diastereomeric isomer in 88% yield after regular
aqueous work-up and flash column chromatography.
Complex 9 was obtained previously from TiCl4-assisted
intramolecular cyclization of the ester–irondiene com-
plex 4g [5]. It is important to mention that the isolation
of (s, h3-allyl)Fe(CO)3 complex (9) is different from
those found in Pearson’s group for the intramolecular
cyclization of the tricarbonylmyrceneiron complex [4].
Reaction of the tricarbonylmyrceneiron(0) with oxalyl
chloride gave an acid chloride intermediate. Aluminum
chloride-assisted intramolecular acylation of the diene
ligand produced cyclized ketone. However, addition of
oxalyl chloride followed by AlCl3 to complex 4a using
Pearson’s protocols also provided (s, h3-allyl)Fe(CO)3
complex (9) in 80% yield. None of the cyclized ketone
can be found. The different reaction path of complex 4a
may be due to the position of the side chain. Complex
2.1. Synthesis of starting acid complexes
The starting complexes 4a–c were prepared by the
addition of the corresponding ester functionalized
zinc–copper reagents to the (h5-pentadienyl)Fe(CO)3
cation salt followed by hydrolysis of the resulting ester
complexes to the acid complexes according to the litera-
ture procedures [2,6]. Complex 4d bearing a phenyl
moiety at the terminal position of the diene ligand was
synthesized as follows (Scheme 1). Addition of the
phenyl Gringard reagent to (h4-trans-2,4-pentadien-1-
al)Fe(CO)3 (5) [7] produced an alcohol (6) in 84% yield.
The reaction of 6 with tetrafluoroboric acid and acetic
anhydride yielded a cation (7) in 73% yield [8]. Addi-
tion of the zinc–copper reagent [9], derived from ethyl
3-iodopropionate, to cation 7 gave an ester complex 8
in 70% yield. Hydrolysis of 8 using KOH in MeOH–
THF–H2O furnished acid complex 4d in 90% yield.
Complex 4e bearing a naphthyl moiety was synthesized
in the similar sequence starting from the naphthyl
Gringard reagent and complex 5 in 41% overall yield
(four steps) (Scheme 1).
3
and the intermediate derived from tricar-
bonylmyrceneiron(0) bearing an acid chloride side
chain at the internal position of the diene ligand under-
went Friedel–Crafts acylation, while complex 4a with
an acid chloride side chain at the terminal position
produced (s, h3-allyl)Fe(CO)3 complex.
2.2. Formation of (|, p3-allyl)Fe(CO)3 complexes
The isolation of ester (s, h3-allyl)Fe(CO)3 complex
(9) may indicate that acid chloride 10 was formed
initially (Scheme 2). Detachment of the olefin ligand
would give the unsaturated-16-electron metal species
11. For steric reasons, the acid chloride functional
group will point away from the metal center in the
transition-state conformation. Endo CꢀH bond inser-
tion at the a-carbon of 11 into the iron center would
generate the iron–hydride intermediate with the relative
Our cyclization study began with complex 4a. Oxalyl
chloride (two molar equivalents) was added to a solu-
tion of acid complex 4a in CH2Cl, at 0°C and the
reaction mixture was stirred at 0°C for 30 min. The
reaction was performed in the expectation that acid
chloride 4f would be generated in situ before the addi-
tion of AlCl3. However, TLC analysis showed that the
expected ester complex 4g [5] was not present upon
quenching an aliquot with ethanol, and the reaction led
Scheme 1.

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M.-C.P. Yeh et al. / Journal of Organometallic Chemistry 599 (2000) 128–134
Scheme 2.
stereochemistry depicted in 12. Hydride addition to the
olefin ligand produced 13. Reattachment of the pendant
double bond to the metal center led to the formation of
14, which upon quenching with ethanol produced 9. It
is important to note that two new stereogenic centers
(the a- and allylic carbons) of 9 are created; however,
only the single diastereomer shown was isolated.
Using the same approach, we are able to obtain (s,
h3-allyl)Fe(CO)3 complexes (18–20) in good yields (80–
88%) via addition of oxalyl chloride to acid complexes
15–17 [5], respectively, followed by quenching the reac-
tion mixture with ethanol.
reaction of 4a with oxalyl chloride (1.2 molar equiva-
lents) and Et3N (1.2 molar equivalents) in CH2Cl2 at
0°C for 45 min. Addition of AlCl3 (1.5 molar equiva-
lents) in CH2Cl2 to the ketene intermediate at 25°C for
1 h gave a major product in 85% yield, identified as
complex 21a. The 13C-NMR spectrum of complex 21a
has the usual ironcarbonyl chemical shift at 210 ppm.
However, the CO of the ketone is not present in the
13C-NMR spectrum between the 190–230 ppm region.
The reason for not observing the CO of the ketone
peak in the 13C-NMR spectrum of 21a may be due to
the paramagnetic effect caused by the iron center. Nev-
ertheless, the infrared spectrum of complex 21a shows a
sharp ketone stretch at 1676 cm−1 and the usual iron-
1
carbonyl bands at 2056 and 1987 cm−1. The H-NMR
spectrum of 21a has the characteristic chemical shifts at
5.62 and 5.51 ppm for the internal vinyl protons. The
chemical shifts of the vinyl protons stated above are
consistent with those found for most acyclic (h4-di-
ene)Fe(CO)3 complexes.
The ketene intermediate 22 formed presumably upon
treatment of 4a with oxalyl chloride and triethylamine
(Scheme 3). The formation of 21a may have started
from the AlCl3-assisted nucleophilic addition of the
diene ligand of 22 at the ketene carbon center to give
the cyclized intermediate 23, which led to the formation
of complex 21a upon deprotonation at the a-carbon.
Under the same reaction conditions, intramolecular
cyclization of complexes 4b–e using oxalyl chloride,
AlCl3 and Et3N also produced the expected cyclopen-
2.3. Intramolecular Friedel–Crafts acylation
The intramolecular acylation of the acyclic (h4-di-
ene)Fe(CO)3 complexes using the acid chloride func-
tionality failed as stated above; thus,
electrophilic carbon center must be considered. We then
turned our effort to the more electrophilic ketene func-
tionality. The acid was converted to the ketene by the
a
more

M.-C.P. Yeh et al. / Journal of Organometallic Chemistry 599 (2000) 128–134
131
Scheme 3.
tanone derivatives 21b–e in fair to modest yields (21b,
4. Experimental
64%; 21c, 76%; 21d, 46% and 21e, 33%). The structure
of complex 21d is further secured by X-ray diffraction
analysis. The ORTEP structure (supplementary material)
of 21d clearly indicates that the carbonyl of the cy-
clopentanone moiety is in the closed proximity of the
iron center. Due to the paramagnetic effect caused by
the iron, the carbonyl of the cyclopentanone is not
present in the 13C-NMR spectrum of 21d and the
observation is consistent with those found for 21a–c
and 21e.
4.1. General
All reactions were run under a nitrogen atmosphere
in oven-dried glassware unless otherwise indicated. An-
hydrous solvents or reaction mixtures were transferred
via an oven-dried syringe or cannula. Diethyl ether
(ether) and tetrahydrofuran (THF) were distilled under
nitrogen from a deep blue sodium benzophenone ketyl
solution. Methylene chloride was distilled from calcium
hydride. Complexes 4a–c were synthesized according to
the literature procedures [5,6]. Flash column chro-
matography, following the method of Still et al. [10],
was carried out with Merck silica gel (Kieselgel 60,
230–400 mesh) using the indicated solvents. Analytical
thin-layer chromatography was performed with silica
gel 60 F254 plastic plates of 0.2 mm thickness from
Merck. The term concentration refers to the removal of
solvent with an aspirator pump (Yamato instrument
Co. Model WP-15) with a Buchi Rotovapor-R. The
term under nitrogen implies that the apparatus was
evacuated (oil pump) and then filled with nitrogen three
times. Melting points were determined in open capil-
laries with a Thomas–Hoover apparatus and are un-
corrected. 1H nuclear magnetic resonance (NMR)
spectra were obtained with a JEOL EX 400 instrument
(400 MHz). Chemical shifts are reported in parts per
million with either tetramethylsilane (0.00 ppm) or
CHCl3 (7.26 ppm) as internal standard. 13C-NMR spec-
tra were recorded with a JEOL EX 400 spectrometer
(100.4 MHz) with CDCl3 (77.0 ppm) as the internal
standard. Infrared (IR) spectra were recorded with a
JASCO IR-700 spectrometer. Mass spectra were ac-
quired on a JEOL JMS-D 100 spectrometer at an
ionization potential of 70 eV and are reported as mass/
charge (m/e) with percent relative abundance. High-res-
olution mass spectra were obtained with an AEI MS-9
double focusing mass spectrometer and a JEOL JMS-
HX 110 spectrometer at the Department of Chemistry,
Central Instrument Center, Taichung, Taiwan.
It is important to mention that the intramolecular
Friedel–Crafts acylation of acyclic (h4-diene)Fe(CO)3
complexes is limited to the formation of cyclopen-
tanone derivatives. Attempted intramolecular acylation
using ether other than three methylene groups, for
example complexes 15–17, failed to give cyclized prod-
ucts. The starting acid complexes were recovered upon
quenching the reaction mixture with saturated aqueous
NH4Cl solution.
3. Conclusions
The reactions of the iron–diene complexes bearing
an acid functionality with oxalyl chloride afford (s,
h3-allyl)Fe(CO)3 complexes in diastereoselective fash-
ion, in which CꢀH insertion at the a-carbon into the
iron center takes place. Intramolecular Friedel–Crafts
acylation occurs upon treating the acid complexes with
oxalyl chloride and AlCl3 in the presence of triethyl-
amine to afford diene–iron complexes containing a
cyclopentanone moiety.

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M.-C.P. Yeh et al. / Journal of Organometallic Chemistry 599 (2000) 128–134
4.2. General procedure I: formation of (|
step without further purification. To 100 ml of Schlenk
flask at 5°C under nitrogen was added cation 7 (0.65 g,
1.76 mmol) and 20 ml of THF. To the reaction mixture
was added via syringe the zinc–copper reagent [Zn-
(CuCN)(CH2)2CO2Et] [9] (7.23 mmol) in 10 ml of THF.
The reaction was stirred at 25°C for 3 h. The reaction
mixture was quenched with 15 ml of saturated aqueous
ammonium chloride solution. The reaction mixture was
diluted with 100 ml of 5% ethylacetate–hexanes. The
organic solution was washed with water (3×100 ml)
and brine (3×100 ml), dried over anhydrous magne-
sium sulfate (15 g), and concentrated to give the crude
mixture. Flash column chromatography (silica gel, 10%
ethylacetate–hexane) of the crude mixture gave ester
complex 8 as a deep red oil. 1H-NMR (CDCl3, 400
MHz): l 1.18 (t, J=7.1 Hz, 3H); 1.36 (m, 1H); 1.55–
1.65 (m, 1H); 1.73–1.75 (m, 2H); 2.21–2.25 (m, 2H);
2.49 (m, 1H); 3.2 (d, J=9.8 Hz, 1H); 4.05 (q, J=3.1
Hz, 2H); 5.23 (dd, J=7.1, 5.6 Hz, 1H); 5.92 (dd,
J=9.6, 5.4 Hz, 1H); 7.10–7.19 (m, SH). To 100 ml
round bottom flask, at 5°C under nitrogen, was added
complex 8 (0.39 g, 1.01 mmol), KOH (0.29 g, 5.05
mmol), 10 ml of THF, 10 ml of water and 10 ml of
MeOH. The reaction was stirred at 25°C for 1 h. The
reaction mixture was quenched with 15 ml of 5% HCl
solution and then diluted with 100 ml of 20% ethylac-
etate–hexane. The organic solution was washed with
water (3×100 ml) and brine (3×100 ml), dried over
anhydrous magnesium sulfate (10 g), and concentrated
to give the crude mixture. Flash column chromatogra-
phy (silica gel, 50% ethylacetate–hexane) of the crude
mixture gave acid complex 4d (0.32 g, 90%) as a light
yellow powder. The overall yield (four steps) for the
synthesis of complex 4d from complex 5 was 39%. m.p.
p3-allyl)Fe(CO)3 complexes from acid complexes
To a 50 ml Schlenk flask was added 1.0 molar
equivalent of an acid complex and 10 ml of CH2Cl2.
The mixture was degassed three times. The reaction was
cooled to 0°C under nitrogen and added slowly 2.0
molar equivalents of oxalyl chloride. The reaction was
stirred at 0°C for 2 h and then quenched with 5.0 ml of
ethanol. The reaction mixture was concentrated on
rotary evaporator to give the crude mixture.
4.3. General procedure II: intramolecular
Freidel–Crafts acylation of acyclic
diene–irontricarbonyl complexes
To a 50 ml Schlenk flask was added 1.0 molar
equivalent of an acid complex and 10 ml of CH2Cl2.
The mixture was degassed three times. The reaction was
cooled to 0°C under nitrogen and added slowly 1.2
molar equivalents of oxalyl chloride and 1.2 molar
equivalents of triethylamine. The reaction was stirred at
25°C for 45 min. The reaction mixture was cooled to
0°C and was added 1.5 molar equivalents of AlCl3 in 10
ml of CH2Cl2. The reaction was stirred at 25°C for 1 h
and then quenched with saturated aqueous NH4Cl solu-
tion. The reaction mixture was diluted with 100 ml of
CH2Cl2. The organic solution was washed with water
(3×100 ml) and brine (3×100 ml), dried over anhy-
drous magnesium sulfate (10 g), and concentrated to
give the crude mixture.
4.4. Synthesis of complex 4d
1
To a 50 ml Schlenk flask under nitrogen was added
complex 5 (1.48 g, 6.60 mmol) and 20 ml of ether. The
reaction was cooled to −78°C and 4.0 ml (2.0 M, 8.0
mmol) of phenyl Grignard reagent in ether was added
slowly. The reaction was stirred at −78°C for 1 h. The
reaction mixture was quenched with 10 ml of saturated
aqueous NH4Cl solution. The reaction mixture was
diluted with 50 ml of CH2Cl2. The organic solution was
washed with water (3×100 ml) and brine (3×100 ml),
dried over anhydrous magnesium sulfate (10 g), and
concentrated to give the crude mixture. Flash column
chromatography (silica gel, 5% ethylacetate–hexane) of
the crude mixture gave complex 6 (1.25 g, 84%) as an
orange oil. Complex 6 was used for the next step
without further purification. To a 50 ml Schlenk flask
under nitrogen at 5°C was added complex 6 (1.25 g, 4.3
mmol) and 10 ml of Ac2O. To the reaction mixture at
5°C was added 0.54 ml (8.6 mmol) of tetrafluoroboric
acid. The reaction was stirred at 5°C for 1 h followed
by the addition of 20 ml of ether. The yellow precipitate
was filtered and dried via vacuo to give cation 7 (0.92 g,
73%) as a yellow solid. Cation 7 was used for the next
(dec.) 103°C; H-NMR (CDCl3, 400 MHz): l 1.36 (m,
1H); 1.55–1.66 (m, 1H); 1.78 (m, 2H); 2.36–2.38 (m,
2H); 2.56 (m, 1H); 3.60 (d, J=9.8 Hz, 1H); 5.29 (dd,
J=7.6, 5.4 Hz, 1H); 5.99 (dd, J=9.8, 5.1 Hz, 1H);
7.17–7.26 (m, 5H). 13C-NMR (CDCl3, 400 MHz): l
27.8; 29.1; 33.2; 58.4; 60.7; 87.5; 89.0; 126.0; 126.5;
128.6; 140.1; 178.6; 210.9. IR (CH2Cl2): 3397; 3062;
3052; 3048; 2987; 2307; 2044; 1974; 1748; 1709; 1604;
1452 cm−1. EI MS m/z (%) of major fragments: 342
(M+, 1.2%); 314 (20); 286 (100); 200 (24); 198 (13).
4.5. Synthesis of complex 4e
Complex 4e was synthesized starting from complex 5
and naphthyl Grignard reagent according to the proce-
dure stated above. The overall yield (four steps) for the
synthesis of complex 4e (an orange powder) from com-
1
plex 5 was 41%. m.p. 115–124°C; H-NMR (CDCl3,
400 MHz): l 1.26 (m, 1H); 1.66 (m, 1H); 1.88 (m, 2H);
2.38 (m, 2H); 2.70 (m, 1H); 3.80 (d, J=10 Hz, 1H);
5.40 (dd, J=8.2, 5 Hz, 1H); 6.26 (dd, J=10, 5 Hz,
1H); 7.27–8.14 (m, 7H). 13C-NMR (CDCl3, 400 MHz):

M.-C.P. Yeh et al. / Journal of Organometallic Chemistry 599 (2000) 128–134
133
l 28.8; 30.3; 41.7; 54.4; 58.4; 83.6; 88.3; 121.0; 123.0;
4.9. Formation of (|, p3-allyl)Fe(CO)3 complex (20)
125.9; 126.5; 126.9; 127.8; 129.6; 131.6; 134.7; 136.9;
183.0; 212.8. IR (CH2Cl2): 3053; 2993; 2974; 1747;
1711; 1606; 1423; 1361; 1298; 1126 cm−1. EI MS m/z
(%) of major fragments: 406 (M+, 1%); 322 (100); 266
(46); 193 (40); 179 (88). High-resolution MS for
C18H18O2Fe(M+): Anal. Calc.: 322.0556. Found:
322.0658.
The crude mixture obtained from intramolecular cy-
clization of complex 17 (0.5 g, 1.70 mmol), according to
Section 4.2 was purified via flash column chromatogra-
phy (silica gel, 10% ethylacetate–hexane) to give 20
1
(0.48 g, 1.40 mmol, 87%) as a yellow oil [5]. H-NMR
(CDCl3, 400 MHz): l 1.27 (t, J=6.9 Hz, 3H); 1.42–
1.78 (m, 4H); 1.97 (m, 2H); 2.03 (d, J=6.3 Hz, 3H);
2.33 (t, J=7.3 Hz, 2H); 2.52 (m, 1H); 3.95 (m, 2H);
4.13 (q, J=7.3 Hz, 2H); 4.91 (t, J=12.2 Hz, 1H).
13C-NMR (CDCl3, 400 MHz): l 14.2; 20.1; 24.7; 28.7;
31.6; 34.1; 34.9; 60.3; 84.1; 89.2; 104.8; 173.6; 205.2;
207.7. IR (CH2Cl2): 3084; 3029; 2938; 2085; 2033; 2004;
4.6. Formation of (|, p3-allyl)Fe(CO)3 complex (9)
The crude mixture obtained from intramolecular cy-
clization of complex 4a (0.6 g, 2.26 mmol), according to
Section 4.2, was purified via flash column chromatogra-
phy (silica gel, 10% ethylacetate–hexane) to give 9 (0.55
g, 1.88 mmol, 83%) as a yellow oil [5]. 1H-NMR
(CDCl3, 400 MHz): l 1.28 (t, J=7.3 Hz, 1H); 1.98–
2.03 (m, 3H); 2.04 (d, J=6.4 Hz, 3H); 2.47 (t, J=6.8
Hz, 1H); 2.57 (m, 1H); 3.95 (m, 1H); 4.01 (m, 1H); 4.16
(q, J=7.3 Hz, 2H); 4.94 (t, J=12.4 Hz, 1H). 13C-
NMR (CDCl3, 400 MHz): l 14.2; 20.1; 26.9; 33.5; 34.3;
60.5; 84.5; 87.7; 104.9; 172.9; 205.0; 207.5. IR (CH2Cl2):
3067; 3046; 2992; 2982; 2087; 2035; 2006; 1728; 1424;
1728; 1566; 1437; 1414; 1302; 1103 cm−1
.
4.10. Tricarbonyl(p4-2-allylidenecyclopentan-1-one)iron
(21a)
The crude mixture obtained from intramolecular
Friedel–Crafts acylation (Section 4.3) of complex 4a
(0.75 g, 2.69 mmol) was purified via flash column
chromatography (silica gel, 10% ethylacetate–hexane)
to give 21a (0.60 g, 2.29 mmol, 85%) as a yellow oil.
1H-NMR (CDCl3, 400 MHz); l 1.85 (m, 2H); 2.03 (m,
2H); 2.14 (m, 2H); 2.40 (m, 2H); 5.51 (m, 1H); 5.62 (d,
J=4.0 Hz, 1H). 13C-NMR (CDCl3, 400 MHz): l 20.7;
37.8; 38.1; 46.0; 73.7; 88.1; 89.8; 209.7. IR (CH2Cl2):
3011; 2970; 2056; 1987; 1676; 1454; 1408; 1334; 1103
cm−1. EI MS m/z (%) of major fragments: 262 (M+,
2%); 234 (22); 206 (40); 178 (106); 152 (20). High-reso-
lution MS for C9H10O2Fe(M+ꢀ2CO): Anal. Calc.:
206.0030. Found: 206.0038.
1256; 1155; 929 cm−1
.
4.7. Formation of (|, p3-allyl)Fe(CO)3 complex (18)
The crude mixture obtained from intramolecular cy-
clization of complex 15 (0.6 g, 2.26 mmol), according to
Section 4.2, was purified via flash column chromatogra-
phy (silica gel, 10% ethylacetate–hexane) to give 18
1
(0.55 g, 1.88 mmol, 83%) as a yellow oil [5]. H-NMR
(CDCl3, 400 MHz): l 1.30 (t, J=7.3 Hz, 3H); 2.03 (d,
J=6.8 Hz, 3H); 2.36 (m, 1H); 2.65–2.79 (m, 2H); 3.84
(m, 1H); 4.00 (m, 1H); 4.19 (q, J=7.3 Hz, 2H); 5.02 (t,
J=12.2 Hz, 1H). 13C-NMR (CDCl3, 400 MHz); 14.2;
20.1; 30.1; 35.7; 60.8; 84.8; 86.2; 105.2; 172.2; 205.2;
205.5; 207.2. IR (CH2Cl2): 3005; 2967; 2087; 2037;
2006; 1730; 1628; 1564; 1433; 1416; 1375; 1292; 1109;
4.11. Tricarbonyl[p4-2(trans-3-methylallylidenecyclo-
pentan-1-one)]iron (21b)
924 cm−1
.
The crude mixture obtained from intramolecular
Friedel–Crafts acylation (Section 4.3) of complex 4b
(0.70 g, 2.34 mmol) was purified via flash column
chromatography (silica gel, 10% ethylacetate–hexane)
to give 21b (0.49 g, 1.78 mmol, 64%) as a yellow oil.
1H-NMR (CDCl3, 400 MHz): l 1.50 (d, J=6.4 Hz,
3H); 1.82 (m, 2H); 1.97 (m, 1H); 2.13 (m, 1H); 2.39 (m,
1H); 2.46 (m, 1H); 2.84 (m, 1H); 5.31 (dd, J=9.5, 5.7
Hz, 1H); 5.44 (d, J=5.4 Hz, 1H). 13C-NMR (CDCl3
400 MHz): l 19.9; 20.5; 37.8; 37.9; 64.4; 73.2; 83.4;
93.1; 210.0. IR (CH2Cl2): 3069; 3048; 2986; 2048; 1981;
1672; 1609 cm−1. El MS m/z (%) of major fragments:
248 (M+ꢀCO, 23%); 220 (35); 192 (100); 164 (34); 121
(29); 95 (17); 84 (34); 56 (47). High-resolution MS for
C12H12O4Fe(M+): Anal. Calc.: 276.0085. Found:
276.0094.
4.8. Formation of (|, p3-allyl)Fe(CO)3 complex (19)
The crude mixture obtained from intramolecular cy-
clization of complex 16 (0.5 g, 1.79 mmol), according to
Section 4.2 was purified via flash column chromatogra-
phy (silica gel, 10% ethylacetate–hexane) to give 19
1
(0.46 g, 1.50 mmol, 83%) as a yellow oil [5]. H-NMR
(CDCl3, 400 MHz): l 1.27 (t, J=6.8 Hz, 3H); 1.64–
1.78 (m, 3H); 2.04 (d, J=6.3 Hz, 3H); 2.17 (m, 1H);
2.37 (t, J=7.4 Hz, 2H); 2.54 (m, 1H); 3.96–3.99 (m,
2H); 4.15 (q, J=6.8 Hz, 2H); 4.91 (t, J=12.7 Hz, 1H).
13C-NMR (CDCl3, 400 MHz): l 14.3; 20.1; 24.5; 31.4;
34.0; 34.9; 60.4; 84.3; 88.7; 104.8; 173.3; 205.1; 205.2;
207.6. IR (CH2Cl2): 3383; 3067; 2992; 2982; 2085; 2035;
2004; 1728; 1427; 1419; 1289; 1242; 1182; 1153 cm−1
.

134
M.-C.P. Yeh et al. / Journal of Organometallic Chemistry 599 (2000) 128–134
4.12. Tricarbonyl[p4-(2-methylallylidenecyclo-
pentan-1-one)]iron (21c)
J=8 Hz, 1H); 6.31 (dd, J=16, 8 Hz, 1H); 7.25–8.15
(m, 7H). 13C-NMR (CDCl3, 400 MHz): l 20.0; 37.9;
38.22; 61.5; 73.0; 85.6; 86.7; 121.6; 123.6; 125.6, 126.7;
127.3; 128.5; 129.3; 132.5; 134.6; 135.9; 212.9. IR
(CH2Cl2): 3053; 3045; 2974; 2050; 1986; 1674; 1608;
1452 cm−1. EI MS m/z (%) of major fragments: 388
(M+, 1.7%); 304 (100); 191 (24); 165 (33); 152 (28); 56
(9). High-resolution MS for C18H16OFe(M+ꢀ3CO):
Anal. Calc.: 304.0551. Found: 304.0552.
The crude mixture obtained from intramolecular
Friedel–Crafts acylation (Section 4.3) of complex 4c
(0.70 g, 2.34 mmol) was purified via flash column
chromatography (silica gel, 10% ethylacetate–hexane)
to give 21c (0.49 g, 1.78 mmol, 76%) as a yellow oil.
1H-NMR (CDCl3, 400 MHz): l 1.85 (m, 2H); 1.99 (m,
1H); 2.13 (m, 3H); 2.22 (s, 3H); 2.40 (m, 2H); 5.52 (s,
1H). 13C-NMR (CDCl3, 400 MHz): l 20.6; 24.4; 37.66;
37.9; 48.4; 70.2; 87.9; 107.2; 209.7. IR (CH2Cl2): 3067;
3046; 2984; 2058; 1984; 1676; 1582; 1424; 1265; 1248;
1095; 914; 875; 756 cm−1. EI MS m/z (%) of major
fragments: 248 (M+−CO, 25%); 220 (40); 192 (100);
176 (82); 149 (62). High resolution MS for
C11H12O3Fe(M+−CO): Anal. Calc.: 248.0136. Found:
248.0131.
Acknowledgements
We thank the National Science Council (88-2113-M-
003-010) of the Republic of China for financial support.
References
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The crude mixture obtained from intramolecular
Friedel–Crafts acylation (Section 4.3) of complex 4d
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chromatography (silica gel, 10% ethylacetate–hexane)
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powder: m.p. (dec.) 144°C. 1H-NMR (CDCl3, 400
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(m, 1H); 2.53 (m, 1H); 3.97 (m, 1H); 5.63 (d, J=8 Hz,
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(CDCl3, 400 MHz): l 20.0; 37.6; 37.8; 66.9; 72.9; 84.3;
87.0; 127.5; 127.9; 129.3; 139.9; 212.2. IR (CH2Cl2):
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EI MS m/z (%) of major fragments: 254 (M+ꢀ3CO,
32%); 198 (94); 155 (21); 141 (100); 115 (38); 91 (28); 71
(7). High-resolution MS for C14H14OFe(M+ꢀ3CO):
Anal. Calc.: 254.0394. Found: 254.0396.
4.14. Tricarbonyl[p2-(trans-3-naphthylallylidenecyclo-
pentan-1-one)iron (21e)
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(0.35 g, 0.86 mmol) was purified via flash column
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to give 21e (0.11 g, 0.28 mmol, 33%) as a deep red
powder: m.p. 118–120°C. 1H-NMR (CDCl3, 400
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