Lewis acid promoted intramolecular cyclization of (η4-diene)Fe(CO)3 complexes bearing functionalized side chains

Article abstract of DOI:10.1021/om9703301

Addition of aluminum chloride to the (η⁴-cyclohexadiene)Fe(CO)₃ complex bearing an acid chloride side chain at C-5 gives a cyclic keto complex, whereas Lewis acid assisted intramolecular cyclization of acyclic (η⁴-butadiene)Fe(CO)₃ complexes containing an aldehyde, an ester, or a nitrile functionality produces (σ,η³-allyl)tricarbonyliron complexes. Treatments of the (η⁴-butadiene)Fe(CO)₃ complexes bearing a chromium carbene moiety in refluxing toluene lead to formation of furan derivatives by intramolecular addition of the diene ligand to the chromium carbene carbon center.

Full text of DOI:10.1021/om9703301

Organometallics 1997, 16, 4435-4444
4435
Lew is Acid P r om oted In tr a m olecu la r Cycliza tion of
4
( -Dien e)F e(CO)3 Com p lexes Bea r in g F u n ction a lized
Sid e Ch a in s
Ming-Chang P. Yeh,* L.-W. Chuang, S.-C. Chang, M.-L. Lai, and C.-C. Chou
Department of Chemistry, National Taiwan Normal University, 88 Section 4,
Ding-J ou Road, Taipei, Taiwan, 117 ROC
Received April 18, 1997X
Addition of aluminum chloride to the (η4-cyclohexadiene)Fe(CO)3 complex bearing an acid
chloride side chain at C-5 gives a cyclic keto complex, whereas Lewis acid assisted
intramolecular cyclization of acyclic (η4-butadiene)Fe(CO)3 complexes containing an aldehyde,
an ester, or a nitrile functionality produces (σ,η3-allyl)tricarbonyliron complexes. Treatments
of the (η4-butadiene)Fe(CO)3 complexes bearing a chromium carbene moiety in refluxing
toluene lead to formation of furan derivatives by intramolecular addition of the diene ligand
to the chromium carbene carbon center.
The chemistry of (η4-1,3-diene)tricarbonyliron(0) com-
Ch a r t 1
plexes is a subject of continuing interest. The general
applications of the complexes are (i) electrophilic reac-
tions with reactive carbon nucleophiles;1 (ii) hydride
abstraction, followed by reaction with a number of
different nucleophiles;2 and (iii) Friedel-Crafts reac-
tions with acid chlorides.3 Recently, we reported that
sequential additions of nucleophiles to (η5-pentadienyl)-
tricarbonyliron(0) and (η5-cyclohexadienyl)tricarbonyl-
iron(0) cations afforded fused and bridged bicyclic and
tricyclic skeletons.4 Surprisingly, only limited examples
of intramolecular nucleophilic reactions of the tricar-
bonylmyrceneiron(0) complex with carbon electrophiles
have been reported.5 The reactions involved protonation
or acylation of the pendant free double bond of the
tricarbonylmyrceneiron(0) complex to generate the car-
bonium ion or the acyl chloride intermediate. Intramo-
lecular nucleophilic additions of the diene ligand to the
electron-deficient carbon centers gave cyclized products.
In this paper, we report that Lewis acid promoted intra-
molecular cyclization of (η4-1,3-diene)tricarbonyliron(0)
complexes bearing carbon electrophiles such as acid
chlorides, aldehydes, esters, and nitriles generates cyclic
ketones and (σ,η3-allyl)tricarbonyliron complexes, re-
spectively, whereas treatments of complexes containing
a chromium carbene moiety provide furan derivatives.
P r ep a r a tion of Sta r tin g Com p lexes. The starting
complexes 1a -f (Chart 1) were easily prepared by
addition of the corresponding highly functionalized
zinc-copper reagents RCu(CN)ZnI to the (η5-pentadi-
enyl)tricarbonyliron cation salt.6 Aldehyde derivatives
2a -c were obtained by reduction of the corresponding
ester complexes with diisobutylaluminum hydride
(DIBAL) at -78 °C in good yields. The acid complexes
3a ,b were synthesized by hydrolysis of the correspond-
ing ester complexes4a using KOH in MeOH-THF-H2O
at 23 °C in good yields (85 and 98% yields, respectively).
Finally, (η4-diene)Fe(CO)3 complexes bearing a Fischer
carbene moiety were synthesized as follows. Treatment
X Abstract published in Advance ACS Abstracts, August 15, 1997.
(1) (a) Semmelhack, M. F.; Herndon, J . W. Organometallics 1983,
2, 363. (b) Semmelhack, M. F.; Herndon, J . W.; Liu, J . K. Organome-
tallics 1983, 2, 1885. (c) Semmelhack, M. F.; Herndon, J . W.; Springer,
J . P. J . Am. Chem. Soc. 1983, 15, 2497. (d) Semmelhack, M. F.; Le, H.
T. M. J . Am. Chem. Soc. 1984, 106, 2715. (e) Semmelhack, M. F.;
Herndon, J . W. J . Organomet. Chem. 1984, 265, C15. (f) Semmelhack,
M. F.; Le, H. T. M. J . Am. Chem. Soc. 1985, 107, 1455. (g) Yeh, M. C.
P.; Kang, K. K.; Hwu, C. C. J . Chin. Chem. Soc. 1991, 38, 475.
(2) (a) Birch, A. J .; Hass, M. A. J . Chem. Soc. C 1971, 2465. (b) Birch,
A. J .; Williamson, D. H. J . Chem. Soc., Perkin Trans. 1 1973, 1982. (c)
Pearson, A. J . In Chemistry of the Carbon-Metal Bond; Hartley, F.
R., Patai, S., Eds.; Wiley: Chichester, UK, 1987; Vol. 14, Chapter 10.
(d) Pearson, A. J .; Zettler, M. W. J . Am. Chem. Soc. 1989, 111, 3908.
(3) (a) Graf, R. E.; Lillya, C. P. J . Organomet. Chem. 1976, 122, 377.
(b) Birch, A. J .; Pearson, A. J . J . Chem. Soc., Chem. Commun. 1976,
601.
(4) (a) Yeh, M. C. P.; Sheu, B. A.; Fu, H. W.; Tau, S. I.; Chuang, L.
W. J . Am. Chem. Soc. 1993, 115, 5941. (b) Yeh, M. C. P.; Chuang, L.
W.; Hwu, C. C.; Sheu, J . M.; Row, L. C. Organometallics 1995, 14,
3396.
(5) (a) Birch, A. J .; Pearson, A. J . J . Chem. Soc., Chem. Commun.
1976, 601. (b) Pearson, A. J . Aust. J . Chem. 1976, 29, 1841.
(6) Yeh, M. C. P.; Sun, M. L.; Lin, S. K. Tetrahedron Lett. 1991, 32,
113.
S0276-7333(97)00330-0 CCC: $14.00 © 1997 American Chemical Society

4436 Organometallics, Vol. 16, No. 20, 1997
Yeh et al.
Sch em e 1
of 1.5 molar equiv of [tetramethylammonium(phenyl)-
carbenyl oxide]pentacarbonylchromium (4) with 1.5
performed in the expectation that a fused bicyclic keto
complex, such as 7a , would be generated via Lewis acid
assisted intramolecular Friedel-Crafts reaction. The
infrared spectrum of the isolated complex shows a sharp
ketone stretch at 1690 cm-1 and the usual iron CO
bands at 2038 and 1972 cm-1. The 13C NMR spectrum
of the complex has the usual ketone chemical shift at
204 ppm and the iron CO chemical shift at 210 ppm.
1
However, the H NMR spectrum of the complex shows
only one vinyl proton at 5.57 ppm. Thus, the crude (η4-
diene)Fe(CO)3 complex was treated with 2,4-dinitro-
phenylhydrazone to give the hydrazone derivative 8a ,
which structure was confirmed by X-ray diffraction
analysis and was consistent with the spectral data
discussed above for the keto complex 8b. The formation
of the fused bicyclic skeleton of the keto complex 8b may
involve the initial formation of the acid chloride 9a
followed by Lewis acid promoted double bond migration
to give 9b. Intramolecular Friedel-Crafts reaction of
9b lead to formation of 8b. The Lewis acid promoted
double bond migration of iron-diene complexes, pre-
sumably via a hydride abstraction/readdition process,
had been reported in the literature.8 However, under
the same reaction conditions, intramolecular Friedel-
Crafts reaction of an acyclic acid complex, for example,
3b, gave an unidentified crude oil. None of the desired
keto complex was isolated.
molar equiv of acetyl bromide at -10 °C for 1 h followed
by addition of 1.0 molar equiv of dienol complex 5 at
-10 °C for 2 h gave iron complex 6 with a chromium
carbene moiety at the terminal position of the diene
ligand.7
In t r a m olecu la r E lect r op h ilic Ad d it ion R ea c-
tion s. Our cyclization study began with complex 3a
(Scheme 1). Treatments of complex 3a with oxalyl
chloride (1.2 molar equiv) and triethylamine (1.2 molar
equiv) in CH2Cl2 at 0 °C for 45 min followed by addition
of aluminum chloride (1.5 molar equiv) gave a crude
iron-diene complex in 20% yield. The reaction is
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com -
p lexes. Interestingly, aluminum chloride promoted
intramolecular cyclization of the acyclic complexes with
an aldehyde moiety, for example, 2a , generated (σ,η3-
allyl)tricarbonyliron complex 10a (Chart 2), as the only
diastereomeric isomer isolated. None of the cyclized
product derived from addition of the diene ligand at the
(7) So¨derberg, B. C.; Hegedus, L. S. Organometallics 1990, 9, 3113.
(8) Pearson, A. J .; Zettler, M. W. J . Am. Chem. Soc. 1989, 111, 3908.

Intramolecular Cyclization of (η4-diene)Fe(CO)3 Complexes
Organometallics, Vol. 16, No. 20, 1997 4437
Ch a r t 2
complexes 10 and 11 are created; however, only the
single diastereomer shown was isolated. Due to their
apparent instability, further manipulation of some (σ,η3-
allyl)tricarbonyliron complexes was demonstrated as
follows. Oxidative cleavage of complex 11a with an
carbonyl carbon of the aldehyde functionality was found.
Thus, treatment of 2a with 3.0 molar equiv of aluminum
chloride at 25 °C under nitrogen for 3 h in dichlo-
romethane followed by quenching the reaction mixture
with aqueous ammonium chloride produced a major
product in 21% yield, identified as (σ,η3-allyl)tricarbo-
nyliron complex 10a after purification by flash column
chromatography. The stereochemistry of the allyl ligand
is assigned as shown on the basis of the coupling pattern
for the internal vinyl protons of the allyl ligand. The
1H NMR exhibited a triplet at δ 4.93, assigned to the
proton at the internal allyl carbon. The coupling
constant of 12.2 Hz for the triplet indicated a cis-cis
relationship between allyl protons. Complexes of the
(σ,η3-allyl)tricarbonyliron type were previously made by
reaction of iron pentacarbonyl with vinylcyclopropane,9
addition of lithium reagents to the (η5-pentadienyl)Fe-
(CO)3 cation,10 or intramolecular nucleophilic addition
of (η4-diene)Fe(CO)3 complexes bearing functionalized
side chains at the C-2 position of the diene ligand.11
Similarly, intramolecular cyclization of complexes 2b
using aluminum chloride afforded (σ,η3-allyl)tricarbo-
nyliron derivative 10b in 10% yield. Furthermore,
complexes with an ester or nitrile functional group also
produced (σ,η3-allyl)tricarbonyliron complexes 11a -d
and 12a ,b, respectively, in the presence of Lewis acid.
It is important to mention that only ester functionalized
complexes 1a -d produced (σ,η3-allyl)tricarbonyliron
complexes in good yields (83-88%) and titanium chlo-
ride is the best Lewis acid for the intramolecular
cyclizations.
excess of ethanolic ceric ammonium nitrate (CAN) under
nitrogen provided γ-lactone 16 in 55% yield after
evaporation and flash column chromatography of the
crude residue.12 None of vinylcyclopropane derivatives
is isolated.13 The stereochemistry of the double bond
1
of 16 was assigned as trans on the basis of H NMR
studies. The proton at δ 5.81 as a dq, J ) 16.0, 6.4 Hz,
was assigned to Ha. The coupling constant of Ha-Hb
(J ab) of 16.0 Hz agrees with 14-17 Hz coupling constant
for most trans hydrogens of olefins. However, oxidation
of the complex with one more carbon unit, for example,
11b, with CAN-generated olefins 17a and 17b in a ratio
The formation of (σ,η3-allyl)tricarbonyliron complexes
was suggested in Scheme 2. Because of the coordination
of titanium chloride with the carbonyl and hydroxy of
the ester enol, the ethoxy group will point away from
the metal center in the transition state conformation.
Addition of the R-face of ester enolate 13 at the carbonyl
of the Fe(CO)3 moiety would generate the acyl-hydride
intermediate with the relative stereochemistry depicted
in 14. Rearrangement of 14 might produce (σ,η2-
alkene)tricarbonyliron complex 15. Hydride addition to
the alkene ligand would generate (σ,η3-allyl)tricarbo-
nyliron complex 11a . It is important to note that two
new stereogenic centers of (σ,η3-allyl)tricarbonyliron
of 5:7 in 36% yield. None of the desired δ-lactones was
isolated. The reaction may involve addition of methanol
at the terminal position of the allyl ligand to provide
olefins 17a and 17b. Both olefins were assigned as
trans on the basis of their coupling constants (15.1 and
15.6 Hz, respectively) of the vinyl protons. The forma-
tion of trans-lactone 16 and olefins 17a and 17b may
be derived from syn/anti isomerization via π-allyl/σ-allyl
interconversion of the allyl ligand during the oxidation
process at 25 °C.14 The formation of olefins by oxidative
(9) (a) Aumann, R. J . Am. Chem. Soc. 1974, 96, 2631. (b) Aumann,
R. J . Organomet. Chem. 1973, 47, C29. (c) Aumann, R. J . Organomet.
Chem. 1974, 77, C33. (d) Aumann, R. J . Organomet. Chem. 1974, 78,
C31. (e) Wang, A. H.-J .; Paul, I. C.; Aumann, R. J . Organomet. Chem.
1974, 69, 301. (f) Aumann, R. J . Organomet. Chem. 1974, 66, C6.
(10) (a) Stephenson, G. R.; Voyle, M.; Williams, S. Tetrahedron Lett.
1991, 32, 5265. (b) Donaldson, W. A.; Ramaswamy, M. Tetrahedron
Lett. 1989, 30, 1343. (c) McDaniel, K. F.; Kracker II, L. R.; Thamburaj,
P. K. Tetrahedron Lett. 1990, 33, 2373.
(12) Paquett, L. A.; Ley, S. V.; Maiorana, S.; Schneider, D. F.;Broad-
hurst, M. J .; Boggs, R. A. J . Am. Chem. Soc. 1975, 97, 4658.
(13) Recently, Donaldson has shown a diastereoselective synthesis
of (σ,η3-allyl)tricarbonyliron complexes and their conversion to vinyl-
cyclopropanes were also reported in the literature: Yun, Y. K.;
Donaldson, W. A. J . Am. Chem. Soc. 1997, 119, 4084.
(14) (a) Becconsall, J . K.; O’Brien, S. J . J . Chem. Soc., Chem.
Commun. 1966, 302. (b) Corradini, P.; Maglio, G.; Musco, A.; Paiaro,
G. J . Chem. Soc., Chem. Commun. 1966, 618.
(11) Wang, J . L.; Ueng, C. H.; Cheng, S. J .; Yeh, M. C. P. Organo-
metallics 1994, 13, 4453.

4438 Organometallics, Vol. 16, No. 20, 1997
Yeh et al.
Sch em e 2
Sch em e 3
F or m a tion of F u r a n Der iva tives via In tr a m o-
lecu la r Nu cleop h ilic Ad d ition of (Dien e)ir on Tr i-
ca r bon yl Com p lexes to th e Ch r om iu m Ca r ben e
Ca r bon Cen ter . Complex 6a was dissolved in toluene,
and the solution was refluxed under nitrogen for 5 h to
produce a major product in 19% yield, identified as (η4-
diene)iron complex 21a (eq 4). Spectroscopic studies
cleavage of (σ,η3-allyl)tricarbonyliron complexes using
CAN in methanol was reported in the literature.15
Interestingly, Lewis acid assisted intramolecular cy-
clization of the cyclic complex containing an aldehyde
functionality, for example, complex 2c, produced tet-
rahydrobenzopyran-iron complex 19 in 56% yield as the
sole product isolated (Scheme 3). However, our ap-
proach to the synthesis of the heterobicyclic complex 19
is different from that developed in Pearson’s group.16
In the previous method, tetrahydrobenzofuran-iron
complexes were obtained by oxidative cyclization of (η4-
cyclohexadiene)Fe(CO)3 complexes bearing an primary
alcohol. The formation of 19 was presumably derived
from Lewis acid assisted hydride migration of 2c to
generate zwitterion 20. Addition of the oxygen anion
at the terminal position of the (η5-cyclohexadienyl)Fe-
(CO)3 cation led to formation of complex 19.
provided the initial evidence for support of the struc-
tural assignments of 21a . The infrared spectrum of 21a
showed the usual iron CO bands at 2031 and 1962 cm-1
.
The 1H NMR spectrum of complex 21a exhibited the
following: a multiplet, centered at δ 7.21, assigned to
the phenyl protons at C-11 and -12; a triplet, centered
at δ 7.16, assigned to the proton at C-10; a doublet,
centered at δ 5.49, assigned to the vinyl proton at C-3;
a multiplet, centered at δ 4.21, assigned to the protons
at C-6; a triplet of doublets, centered at δ 3.45, assigned
to one of the two diastereotopic methylene protons at
C-5; a multiplet, centered at δ 2.88, assigned to the other
diastereotopic methylene protons at C-5; a doublet,
centered at δ 1.38, assigned to the methyl group at C-1;
a doublet of quartets centered at δ 1.10, assigned to the
terminal proton at C-2. The chemical shift of 1.10 for
the terminal proton agrees with that of an endo proton
of most diene-iron complexes bearing an endo substitu-
ent at the other terminal position of the diene ligand.
The 13C NMR spectrum of complex 21a exhibited the
(15) Whitesides, T. H.; Neilan J . P. J . Am. Chem. Soc. 1976, 89, 63.
(16) Pearson, A. J .; Ong, C. W. J . Org. Chem. 1982, 47, 3780.
Pearson, A. J .; Kole, S. L.; Yoon, J . Organometallics 1986, 5, 2075.

Intramolecular Cyclization of (η4-diene)Fe(CO)3 Complexes
Sch em e 4
Organometallics, Vol. 16, No. 20, 1997 4439
following: a signal at δ 212.5 assigned to the carbonyl
of the tricarbonyliron moiety; four signals at δ 136.1,
128.2, 127.8, and 127.5 assigned to C-9, -10, -11, and
-12 (carbons of the phenyl group) ; a signal at δ 117.8
assigned to C-8 ; a signal at δ 89.9 assigned to C-4; a
signal at δ 82.3 assigned to C-3; a signal at δ 65.3
assigned to C-6; a signal at δ 55.8 assigned to C-2; a
signal at δ 34.4 assigned to C-5; a signal at δ 19.8
assigned to C-1. Furthermore, treatment of complex
21a with methanolic CAN provided dihydofuran deriva-
tive 21b in 65% yield after purification by flash column
chromatograph and distillation under reduced pressure
(eq 5). However, under the same reaction conditions,
assigned to the methyl group at C-9. The 13C NMR
spectrum of 22 exhibited the following: a signal at δ
144.7 assigned to the vinyl carbon at C-8; four signals
at δ 141.6, 128.1, 127.3, and 124.9 assigned to phenyl
carbons; a signal at δ 126.5 assigned to the vinyl carbon
at C-7 ; a signal at δ 99.7 assigned to C-1; a signal at δ
67.0 assigned to C-3; a signal at δ 49.3 assigned to C-6;
a signal at δ 37.9 assigned to C-4; a signal at δ 35.9
assigned to C-5; a signal at δ 12.1 assigned to C-9.
The formation of 21a may start with nucleophilic
addition of the diene ligand of 6a at the carbene carbon
center to give the cyclic intermediate 23a , which un-
derwent (π-allyl) syn/anti isomerization (to produce
23b), followed by â-hydride elimination to generate
zwitterion 24. Hydride addition at the terminal position
of the ally ligand produced 25. Detachment of the
chromiumcarbonyl moiety followed by reattachment of
the alkene ligand to the iron center gave complex 21.
However, cyclization of 6b underwent a different reac-
tion pathway (Scheme 5). Due to the steric reason, the
syn/anti isomerization of the disubstituted π-allyl an-
ionic intermediate 26 may be slow. Thus, addition of
the anionic chromium atom at the terminal position of
the allyl ligand may occur to give the metallocyclohex-
ene intermediate 27, which underwent reductive elimi-
nation followed by the detachment of the Fe(CO)3 moiety
cyclization of the complex with an additional methyl
group at the terminal position of the diene ligand, for
example, 6b, afforded a colorless liquid. The compound
does not possess the carbonyl functionality of Fe(CO)3
or Cr(CO)5 on both infrared and 13C NMR spec-
troscopies. The compound was assigned as fused furan
derivative 22 (49% yield, eq 6) on the basis of its 1H
1
NMR and COSY spectrum. The H NMR spectrum of
complex 22 exhibited the following: a multiplet, cen-
tered at δ 7.32, assigned to the phenyl proton at C-11,
-12, -14, and -15; a multiplet, centered at δ 7.22,
assigned to the phenyl proton at C-13; a doublet,
centered at δ 5.60, assigned to the vinyl proton at C-7;
a doublet of doublets of doublets, centered at δ 4.01,
assigned to one of the two diastereotopic methylene
protons at C-3; a triplet of doublets, centered at δ 3.77,
assigned to the other diastereotopic methylene protons
at C-3; a multiplet, centered at δ 2.71, assigned to the
protons at C-6 and C-5; a multiplet centered at δ 2.17
assigned to the protons at C-4 and C-6; a multiplet at δ
1.63, assigned to the proton at C-4; a doublet at δ 1.50,

4440 Organometallics, Vol. 16, No. 20, 1997
Yeh et al.
Sch em e 5
mass spectra were obtained with an AEI MS-9 double-focusing
mass spectrometer and a J EOL J MS-HX 110 spectrometer at
the Department of Chemistry, Central Instrument Center,
Taichung, ROC.
produced the bicyclic skeleton 28. Double bond migra-
tion of 28 furnished 22.17
The reactions described herein demonstrate that
Lewis acid promoted intramolecular cyclization of acy-
clic (η4-diene)Fe(CO)3 complexes containing an alde-
hyde, an ester, or a nitrile functionality provides (σ,η3-
allyl)tricarbonyliron complexes. Intramolecular nucleo-
philic addition of (η4-diene)Fe(CO)3 complexes to the
chromiumcarbene carbon center leads to formation of
furan derivatives.
Gen er a l P r oced u r e for Hyd r olysis of Ester 1 to Acid
3. A solution of potassium hydroxide (0.33 g) in water (5 mL)
at 25 °C was added to ester complexes 1a ,b (1.0 mmol) in 1:1
methanol/THF (10 mL). The reaction mixture was stirred for
4 h at 25 °C, and then it was added to 100 mL of 10% aqueous
hydrochloric acid at 0 °C. The aqueous solution was extracted
two times with 50 mL of 50% ethyl acetate/hexanes. The
resultant solution was washed with water (100 mL × 3) and
brine (100 mL × 3), dried over anhydrous magnesium sulfate
(10 g), and concentrated to give the crude mixture.
Exp er im en ta l Section
[exo-3-( 4-Cycloh exa -1,3-d ien e-5-yl)p r op ion oic a cid ]-
tr ica r bon ylir on (3a ). The crude mixture obtained from the
hydrolysis of the corresponding ester4a (0.97 g, 3.0 mmol) was
purified via flash column chromatography (silica gel, 20% ethyl
acetate/hexanes) to give 3a (0,75 g, 2.6 mmol, 85%) as a yellow
solid mp: 79-80 °C; IR(CH2Cl2) 3500-2800 (br), 2042, 1972,
All reactions were run under a nitrogen atmosphere in oven-
dried glassware unless otherwise indicated. Anhydrous sol-
vents 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 before used. Complexes 1a -f were
synthesized according to the literature procedures.4a Flash
column chromatography, following the method of Still,18 was
carried out with E. 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 E. Merck. The term “con-
centration” 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. The term “flash distillation” refers to a
vacuum distillation at 25 °C with a receiver at -78 °C.
Melting points were determined in open capillaries with a
Thomas-Hoover apparatus and are uncorrected. 1H nuclear
magnetic resonance (NMR) spectra were obtained with a J EOL
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 spectra
were recorded with a J EOL EX 400 spectrometer (100.4 MHz)
with CDCl3 (77.0 ppm) as the internal standard. Infrared (IR)
spectra were recorded with a J asco IR-700 spectrometer. Mass
spectra were acquired on a J EOL J MS-D 100 spectrometer at
an ionization potential of 70 eV and are reported as mass/
charge (m/e) with percent relative abundance. High-resolution
1
1708, 1606, 1437, 1418, 1286, 1041, 940 cm-1; H NMR (400
MHz, CDCl3) δ 5.38 (dd, J ) 6.3, 4.6 Hz, 1 H), 5.29 (td, J )
4.9, 1.5 Hz, 1 H), 3.07 (dd, J ) 6.4, 4.3 Hz, 1 H), 3.04 (dd, J )
4.2, 2.0 Hz, 1 H), 2.29 (t, J ) 7.3 Hz, 2 H), 2.06 (m, 2 H), 1.58
(m, 2 H), 1.23 (br doublet, J ) 14.2 Hz, 1 H); 13C NMR (100.4
MHz, CDCl3) δ 211.9, 180.0 , 85.7, 84.3, 65.3, 59.4, 37.2, 34.2,
32.6, 30.4; MS (30 eV) m/ e (relative intensity) 292 (M+, 4),
264 (19), 236 (57), 208 (75), 160 (100); HRMS (EI) m/ e calcd
for C12H12FeO5 (M+) 292.0034, found 292.0022.
[(5-8- )-cis-5,7-Octa d ien oic a cid ]tr ica r bon ylir on (3b).
The crude mixture obtained from the hydrolysis of 1b4a (0.53
g, 1.70 mmol) was purified via flash column chromatography
(silica gel, 20% ethyl acetate/hexanes) to give 3b (0.46 g, 1.6
mmol, 98%) as a yellow oil: IR (CH2Cl2) 3500-2700 (br), 2047,
1973, 1711, 1453, 1362, 1275, 1223, 1128 cm-1; 1H NMR (400
MHz, CDCl3) δ 5.44 (m, 1 H), 5.30 (t, J ) 7.4 Hz, 1 H), 2.52
(m, 1 H), 2.30 (m, 2 H), 1.86 (d, J ) 7.8 Hz, 1 H), 1.73 (m, 1
H), 1.58 (m, 2 H), 1.43 (d, J ) 9.8 Hz, 1 H), 1.07 (m, 1 H); 13
C
NMR (100.4 MHz, CDCl3) δ 211.1, 179.5, 90.9, 86.8, 59.0, 40.9,
28.1, 27.6; MS (30 eV) m/ e (relative intensity) 252 (M+ - CO,
6), 224 (34), 196 (100), 178 (7), 154 (11), 150 (16), 148 (23),
140 (50), 136 (10), 134 (18), 122 (29), 112 (8), 84 (15), 81 (27),
79 (26), 73 (15), 67 (18), 56 (33), 53 (13); HRMS (EI) m/ e calcd
for C11H12FeO5 (M+) 280.0034, found 280.0036.
In tr a m olecu la r F r ied el-Cr a fts Rea ction of Com p lex
3a . F or m a tion of Com p lex 8a . To a solution of 1.0 mmol
(0.29 g) of complex 3a in 30 mL of methylene chloride was
added a solution of 0.1 mL (1.2 mmol) of oxallyl chloride in
0.17 mL (1.2 mmol) of triethylamine at 0 °C under nitrogen.
(17) Alternatively, intramolecular cyclopropanation followed by iron-
mediated rearrangement of 6a and 6b would produce 21a and 22,
respectively.
(18) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923.

Intramolecular Cyclization of (η4-diene)Fe(CO)3 Complexes
Organometallics, Vol. 16, No. 20, 1997 4441
The reaction mixture was stirred for 45 min followed by
addition of 0.2 g (1.5 mmol) of aluminum chloride in 10 mL of
methylene chloride. The reaction was stirred at 0 °C for 1 h
and was quenched with 50 mL of water. The reaction mixture
was diluted with 200 mL of methylene chloride. The resultant
solution was washed with water (300 mL × 3) and brine (300
mL × 3), dried over anhydrous magnesium sulfate, and finally
concentrated on a rotary evaporator to give the crude mixture
(55 mg, 20%). The above crude mixture in 3 mL of ethanol
was added to a solution of 0.33 g of 2,4-dinitrophenylhydrazine
in 9 mL of phosphoric acid (85% in H2O) and 9 mL of ethanol
(95%) following the literature procedure.19 The reaction
mixture was stirred at 25 °C for 20 min and diluted with 50
mL of ethyl acetate. The resultant solution was washed with
water (100 mL × 3) and brine (100 mL × 3), dried over
anhydrous magnesium sulfate (10 g), and concentrated to give
the crude mixture. The crude mixture was purified via flash
column chromatography (silica gel, 20% ethyl acetate/hexanes)
and recrystallization (ethanol) to give 7 (0.03 g, 0.06 mmol,
6%) as a yellow solid: mp 118 °C (dec); IR (CH2Cl2) 3053, 2988,
2045, 1981, 1616, 1460, 1421, 1337, 1314, 1275, 1267, 1251,
1092 cm-1; 1H NMR (400 MHz, CDCl3) δ 11.0 (s, 1 H), 9.13 (d,
J ) 2.5 Hz, 1 H), 8.31 (dd, J ) 9.7, 2.5 Hz , 1 H), 7.97 (d, J )
9.7 Hz1, H), 5.60 (d, dd, J ) 6.5 Hz, 1 H), 3.30 (t, J ) 4.3 Hz,
1 H), 3.18 (m, 1 H), 2.90 (m, 2 H), 2.70 (m , 1 H), 2.39 (td, J )
11.3, 3.9 Hz, 1 H), 1.91 (m, 1 H), 1.71 (dd, 143.7, 3.4 Hz, 2 H);
13C NMR (100.4 MHz, CDCl3) δ 210.7, 167.6, 144.6, 137.8,
130.0, 128.9, 123.6, 116.6, 113.8, 82.4, 78.8, 59.0, 29.0, 26.1,
23.9, 22.8; MS (EI) m/ e (relative intensity) 454 (22) , 426 (36),
398 (60), 370 (16), 354 (76), 322 (100).
Gen er a l P r oced u r e for Red u ction of Ester 1 to Ald e-
h yd e 2 Usin g Diisobu tyla lu m in u m Hyd r id e. To a solution
of 5.0 mmol of an ester complex in 50 mL of methylene chloride
was added a solution of 6.0 mL (6.0 mmol) of DIBAL (1.0 M in
toluene) at -78 °C . The reaction was stirred at -78 °C for
15 min and was decomposed with 30 mL of 50% toluene/
methanol followed by addition of 30 mL of 10% aqueous
hydrochloric acid. The reaction mixture was diluted with 200
mL of ether. The ethereal solution was washed with water
(300 mL × 3) and brine (300 mL × 3), dried over anhydrous
magnesium sulfate, and concentrated to give the crude mix-
ture.
[(5-8- )-cis-5,7-Octa d ien a l]tr ica r bon ylir on (2a ). The
crude mixture obtained from reduction of the corresponding
ester 1b4a (0.30 g, 1.0 mmol) was purified via flash column
chromatography (silica gel, 10% ethyl acetate/hexanes) to give
2a (0.19 g, 0.72 mmol, 72%) as a yellow oil: 1H NMR (400
MHz, CDCl3) δ 9.72 (t, J ) 1.5 Hz, 1 H), 5.46 (dt, J ) 8.3, 4.9
Hz, 1 H), 5.30 (dd, J ) 7.8, 4.9 Hz, 1 H), 2.42 (m, 1 H), 2.39
(dd, J ) 9.8, 6.4 Hz, 2 H), 1.87 (dd, J ) 7.4, 2.0 Hz, 1 H), 1.72
(m, 1 H, 1.69-1.49 (m, 2 H), 1.43 (dd, J ) 8.3, 1.9 Hz, 1 H),
1.07 (m, 1 H); 13C NMR (100.4 MHz, CDCl3) δ 211.1, 201.9,
90.8, 86.8, 59.0, 43.1, 40.9, 28.2 , 25.1.
the corresponding ester comlex4a (0.97 g, 3.04 mmol) was
purified via flash column chromatography (silica gel, 5% ethyl
acetate/hexanes) to give 2c (0.64 g, 2.3 mmol, 76%) as a yellow
oil: IR (CH2Cl2) 3007, 2936, 2847, 2044, 1970, 1723, 1609,
1424, 1362, 1289, 1094, 918, 654 cm-1 1H NMR (400 MHz,
;
CDCl3) δ 9.73 (s, 1 H), 5.37 (m, 1 H), 5.29 (dd, J ) 5.3, 2.7 Hz,
1 H), 3.04 (m, 2 H), 2.38 (t, J ) 7.3 Hz, 2 H), 2.08-1.98 (m, 2
H), 1.59-1.45 (m, 2 H),1.21 (d, J ) 14.2 Hz, 1 H); 13C NMR
(100.4 MHz, CDCl3) δ 211.9, 201.9, 85.7, 84.5, 65.4, 59.4, 42.4,
37.4, 31.5, 30.6; MS (EI) m/ z (relative intensity): 276 (M+,
2), 248 (12), 220 (52), 192 (52), 190 (62), 134 (100); HRMS (EI)
m/ e calcd for C12H12FeO4 276.0085, found 276.0092.
Gen er a l P r oced u r e for In tr a m olecu la r Nu cleop h ilic
Ad d ition of ( 4-d ien e)F e(CO)3 Com p lexes to Ald eh yd e,
Ester , or Nitr ile F u n ction a l Gr ou p s in th e P r esen ce of
a Lew is Acid . F or m a tion of ( , 3-Allyl)tr ica r bon ylir on
Com p lexes. To a stirred suspension of 3.0 mmol of Lewis
acid (AlCl3 or TiCl4) in 2 mL was added a solution of 1.0 mmol
of a complex in 5.0 mL of methylene chloride at 0 °C under
nitrogen. The reaction temperature was raised to 25 °C. The
reaction was monitored by TLC untill no starting iron com-
plexes was detected. The reaction mixture was then diluted
with 200 mL of methylene chloride. The resultant solution
was washed with water (300 mL × 3) and brine (300 mL × 3),
dried over anhydrous magnesium sulfate, and finally concen-
trated to give the crude mixture.
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 10a .
The crude mixture obtained from intramolecular cyclization
of complex 2a (0.22 g, 0.83 mmol) and AlCl3 was purified via
flash column chromatography (silica gel, 15% ethyl acetate/
hexanes) to give 10a (0.05 g, 0.21 mmol, 21%) as a yellow oil:
IR (CH2Cl2) 3061, 2988, 2948, 2087, 2035, 2006, 1725, 1424,
1269, 1250, 1117, 909 cm-1; 1H NMR (400 MHz, CDCl3) δ 9.84
(s, 1 H), 4.93 (t, J ) 12.2 Hz, 1 H), 4.00 (m, 1 H), 3.89 (m, 1
H), 2.64 (m, 2 H), 2.65 (t, J ) 6.9 Hz, 1 H), 2.05 (d, J ) 5.8 Hz,
3 H), 2.03 (m, 2 H); 13C NMR (100.4 MHz, CDCl3) δ 207.4,
205.1, 204.9, 201.3, 104.9, 87.5 , 84.6, 43.0, 34.2, 24.1, 20.1;
MS (70 eV) m/ e (relative intensity) 264 (M+, 2), 236 (6), 208
(6), 180 (19), 149 (11), 141 (28), 140 (13), 125 (49), 124 (42),
123 (14), 109 (20), 97 (42), 95 (38), 81 (75), 68 (100), 55 (80);
HRMS (EI) m/ e calcd for C8H12FeO (M+ - 3CO) 180.0237,
found 180.0238
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 10b.
The crude mixture obtained from intramolecular cyclization
of complex 2b (0.10 g, 0.35 mmol) and AlCl3 was purified via
flash column chromatography (silica gel, 15% ethyl acetate/
hexanes) to give 10b (0.01 g, 0.02 mmol, 10%) as a yellow oil:
IR (CH2Cl2) 3067, 3046, 2992, 2982, 2085, 2035, 2006, 1713,
1
1607, 1424, 1273, 1248, 1105, 914 cm-1; H NMR (400 MHz,
CDCl3) δ 9.81 (s, 1 H), 4.91 (t, J ) 12.2 Hz, 1 H), 4.01-3.92
(m, 2 H), 2.53 (t, J ) 7.3 Hz, 2 H), 2.52 (m, 1H), 2.04 (d, J )
6.4 Hz, 3 H), 1.82-1.58 (m, 4 H,); 13C NMR (100.4 MHz, CDCl3)
δ 207.6, 205.2, 205.0, 201.9, 104.8, 88.4, 84.3, 43.6, 34.9, 31.3,
21.6 , 20.1; MS (70 eV) m/ e (relative intensity) 278 (M+, 1),
250 (10), 222 (64), 195 (30), 194 (100), 192 (19), 166 (8), 152
(13), 150 (27), 148 (11), 140 (18), 138 (28), 136 (13), 134 (31),
127 (11), 126 (85), 110 (18), 99 (14), 98 (18), 96 (23), 84 (15),
82 (20), 67 (12), 57 (15), 56 (47); HRMS (EI) m/ e calcd for
[(6-9- )-cis-6,8-Non a d ien a l]tr ica r bon ylir on (2b). The
crude mixture obtained from reduction of the corresponding
ester 1c4a (0.32 g, 1.0 mmol) was purified via flash column
chromatography (silica gel, 10% ethyl acetate/hexanes) to give
2b (0.2 g, 0.70 mmol, 70%) as a yellow oil: 1H NMR (400 MHz,
CDCl3) δ 9.74 (t, J ) 1.5 Hz, 1 H), 5.42 (m, 1 H), 5.29 (dd, J )
7.8, 4.9 Hz, 1 H), 2.54 (dd, J ) 13.2, 8.3 Hz, 1 H), 2.38 (td, J
) 7.3, 1.3 Hz, 2 H), 1.86 (dd, J ) 7.8, 1.9 Hz, 1 H), 1.62-1.52
C
12H14FeO4 (M+) 278.0241, found 278.0239.
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 11a .
(m, 3 H), 1.46-1.40 (m , 2 H), 1.26 (m, 1 H), 1.06 (m, 1 H); 13
C
The crude mixture obtained from intramolecular cyclization
of the corresponding ester complex4a (0.60 g, 2.26 mmol) and
TiCl4 was purified via flash column chromatography (silica gel,
10% ethyl acetate/hexanes) to give 11a (0.55 g, 1.88 mmol,
83%) as a yellow oil: IR (CH2Cl2): 3005, 2967, 2087, 2037,
2006, 1730, 1628, 1564, 1433, 1416, 1375, 1292, 1109, 924
NMR (100.4 MHz, CDCl3) δ 211.3, 201.7, 90.7, 86.9, 59.7, 43.6,
40.8, 32.3, 28.4, 21.4; MS (70 eV) m/ e (relative intensity) 278
(M+, 12), 250 (12), 222 (38), 194 (100), 150 (14), 134 (12), 126
(37), 121 (8), 84 (6), 56 (10); HRMS (EI) m/ e calcd for C11H14
-
FeO3 (M+ - CO) 250.0292, found 250.0299.
[exo-3-( 4-Cycloh exa -1,3-d ien e-5-yl)p r op a n a l]tr ica r bo-
n ylir on (2c). The crude mixture obtained from reduction of
1
cm-1; H NMR (400 MHz, CDCl3): δ 5.02 (t , J ) 12.2 Hz, 1
H), 4.19 (q, J ) 7.3 Hz, 2 H), 4.00 (m, 1 H), 3.84 (m, 1 H),
2.79-2.65 (m, 2 H), 2.36 (m , 1 H), 2.03 (d, J ) 6.8 Hz, 3 H),
1.30 (t, J ) 7.3 Hz, 3 H); 13C NMR (100.4 MHz, CDCl3) δ 207.2,
205.5, 205.2, 172.2, 105.2, 86.2, 84.8, 60.8, 35.7, 30.1, 20.1 ,
(19) The hydrazone 8a was formed in the usual way: Pavia, D. L.;
Lampman, G. M.; Kriz, G. S., J r. Introduction to Organic Laboratory
Techniques; W. B. Saunders Co.: Philadephia, PA, 1975; p 668.

4442 Organometallics, Vol. 16, No. 20, 1997
Yeh et al.
14.2; MS (EI) m/ e (relative intensity) 294 (M+, 8) , 266 (4),
246 (100), 210 (90), 182 (18), 155 (84).
of the corresponding cyano complex4a (0.08 g, 0.30 mmol) and
AlCl3 was purified via flash column chromatography (silica gel,
12% ethyl acetate/hexanes) to give 12b (0.03 g, 0.1 mmol, 33%)
as a yellow oil: IR (CH2Cl2) 3065, 3046, 2992, 2961, 2930, 2239,
2087, 2035, 2006, 1462, 1424, 1379, 1278, 1098 cm-1; 1H NMR
(400 MHz, CDCl3) δ 4.93 (t, J ) 12.2 Hz, 1 H), 4.01 (m, 1 H),
3.89 (m, 1 H), 2.57 (m, 1 H), 2.44 (m, 2 H), 2.32 (t, J ) 6.5 Hz,
1 H), 2.05 (d, J ) 5.8 Hz, 3 H,), 1.83 -1.66 (m, 3 H); 13C NMR
(100.4 MHz, CDCl3) δ 207.4, 205.1, 204.9, 119.2, 104.9, 87.3,
84.7, 34.3, 30.9, 24.9, 20.1, 17.1; MS (30 eV) m/ e (relative
intensity) 191 (M+ - 3CO, 56), 152 (14), 122 (33), 108 (34), 97
(21), 81 (27), 71 (37), 69 (100), 55 (27); HRMS (EI) m/ e calcd
for C9H13FeN (M+ - 3CO) 191.0397, found 191.0392.
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 11b.
The crude mixture obtained from intramolecular cyclization
of the corresponding ester complex4a (0.50 g, 1.70 mmol) and
TiCl4 was purified via flash column chromatography (silica gel,
10% ethyl acetate/hexanes) to give 11b (0.46 g, 1.50 mmol,
84%) as a yellow oil: IR(CH2Cl2) 3067, 3046, 2992, 2982, 2087,
1
2035, 2006, 1728, 1424, 1256, 1155, 929 cm-1 ; H NMR (400
MHz, CDCl3) δ 4.94 (t, J ) 12.2 Hz, 1 H), 4.16 (q, J ) 7.3 Hz,
2 H), 4.01 (m, 1 H), 3.95 (m, 1 H), 2.57 (m, 1 H), 2.47 (t, J )
6.8 Hz, 1 H), 2.04 (d, J ) 6.4 Hz, 3 H), 2.03-1.98 (m, 3 H),
1.28 (t, J ) 7.3 Hz, 3 H); 13C NMR (100.4 MHz, CDCl3) δ 207.5,
205.3, 205.0, 172.9, 104.9, 87.7, 84.5, 60.5, 34.3, 33.5, 26.9, 20.1,
14.2; MS (70 eV) m/ e (relative intensity) 168 [M+ - Fe(CO)3,
1], 140 (6), 139 (37), 138 (22), 123 (6), 111 (23), 110 (28), 99
(10), 97 (66), 96 (54), 95 (32), 81 (19), 71 (22), 69 (100), 55 (21).
HRMS (EI) m/ e calcd for C10H16O2 [M+ - Fe(CO)3] 168.1150,
found 168.1146.
F or m a tion of -tr a n s-1-P r op en yl- -bu tyr ola cton e (16).
To a solution of ceric ammonium nitrate (5.92 g, 10.8 mmol)
in 25 mL of ethanol was added a solution of complex 11a (0.55
g, 1.88 mmol) in 5.0 mL of ethanol. The reaction was stirred
at room temperature under nitrogen for 18 h. The solvent was
removed under reduced pressure, and the residue was diluted
with water (100 mL). The aqueous solution was extracted with
methylene chloride (50 mL × 3). The resultant solution was
washed with water (200 mL × 3) and brine (200 mL × 3), dried
over anhydrous magnesium sulfate (20 g), and concentrated
to give the crude mixture. The crude mixture was purified
via flash column chromatography (silica gel, 5% ethyl acetate/
hexanes) to give 16 (0.13 g, 1.03 mmol, 55%): IR (CH2Cl2)
3013, 2928, 2856, 1773, 1676, 1578, 1456, 1377, 1325, 1215,
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 11c.
The crude mixture obtained from intramolecular cyclization
of the corresponding ester complex4a (0.50 g, 1.70 mmol) and
TiCl4 was purified via flash column chromatography (silica gel,
10% ethyl acetate/hexanes) to give 11c (0.48 g, 1.48 mmol,
87%) as a yellow oil: IR (CH2Cl2) 3383, 3067, 2992, 2982, 2085,
2035, 2004, 1728, 1427, 1419, 1289, 1242, 1182, 1153 cm-1
;
1H NMR (400 MHz, CDCl3) δ 4.91 (t, J ) 12.7 Hz, 1 H), 4.15
(q, J ) 6.8 Hz, 2 H), 3.99-3.96 (m, 2 H), 2.54 (m, 1 H), 2.37 (t,
J ) 7.4 Hz, 2 H), 2.17 (m, 1 H), 2.04 (d, J ) 6.3 Hz, 3 H),
1.78-1.64 (m, 3 H), 1.27 (t, J ) 6.8 Hz, 3 H); 13C NMR (100.4
MHz, CDCl3) δ 207.6 , 205.2 , 205.1, 173.3, 104.8, 88.7, 84.3,
60.4, 34.9, 34.0, 31.4, 24.5 , 20.1 , 14.3; MS (70 eV) m/e (relative
intensity) 266 (M+ - 2CO, 1), 238 (2), 199 (4), 198 (26), 183
(3), 182 (9), 156 (3), 155 (7), 154 (5), 153 (18), 152 (18), 137
(14), 125 (39), 124 (11), 111 (24), 110 (55), 101 (20), 97 (48), 94
(36), 84 (34), 81 (40), 71 (26), 69 (100), 67 (39), 55 (40); HRMS
(EI) m/ e calcd for C11H18FeO2 (M+ - 3CO) 238.0656, found
238.0655.
1
1176, 1120, 1011, 972, 848 cm-1; H NMR (400 MHz, CDCl3)
δ 5.81 (dq, J ) 16.0, 6.4 Hz, 1 H), 5.53 (ddd, J ) 16.0, 7.0, 1.4
Hz, 1 H), 4.89 (q, J ) 7.3 Hz, 1 H), 2.54 (m, 1 H), 2.38 (m, 1
H), 1.98 (m , 2 H), 1.75 (dd, J ) 6.4, 1.4 Hz, 3 H); 13C NMR
(100.4 MHz, CDCl3) δ 177.0, 130.4, 128.7, 81.1, 28.7, 17.6; MS
(EI) m/ e (relative intensity) 126 (M+, 78) , 111 (100), 85 (30),
67 (28), 56 (22), HRMS (EI) m/ e calcd for C7H10O2 126.0681,
found 126.0676
Eth yl tr a n s-2-Eth oxy-6-octen oa te (17a ). To a solution
of ceric ammonium nitrate (7.50 g, 13.8 mmol) in 45 mL of
ethanol was added a solution of complex 11b (0.20 g, 0.70
mmol) in 5.0 mL of ethanol. The reaction was stirred at 25
°C under nitrogen for 18 h. The solvent was concentrated
under reduced pressure, and the residue was diluted with
water (100 mL). The aqueous solution was extracted with
methylene chloride (50 mL × 3). The resultant solution was
washed with with water (200 mL × 3) and brine (200 mL ×
3), dried over anhydrous magnesium sulfate (25 g), and
concentrated to give the crude mixture. Flash column chro-
matography of the crude mixture (silica gel, 5% ethylacetate/
hexanes) gave 17a (0.03 g, 0.14 mmol, 11%) and 17b (0.04,
0.19 mmol, 16%) as colorless liquid.
Eth yl cis-2-Eth oxy-4-octen oa te (17a ): 1H NMR (400
MHz, CDCl3) δ 5.58 (dq, J ) 15.6, 6.8 Hz, 1 H), 5.30 (dd, J )
15.6, 8.3 Hz, 1 H), 4.13 (q, J ) 6.8 Hz, 2 H), 3.55 (m, 2 H),
3.28 (m, 1 H), 2.29 (t, J ) 7.3 Hz, 2 H), 1.69 (dd, J ) 6.3, 1.4
Hz, 3 H), 1.68 (m, 2 H), 1.46 (m, 2 H), 1.25 (t, J ) 6.8 Hz, 3
H), 1.16 (t, J ) 6.8 Hz, 3 H); 13C NMR (100.4 MHz, CDCl3) δ
173.7, 132.1, 128.2, 80.2, 63.2, 60.2, 35.1, 34.2, 21.1, 17.6, 15.3,
14.2; MS (30 eV) m/ e (relative intensity) 214 (M+, 0.1), 185
(3), 169 (7), 139 (7), 123 (15), 111 (5), 100 (8), 99 (100), 95 (9),
81 (21), 79 (5), 71 (75), 69 (5), 67 (6), 55 (13); HRMS (EI) m/ e
cacld for C12H22O3 (M+) 214.1569 found 214.1568
Eth yl tr a n s-2-Eth oxy-4-octen oa te (17b): 1H NMR (400
MHz, CDCl3) δ 5.56 (dt, J ) 15.6, 6.8 Hz, 1 H), 5.37 (dd, J )
15.6, 7.9 Hz, 1 H), 4.13 (q, J ) 6.8 Hz, 2 H), 3.78 (pentet, J )
7.3 Hz, 1 H), 3.49 (dq, J ) 13.7, 6.8 Hz 1 H), 3.33 (dq, J )
13.7, 7.3 Hz, 1 H), 2.30 (t, J ) 7.3 Hz, 2 H), 2.08 (q, J ) 6.8
Hz, 2 H), 1.72 (m, 2 H), 1.24 (m, 2 H), 1.20 (m, 7 H); 13C NMR
(100.4 MHz, CDCl3) δ 173.5, 133.4, 130.9, 76.1, 63.2, 60.2 ,
33.6, 31.5, 24.4, 21.7, 15.4, 14.2; MS (30 eV) m/ e (relative
intensity) 214 (M+, 1), 199 (10), 185 (3), 169 (18), 168 (38),
141 (10), 139 (9), 125 (14), 123 (54), 111 (62), 99 (100), 97 (32),
95 (46), 94 (78), 86 (18), 83 (29), 71 (78), 67 (25),55 (35); HRMS
(EI) m/ e calcd for C12H22O3 (M+) 214.1569 found 214.1566.
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 11d .
The crude mixture obtained from intramolecular cyclization
of the corresponding complex4a (0.54 g, 1.62 mmol) and TiCl4
was purified via flash column chromatography (silica gel, 12%
ethyl acetate/hexanes) to give 11d (0.48 g, 1.43 mmol, 88%)
as a yellow oil: IR (CH2Cl2) 3084, 3029, 2938, 2085, 2033, 2004,
1728, 1566, 1437, 1414, 1302, 1103 cm-1; 1H NMR (400 MHz,
CDCl3) δ 4.91 (t , J ) 12.2 Hz, 1 H), 4.13 (q, J ) 7.4 Hz, 2 H,),
3.95 (m, 2 H), 2.52 (m, 1 H), 2.33 (t, J ) 7.3 Hz, 2 H), 2.03 (d,
J ) 6.3 Hz, 3 H), 1.97 (m, 2 H), 1.78-1.42 (m, 4 H), 1.27 (t, J
) 6.9 Hz, 3 H); 13C NMR (100.4 MHz, CDCl3) δ 207.7, 205.2,
205.0, 173.6, 104.8, 89.2, 84.1, 60.3, 34.9, 34.1, 31.6, 28.7, 24.7,
20.1, 14.2; MS (EI) m/ e (relative intensity) 336 (M+, 2), 288
(100), 252 (70), 206 (18), 197 (40), 184(72), 149(41), 123(23),
91(25); HRMS (EI) m/ e calcd for C12H20FeO2 (M+ - 3CO)
252.0805, found 2252.0812.
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 12a .
The crude mixture obtained from intramolecular cyclization
of the corresponding cyano complex4a (0.08 g, 0.22 mmol) and
AlCl3 was purified via flash column chromatography (silica gel,
12% ethyl acetate/hexanes) to give 12a (0.02 g, 0.05 mmol,
23%) as a yellow oil: IR (CH2Cl2) 3065, 3052, 2988, 2249, 2087,
1
2037, 2008, 1424, 1281, 1262, 1248, 914 cm-1; H NMR (400
MHz, CDCl3) δ 4.96 (t, J ) 12.2 Hz, 1 H), 4.03 (m, 1 H), 3.81
(m, 1 H), 2.66 (m, 1 H), 2.54 (t, J ) 6.4 Hz, 2 H), 2.13-2.05
(m, 2 H), 2.05 (d, J ) 6.3 Hz, 3 H); 13C NMR (100.4 MHz,
CDCl3) δ 207.0, 204.7, 203.3, 118.9, 105.0, 85.2, 85.1, 33.7, 27.2,
20.1, 16.8; MS (70 eV) m/ e (relative intensity) 233 (M+ - CO,
10), 213 (46), 205 (42), 178 (50), 177 (41),176 (100), 150 (32),
134 (29), 122 (39), 110 (10), 94 (39), 83 (67), 81 (43), 55 (25);
HRMS (EI) m/ e calcd for C8H11FeN (M+ - 3CO) 177.0241,
found 177.0246.
F or m a tion of ( , 3-Allyl)tr ica r bon ylir on Com p lex 12b.
The crude mixture obtained from intramolecular cyclization

Intramolecular Cyclization of (η4-diene)Fe(CO)3 Complexes
Organometallics, Vol. 16, No. 20, 1997 4443
In tr a m olecu la r Cycliza tion of Com p lex 2c. F or m a -
tion of Com p lex 19. A solution of complex 2c (0.64 g, 2.31
mmol) in 10.0 mL of methylene chloride at 0 °C under nitrogen
was added to a stirred suspension of 0.92 g (6.93 mmol) of AlCl3
in 2 mL of methylene chloride. The reaction temperature was
raised to 25 °C. The reaction was monitored by TLC untill no
starting iron complex was detected. The reaction mixture was
diluted with 200 mL of methylene chloride. The resultant
solution was washed with water (300 mL × 3) and brine (300
mL × 3), dried over anhydrous magnesium sulfate, and finally
concentrated to give the crude mixture. Flash column chro-
matography (silica gel, 25% ethyl acetate/hexanes) gave
complex 19 (0.36 g, 1.29 mmol, 56%) as a yellow oil: IR (CH2-
3 h. To the reaction mixture at 0 °C, a solution of aqueous
sodium hydroxide (3.0 mL, 3.0 N) was added followed by
addition of aqueous hydrogen peroxide (35%, 2.0 mL). The
reaction was allowed to stirred at 0 °C for 1 h and was
quenched with 5.0 mL of 10% aqueous hydrochloric acid
solution. The reaction mixture was diluted with 200 mL of
ether. The ethereal solution was washed water (200 mL × 3)
and brine (200 mL × 3), dried over magnesium sulfate (10 g),
and concentrated to give the crude mixture. Flash column
chromatograpy of the crude mixture on the silica gel (20% ethyl
acetate/hexanes) gave 0.21 g (0.84 mmol, 74%) of complex 5b
as a yellow oil: IR (CH2Cl2) 3684, 3605, 3056, 3025, 2988, 2926,
2039, 1961, 1607, 1445, 1381, 1279,1258, 1044, 847, 793, 741,
Cl2) 3057, 2984, 2049, 1975, 1624, 1582, 1451, 1400, 1072 cm-1
;
712, 691 cm-1 1H NMR (400 MHz, CDCl3) δ 5.04 (m, 2 H),
;
1H NMR (400 MHz, CDCl3) δ 5.45 (dd, J ) 5.4, 4.9 Hz, 1 H),
5.39 (dd, J ) 5.8, 4.8 Hz, 1 H), 3.73 (m, 2 H), 3.40 (m, 1 H),
3.07 (t, J ) 4.4 Hz, 1 H), 3.03 (dd, J ) 5.4, 4.4 Hz, 1 H), 1.97
(m, 1 H), 1.64 (m, 2 H), 1.30 (m, 1 H), 0.97 (m, 1 H); 13C NMR
(100.4 MHz, CDCl3) δ 211.3, 85.9, 84.9, 73.8, 63.4, 62.9, 58.9,
37.1, 28.9, 21.5; MS (EI) m/ e (relative intensity): 248 (63),
3.68 (m, 1 H), 3.61 (m, 1 H), 1.95 (m, 1 H), 1.72 (m, 1 H), 1.39
(d, J ) 6.4 Hz, 3 H), 1.15 (m, 1 H), 1.00 (q, J ) 7.3 Hz, 1 H);
13C NMR (100.4 MHz, CDCl3) δ 212.5, 85.4, 83.9 , 63.8, 58.2 ,
36.9, 19.1; MS (EI, 70 eV) m/ e (relative intensity) 252 (M+,
17), 224 (49), 196 (56), 168 (100), 140 (76), 122 (47), 84 (59),
56 (38); HRMS (EI) m/ e calcd for C10H12FeO4 (M+) 252.0085,
found 252.0076.
218 (36),190 (100), 162 (17); HRMS (EI) m/ e calcd for C12H12
-
FeO4 276.0084, found 276.0087.
Syn th esis of Ch r om iu m Ca r ben e Com p lex 6a . To a
solution of [tetramethylammonium(phenyl)carbenyl oxide]-
pentacarbonylchromium (4) (1.89 g, 5.1 mmol) in 60 mL of CH2-
Cl2 was added acetyl bromide (0.38 mL, 5.1 mmol) at -10 °C
under nitrogen.7 The reaction mixture turned red immedi-
ately. A solution of complex 5a (0.81 g, 3.4 mmol) in 3.0 mL
of CH2Cl2 was added slowly to the reaction at -10 °C. The
reaction mixture was stirred at 0 °C for 2 h before being
filtered through a bed of Celite. The resultant solution was
concentrated to give a crude mixture. Flash column chroma-
tography of the crude mixture (silica gel, 5% ethyl acetate/
hexanes) produced complex 6a (1.37 g, 2.6 mmol, 78%) as a
red oil: IR (CH2Cl2) 3030, 2980, 2062, 2048, 1946, 1605, 1437,
Syn th esis of [(3-6- )-tr a n s-3,5-Hexa d ien ol]tr ica r bo-
n ylir on Com p lex (5a ). Ethyl trans-3,5-hexadienoate (2.9 g,
20.7 mmol, 87%) was synthesized starting from ethyl sorbate
(3.3 g, 23.7 mmol) according to the literature procedure.20
Complexation of ethyl trans-3,5-hexadienoate with 7.9 g (0.022
mol) of Fe2(CO)9 gave the corresponding [(3-6-η)-ethyl trans-
3,5-hexadienoate]tricarbonyliron complex (3.14 g, 0.011 mol,
57%). Reduction of the complex with Diisobutylaluminum
hydride (20 mL, 1.0 M in toluene) at 0 °C accoding to the
procedure described above produced the desired complex 5a
(1.2 g, 5.0 mmol, 93%) as a yellow oil after workup and
purification by flash column chromatography (silica gel, 20%
ethyl acetate/hexanes): IR (CH2Cl2) 3615, 3065, 3046, 2984,
2938, 2882, 2047, 1977, 1607, 1474, 1424, 1383, 1281, 1263,
1
1418, 1292, 1157 cm-1; H NMR (400 MHz, CDCl3) δ 7.40-
7.42 (m, 3 H,), 7.18 (d, J ) 6.8 Hz, 2 H), 5.29 (m, 2 H), 4.76
(m, 1 H), 4.66 (m, 1 H), 2.45 (m, 1 H), 2.11 (m, 1 H), 1.79 (m,
1 H), 1.07 (d, J ) 7.3 Hz, 1 H), 0.36 (d, J ) 8.3 Hz, 1 H); 13C
NMR (100.4 MHz, CDCl3) δ 350.8, 224.3, 216.1, 211.3, 153.4
, 129.8, 128.3, 122.0, 88.1, 82.3, 80.8, 56.9, 40.5, 33.9; MS (EI,
70 eV) m/ e (relative intensity): 518 (M+, 5), 462 (8), 434 (10),
378 (59), 322 (49), 294 (100), 264 (32), 210 (14), 134 (17), 129
(27), 108 (20), 52 (41); HRMS (EI) m/ e calcd for C21H14CrFeO9
(M+) 517.9392, found 517.9396.
1246, 1042, 907, 841, 785, 633 cm-1 1H NMR (400 MHz,
;
CDCl3) δ 5.24 (m, 2 H), 3.73 (m, 1 H), 3.63 (dt, J ) 10.2, 7.3
Hz, 1 H), 1.98 (m, 1 H), 1.79 (m, 1 H), 1.72 (d, J ) 5.4 Hz, 1
H), 1.04 (q, J ) 7.3 Hz, 1 H), 0.31 (dd, J ) 8.3, 2.4 Hz, 1 H);
13C NMR (100.4 MHz, CDCl3) δ 211.8, 88.3, 81.6, 63.8, 59.5,
39.9, 36.9; MS (EI, 70 eV) m/ e (relative intensity) 238 (M+,
9), 210 (63), 182 (88), 154 (100), 134 (100), 108 (62), 56 (71)-
HRMS (EI) m/ e calcd for C9H10FeO4 (M+) 237.9928, found
237.9936.
Syn th esis of Ch r om iu m Ca r ben e Com p lex 6b. To a
solution of 47 (0.31 g, 0.83 mmol) in 12 mL of methylene
chloride was added acetyl bromide (0.062 mL, 0.83 mmol) at
-10 °C under nitrogen. The reaction mixture turned red
immediately. To the reaction mixture was added slowly a
solution of complex 5b (0.066g, 0.26 mmol) in 3.0 mL of CH2-
Cl2 at -10 °C. The reaction mixture was stirred at 0 °C for 2
h before being filtered through a bed of Celite. The resultant
solution was concentrated to give a crude mixture. Flash
column chromatography of the crude mixture (5% ethyl
acetate/hexanes) produced complex 6b (0.11g, 0.20 mmol, 77%)
as a red oil: IR (CH2Cl2) 3073, 3042, 2996, 2976, 2411, 2305,
2062, 2043, 1946, 1715, 1607, 1453, 1428, 1381, 1316, 1242,
1159, 1103, 929 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.37-7.44
(m, 3 H,), 7.18 (d, J ) 6.8 Hz, 2 H), 5.09 (m, 2 H), 4.76 (m, 1
H), 4.65 (m, 1 H), 2.43 (m, 1 H), 2.07 (m, 1 H), 1.40 (d, J ) 6.4
Hz, 3 H), 1.19 (m, 1 H), 1.03 (q, J ) 7.3 Hz, 1 H); 13C NMR
(100.4 MHz, CDCl3) δ 350.5 , 224.2, 216.1, 212.1, 153.5, 129.8,
128.3, 122.1, 85.9, 83.7, 81.0, 58.3, 55.8, 33.9, 19.1; MS (EI,
70 eV) m/ e (relative intensity): 532 (M+, 3), 476 (8), 392 (30),
364 (8), 336 (60), 308 (74), 278 (20), 256 (41), 226 (17), 198
(28), 174 (19), 129 (90), 80 (50), 52 (100); HRMS (EI) m/ e calcd
for C22H16CrFeO9 (M+) 531.9549, found 531.9546.
Syn th esis of [(3-6- )-tr a n s-3-tr a n s-5-Hep ta d ien ol]tr i-
ca r bon ylir on Com p lex (5b). To a stirred suspension of 0.32
g (1.04 mmol) of (η5-trans-1-methylpentadienyl)Fe(CO)3 cation4a
in 7.0 mL of CH2Cl2 was added a solution of 0.33 g (1.25 mmol)
of triphenylphosphine in 5 mL of methylene chloride under
nitrogen at 25 °C . The reaction mixture was allowed to stirred
at 25 °C for 12 h, and the solvent was concentrated under
reduced pressure. The residue was diluted with 5.0 mL of THF
and cooled to -78 °C. To the above solution was added slowly
n-butyllithium (0.8 mL, 1.2 mmol, 1.5 M in hexanes) via
syringe. The reaction mixture was allowed to stirred at -78
°C for 1 h followed by addition of 0.095 g (3.1 mmol) of
paraformaldehyde. The reaction was stirred at 0 °C for 6 h.
The mixture was diluted with 200 mL of hexane, and the
hexane solution was washed with water (200 mL × 3) and
brine (200 mL × 3), dried over anhydrous magnesium sulfate,
and concentrated to give the crude mixture. Flash column
chromatograpy of the crude mixture on the silica gel (hexanes)
gave [(3-6-η)-trans-3-trans-5-1,3,5-heptatriene]tricarbonyl-
iron complex (0.15 g, 0.65 mmol, 63%). To a solution of 0.26
g (1.1 mmol) of [(3-6-η) trans-3-trans-5-1,3,5-heptatriene]-
tricarbonyliron complex in 20 mL of THF was added a solution
of 1.0 M BH3‚THF (2.2 mL) under nitrogen at 0 °C. After 30
min at 0 °C, the mixture is stirred at 25 °C for an additional
F or m a tion of Dih yd r ofu r a n Ir on Com p lex 21a .
A
solution of complex 6a (0.32 g, 0.62 mmol) in 50 mL of toluene
was heated at reflux for 5 h. The reaction mixture was filtered
through a bed of Celite, and the solvent was concentrated.
Flash column chromatography of the residue (silica gel, 3%
(20) Stevens, R, V; Cherpeck, R. E.; Harrison, B. L.; Lai, J .; Lapalme,
R. J . Am. Chem. Soc. 1976, 98, 6317.

4444 Organometallics, Vol. 16, No. 20, 1997
Yeh et al.
ethyl acetate/hexanes) gave complex 21a (0.039 g, 0.12 mmol,
19%) as a yellow oil: IR (CH2Cl2) 3067, 3057, 3049, 2992, 2982,
2031, 1962, 1601, 1481, 1453, 1422, 1399, 1368, 1277, 1262,
1252, 1188, 1103, 1044, 856, 828, 812, 787, 748, 721, 691, 629
186 (M+, 100), 171 (26), 157 (5), 128 (4), 105 (13), 94 (2), 77
(7). HRMS (EI) m/z : calcd for C13H14O (M+) 186.1045, found
186.1051.
F or m a tion of F u r a n Der iva tive 22. A solution of com-
plex 6b (0.27 g, 0.51 mmol) in 50 mL of toluene was heated at
reflux for 5 h. The reaction mixture was filtered through a
bed of Celite, and the solvent was concentrated. Flash column
chromatography of the residue (silica gel, 3% ethyl acetate/
hexanes) gave complex 22 (0.050 g, 0.25 mmol, 49%) as a
colorless oil: IR (CH2Cl2) 3059, 2986, 2062, 1970, 1605, 1491,
1447, 1424, 1316, 1281, 1269, 1086, 1059, 1026, 903, 872, 822,
1
cm-1; H NMR (400 MHz, CDCl3) δ 7.21-7.08 (m, 5 H), 5.49
(d, J ) 8.8 Hz, 1 H), 4.21 (m, 2 H), 3.45 (td, J ) 10.7, 6.2 Hz,
1 H), 2.88 (m, 1 H), 1.38 (d, J ) 6.3 Hz, 3 H), 1.10 (dq, J ) 8.8,
6.3 Hz, 1 H); 13C NMR (100.4 MHz, CDCl3) δ 212.5, 136.1,
128.2, 127.8 and 127.5, 117.8, 89.9, 82.3, 65.3, 55.8, 34.4, 19.8;
MS (EI, 70 eV) m/ e (relative intensity) 326 (M+, 3), 298 (24),
270 (22), 242 (100), 212 (13),105 (9), 77 (14); HRMS (EI) m/ e
calcd for C16H14FeO4 (M+) 326.0241, found 326.0240.
1
752, 723, 666, 615 cm-1; H NMR (400 MHz, CDCl3) δ 7.31-
F or m a tion of Dih yd r ofu r a n Der iva tive 21b. To a
solution of CAN (1.0 g, 2.0 mmol) in 6 mL of ethanol was added
a solution of complex 21a (32 mg, 0.10 mmol) in 5.0 mL of
ethanol. The reaction was stirred at 25 °C under nitrogen for
18 h. The solvent was concentrated under reduced pressure,
and the residue was diluted with water (50 mL). The aqueous
solution was extracted with methylene chloride (30 mL × 3).
The resultant solution was washed with with water (100 mL
× 3) and brine (100 mL × 3), dried over anhydrous magnesium
sulfate (15 g), and concentrated to give the crude mixture.
Flash column chromatography of the crude mixture (silica gel,
3% ethylacetate/hexanes) gave 21b (12 mg, 0.65 mmol, 65%)
as a colorless oil. IR (CH2Cl2) 3067, 3050, 2984, 2930, 2305,
2047, 1975, 1603, 1493, 1424, 1376, 1316, 1262, 1069, 1028,
909, 868, 795, 758, 698, 639 cm-1; 1H NMR (400 MHz, CDCl3)
δ 7.53 (d, J ) 6.8 Hz, 2 H), 7.38 (dd, J ) 7.3, 6.8 Hz, 2 H),
7.31 (t, J ) 7.3 Hz, 1 H, H at C-12), 6.53 (d, J ) 15.6 Hz, 1 H),
5.46 (dq, J ) 15.6, 6.8 Hz, 1 H), 4.44 (t, J ) 9.3 Hz, 2 H), 2.93
(t, J ) 9.3 Hz, 2 H), 1.82 (d, J ) 6.8 Hz, 3 H); 13C NMR (100.4
MHz, CDCl3) δ 150.8, 131.7, 129.7, 128.2, 127.7, 124.4, 123.5,
111.0, 68.4, 32.3, 18.6; MS (EI, 70 eV) m/ e (relative intensity)
7.33 (m, 4 H), 7.22 (m, 1 H), 5.60 (d, J ) 1.5 Hz, 1 H), 4.01
(ddd, J ) 8.3, 6.8, 4.4 Hz, 1 H), 3.77 (td, J ) 8.3, 6.4 Hz, 1 H),
2.71 (m, 2 H), 2.17 (m, 2 H), 1.63 (m, 1 H), 1.50 (d, J ) 1.5 Hz,
3 H); 13C NMR (100.4 MHz, CDCl3) δ 144.7, 141.6, 128.1, 127.3,
126.5, 124.9, 99.7, 67.0 , 49.3 37.9, 35.9, 12.1; MS (EI, 70 eV)
m/ e (relative intensity) 200 (M+, 100), 185 (35), 171 (23), 156
(59), 128 (11), 123 (50), 105 (18), 95 (4), 77 (2); HRMS (EI)
m/ e calcd for C14H16O (M+) 200.1201, found 200.1195.
Ack n ow led gm en t . Support of this research from
the National Science Council (Grant NSC 85-2113-M-
003-007) of the Republic of China is gratefully acknowl-
edged.
Su p p or tin g In for m a tion Ava ila ble: ORTEP diagram
showing the atom-numbering scheme and tables of crystal-
lographic data and bond lengths and angles for 8a (5 pages).
Ordering information is given on any current masthead page.
OM9703301