Activation of the vinylic C-Cl bond by complexation of Fe(CO)3: Palladium-catalyzed coupling reactions of (η4-chlorodiene) tricarbonyliron complexes

Article abstract of DOI:10.1021/om0606800

The reactions of 1-chloro- or 2-chloro-substituted (η⁴-1,3- cyclohexadiene)Fe(CO)₃ complexes with terminal alkynes under the catalysis of PdCl2(PPh3)2/CuI at 45-60°C led to the formation of the corresponding Sonogashira coupling prod

Full text of DOI:10.1021/om0606800

Organometallics 2007, 26, 223-229
223
Activation of the Vinylic C-Cl Bond by Complexation of Fe(CO)3:
Palladium-Catalyzed Coupling Reactions of
(η4-Chlorodiene)tricarbonyliron Complexes†
Qian Chen and Chaozhong Li*
Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road,
Shanghai 200032, Peoples Republic of China
ReceiVed July 30, 2006
The reactions of 1-chloro- or 2-chloro-substituted (η4-1,3-cyclohexadiene)Fe(CO)3 complexes with
terminal alkynes under the catalysis of PdCl2(PPh3)2/CuI at 45-60 °C led to the formation of the
corresponding Sonogashira coupling products in 64-97% yields. The complexes also underwent smoothly
the intermolecular Heck reactions with activated alkenes under the catalysis of Pd(OAc)2/PPh3 at 60 °C
to afford the expected coupling products in 39-83% yields. On the other hand, the corresponding
uncomplexed molecule 2-chloro-1,3-cyclohexadiene remained inert under the same reaction conditions.
These results clearly demonstrated the strong activation effect of Fe(CO)3 on the oxidative cleavage of
the vinylic C-Cl bond.
tion of Cr(CO)3 to chloroarenes also significantly reduces the
C-Cl bond dissociation energies (BDEs).7
Introduction
Aryl and vinyl halides are important materials in synthetic
organic chemistry. Among them, aryl and vinyl chlorides are
especially attractive for synthetic purposes because of their ready
availability and low cost. However, the high stability of the
C(sp2)-Cl bond makes them inert in many cases.1
While the activation of aryl C-Cl bonds by the complexation
of a M(CO)3 moiety has been extensively investigated, the
possibility of activating vinylic C-Cl bonds remains virtually
unknown,8 although it is also well documented that the
coordination of a M(CO)3 such as Fe(CO)3 on a diene strongly
reduces the electron density of the CdC double bonds and
facilitates nucleophilic additions.9 Owing to the similarity
between aryl chlorides and vinyl chlorides and the even more
versatile chemistry of the latter, we extended our interests4,7 to
the activation of vinylic C-Cl bonds in alkene-metal com-
plexes. We here report that the complexation of Fe(CO)3 on
chlorodienes significantly activates the C(sp2)-Cl bond toward
oxidative Pd0 insertion. The effect of Fe(CO)3 on the C-Cl
BDEs is also briefly discussed.
It is well documented that the coordination of a Cr(CO)3 or
Mn(CO)3 moiety on an arene ring significantly reduces the
+
electron density of the arene ring and facilitates nucleophilic2
and radical3,4 additions. The complexation of Cr(CO)3 or Mn-
(CO)3+ also activates aryl C-Cl bonds toward oxidative addition
to Pd0 complexes, thus allowing a number of subsequent
reactions such as the Heck reaction or carbonylation to proceed
smoothly.5,6 More recently, we demonstrated that the coordina-
† Dedicated to Professor Jiabi Chen on the occasion of his 65th birthday.
* Corresponding author. E-mail: clig@mail.sioc.ac.cn.
(1) Grushin, V. V.; Alper, H. Chem. ReV. 1994, 94, 1047.
Results and Discussion
(2) For reviews, see: (a) Semmelhack, M. F. In ComprehensiVe Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: New York, 1991;
Vol. 4, p 517. (b) Semmelhack, M. F. In ComprehensiVe Organometallic
Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.;
Pergamon: New York, 1995; Vol. 12, p 979. (c) Pape, A. R.; Kaliappan,
K. P.; Ku¨ndig, E. P. Chem. ReV. 2000, 100, 2917. (d) Rose-Munch, F.;
Rose, E. Eur. J. Inorg. Chem. 2002, 1269. (e) Rose-Munch, F.; Rose, E. In
Modern Arene Chemistry; Astruc, D., Ed.; Viley-VCH: Weinheim,
Germany, 2002; p 368. (f) Transition Metal Arene π-Complexes in Organic
Synthesis and Catalysis. In Topics in Organometallic Chemistry; Ku¨ndig,
E. P., Ed.; Springer: Berlin, Germany, 2004; Vol. 7.
(3) (a) Schmalz, H.-G.; Siegel, S.; Bats, J. W. Angew. Chem., Int. Ed.
Engl. 1995, 34, 2383. (b) Schmalz, H.-G.; Siegel, S.; Schwarz, A.
Tetrahedron Lett. 1996, 37, 2947. (c) Hoffmann, O.; Schmalz, H.-G. Synlett
1998, 1426. (d) Merlic, C. A.; Miller, M. M.; Hietbrink, B. N.; Houk, K.
N. J. Am. Chem. Soc. 2001, 123, 4904. (e) Schwarz, O.; Brun, R.; Bats, J.
W.; Schmalz, H.-G. Tetrahedron Lett. 2002, 43, 1009. (f) Schmalz, H.-G.;
Kiehl, O.; Gotov, B. Synlett 2002, 1253.
(4) (a) Lin, H.; Zhang, H.; Yang, L.; Li, C. Org. Lett. 2002, 4, 823. (b)
Lin, H.; Yang, L.; Li, C. Organometallics 2002, 21, 3848. (c) Lin, H.; Yang,
L.; Li, C. Chin. J. Chem. 2003, 21, 797. (d) Lin, H.; Shen, M.; Yang, L.;
Li, C. Chin. J. Org. Chem. 2003, 23, 944. (e) Cao, L.; Shen, M.; Li, C.
Organometallics 2005, 24, 5983.
(5) For reviews, see: (a) Carpentier, J. F.; Petit, F.; Mortreux, A.; Dufaud,
V.; Basset, J.-M.; Thivolle-Cazat, J. J. Mol. Catal. 1993, 81, 1. (b) Prim,
D.; Andrioletti, B.; Rose-Munch, F.; Rose, E.; Couty, F. Tetrahedron 2004,
60, 3325.
The Sonogashira coupling of terminal alkynes with aryl/vinyl
halides and triflates serves as a straightforward and powerful
method for the formation of carbon-carbon bonds.10 However,
aryl/vinyl iodides or bromides are typically employed for the
coupling, while ordinary vinyl chlorides are usually unreactive
(6) For recent selected examples, see: (a) Jackson, R. F. W.; Turner,
D.; Block, M. H. Synlett 1996, 862. (b) Kamikawa, K.; Watanabe, T.;
Uemura, M. J. Org. Chem. 1996, 61, 1375. (c) Bra¨se, S. Tetrahedron Lett.
1999, 40, 6757. (d) Ku¨ndig, E. P.; Ratni, H.; Crousse, B.; Bernardinelli, G.
J. Org. Chem. 2001, 66, 1852. (e) Gotov, B.; Schmalz, H. G. Org. Lett.
2001, 3, 1753. (f) Gotov, B.; Kaufmann, J.; Schumann, H.; Schmalz, H. G.
Synlett 2002, 361. (g) Gotov, B.; Kaufmann, J.; Schumann, H.; Schmalz,
H. G. Synlett 2002, 1161. (h) Auffrant, A.; Prim, D.; Rose-Munch, F.; Rose,
E.; Schouteeten, S.; Vaissermann, J. Organometallics 2003, 22, 1898. (i)
Ku¨ndig, E. P.; Chaudhuri, P. D.; House, D.; Bernardinelli, G. Angew. Chem.,
Int. Ed. 2006, 45, 1092.
(7) Lin, H.; Chen, Q.; Cao, L.; Yang, L.; Wu, Y.-D.; Li, C. J. Org. Chem.
2006, 71, 3328.
(8) Fairlamb et al. reported the Suzuki coupling of a (bromo-η4-2-pyrone)-
Fe(CO)3 complex that proceeded under milder conditions than that of the
uncomplexed 2-pyrone. See: Fairlamb, I. J. S.; Syvanne, S. M.; Whitwood,
A. C. Synlett 2003, 1693.
(9) For reviews see: (a) Gre´e, R. Synthesis 1989, 341. (b) Cox, L. R.;
Ley, S. V. Chem. Soc. ReV. 1998, 27, 301.
10.1021/om0606800 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 12/07/2006

224 Organometallics, Vol. 26, No. 1, 2007
Chen and Li
Table 1. The Sonogashira Coupling of Complex 1a with
Phenylacetylene
Table 2. Sonogashira Reactions of Vinyl Chlorides 1a-c
and 5 at 60 °Ca
time
(h)
yield
(%)b
entry
1
conditionsa
Pd(OAc)2 (2.5 mol %), PPh3 (10 mol %),
Cs2CO3 (2 equiv), CH3CN, 65 °C
Pd(OAc)2 (10 mol %), PPh3 (20 mol %),
in Et3N, 45 °C
PdCl2(PPh3)2 (5 mol %), Cul (5 mol %),
in Et3N, 45 °C
4
4
3
20
64
93
2
3
b
a Phenylacetylene (1.0 equiv) was used. Isolated yield based on 1a.
under mild reaction conditions. In order to test the possible
activation of the vinylic C-Cl bond by coordination of Fe-
(CO)3, (η4-1-chloro-1,3-cyclohexadiene)Fe(CO)3 (1a),11 (η4-2-
chloro-1,3-cyclohexadiene)Fe(CO)3 (1b), and (η4-1-chloro-1,3-
butadiene)Fe(CO)3 (1c) were first prepared. The reaction of
2-chloro-1,3-cyclohexadiene with triiron dodecacarbonyl in
refluxing benzene afforded the mixture of 1a (62%) and 1b
(15%).12 Apparently the chlorodiene underwent partial isomer-
ization during the complexation process. Complex 1c was
synthesized similarly by reaction of triiron dodecacarbonyl with
a The yields were isolated yields based on the starting vinyl chlorides.
bThe reaction temperature was 45 °C.
1
1-chloro-1,3-butadiene (E/Z ) 6:1 determined by H NMR),
yields. Similarly, the 2-chloro-substituted diene-Fe(CO)3 com-
plex 1b underwent smooth coupling with terminal alkynes in
high efficiency. The yields of products 3a-c in the reactions
of 1b were even slightly higher than those of 2a-c in the
corresponding reactions of 1a. As the simpler analogue of 1a,
complex 1c also gave the corresponding coupling product 4 in
high yield. In all the cases tested for complexes 1a-c, the
expected coupling products were obtained in satisfactory yields
under mild experimental conditions. On the other hand, the
corresponding uncomplexed vinyl chlorides such as 2-chloro-
1,3-cyclohexadiene (5) did not give the expected coupling
products in reaction with phenylacetylene under the same
conditions (Table 2). Only the self-coupling of phenylacetylene
leading to the formation of 1,4-diphenyl-1,3-butadiyne was
observed, while the chloride 5 remained unchanged under the
above experimental conditions.
The above different reactivities of 1a-c and 5 in Sonogashira
coupling are noteworthy, which strongly indicates the activation
of the vinylic C-Cl bond toward Pd(0) insertion by complex-
ation with Fe(CO)3. The activation should be attributed to the
powerful electron-withdrawing effect of the Fe(CO)3 moiety.
The above mild reaction conditions also imply that the reactivity
of the complexed vinyl chlorides 1 toward Pd(0) insertion is
similar to that of an ordinary aryl iodide or bromide.13c
Moreover, the activation effect of Fe(CO)3 on vinylic C-Cl
bonds is comparable to that of Cr(CO)3 on aryl C-Cl bonds,14
as the Sonogashira coupling of (η6-chlorobenzene)Cr(CO)3 with
phenylacetylene was conducted under similar experimental
conditions but at refluxing temperature of THF.14c
which in turn was prepared in situ by the Wittig reaction of
acrolein with (chloromethyl)triphenylphosphonium bromide. We
then chose complex 1a as the model substrate to explore its
coupling reaction with phenylacetylene. Three conventional
literature procedures13 for the Sonogashira coupling of aryl
iodides were directly applied to the reaction of complex 1a,
and the results are listed in Table 1. To our delight, the expected
coupling product 2a was achieved in all three cases. With 5
mol % of PdCl2(PPh)3 as the catalyst and 5 mol % of CuI as
the cocatalyst,13c the reaction of 1a with phenylacetylene in
triethylamine at 45 °C for 3 h afforded complex 2a in 93%
yield (entry 3, Table 1).
We then prepared Fe(CO)3 complexes 1a-c and carried out
their Sonogashira reactions with terminal alkynes under the
catalysis of PdCl2(PPh)3/CuI without further optimization. The
results are summarized in Table 2. The coupling of 1a with
1-hexyne did not occur at 45 °C. However, when the reaction
temperature was raised to 60 °C, the reaction proceeded
smoothly and the coupling product 2b was achieved in 77%
yield. Other terminal alkynes such as 2-propyn-1-ol and 3-butyn-
1-ol also gave the expected coupling products 2c,d in high
(10) For reviews, see: (a) Sonogashira, K. In Metal-Catalyzed Cross-
Coupling Reactions; Diederich, F., Stang, P. J., Eds.; Wiley-VCH: Wein-
heim, Germany, 1998; p 203. (b) Sonogashira, K. In Handbook of
Organopalladium Chemistry for Organic Synthesis; Negishi, E., de Meijere,
A., Eds.; Wiley-VCH: New York, 2002; p 493. (c) Littke, A. F.; Fu, G. C.
Angew. Chem., Int. Ed. 2002, 41, 4176. (d) Negishi, E.; Anastasia, L. Chem.
ReV. 2003, 103, 1979.
(11) Slupczynski, M.; Wolszczak, I.; Kosztolowicz, P. Inorg. Chim. Acta
1979, 33, L97.
(12) The reaction of 2-chloro-1,3-cyclohexadinene with the more com-
monly used Fe2(CO)9 or Fe(CO)5 in refluxing benzene did not give any 1a
or 1b. With the catalysis of 1,4-diphenyl-1-aza-1,3-butadiene (40 mol %),
the above reaction (with Fe2(CO)9) afforded a mixture of 1a and 1b in
only 29% overall yield. A tentative explanation for these different results
is that the vinylic Cl-substitution reduces the electron density of the diene,
which becomes less reactive toward Fe(CO)3 complexation.
(13) (a) Cheng, J.; Sun, Y.; Wang, F.; Guo, M.; Xu, J.-H.; Pan, Y.; Zhang,
Z. J. Org. Chem. 2004, 69, 5428. (b) Ravikanth, M.; Strachan, J. P.; Li, F.;
Lindsey, J. S. Tetrahedron 1998, 54, 7721. (c) Takahashi, S.; Kuroyama,
Y.; Sonogashira, K.; Hagihara, N. Synthesis 1980, 627.
Having succeeded in the Sonogashira reactions of vinyl
chloride-Fe(CO)3 complexes 1, we were encouraged to explore
(14) For examples of Sonogashira couplings of (η6-chloroarene)Cr(CO)3
complexes, see: (a) Szewczyk, J.; Gryff-Keller, A. J. Organomet. Chem.
1992, 424, 41. (b) Mu¨ller, T. J. J.; Lindner, H. J. Chem. Ber. 1996, 129,
607. (c) Mu¨ller, T. J. J.; Ansorge, M.; Lindner, H. J. Chem. Ber. 1996,
129, 1433. (d) Mu¨ller, T. J. J.; Ansorge, M. Chem. Ber. 1997, 130, 1135.
(e) Mu¨ller, T. J. J.; Ansorge, M. Tetrahedron 1998, 54, 1457. (f) Mu¨ller,
T. J. J.; Ansorge, M.; Aktah, D. Angew. Chem. 2000, 112, 1323.

ActiVation of the Vinylic C-Cl Bond
Organometallics, Vol. 26, No. 1, 2007 225
Figure 1. ORTEP drawings of complexes 6a and 8b.
Table 3. Synthesis of 6a via the Reaction of 1a at 60 °C
to PPh3 was 2:1, 6a was achieved in 72% yield (entry 7, Table
3). Changing the base from Cs2CO3 to K2CO3 or the palladium
source from Pd(OAc)2 to Pd(dba)2 resulted in a decrease of the
product yield (entries 9 and 10, Table 3). Thus, we concluded
that the optimized combination for the Heck reaction of 1a was
to use 10 mol % of Pd(OAc)2 as the catalyst, 5 mol % of PPh3
as the ligand, 1.5 equiv of Cs2CO3 as the base, and CH3CN as
the solvent, and the reaction was set at 60 °C for 1 h.
We then conducted the Heck reactions of complexes 1a-c
under the optimized conditions. The results are illustrated in
Table 4. The reactions of 1a with activated alkenes afforded
the corresponding coupling products 6a-e in 34-72% yields
with an excellent stereoselectivity. Electron-rich alkenes such
as 1-octene were unreactive. Interestingly, the side-chain in
complexes 6 exists predominantly in an s-trans conformation,
as evidenced by the X-ray crystal structure of 6a and the 2D
NOESY spectra of 6b. This might be attributed to the steric
effect of the Fe(CO)3 moiety, which increases the rotational
barrier between s-trans and s-cis conformations.
Complex 1b also underwent smoothly the Heck reactions with
activated alkenes to give the coupling products as a mixture of
7a-d and 8b-d in moderate to good yields. Complexes 7b-d
and their isomers 8b-d could not be separated by column
chromatography on silica gel. Fortunately, we were able to
isolate compound 8b in a pure form by repeated recrystallization,
whose structure was firmly established by an X-ray diffraction
experiment (Figure 1). Apparently the initially formed com-
plexes 7b-d underwent partial isomerization to complexes
8b-d under the experimental conditions, which might be caused
by the electron-withdrawing carbonyl group in 7b-d.18 The
open-chain analogue of 1a, complex 1c, also reacted with
styrene to give the coupling product 9, albeit in 39% yield. As
a comparison, the parent vinyl chloride 5 was unreactive under
the above reaction conditions.
entrya
[Pd]/[PPh3]
base
solvent
yield (%)b
1
2
3
4
5
6
7
8
1/4
1/4
1/4
1/10
1/2
1/1
2/1
10/1
2/1
2/1
Et3N
THF
THF
26
30
43
19
63
65
72
60
65
47
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
K2CO3
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
9
10c
Cs2CO3
a Reaction conditions: 1a (0.22 mmol), styrene (0.88 mmol), Pd(OAc)2
b
(0.022 mmol), base (0.33 mmol), solvent (3 mL), PPh3, 60 °C, 1 h. Isolated
c
yield based on 1a. Pd(dba)2 was used.
their Heck reactions with alkenes. Palladium-catalyzed Heck
reactions have been intensively studied and firmly established
as a powerful tool in synthetic organic chemistry.15 However,
aryl (or vinyl) iodides or bromides are generally employed as
the substrates, while aryl or vinyl chlorides are usually unre-
active under similar conditions. To facilitate the Heck coupling
of aryl chlorides, harsh reaction conditions (higher temperature,
longer reaction time, etc.) or the use of exquisite electron-rich
phosphane ligands is usually required.10c,16
We first examined the reaction of complex 1a with styrene
under typical conditions for the Heck reaction of aryl iodides:
10 mol % of Pd(OAc)2 as the catalyst, 40 mol % of PPh3 as the
ligand, Et3N as the base, and THF as the solvent.17 When the
mixture was heated at 60 °C for 1 h, the expected product 6a
was obtained in 26% yield (eq 1), whose structure was
unambiguously determined by an X-ray diffraction experiment
shown in Figure 1.
The results in Table 4 have again demonstrated the powerful
activation effect of Fe(CO)3 on vinylic C-Cl bonds. The vinyl
chlorides in 1 are even more reactive than an ordinary aryl
bromide toward Heck coupling. For example, the Heck reaction
of an aryl bromide with acrolein under the catalysis of Pd(OAc)2/
PPh3 had to be conducted at a much higher temperature (130
°C).19 Again, the effect of Fe(CO)3 on a vinylic C-Cl bond
closely resembles that of Cr(CO)3 on a aryl C-Cl bond20 as
the Heck reaction of the p-chlorotoluene-Cr(CO)3 complex with
methyl vinyl ketone proceeded under similar experimental
conditions (PdCl2(PPh3)2, Et3N, 70 °C, 58% yield).20a
We then carried out a brief optimization of experimental
conditions for 1a, and the results are summarized in Table 3.
With the use of Cs2CO3 as the base, the yield of 6a was slightly
increased (entry 2, Table 3). Switching the solvent from THF
to CH3CN increased the yield further to 43% (entry 3, Table
3). The amount of PPh3 employed proved to be critical to the
outcome (entries 3-8, Table 3). When the ratio of Pd(OAc)2
(15) For reviews, see: (a) Cabri, W.; Candiani, I. Acc. Chem. Res. 1995,
28, 2. (b) de Meijere, A.; Meyer, F. E. Angew. Chem., Int. Ed. Engl. 1994,
33, 2379.
(16) For a review, see: (a) Whitcombe, N. J.; Hii, K. K.; Gibson, S. E.
Tetrahedron 2001, 57, 7449.
(17) For an example, see: Herrmann, W. A.; Brossmer, C.; Oefele, K.;
Beller, M.; Fischer, H. J. Mol. Catal. A: Chem. 1995, 103, 133.
(18) For similar examples, see: (a) Martina, D.; Brion, F. Tetrahedron
Lett. 1982, 23, 865. (b) Goldschmidt, Z.; Bakal, Y. J. Organomet. Chem.
1984, 269.191. (c) Hafner, A.; von Philipsborn, W.; Salzer, A. Angew. Chem.
1985, 97, 136; Angew. Chem., Int. Ed. Engl. 1985, 24, 126.
(19) For an example, see: Spencer, A. J. Organomet. Chem. 1984, 270,
115.

226 Organometallics, Vol. 26, No. 1, 2007
Chen and Li
Table 4. Heck Reactions of Vinyl Chlorides 1a-c and 5a
The vinylic C-Cl bond activation toward oxidative addition
also implies that the C-Cl BDEs of complexes 1 might be
lowered relative to the noncomplexed chlorodiene. Therefore,
as an extension, the C-Cl BDEs of complexes 1a and 1b as
well as their parent uncomplexed chlorodienes were estimated
by density functional calculations (B3LYP), which have been
demonstrated to be an accurate tool in the theoretical study of
iron complex systems.23 The geometries were optimized with
basis set I (BSI)s6-31G* for C, H, O, and Cl and LANL2DZ
for Fesand the energies were estimated with basis set II
(BSII)s6-311+G* for C, H, O, Cl and SDDALL for Fe.7
Vibrational frequency calculation was done for each structure,
and the calculated BDEs were enthalpy corrected (see the
Supporting Information for details). The calculations reveal that
the C-Cl BDE of complex 1a is 4.1 kcal/mol lower in energy
than that of 1-chloro-1,3-cyclohexadiene, while the C-Cl BDE
of 1b is 6.4 kcal/mol lower in energy than that of 2-chloro-
1,3-cyclohexadiene (5). The results indicate that the coordination
of Fe(CO)3 significantly reduces the C-Cl BDEs of chloro-
dienes by more than 4 kcal/mol, which is comparable to the
effect of Cr(CO)3 complexation on chlorobenzene (a reduction
of 4.5 kcal/mol).7 This implies that the radical chemistry of (η6-
chloroarene)Cr(CO)3 complexes might be extended to chloro-
diene-Fe(CO)3 complexes, which is now being actively pursued
in our laboratory.
Conclusion
In summary, the chemistry detailed above provides a facile
entry to the synthesis of various triene- and ynediene-Fe(CO)3
complexes with the simple (η4-chlorodiene)Fe(CO)3 complexes
as the starting materials. More importantly, these results clearly
demonstrate for the first time that the vinylic C-Cl bond is
significantly activated upon complexation with Fe(CO)3, thus
allowing a number of reactions such as Heck coupling and
Sonogashira coupling to proceed smoothly under mild reaction
conditions typical for aryl iodides. This finding should be of
important application in organic synthesis.
a The yields were isolated yields based on the corresponding complexes
1. Determined by H NMR.
b
1
The above successful Sonogashira reactions and Heck reac-
tions of complexes 1 clearly indicate the efficient activation of
the vinylic C-Cl bond toward Pd(0) insertion by complexation
of Fe(CO)3, which should be of important application in the
synthesis of other functionalized (η4-diene)Fe(CO)3 complexes.
For example, as a preliminary result, the palladium-catalyzed
reaction of complex 1a with 2-pyrrolidinone afforded the
corresponding substitution product 10 in 43% isolated yield
without further optimization (eq 2).
Experimental Section
NMR spectra were recorded in CDCl3 (1H at 300 MHz and 13
C
at 75.4 MHz) using TMS as an internal standard. Most products
were purified by flash chromatography on silica gel with hexane-
ethyl acetate in an appropriate ratio as the eluent. Melting points
are uncorrected. 2-Chloro-1,3-cyclohexadiene (5) was prepared
according to the literature method.24
(22) For examples, see: (a) Holmes, J. D.; Pettit, R. J. Am. Chem. Soc.
1963, 85, 2531. (b) Emerson, G. F.; Mahler, J. E.; Kochhar, R.; Pettit, R.
J. Org. Chem. 1964, 29, 3620. (c) Thompson, D. J. J. Organomet. Chem.
1976, 108, 381. (d) Shvo, Y.; Hazum, E. J. Chem. Soc., Chem. Commun.
1974, 336. (e) Brener, L.; McKennis, J. S.; Pettit, R. Org. Synth. 1976, 55,
43. (f) Franck-Neumann, M.; Heitz, M. P.; Martina, D. Tetrahedron Lett.
1983, 24, 1615. (g) Franck-Neumann, M.; Miesch-Gross, L; Gateau, C.
Eur. J. Org. Chem. 2000, 3693. (h) Franck-Neumann, M.; Geoffroy, P.;
Hanss, D. Tetrahedron Lett. 2002, 43, 2277.
(23) For recent examples, see: (a) Limanto, J.; Khuong, K. S.; Houk,
K. N.; Snapper, M. L. J. Am. Chem. Soc. 2003, 125, 16310. (b) Pandey, K.
K.; Lein, M.; Frenking, G. J. Am. Chem. Soc. 2003, 125, 1660. (c)
Quinonero, D.; Musaev, D. G.; Morokuma, K. Inorg. Chem. 2003, 42, 8449.
(d) Vrajmasu, V. V.; Muenck, E.; Bominaar, E. L. Inorg. Chem. 2004, 43,
4867. (e) Serres, R. G.; Grapperhaus, C. A.; Bothe, E.; Bill, E.; Weyher-
mueller, T.; Neese, F.; Wieghardt, K. J. Am. Chem. Soc. 2004, 126, 5138.
(f) Schobert, R.; Mangold, A.; Baumann, T.; Milius, W.; Hampel, F. J.
Organomet. Chem. 2004, 689, 575. (g) Danks, T. N.; Wagner, G. Dalton
Trans. 2005, 2933. (h) Byers, J. H.; Sontum, S. F.; Dimitrova, T. S.; Huque,
S.; Zegarelli, B. M.; Zhang, Y.; Jasinski, J. P.; Butcher, R. J. Organome-
tallics 2006, 25, 3787.
With the easy complexation of dienes with the Fe(CO)3
moiety21 and the ready decomplexation of diene-Fe(CO)3
complexes under mild conditions,22 the above methodology
should be of application in organic synthesis. As an example,
complex 2c underwent decomplexation to afford the corre-
sponding ynediene in 68% yield by treatment with H2O2
according to the literature procedure22f (see Supporting Informa-
tion). It should also be noted that the complexation offers not
only a reactivity enhancement but also an opportunity for
asymmetric synthesis because all complexes are chiral.6i
(20) For examples of Heck couplings of (η6-chloroarene)Cr(CO)3
complexes, see: (a) Scott, W. J. J. Chem. Soc., Chem. Commun. 1987,
1755. (b) Crousse, B.; Xu, L.-H.; Bernardelli, G.; Ku¨ndig, E. P. Synlett
1998, 658. (c) Ratni, H.; Crousse, B.; Ku¨ndig, E. P. Synlett 1999, 626. (d)
Kamikawa, K.; Harada, K.; Uemura, M. Tetrahedron: Asymmetry 2005,
16, 1419. (e) References 6c and 6d.
(24) Banerjee, S.; Engel, R.; Axelard, G. Phosphorus Sulfur 1983, 15,
15.
(21) For a review, see: Kno¨lker, H.-J. Chem. ReV. 2000, 100, 2941.

ActiVation of the Vinylic C-Cl Bond
Organometallics, Vol. 26, No. 1, 2007 227
(η4-1-Chloro-1,3-cyclohexadiene)tricarbonyliron (1a) and (η4-
2-chloro-1,3-cyclohexadiene)tricarbonyliron (1b). To a solution
of 2-chloro-1,3-cyclohexadiene (5) (5.3 g, 46 mmol) in anhydrous
benzene (350 mL) was added triiron dodecacarbonyl (11.6 g, 23
mmol) under nitrogen atmosphere. The mixture was refluxed for
24 h and then cooled to room temperature. The resulting mixture
was filtered, and the filtrate was concentrated under reduced
pressure. The residue was purified by flash chromatography on silica
gel using hexane as the eluent to give complex 1a (3.6 g, 62%
yield based on triiron dodecacarbonyl) and complex 1b (0.85 g,
15% yield based on triiron dodecacarbonyl). Complex 1a: yellowish
oil. IR (CH2Cl2): ν (cm-1) 2051, 1974. 1H NMR (300 MHz,
CDCl3): δ 1.68-1.72 (1H, m), 1.85-2.14 (3H, m), 3.08-3.13 (1H,
m), 5.12 (1H, dd, J ) 6.3, 5.4 Hz), 5.55 (1H, d, J ) 4.5 Hz). 13C
NMR (CDCl3): δ 25.3, 34.0, 60.3, 81.8, 84.6, 85.5, 210.6. EIMS:
m/z (rel intensity) 254 (M+, 6), 226 (37), 198 (13), 170 (40), 134
(88), 84 (30), 77 (51), 56 (100). HRMS calcd for C9H8ClFeO3 (M+
+ 1): 254.9511. Found: 254.9506. Complex 1b: yellowish oil.
IR (CH2Cl2): ν (cm-1) 2051, 1979. 1H NMR (300 MHz, CDCl3):
δ 1.49-1.60 (2H, m), 1.72-1.79 (2H, m), 2.96-3.00 (1H, m),
3.47-3.50 (1H, m), 5.64 (1H, d, J ) 6.3 Hz). 13C NMR (CDCl3):
δ 23.3, 25.3, 55.6, 63.6, 87.5, 109.0, 210.2. EIMS: m/z (rel
intensity) 254 (M+, 6), 226 (43), 198 (17), 170 (43), 134 (100), 91
(43), 77 (26), 56 (31). Anal. Calcd for C9H7ClFeO3: C, 42.48; H,
2.77. Found: C, 42.55; H, 3.03.
(35), 234 (100), 202 (19), 178 (58), 56 (48). Anal. Calcd for C15H16-
FeO3: C, 63.78; H, 3.78. Found: C, 63.91; H, 3.76.
Complex 2b: yellowish oil. IR (CH2Cl2): ν (cm-1) 2044,1969.
1H NMR (300 MHz, CDCl3): δ 0.91 (3H, t, J ) 6.9 Hz), 1.36-
1.47 (4H, m), 1.63-1.68 (2H, m), 1.84-1.88 (2H, m), 2.20 (2H,
t, J ) 6.9 Hz), 3.16-3.18 (1H, m), 5.17 (1H, dd, J ) 6.3, 4.2 Hz),
5.47 (1H, d, J ) 4.8 Hz). 13C NMR (CDCl3): δ 13.6, 19.0, 21.9,
25.0, 28.7, 30.9, 60.7, 61.2, 83.1, 84.4, 86.4, 88.2, 211.6. EIMS:
m/z (rel intensity) 272 (M+ - CO, 17), 244 (40), 216 (46), 214
(46), 172 (97), 115 (54), 91 (54), 56 (100). Anal. Calcd for C15H16-
FeO3: C, 60.03; H, 5.37. Found: C, 60.16; H, 5.19.
Complex 2c: yellowish oil. IR (CH2Cl2): ν (cm-1) 2044, 1969.
1H NMR (300 MHz, CDCl3): δ 1.53 (1H, t, J ) 6.0 Hz), 1.64-
1.68 (2H, m), 1.84-1.90 (2H, m), 3.24-3.26 (1H, m), 4.31 (2H,
d, J ) 6.3 Hz), 5.23 (1H, dd, J ) 6.3, 4.2 Hz), 5.52 (1H, d, J )
4.2 Hz). 13C NMR (CDCl3): δ 24.0, 27.1, 50.6, 56.7, 60.8, 82.1,
82.9, 87.1, 89.0, 210.1. EIMS: m/z (rel intensity): 273 (M+ - 1,
2), 246 (16), 218 (38), 190 (18), 172 (60), 150 (14), 115 (53), 56
(100). Anal. Calcd for C12H10FeO4: C, 52.59; H, 3.68. Found: C,
52.51; H, 3.88.
Complex 2d: yellowish oil; IR (CH2Cl2): ν (cm-1) 2043, 1969.
1H NMR (300 MHz, CDCl3): δ 1.62-1.77 (3H, m), 1.85-1.89
(2H, m), 2.50 (2H, t, J ) 6.0 Hz), 3.21-3.24 (1H, m) 3.69 (2H,
dt, J ) 6.6, 6.0 Hz), 5.21 (1H, dd, J ) 6.3, 4.2 Hz), 5.49 (1H, d,
J ) 4.2 Hz). 13C NMR (CDCl3) δ 23.8, 25.0, 28.5, 59.3, 61.2,
61.6, 82.1, 83.5, 86.4, 88.2, 211.5. EIMS: m/z (rel intensity) 287
(M+ - 1, 0.4), 260 (2), 232 (11), 148 (21), 128 (45), 117 (43),
115 (100), 91 (45). Anal. Calcd for C13H12FeO4: C, 54.20; H, 4.20.
Found: C, 54.31; H, 4.16.
Complex 2e: yellowish oil. IR (CH2Cl2): ν (cm-1) 2047, 1975.
1H NMR (300 MHz, CDCl3): δ 0.00 (9H, s), 1.48-1.54 (2H, m),
1.69-1.74 (2H, m), 3.07-3.09 (1H, m), 5.05 (1H, dd, J ) 5.4, 5.1
Hz), 5.38 (1H, d, J ) 4.2 Hz). 13C NMR (CDCl3): δ 0.0, 25.1,
27.8, 58.7, 61.6, 83.8, 88.4, 89.6, 109.8, 211.2. ESIMS: m/z 317
(M+ + 1). Anal. Calcd for C14H16FeO3Si: C, 53.18; H, 5.10.
Found: C, 53.08; H, 4.90.
Complex 3a: yellowish oil. IR (CH2Cl2): ν (cm-1) 2045, 1972.
1H NMR (300 MHz, CDCl3): δ 1.54-1.84 (4H, m), 3.16-3.21
(1H, m), 3.43-3.45 (1H, m), 5.67 (1H, d, J ) 6.3 Hz), 7.30-7.33
(3H, m), 7.45-7.48 (2H, m). 13C NMR (CDCl3): δ 23.7, 24.3,
60.9, 65.0, 84.9, 86.4, 87.6, 89.6, 122.7, 128.4, 128.5, 131.7, 211.0.
EIMS: m/z (rel intensity) 320 (M+, 1), 292 (16), 264 (35), 236
(20), 234 (100), 202 (19), 178 (61), 56 (40). Anal. Calcd for C15H16-
FeO3: C, 63.78; H, 3.78. Found: C, 64.13; H, 3.74.
Complex 3b: yellowish oil. IR (CH2Cl2): ν (cm-1) 2044, 1971.
1H NMR (300 MHz, CDCl3): δ 0.91 (3H, t, J ) 6.9 Hz), 1.38-
1.78 (8H, m), 2.30 (2H, t, J ) 6.9 Hz), 3.07-3.11 (1H, m), 3.32-
3.34 (1H, m), 5.52 (1H, d, J ) 6.3 Hz). 13C NMR (CDCl3): δ
13.6, 18.9, 21.9, 23.6, 24.2, 30.6, 60.1, 65.3, 78.4, 86.4, 87.8, 89.2,
211.2. EIMS: m/z (rel intensity) 272 (M+ - CO, 12), 244 (29),
216 (33), 214 (31), 186 (29), 172 (65), 115 (49), 56 (100). Anal.
Calcd for C15H16FeO3: C, 60.03; H, 5.37. Found: C, 60.24; H,
5.56.
Complex 3c: yellowish oil. IR (CH2Cl2): ν (cm-1) 2046, 1971.
1H NMR (300 MHz, CDCl3): δ 1.52-1.79 (5H, m), 3.13-3.18
(1H, m), 3.32-3.34 (1H, m) 4.39 (2H, d, J ) 6.0 Hz), 5.58 (1H,
d, J ) 6.6 Hz). 13C NMR (CDCl3): δ 23.6, 24.1, 51.4, 60.9, 64.9,
83.8, 84.0, 84.4, 89.7, 210.9. EIMS: m/z (rel intensity) 273 (M+
- 1, 1), 246 (17), 218 (34), 190 (8), 172 (63), 150 (87), 115 (55),
56 (100). Anal. Calcd for C12H10FeO4: C, 52.59; H, 3.68. Found:
C, 52.40; H, 3.83.
Complex 4: yellowish oil. 1H NMR (300 MHz, CDCl3): δ 0.41
(1H, dd, J ) 9.0, 1.8 Hz), 0.96 (1H, d, J ) 8.1 Hz), 1.49 (1H, t,
J ) 5.4 Hz), 1.85 (1H, dd, J ) 7.2, 2.7 Hz), 4.25 (2H, d, J ) 3.6
Hz), 5.26-5.33 (1H, m), 5.50 (1H, dd, J ) 8.4, 4.8 Hz). 13C NMR
(CDCl3): δ 38.1, 39.7, 51.6, 82.6, 83.5, 87.4, 88.1, 210.4. EIMS:
m/z (rel intensity) 230 (M+ - H2O, 18), 202 (5), 201 (49), 186
(η4-1-Chloro-1,3-butadiene)tricarbonyliron (1c). Butyllithium
(23 mL, 57.5 mmol, 2.5 M solution in hexanes) was added slowly
to (chloromethyl)triphenylphosphonium bromide (23 g, 59 mmol)
in anhydrous THF (150 mL) at -78 °C under nitrogen atmosphere.
After stirring for 15 min, acrolein (3.5 mL, 55 mmol) was
introduced slowly. The mixture was stirred at room temperature
for 4 h. Water (25 mL) was added. The reaction mixture was
directly distilled to give 1-chloro-1,3-butadiene solution in THF
(65-70 °C/760 mmHg). The solution was dried over anhydrous
Na2SO4 and then directly added to anhydrous hexane (200 mL)
under nitrogen atmosphere. Triiron dodecacarbonyl (5.8 g, 11.5
mmol) was then introduced. The mixture was refluxed for 24 h
and then cooled down to room temperature. The resulting mixture
was filtered, and the filtrate was concentrated under reduced
pressure. The residue was purified by flash chromatography on silica
gel using hexane as the eluent to give complex 1c (1.2 g, 47%
yield based on triiron dodecacarbonyl) as a yellowish oil. IR (CH2-
1
Cl2): ν (cm-1) 2048, 1975. H NMR (300 MHz, CDCl3): δ 0.19
(1H, dd, J ) 12.3, 3.0 Hz), 1.71-1.74 (1H, m), 2.48 (1H, d, J )
6.3 Hz), 5.17-5.25 (1H, m), 5.51 (1H, dd, J ) 11.1, 6.0 Hz). 13
C
NMR (CDCl3): δ 38.8, 63.7, 82.2, 86.1. EIMS: m/z (rel intensity)
228 (M+, 4), 200 (17), 172 (13), 144 (21), 108 (100), 91 (16), 84
(20), 56 (49). HRMS calcd for C7H5ClFeO3 (M+): 227.9277.
Found: 227.9275.
Typical Procedure for the Sonogashira Reaction of Com-
plexes 1. PdCl2(PPh3)2 (7 mg, 0.01 mmol) and CuI (2 mg, 0.01
mmol) were added successively to complex 1a (51 mg, 0.2 mmol)
in anhydrous Et3N (2 mL) under nitrogen atmosphere. After stirring
for 5 min at room temperature, phenylacetylene (0.024 mL, 0.2
mmol) was introduced. The mixture was stirred at 45 °C for 3 h.
Cold ice water (10 mL) was then added, and the reaction mixture
was extracted twice with diethyl ether (20 mL) and then dried over
anhydrous Na2SO4. After removal of the solvent, the residue was
then purified by flash chromatography on silica gel using hexane
as the eluent to give complex 2a as a yellowish oil. Yield: 58 mg
1
(93%). IR (CH2Cl2): ν (cm-1) 2044, 1971. H NMR (300 MHz,
CDCl3): δ 1.71-1.80 (2H, m), 1.92-1.98 (2H, m), 3.25-3.28 (1H,
m), 5.25 (1H, dd, J ) 6.3, 4.5 Hz), 5.63 (1H, d, J ) 4.5 Hz), 7.25-
7.28 (3H, m), 7.36-7.41 (2H, m). 13C NMR (CDCl3): δ 25.2, 28.1,
59.0, 61.7, 83.8, 85.5, 88.0, 93.9, 123.6, 127.8, 128.2, 131.4, 211.3.
EIMS: m/z (rel intensity) 320 (M+, 1), 292 (15), 264 (25), 236

228 Organometallics, Vol. 26, No. 1, 2007
Chen and Li
(30), 139 (29), 122 (47), 76 (49), 59 (100). HRMS calcd for C10H6-
FeO3 (M+ - H2O): 229.9666. Found: 229.9675.
(12), 236 (100), 179 (16), 178 (19), 56 (16). Anal. Calcd for C17H14-
FeO3: C, 63.38; H, 4.38. Found: C, 63.44; H, 4.31.
Typical Procedure for the Heck Reaction of Complexes 1.
Pd(OAc)2 (5 mg, 0.022 mmol), PPh3 (3 mg, 0.011 mmol), and
cesium carbonate (108 mg, 0.33 mmol) were added successively
to the solution of complex 1a (56 mg, 0.22 mmol) in anhydrous
CH3CN (3 mL) under nitrogen atmosphere. The mixture was stirred
at room temperature for 30 min. Styrene (0.11 mL, 0.88 mmol)
was then introduced, and the resulting mixture was stirred at 60
°C for 1 h. The reaction solution was cooled to room temperature,
and CH2Cl2 (20 mL) was added. The mixture was then filtered,
and the filtrate was concentrated under reduced pressure. The
residue was purified by flash chromatography on silica gel using
hexane as the eluent to give complex 6a as a yellowish solid.
Yield: 51 mg (72%). Mp: 109-110 °C. IR (KBr): ν (cm-1) 2028,
1974. 1H NMR (300 MHz, CDCl3): δ 1.52-1.68 (1H, m), 1.76-
1.87 (1H, m), 1.93-2.04 (1H, m), 2.23-2.33 (1H, m), 3.27-3.32
(1H, m), 5.27 (1H, dd, J ) 6.3, 4.5 Hz), 5.45 (1H, d, J ) 4.2 Hz),
6.47 (2H, AB, J ) 16.8 Hz), 7.18-7.40 (5H, m). 13C NMR
(CDCl3): δ 24.3, 24.4, 61.3, 78.2, 82.3, 87.2, 125.6, 126.0, 127.2,
128.7, 134.8, 137.3, 212.1. EIMS: m/z (rel intensity) 322 (M+, 3),
294 (25), 266 (19), 238 (21), 237 (18), 236 (100), 234 (15), 178
(17). Anal. Calcd for C17H14FeO3: C, 63.38; H, 4.38. Found: C,
63.22; H, 4.47.
Complexes 7b and 8b: yellowish oil. Two isomers in ∼1:1 ratio.
1H NMR (300 MHz, CDCl3) 7b: δ 1.63-1.67 (2H, m), 1.74-
1.89 (2H, m), 2.33 (3H, s), 3.37-3.39 (1H, m), 3.51-3.53 (1H,
m), 5.57 (1H, d, J ) 7.5 Hz), 6.43 (1H, d, J ) 16.2 Hz), 7.20 (1H,
d, J ) 15.3 Hz); 8b: δ 1.15 (1H, d, J ) 8.1 Hz), 1.77-1.79 (1H,
m), 1.93-2.13 (2H, m), 2.13 (3H, s), 2.23-2.32 (2H, m), 5.72
(1H, d, J ) 8.1 Hz), 6.04-6.08 (1H, m), 6.40 (1H, d, J ) 9.6 Hz).
13C NMR (CDCl3) 7b: δ 23.9, 24.4, 27.7, 59.6, 64.0, 89.1, 97.8,
125.5, 143.9, 203.6, 210.7; 8b: δ 22.8, 23.8, 29.7, 51.5, 57.9, 78.3,
95.4, 125.4, 132.4, 197.7, 209.6. EIMS: m/z (rel intensity) 288
(M+, 1), 260 (2), 232 (21), 204 (28), 202 (88), 148 (68), 56 (100),
40 (84). Anal. Calcd for C13H12FeO4: C, 54.20; H, 4.20. Found:
C, 54.19; H, 4.21.
Complexes 7c and 8c: yellowish oil. Two isomers in ∼3:1 ratio.
1
IR (CH2Cl2): ν (cm-1) 2046, 1972, 1674. H NMR (300 MHz,
CDCl3) 7c: δ 1.61-1.69 (2H, m), 1.84-1.94 (2H, m), 3.40-3.43
(1H, m), 3.50-3.52 (1H, m), 5.60 (1H, d, J ) 7.5 Hz), 6.38 (1H,
dd, J ) 15.9, 7.5 Hz), 7.20 (1H, d, J ) 15.6 Hz), 9.63 (1H, d, J )
7.2 Hz); 8c: δ 1.17 (1H, dd, J ) 8.1, 4.2 Hz), 1.77-1.79 (1H, m),
1.93-2.13 (2H, m), 2.23-2.32 (2H, m), 5.70 (1H, d, J ) 8.1 Hz),
6.08-6.12 (1H, m), 6.40 (1H, d, J ) 9.6 Hz), 9.32 (1H, d, J ) 4.2
Hz). 13C NMR (CDCl3) 7c: δ 23.8, 24.4, 59.9, 64.8, 78.0, 89.5,
125.0, 153.2, 192.9, 210.4; 8c: δ 22.8, 23.7, 52.3, 58.8, 94.2, 98.8,
126.9, 133.0, 196.8, 209.1. EIMS: m/z (rel intensity) 274 (M+, 1),
246 (2), 218 (14), 190 (17), 188 (32), 160 (14), 56 (65), 40 (100).
Anal. Calcd for C12H10FeO4: C, 52.59; H, 3.68. Found: C, 52.36;
H 3.65.
Complex 6b: yellowish solid. Mp: 78-79 °C. IR (CH2Cl2): ν
1
(cm-1) 2043, 1969, 1665. H NMR (300 MHz, CDCl3): δ 1.49-
1.53 (1H, m), 1.82-1.84 (1H, m), 1.98-2.06 (2H, m), 2.26 (3H,
s), 3.42-3.46 (1H, m), 5.36 (1H, dd, J ) 6.3, 4.5 Hz), 5.55 (1H,
d, J ) 4.2 Hz), 6.09 (1H, d, J ) 16.2 Hz), 6.81 (1H, d, J ) 15.9
Hz). 13C NMR (CDCl3): δ 23.9, 24.7, 27.2, 62.9, 73.2, 84.4, 89.1,
124.3, 150.7, 197.9, 210.8. EIMS: m/z (rel intensity) 288 (M+, 1),
260 (5), 232 (27), 204 (36), 202 (96), 148 (100), 105 (38), 56 (75).
Anal. Calcd for C13H12FeO4: C, 54.20; H, 4.20. Found: C, 54.22;
H, 4.15.
Complexes 7d and 8d: yellowish oil. Two isomers in ∼6:1 ratio.
IR (KBr): ν (cm-1) 2043, 1968, 1717. 1H NMR (300 MHz, CDCl3)
7d: δ 1.60-1.65 (2H, m), 1.81-1.87 (2H, m), 3.32-3.34 (1H,
m), 3.46-3.49 (1H, m), 3.77 (3H, s), 5.54 (1H, d, J ) 6.6 Hz),
6.12 (1H, d, J ) 15.6 Hz), 7.37 (1H, d, J ) 15.6 Hz); 8d: δ 1.19
(1H, d, J ) 8.1 Hz), 1.77-1.79 (1H, m), 1.93-2.13 (2H, m), 2.23-
2.32 (2H, m), 3.66 (3H, s), 5.72 (1H, d, J ) 8.1 Hz), 6.01-6.08
(1H, m), 6.41 (1H, d, J ) 9.6 Hz). 13C NMR (CDCl3) 7d: δ 23.8,
24.4, 51.7, 59.4, 63.7, 80.0, 89.0, 116.5, 145.3, 166.5, 210.8.
EIMS: m/z (rel intensity) 304 (M+, 2), 276 (13), 248 (21), 220
(15), 218 (52), 160 (100), 131 (27), 56 (49). Anal. Calcd for C13H12-
FeO5: C, 51.35; H, 3.98. Found: C, 51.64; H, 4.01.
Complex 6c: yellowish solid. Mp: 110-111 °C. IR (CH2Cl2):
ν (cm-1) 2044, 1972, 1673. 1H NMR (300 MHz, CDCl3): δ 1.50-
1.56 (1H, m), 1.80-1.87 (1H, m), 1.97-2.09 (2H, m), 3.48-3.50
(1H, m), 5.38 (1H, dd, J ) 6.3, 4.2 Hz), 5.60 (1H, d, J ) 4.2 Hz),
6.13 (1H, dd, J ) 15.6, 7.8 Hz), 6.79 (1H, d, J ) 15.6 Hz), 9.50
(1H, d, J ) 7.5 Hz). 13C NMR (CDCl3): δ 23.9, 24.8, 63.5, 72.5,
84.9, 89.1, 126.1, 160.3, 193.4, 210.5. EIMS: m/z (rel intensity)
274 (M+, 1), 246 (8), 218 (27), 190 (27), 188 (62), 160 (30), 56
(100), 40 (61). Anal. Calcd for C12H10FeO4: C, 52.59; H, 3.68.
Found: C, 52.50; H, 3.66.
Complex 9: yellowish solid. Mp: 109-110 °C. IR (CH2Cl2):
1
ν (cm-1) 2042, 1971. H NMR (300 MHz, CDCl3): δ 0.61 (1H,
1
dd, J ) 9.3, 2.7 Hz), 1.86 (1H, dd, J ) 6.6, 2.1 Hz), 2.00 (1H, dd,
J ) 9.6, 9.3 Hz), 5.23-5.31 (1H, m), 5.48 (1H, dd, J ) 9.0, 4.5
Hz), 6.22 (1H, dd, J ) 15.3, 9.9 Hz), 6.57 (1H, d, J ) 15.3 Hz),
7.18-7.36 (5H, m). 13C NMR (CDCl3): δ 39.6, 63.1, 81.5, 85.8,
126.0, 127.4, 128.7, 130.2, 131.0, 137.2, 211.5. EIMS: m/z (rel
intensity) 296 (M+, 1), 268 (21), 240 (20), 212 (76), 134 (94), 115
(28), 91 (49), 56 (100). Anal. Calcd for C15H12FeO3: C, 60.84; H,
4.08. Found: C, 60.72; H, 4.40.
Complex 6d: yellowish oil. H NMR (300 MHz, CDCl3): δ
1.43-1.53 (1H, m), 1.74-1.86 (1H, m), 1.92-2.09 (2H, m), 3.37-
3.42 (1H, m), 3.74 (3H, s), 5.33 (1H, dd, J ) 6.3, 4.2 Hz), 5.53
(1H, d, J ) 4.2 Hz), 5.82 (1H, d, J ) 15.6 Hz), 7.03 (1H, d, J )
15.6 Hz). 13C NMR (CDCl3): δ 23.9, 24.6, 51.5, 62.7, 73.0, 84.1,
89.0, 114.6, 151.7, 167.5, 210.8. EIMS: m/z (rel intensity) 304
(M+, 3), 276 (25), 248 (23), 220 (30), 218 (66), 190 (17), 160 (100),
56 (23). HRMS calcd for C13H12FeO5: 304.0034. Found: 304.0034.
Complex 10. Pd(OAc)2 (4.5 mg, 0.02 mmol), PPh3 (10.5 mg,
0.04 mmol), and cesium carbonate (98 mg, 0.3 mmol) were added
successively to the solution of complex 1a (51 mg, 0.2 mmol) in
anhydrous toluene (5 mL) under nitrogen atmosphere. The mixture
was stirred at room temperature for 30 min. 2-Pyrrolidinone (20
mg, 0.24 mmol) was then introduced, and the resulting mixture
was stirred at 85 °C for 1 h. The resulting solution was cooled to
room temperature, and CH2Cl2 (20 mL) was added. The mixture
was then filtered, and the filtrate was concentrated under reduced
pressure. The residue was then purified by flash chromatography
on silica gel (petroleum ether/ethyl acetate, 4:1) to give complex
Complex 6e: yellowish solid. Mp: 112-113 °C. IR (KBr): ν
1
(cm-1) 2214, 2045, 1970. H NMR (300 MHz, CDCl3): δ 1.44-
1.48 (1H, m), 1.80-2.06 (3H, m), 3.43-3.48 (1H, m), 5.22 (1H,
d, J ) 15.9 Hz), 5.36 (1H, dd, J ) 6.0, 5.1 Hz), 5.60 (1H, d, J )
3.9 Hz), 6.70 (1H, d, J ) 15.9 Hz). 13C NMR (CDCl3): δ 23.2,
24.4, 63.1, 71.7, 84.5, 88.4, 92.4, 118.7, 157.3, 210.3. EIMS: m/z
(rel intensity) 271 (M+, 3), 243 (15), 215 (26), 187 (60), 185 (100),
91 (14), 84 (18), 56 (49). Anal. Calcd for C12H9FeNO3: C, 53.17;
H, 3.35; N, 5.17. Found: C, 53.07; H, 3.28; N, 5.01.
1
Complex 7a: yellowish oil. H NMR (300 MHz, CDCl3): δ
1.52-1.72 (2H, m), 1.74-1.94 (2H, m), 3.20-3.24 (1H, m), 3.66-
3.68 (1H, m), 5.50 (1H, d, J ) 6.3 Hz), 6.79 (2H, AB, J ) 15.9
Hz), 7.23-7.46 (5H, m). 13C NMR (CDCl3): δ 24.2, 24.5, 59.1,
61.2, 85.8, 101.1, 126.6, 127.9, 128.0, 128.1, 128.6, 136.5, 211.6.
EIMS: m/z (rel intensity) 322 (M+, 4), 294 (29), 266 (20), 238
1
10 as a yellowish oil. Yield: 26 mg (43%). H NMR (300 MHz,
CDCl3): δ 1.52-1.58 (1H, m), 1.65-1.74 (1H, m), 1.79-1.90 (1H,
m), 1.96-2.08 (3H, m), 2.39-2.45 (2H, m), 3.17-3.20 (1H, m),
3.28-3.35 (1H, m), 3.70-3.77 (1H, m), 5.22 (1H, dd, J ) 6.0, 5.4

ActiVation of the Vinylic C-Cl Bond
Organometallics, Vol. 26, No. 1, 2007 229
Hz), 6.32 (1H, d, J ) 4.8 Hz). 13C NMR (CDCl3): δ 18.3, 24.1,
25.7, 32.3, 49.9, 61.3, 80.9, 84.6, 85.2, 173.7, 211.7. EIMS: m/z
(rel intensity) 303 (M+, 1), 217 (78), 163 (43), 162 (100), 106 (86),
77 (50), 56 (39), 41 (41). HRMS calcd for C13H13FeNaNO4 (M+
+ Na): 326.0092. Found: 326.0099.
and 20672136). We thank Prof. Yun-Dong Wu of HKUST for
valuable discussions on this project.
Supporting Information Available: 1H and 13C NMR spectra
of the compounds without elemental analysis, 2D NOESY spectrum
of 6b, and DFT calculation results (PDF) as well as X-ray crystal
data of complexes 6a and 8b (CIF). This material is available free
of charge via the Internet at http://pubs.acs.org.
Acknowledgment. This project was supported by the
National Natural Science Foundation of China (Nos. 20325207
OM0606800