Iron-catalyzed transformations of 2-chloro-1,6-heptadienes

Article abstract of DOI:10.1002/ejoc.200300660

(Phosphane)iron complexes in the presence of excess trialkylaluminium reagents catalyze various transformations of 2-chloro-α,ω-dienes, depending on their structure. Most notably, in the cases of simple 2-chloro-1,6-heptadienes, cyclization with transfer of the alkyl group (Me and Et) from the corresponding trialkylaluminium compound was observed to give 2-alkyl-1-methylidenecyclopentanes. Reaction with 2-chloro-1,7-octadiene afforded the product of reductive dehalogenation. In the case of 2-chloro-4-aza-1,6-heptadiene a partial or complete hydrogenation of the double bonds was observed depending on the amount of trialkylaluminum reagent used. Interestingly, allyl(2-chloroallyl)malonate underwent C-C bond cleavage with the loss of an allyl group to give (2-chloroallyl)malonate. In the presence of ruthenium catalysts only reductive dehalogenation was observed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejoc.200300660

FULL PAPER
Iron-Catalyzed Transformations of 2-Chloro-1,6-heptadienes
[a]
[a]
[b]
David Ne cˇ as, Martin Kotora,* and Ivana C ´ı sa rˇ ov a´
Keywords: Carboferration / Cyclization / Dienes / Homogeneous catalysis / Iron
(
Phosphane)iron complexes in the presence of excess trialky-
partial or complete hydrogenation of the double bonds was
observed depending on the amount of trialkylaluminum re-
laluminium reagents catalyze various transformations of 2-
chloro-α,ω-dienes, depending on their structure. Most not- agent used. Interestingly, allyl(2-chloroallyl)malonate under-
ably, in the cases of simple 2-chloro-1,6-heptadienes, cycliza- went C−C bond cleavage with the loss of an allyl group to
tion with transfer of the alkyl group (Me and Et) from the
corresponding trialkylaluminium compound was observed to
give 2-alkyl-1-methylidenecyclopentanes. Reaction with 2-
give (2-chloroallyl)malonate. In the presence of ruthenium
catalysts only reductive dehalogenation was observed.
chloro-1,7-octadiene afforded the product of reductive deha- ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
logenation. In the case of 2-chloro-4-aza-1,6-heptadiene a
Germany, 2004)
Introduction
Results and Discussion
The development of efficient and cheap catalytic systems
Our initial interest stemmed from the fact that it would
for complex transformations of organic compounds is of be of general synthetic interest to explore possibilities of
general synthetic interest. Iron and its compounds, because replacing the usually expensive palladium catalysts by much
of their low cost and non-toxicity, are ideal starting materi- cheaper iron catalysts. One such reaction that would benefit
als for such a venture. In their pioneering work almost 30 from this is the Pd-catalyzed Heck reaction, in particular
years ago, Kochi and co-workers clearly showed the syn- its intramolecular variant: cyclization of 2-halo-1,6-dienes
[
13,14]
thetic potential of iron-based catalysts for cross-coupling gives 1,3-dimethylenecycloalkanes.
For that purpose,
[
1]
reactions. However, these findings were overshadowed by we decided to mimic the Pd-based catalytic system by the
the introduction of Pd catalysts. Nevertheless, in recent ye- use of a mixture of FeCl /3PPh (5 mol %), with an excess
3
3
ars there has been a revival of interest in the development of AlEt as a reductant and carrying out the reaction in
3
of iron-based catalysis in organic synthesis. For example, toluene at 20 °C for 36 h. Gratifyingly, a reaction was ob-
iron compounds have been used as catalysts for cross served, although compound 2a was formed in 57% yield
[
2Ϫ4]
[5]
[6]
coupling,
cycloadditions, CO insertion, carbozinc- instead of the expected Heck-type product (Scheme 1). The
[
7]
[8]
[9]
ation, carbolithiation, carboalumination, conjugated formation of compound 2, which is the product of ethyl
[
10]
[11]
addition,
ein we would like to present results obtained in a study of molecular alkyl-group transfers during the Heck reaction
phosphane)iron-catalyzed reactions of 2-chloro-α,ω-dienes under Pd catalysis are rare.[11] Moreover, no traces of the
with trialkylaluminium reagents, notably the alkylative expected exocyclic 1,3-diene (the Heck reaction product)
and vinylcyclopropane rearrangement.
Her- group transfer and cyclization, is significant, because inter-
(
cyclization of 2-chloro-1,6-heptadienes.[
12]
were found in the reaction mixture. This result caught our
attention and we set out to check the influence of an Fe-
based catalytic system on the course of the reaction. The
results are summarized in Table 1.
[
[
a]
b]
Department of Organic and Nuclear Chemistry, Faculty of
Science, Charles University,
Albertov 2030, 12843 Prague 2, Czech Republic
Fax: (internat.) ϩ 420-221/951-326
E-mail: kotora@natur.cuni.cz
Department of Inorganic Chemistry, Faculty of Science,
Charles University,
Albertov 2030, 12843 Prague 2, Czech Republic
Fax: (internat.) ϩ 420-221/951-253
E-mail: cisarova@natur.cuni.cz
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Scheme 1. Fe-catalyzed alkylative cyclization of 2-chloro-1,6-diene
(1a) to 2-alkyl-1-methylenecyclopentanes 2a
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejoc.200300660
Eur. J. Org. Chem. 2004, 1280Ϫ1285

Iron-Catalyzed Transformations of 2-Chloro-1,6-heptadienes
FULL PAPER
Table 1. Ligand effect on the Fe-catalyzed cyclization of 1a to 2a
sulted only in low yields of 3a. The structure of 3a was
unequivocally confirmed by a single-crystal X-ray analysis
(Figure 1). The cyclization of chlorodiene 1b (19:1 mixture
of trans and cis isomers), bearing a 2-butenyl moiety, gave
rather low yields of the corresponding products with both
Entry[a]
Fe salt[b]
Yield [%][c]
Ligand
PPh
DPEphos
dppe
dppp
dppb
dppf
mol %
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
3
3
3
3
3
3
3
3
3
3
3
15
5
5
5
5
57 (30)
80 (60)
0
0
34
19
51
46
47
56
21
28
27
40
42
40
87 (65)
catalytic systems. The reaction with AlEt gave 2b as a mix-
3
1
ture of diastereoisomers in a 3:1 ratio (according to H and
C NMR spectroscopy) in 30% and 29% yields and with
13
AlMe gave 3b in 23% and 24% yields, respectively. Interest-
5
3
P(o-tolyl)
P(O)PPh
P(OEt)
AsPh
3
15
15
15
15
ingly, the use of MAO as the source of the methyl group
did not result in any reaction. Surprisingly, attempts to
carry out alkylative cyclization with 1c, bearing a methallyl
3
3
0
1
2
3
4
5
6
7
3
moiety, were not successful. The reaction of 1c with AlEt3
[Fe(acac)
3
]
]
]
Fe(acac)
[Fe(acac)
[Fe(dbm)
[Fe(dbm)
[Fe(dbm)
3
PPh
DPEphos
3
15
5
resulted in the formation of a complex reaction mixture in
3
which only the starting material 1c and the product of the
cross-coupling reaction (2c; 47%) were identified by spec-
troscopic methods (GC-MS, NMR spectroscopy). Also, the
reaction with AlMe3 furnished only traces of the cross-
coupling product 3c. Similarly, the use of 1d, bearing a 3-
3
3
3
]
]
]
PPh
DPEphos
3
15
5
[FeCl
2
(PPh
3
)
2
]
[
a]
[b]
Reactions were carried out at 20 °C. 5 mol % of iron salt was butenyl moiety, in the reaction with AlEt did not give the
3
[
c] 1
used.
H NMR yields. Isolated yields are in parentheses.
cyclized product, instead reductive dehalogenation to 4d
was observed in 80% yield.
These results clearly show that the course of the reaction
is governed to a great extent by both the counterion in the
Fe salt and the nature of the ligand. The good result, 80%
yield of 2, was obtained with a combination of the biden-
Table 2. Alkylative cyclization of 2-chloro-α,ω-dienes 1 in the pres-
ence of Fe catalysts and alkylaluminium reagents
tate phosphane DPEphos and FeCl (Entry 2). The use of
3
other bidentate phosphanes either did not result in any re-
action (Entry 3,4) or gave low yields of 2 (Entries 5, 6).
Monodentate phosphanes and arsanes (Entries 7Ϫ10) gave
similar results to the one obtained with PPh (Entry 1).
3
Interestingly, the use of iron() 1,3-dionates [Fe(acac) and
3
Fe(dbm) ], which are known to be good catalysts for cross-
3
coupling reactions, gave rather low yields of the cyclized
product 2a whether alone (Entries 11, 14) or in a combi-
nation with phosphanes (Entries 12, 13, 15, 16). Interest-
ingly, the best yield of 2a (87%) was obtained in the reaction
[15]
with rather unstable [FeCl (PPh ) ] (Entry 17).
In ad-
2
3 2
dition, when the reaction was carried out at 80 °C, even
monodentate phosphanes such as PPh and P(o-tolyl) were
3
3
as effective as DPEphos, and compound 2a was formed in
80 and 83% yield, respectively.
Our subsequent work was directed to check the scope of
the reaction with respect to: (i) the double-bond substi-
tution in 1, (ii) the extent of the Me and Et group transfer,
(
iii) a catalytic system (ligand and metal effect), and (iv) the
[
a]
source of the transferable alkyl group (various alkylalu-
minium compounds as well as other potential organometal-
lic reagents were tested). In this regard the cyclization was
checked with variously substituted 2-chloro-1,6-heptadienes
A ϭ FeCl
3
(5 mol %)/DPEphos (10 mol %), B ϭ FeCl
3
(5
[
b] 1
mol %)/PPh
3
(15 mol %).
H NMR yields. Isolated yields are in
[
c]
[d]
parentheses. 3:1 mixture of diastereoisomers. Yield and struc-
ture determined by GC-MS analysis.
1aϪd, with various catalytic systems under different reac-
tion conditions. The results are summarized in Table 2. In
Reaction with other stronger or weaker Lewis-acidic or-
the case of alkylative cyclization of 1a ethyl-group transfer ganometallic reagents, such as chlorodiethylaluminium (Al-
proceeded well with both catalytic systems A and B, fur- ClEt ), triethylborane (BEt ), and diethylzinc (ZnEt ), did
2
3
2
nishing 2a in 80 and 83% yields, respectively. Methyl-group not yield any products and the starting material remained
transfer proceeded well with AlMe and catalyst B affording intact. Attempts to carry out the reaction with simple α,ω-
3
73% of 3a. Attempts to induce cyclization with MAO re- dienes were also unsuccessful.
Eur. J. Org. Chem. 2004, 1280Ϫ1285
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1281

D. Ne c˘ as, M. Kotora, I. C ´ı sa r˘ ov a´
FULL PAPER
step of the reaction mechanism is not oxidative addition of
the CϪCl bond to the reduced iron atom and that it must
proceed through a different pathway. This is supported by
the following facts. Firstly, attempts to achieve cross-coup-
ling with several vinyl chlorides (cyclohexenyl chloride, β-
chlorostyrene) and AlEt were not successful. In the former
3
case an intractable mixture was formed, and in the latter
the cross-coupling product was formed in only 10% yield.
Similar phenomena have been observed previously.[ Sec-
ondly, the reaction of 1a with an organomagnesium reagent
3b]
[
4]
resulted only in the cross-coupling reaction. Although we
were not able to track the course of the reaction mixture
by spectroscopic methods (NMR studies did not give any
information), we assume that the catalytically active species
is a cationic alkyliron() complex that is generated by the
reaction of iron() compounds with trialkylaluminium
compounds. It has been shown that iron complexes undergo
Figure 1. View of 3a with displacement ellipsoids set at 50% prob-
[
16]
[17]
alkylation and reduction, resulting in the formation of
alkyliron() species. It is reasonable to expect that the excess
of trialkylaluminium reagent ensures that the iron() com-
ability
[
18]
plexes are converted into the cationic species.
However,
Ruthenium, which is in the same group as iron, was ex-
pected to have similar properties and, as expected, conver-
sion of the starting materials 1aϪd was observed in the
presence of a catalytic amount of [RuCl (PPh ) ] (5 mol %)
the alkylaluminium complexes differ in their reactivity with
[
19]
non-stabilized alkyliron compounds.
The formation of
cationic species is supported by the observation that the re-
action does not proceed with organomagnesium or or-
ganozinc compounds. The proposed reaction mechanism is
depicted in Scheme 3 and consists of the following steps:
2
3 3
and AlEt (2 equiv.) at 20 °C; however, in all cases reductive
3
dechlorination to the corresponding dienes 4aϪd took
place in 45Ϫ79% yields (Scheme 2). No traces of cyclized
products were detected.
(i) formation of the cationic species, (ii) carbometalation
(
carboferration) of the double bond to give a secondary
[
20]
alkyliron compound,
(iii) intramolecular carbometal-
ation of the second double bond (vinyl chloride moiety) to
give a primary alkyliron compound, and, finally, (iv) β-
chloride elimination to give the product and iron() chlo-
ride that returns back into the catalytic cycle.
Scheme 2. Ru-catalyzed reductive dehalogenation of 2-chloro-α,ω-
dienes 1 to α,ω-dienes 2 and 4
The above-mentioned results indicate that several com-
peting reaction pathways may take place in the Fe-catalyzed
cyclization and that the major one might be the result of a
combination of several factors. At the first approximation
it is obvious that the course of the reaction is governed by
steric factors: (i) alkylative cyclization proceeds only with
unsubstituted or terminally substituted dienes 1a,b, and (ii)
in the case of the substrate with an internally substituted
double bond (1c) the cross-coupling reaction prevails. Sec-
ondly, a certain role may also be played by the size of the
Scheme 3. Proposed catalytic cycle for the iron-catalyzed alkyl-
ative cyclization
It is noteworthy to mention that the presumed carboferr-
linker (i.e. formation of a five- or six-membered ring) be- ation step proceeds in the opposite manner to the ‘‘normal’’
[
21,22]
[22,23]
cause the reaction of diene 1d gave only the product of re- carbometalation of alkenes
and of α,ω-dienes
ob-
ductive dehalogenation. A cooperative coordination of the served for early transition metal catalysis (e.g. Zr). Al-
double bond of the vinyl chloride moiety to the iron atom though the true nature of this effect is not yet clear, a simi-
cannot be excluded.
lar phenomenon has been observed during iron-catalyzed
As far as the details of the reaction mechanism are con- dimerization of 1-alkenes that resulted in the predominant
[
20d]
cerned, there is enough evidence to suggest that the initial formation of linear products.
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Eur. J. Org. Chem. 2004, 1280Ϫ1285

Iron-Catalyzed Transformations of 2-Chloro-1,6-heptadienes
FULL PAPER
Other 2-chloro-1,6-heptadienes such as 5 and 6 were
tested under the same conditions as well. However, in both
cases the course of the reaction took a different pathway.
The reaction of 5 with triethylaluminium resulted either in
Experimental Section
General Remarks: THF and toluene were distilled from sodium
benzophenone ketyl. All other reagents were obtained from com-
partial or total reduction of the double bonds to give 7 mercial sources. GC analyses were performed with a Shimadzu
or 8 depending on the amount of triethylaluminium used GC-17A chromatograph equipped with a ZB-5 column (5% phe-
nyl-, 95% dimethylpolysiloxane). Infrared spectra were recorded
(
Scheme 4). Thus, the reaction in the presence of 4 equiv.
1
13
with a Bruker IFS 88 spectrometer. H and C NMR spectra were
recorded as CDCl solutions with a Varian UNITY 400 INOVA
of AlEt afforded 7 and 8 in 75 and 11% yield, respectively.
When a large excess of AlEt (8 equiv.) was used, only the
formation of 8 was observed. It is worth mentioning that
possible products of cross-coupling or reductive dehalogen-
ation were not detected, and that the reduction takes place
initially at the unactivated double bond.
3
3
3
1
13
4
spectrometer ( H at 400 MHz, C at 100 MHz) with SiMe as an
internal standard. Melting points (uncorrected) were determined
by using a Bo e¨ tius melting point apparatus. Mass spectra were ob-
tained with a Finnigan Mat Incos 50 instrument. All reactions were
1
carried out under argon in oven-dried Schlenk tubes. The H NMR
yields were determined by using an internal standard (mesitylene).
Compounds 1aϪd[ and 5,
24]
[25]
were prepared according to pre-
viously reported procedures. Compound 6 was prepared by alky-
lation of allyl malonate with 2,3-dichloropropene in MeCN under
basic conditions.
Scheme 4. Fe-catalyzed reduction of 2-chloro-4-aza-1,6-hep-
tadiene 7
General Procedure for Iron-Catalyzed Reactions of 2-Chloro-α,ω-
dienes with AlR
3 3
: An AlR solution in toluene or hexane (1 mmol)
was added to a solution of 2-chloro-α,ω-diene (0.5 mmol), phos-
Interestingly, a completely different reaction pathway was phane (0.075 mmol for monodentate or 0.025 mmol for bidentate
observed in the case of the reaction of 6 with triethylalumi- phosphanes), and iron() salt (0.025 mmol) in dry toluene (3 mL)
under argon. The reaction mixture was stirred under argon at 20
nium. Instead of the expected cyclization, deallylation of 6
°
C for 36 h. After that, it was quenched with water (1 mL) followed
to 9 was observed in 47% yield (Scheme 5). The reaction
proceeded very cleanly and the final reaction mixture con-
sisted only of 9 and unchanged starting material 6. It is
necessary to emphasize that possible products of cross-
coupling or reductive dehalogenation were not detected,
by 3  HCl (3 mL). The organic layer was separated and dried
(Na
2 4
SO ). The product was separated by column chromatography
(
silica gel, hexane), and purified by HPLC chromatography (silica
gel; hexane).
and that this reaction proceeded only in the presence of a 3-Methylidene-4-propylspiro[cyclopentane-1,9Ј-fluorene] (2a): Chlo-
rodiene 1a (141 mg, 0.5 mmol), DPEPhos (13.5 mg, 0.025 mmol),
FeCl (4 mg, 0.025 mmol) and a 2  solution AlEt in toluene
0.5 mL, 1 mmol). Yield 80% ( H NMR). 1H NMR (CDCl
SiMe ): δ ϭ 0.95 (t, J ϭ 7.2 Hz, 3 H), 1.32Ϫ1.44 (m, 2 H),
.44Ϫ1.56 (m, 1 H), 1.81Ϫ1.91 (m, 1 H), 1.96Ϫ2.04 (m, 1 H),
catalytic amount of Fe complexes. The preference for the
cleavage of the unactivated CϪC bond was rather unexpec-
ted and it is unique to this substrate; attempts to carry out
the same reaction with other allylmalonates remained fruit-
less.
3
3
1
(
3
,
4
1
2
1
.09Ϫ2.16 (m, 1 H), 2.58 (dm, J ϭ 16.2 Hz, 1 H), 3.04 (dm, J ϭ
5.4 Hz, 2 H), 5.05Ϫ5.09 (m, 2 H), 7.25Ϫ7.35 (m, 4 H), 7.41Ϫ7.51
1
3
(
m, 2 H), 7.68Ϫ7.72 (m, 2 H) ppm. C NMR (CDCl
3
): δ ϭ 14.29,
0.93, 38.19, 43.35, 45.41, 45.79, 55.50, 106.29, 119.62, 119.65,
22.60, 123.24, 126.90, 127.00, 127.26, 127.36, 139.23, 139.90,
51.42, 153.34, 156.14 ppm. IR (CHCl
): ν˜ ϭ 3070, 3039, 3023,
018, 2961, 2930, 2874, 1449, 1223, 1217, 1206, 1200, 888 cm
2
1
1
3
3
Ϫ1
.
Scheme 5. Fe-catalyzed deallylation of allyl(2-chloroallyl)malonate
ϩ
6
to (2-chloroallyl)malonate 9
EI-MS: m/z (%) ϭ 274 (80) [M ], 231 (82), 217 (85), 203 (90), 178
100), 165 (27). HRMS: calcd. for C21 22 274.1721, found
22: calcd. C 91.92, H 8.08; found C 91.82, H 8.29.
(
2
H
74.1714. C21H
Conclusion
4
-(But-2-yl)-3-methylidenespiro[cyclopentane-1,9Ј-fluorene]
(2b):
Chlorodiene 1b (148 mg, 0.5 mmol), DPEPhos (13.5 mg,
In summary, we have shown that 2-chloro-α,ω-dienes un- 0.025 mmol), FeCl (4 mg, 0.025 mmol) and a 2  solution of AlEt
dergo various iron-catalyzed transformations in the pres- in toluene (0.5 mL, 1 mmol). Yield 30% ( H NMR) (mixture of
ence of trialkylaluminium compounds, such as alkylative diastereoisomers, 3:1). Major diastereomer: H NMR (CDCl ,
3
cyclization, reductive dehalogenation, cross-coupling reac-
tions, CϪC bond cleavage, or double bond hydrogenation,
depending on their structural features. In this regard the
most noteworthy reaction is the new and hitherto unre-
ported alkylative cyclization accompanied by Me or Et
group transfer, which proceeds through reverse carbometal-
ation (carboferration) of the double bond. Moreover, other
3
3
1
1
SiMe
H), 1.19Ϫ1.30 (m, 1 H), 1.30Ϫ1.42 (m, 1 H), 1.77Ϫ1.82 (m, 1 H),
.84Ϫ1.89 (m, 1 H), 2.20 (dd, J ϭ 12.8, 10.8 Hz, 1 H), 2.47 (dd,
J ϭ 15.6, 1.6 Hz, 1 H), 3.00 (dm, J ϭ 15.6 Hz, 1 H), 3.14Ϫ3.24
m, 1 H), 5.04Ϫ5.07 (m, 1 H), 5.11Ϫ5.15 (m, 1 H), 7.21Ϫ7.46 (m,
4
): δ ϭ 0.94 (t, J ϭ 7.2 Hz, 3 H), 1.00 (d, J ϭ 6.8 Hz, 3
1
(
13
4
H), 7.52 (d, J ϭ 7.2 Hz, 2 H), 7.68Ϫ7.73 (m, 2 H) ppm.
NMR (CDCl ): δ ϭ 12.50, 17.26, 29.91, 38.81, 41.14, 46.86, 48.95,
5.38, 107.50, 119.66, 122.47, 123.31, 126.90, 127.06, 127.23,
C
3
5
results indicate that there is rich synthetic potential of iron- 127.33, 139.15, 140.04, 151.02, 153.34, 154.42) ppm. Minor dia-
1
catalyzed transformations.
stereomer: H NMR (CDCl
3
, Me
4
Si): δ ϭ 0.98 (t, J ϭ 7.2 Hz, 3
Eur. J. Org. Chem. 2004, 1280Ϫ1285
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1283

D. Ne c˘ as, M. Kotora, I. C ´ı sa r˘ ov a´
FULL PAPER
H), 1.01 (d, J ϭ 6.8 Hz, 3 H), 1.19Ϫ1.30 (m, 1 H), 1.30Ϫ1.42 (m,
Acknowledgments
1
H), 1.59Ϫ1.72 (m, 2 H), 2.21 (dd, J ϭ 12.8, 10.8 Hz, 1 H), 2.43
(
dd, J ϭ 15.6, 1.6 Hz, 1 H), 3.00 (dm, J ϭ 15.6 Hz, 1 H), 3.04Ϫ3.14
This work was supported by the Fund for the Development of
Higher Education, Czech Republic (project no. 2800). The authors
thank Dr. Iva Ti sˇ lerov a´ for NMR measurements and Dr. Martin
(m, 1 H), 5.04Ϫ5.07 (m, 1 H), 5.11Ϫ5.15 (m, 1 H), 7.21Ϫ7.46 (m,
1
3
4
H), 7.52 (d, J ϭ 7.2 Hz, 2 H), 7.68Ϫ7.73 (m, 2 H) ppm.
): δ ϭ 12.18, 13.90, 28.19, 38.17, 39.50, 46.52, 47.27,
5.38, 106.79, 119.66, 122.47, 123.31, 126.90, 127.06, 127.23,
27.33, 139.15, 140.04, 151.02, 153.34, 155.06 ppm. IR (CHCl ):
C
ˇ
St ´ı cha for MS measurements.
NMR (CDCl
5
1
3
3
Ϫ1
ν˜ ϭ 3068, 2962, 2930, 2875, 1449, 1379, 908, 886 cm . EI-MS: m/
z (%) ϭ 288 (12) [M ], 233 (64), 219 (100), 203 (78), 191 (96),
1
[
1] [1a]
ϩ
T. Tamura, J. K. Kochi, J. Am. Chem. Soc. 1971, 93,
[1b]
1
3
1
487Ϫ1489.
T. Tamura, J. K. Kochi, Synthesis 1971,
78 (79), 165 (26). C20
H20: calcd. C 91.61, H 8.39; found C 91.75,
03Ϫ305. [ T. Tamura, J. K. Kochi, Bull. Chem. Soc. Jpn.
1c]
H 8.42.
971, 44, 3063Ϫ3073. [ T. Tamura, J. K. Kochi, J. Organomet.
1d]
[1e]
Chem. 1971, 31, 289Ϫ309.
S. M. Neumann, J. K. Kochi, J.
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2]
1f]
4
-Ethyl-3-methylidenespiro[cyclopentane-1,9Ј-fluorene] (3a): Chloro-
diene 1a (141 mg, 0.5 mmol), DPEPhos (13.5 mg, 0.025 mmol),
FeCl
[
For recent papers on iron-catalyzed cross-coupling reactions of
3
(4 mg, 0.025 mmol) and a 2  solution of AlMe
3
in hexane
[2a]
1
vinyl halides, see: [ G. Cahiez, S. Marquais, Pure Appl. Chem.
(
0.5 mL, 1 mmol). Yield 36% ( H NMR). M.p. 53Ϫ54 °C (MeOH),
2b]
1
1996, 68, 53Ϫ60.
G. Cahiez, H. Avedissian, Synthesis 1998,
199Ϫ1205. [ W. Dohle, F. Kopp, G. Cahiez, P. Knochel,
Synlett 2001, 1901Ϫ1904.
[3] [3a]
3 4
H NMR (CDCl , SiMe ): δ ϭ 0.98 (t, J ϭ 7.5 Hz, 3 H), 1.48Ϫ1.60
2c]
1
(
2
m, 1 H), 1.87Ϫ1.98 (m, 1 H), 2.01 (dd, J ϭ 13.0, 10.4 Hz, 1 H),
.13 (ddd, J ϭ 13.0, 8.1, 1.7 Hz, 1 H), 2.58 (dm, J ϭ 16.0 Hz, 1
H), 2.93Ϫ3.03 (m, 1 H), 3.04 (dm, J ϭ 16.0 Hz, 1 H), 5.05Ϫ5.10
A. Fürstner, A. Leitner, Angew. Chem. 2002, 41, 632Ϫ635;
[3b]
Angew. Chem. Int. Ed. 2002, 41, 609Ϫ612.
A. Fürstner, A.
(m, 2 H), 7.22Ϫ7.28 (m, 1 H), 7.29Ϫ7.36 (m, 3 H), 7.41Ϫ7.46 (m,
Leitner, M. Mendez, H. Krause, J. Am. Chem. Soc. 2002, 124,
13
[3c]
1
H), 7.48Ϫ7.51 (m, 1 H), 7.68Ϫ7.73 (m, 2 H) ppm. C NMR
): δ ϭ 12.05, 28.53, 45.15, 45.33, 45.50, 55.45, 106.46,
19.63, 119.66, 122.60, 123.27, 126.91, 127.01, 127.25, 127.36,
39.22, 139.92, 151.38, 153.35, 155.84 ppm. IR (CHCl
): ν˜ ϭ 3069,
963, 2929, 2876, 1653, 1478, 1449 cm . EI-MS: m/z (%) ϭ 260
13856Ϫ13863.
A. Fürstner, A. Leitner, Angew. Chem. 2003,
(CDCl
3
115, 320Ϫ323; Angew. Chem. Int. Ed. 2003, 42, 308Ϫ311.
Cross coupling of 2-bromo-1,6-heptadienes with alkyl Grig-
nard reagents: N. Ostergaard, B. T. Pedersen, N. Skjærbæk, P.
Vedsø, M. Begtrup, Synlett 2002, 1889Ϫ1891.
[
[
4]
5]
1
1
2
3
Ϫ1
H. Ohara, T. Itoh, M. Nakamura, E. Nakamura, Chem. Lett.
ϩ
20
(82) [M ], 231 (88), 217 (69), 203 (99), 178 (100), 165 (31). C20H :
2
001, 624Ϫ625.
M. Wenz, D. Grossbach, M. Beitel, S. Blechert, Synthesis
999, 607Ϫ614.
M. Nakamura, A. Mirai, E. Nakamura, J. Am. Chem. Soc.
000, 122, 978Ϫ979.
calcd. C 92.26, H 7.74; found C 92.26, H 7.8.
[6]
1
[
[
7]
8]
3
-Methylidene-4-(2-propyl)spiro[cyclopentane-1,9Ј-fluorene]
Chlorodiene 1b (148 mg, 0.5 mmol), DPEPhos (13.5 mg,
.025 mmol), FeCl (4 mg, 0.025 mmol) and a 2  solution of
AlMe in hexane (0.5 mL, 1 mmol). Yield 23% ( H NMR).
NMR (CDCl , SiMe ): δ ϭ 1.00 (d, J ϭ 6.4 Hz, 3 H), 1.01 (d, J ϭ
.4 Hz, 3 H), 1.89 (ddd, J ϭ 12.8, 8.0, 2.0 Hz, 1 H), 2.09Ϫ2.17 (m,
H), 2.21 (dd, J ϭ 13.6, 10.8 Hz, 1 H), 2.46 (d, J ϭ 15.2 Hz, 1
(3b):
2
M. Hojo, Y. Murakami, H. Aihara, R. Sakurai, Y. Baba, A.
Hosomi, Angew. Chem. 2001, 113, 641Ϫ643; Angew. Chem. Int.
Ed. 2001, 40, 621Ϫ623.
0
3
1
1
3
H
3
4
[9]
A. M. Caporusso, G. Giacomelli, L. Lardicci, J. Chem. Soc.,
Perkin Trans. 1 1979, 3139Ϫ3145.
For conjugate addition, see: J. Christoffers, Synlett 2001,
723Ϫ732 and references cited therein.
D. F. Taber, K. Kanai, Q. Jiang, G. Bui, J. Am. Chem. Soc.
2000, 122, 6807Ϫ6808.
The only other known example of successful alkyl group trans-
fer (benzyl group) is a palladium-catalyzed combination of
Heck cyclization with Suzuki coupling: C. W. Lee, K. S. Oh,
K. S. Kim, K. H. Ahn, Org. Lett. 2000, 2, 1213Ϫ1216.
6
1
[10]
H), 2.97Ϫ3.01 (m, 1 H), 3.01Ϫ3.08 (m, 1 H), 5.06Ϫ5.09 (m, 1 H),
[
[
11]
12]
5
7
4
1
.12Ϫ5.15 (m, 1 H), 7.21Ϫ7.47 (m, 4 H), 7.50Ϫ7.54 (m, 2 H),
.70Ϫ7.74 (m, 2 H) ppm. 13C NMR (CDCl
): δ ϭ 17.4, 21.1, 31.6,
0.2, 46.5, 49.4, 55.3, 107.4, 119.6, 119.7, 122.5, 123.3, 126.9, 127.1,
27.2, 127.3, 139.1, 140.0, 151.0, 153.3, 154.6 ppm. IR (CHCl ):
3
3
Ϫ1
ν˜ ϭ 3067, 2958, 2931, 2872, 1688, 1656, 1641, 1449, 884 cm . EI-
MS: m/z (%) ϭ 274 (82) [M ], 231 (100), 217 (47), 203 (64), 178
ϩ
[13]
For typical examples of a transition-metal-catalyzed cyclization
of 2-halo-1,6-heptadienes, see:
(97), 165 (33). HRMS calcd. for C21
H22: 274.172151; found
[13a]
R. Grigg, P. Stevenson, T.
2
74.172567.
[13b]
Worakun, J. Chem. Soc., Chem. Commun. 1985, 971Ϫ972.
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13c]
2
033Ϫ2048. [
F. E. Meyer, K. H. Ang, A. G. Steining, A. de
X-ray Crystallographic Study: A suitable colorless crystal of dimen-
sion 0.45 ϫ 0.35 ϫ 0.15 mm obtained upon slow evaporation of
the solvent from a solution of 3a in methanol was used for data
collection with a Nonius Kappa CCD diffractometer equipped
with an Oxford cryostream cooler at 150 K. Crystal data: a ϭ
1
Z ϭ 4, monoclinic C2, Mo-K
1
solved by direct methods (SIR97) and refined by weighted full-
[13d]
Meijere, Synlett 1994, 191Ϫ193.
Tetrahedron 1998, 54, 5789Ϫ5804.
B. Møller, K. Undheim,
[14]
Metal-Catalyzed Cross-Coupling Reactions (Eds.: F. Diederich,
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[15b]
G. Booth, J. Chatt, J. Chem. Soc. 1962, 2099Ϫ2106.
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˚
7.3650(5), b ϭ 6.8520(2), c ϭ 12.9910(3) A, β ϭ 99.8540(17)°;
˚
[15c]
α
radiation, λ ϭ 0.71070 A, Dcalcd.
ϭ
7, 828Ϫ830.
Synthesis of Organometallic Compounds: A
Ϫ3
.136 Mg·m . 3429 independent reflections. The structure was
Practical Guide (Ed.: S. Komiya), Wiley & Sons, Chichester,
1997, p. 179.
16]
[31]
[
2
[32]
For the preparation of dimethyl- and diethyl(phos-
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18]
matrix least squares on F (SHELXL-97). Final R and ωR were
.0412 and 0.1040, respectively. CCDC-211049 contains the sup-
0
plementary crystallographic data for this paper. These data can be
obtained free of charge at www.ccdc.cam.ac.uk/conts/retriev-
ing.html [or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-
[17]
[
1
223/336-033; E-mail: deposit@ccdc.cam.ac.uk].
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1285