1,1′-Dialkynylferrocenes as Substrates for Bidirectional Alkyne Metathesis Reaction

Article abstract of DOI:10.1002/ejoc.201500483

In the construction of ferrocene-based molecular wires, alkyne metathesis was investigated as an alternative to palladium-catalyzed coupling reactions for the synthesis of alkynyl ferrocenes. With a Mortreux catalyst system [Mo(CO)₆, 4-chloro-

Full text of DOI:10.1002/ejoc.201500483

FULL PAPER
DOI: 10.1002/ejoc.201500483
1,1Ј-Dialkynylferrocenes as Substrates for Bidirectional Alkyne Metathesis
Reaction
Jingxiang Ma,[a] Nico Krauße,[a] and Holger Butenschön*[a]
Dedicated to Professor Dr. Klaus Banert on the occasion of his 60th birthday
Keywords: Sandwich complexes / Metathesis / Molecular devices / 1,1Ј-Dialkynylferrocenes / Synthetic methods
In the construction of ferrocene-based molecular wires, alk-
yne metathesis was investigated as an alternative to palla-
dium-catalyzed coupling reactions for the synthesis of alk-
ynyl ferrocenes. With a Mortreux catalyst system [Mo(CO)6,
4-chloro- or 2-fluorophenol], (1-propynyl)ferrocenes gave the
1,1Ј-dialkynylferrocenes, a nitridomolybdenum catalyst in-
troduced by Fürstner was tested in bidirectional homo and
cross-alkyne metathesis reactions. Although the homo alk-
yne metathesis products were obtained in poor yields, the
cross-alkyne metathesis reactions afforded the expected
expected homo metathesis products in moderate yields. Be- products in good overall yields.
cause the Mortreux catalyst system is not compatible with
by ethynylene units and are prepared by a building-block
principle in repetitive syntheses. OPEs can be prepared by
Introduction
The continuing miniaturization of electronic devices de- repeated Sonogashira couplings with a very limited number
mands new techniques to overcome principle physical of building blocks.[1,5,6] In addition, they may have end
limitations. Among these, molecular electronics is regarded groups – so-called alligator clips – that allow for attachment
as a possibility to create electronic devices on the molecular at gold electrodes or surfaces, for example thioacetyl or
level, which is considered to be the smallest possible.[1,2] In nitrile groups.[1,7,8] Compound 1 is an example of an OPE-
this context molecular wires have been designed, the most type molecular wire.
popular class of which is oligophenyleneethynylenes
The building principle of OPEs, such as 1, implies that
(OPEs).[3,4] Typically, molecular wires consist of highly con- the structures are rather rigid. They are not prone to adapt
jugated π systems, such as 1,4-phenylene rings, connected their length to the geometrical requirements of a given
[a] Institut für Organische Chemie, Leibniz Universität Hannover,
electrode design. In addition, π–π stacking may occur, so
that more than one molecular wire may be involved. To
overcome these potential problems, our concept involves re-
placement of some, but not all, of the 1,4-phenylene units
Schneiderberg 1B, 30167 Hannover, Germany
E-mail: holger.butenschoen@mbox.oci.uni-hannover.de
http://www.ak-butenschoen.uni-hannover.de
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201500483.
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1,1Ј-Dialkynylferrocenes in Bidirectional Alkyne Metathesis Reactions
by 1,1Ј-ferrocenylene ones as in 2.[9] This renders the com- propynyl)ferrocene (8) with Mortreux catalyst [Mo(CO)6
pounds three-dimensional, which makes π–π stacking less (10 mol-%), 4-chlorophenol (0.3 equiv.) in toluene, 120 °C,
likely. In addition, the possibility of rotations around the 12 h] to give diferrocenylethyne (9) in 40% isolated yield.[26]
cyclopentadienyl–iron–cyclopentadienyl axis allows for lim- With some modifications of the reaction conditions
ited conformational flexibility, similar to that of a foldable [Mo(CO)6 (10 mol-%), 2-fluorophenol (1.0 equiv.) in
ruler. Following this concept, we prepared a number of fer- chlorobenzene, 118 °C, 15 h[27]], we obtained an improved
rocene-based OPEs with varying structural design in ad- yield of 62%. Next, we were interested in the results of
dition to 2, e.g. 3–5.[9–11] Related contributions have been homo metathesis reactions of some building blocks used in
made by Sita[12,13] and by Long.[14]
the syntheses of ferrocene-based molecular wires, namely
As in the case of conventional OPEs, these compounds propynyl compounds 10, 12,[25] and 14. Alkyne 10 was pre-
were prepared predominantly by Sonogashira and related pared in 91% yield by reaction of 1-(tert-butylsulfanyl)-
palladium-catalyzed coupling reactions. Although this ap- 4-(trimethylsilylethynyl)benzene[28] with methyllithium
proach works in many cases, we envisaged alkyne cross followed by iodomethane. As another substrate in this
metathesis as an alternative route to ferrocene systems con- context 1Ј-(4-tert-butylsulfanyl)phenyl-substituted ferro-
nected by triple bonds.[15–23] In a first attempt 1,1Ј-dialk- cene 14 was prepared from 12 in 33% yield by palladium-
ynylferrocenes such as 6[24] were treated with a traditional catalyzed coupling with 1-(tert-butylsulfanyl)-4-iodo-
Mortreux catalyst system that consists of hexacarb- benzene.[10] The 4-(tert-butylsulfanyl)phenyl substituent is
onylmolybdenum and a phenol in a solvent with a high of interest in the context of “alligator clips” in molecular
boiling point such as chlorobenzene. These attempts did not electronics.[1]
provide the desired coupling products, instead unantici-
pated transannular coupling of the alkynyl groups was ob-
served, and respective [4]ferrocenophanes 7 were obtained
in high yields.[25] Here we report investigations towards bi-
directional alkyne metathesis reactions of 1,1Ј-dialkynylfer-
rocenes with catalysts other than the Mortreux system.
The increase in reaction yield observed for 8 was con-
firmed with the other substrates, which gave symmetric alk-
ynes 11,[29] 13, and 15 in satisfactory yields (Table 1). The
tert-butylsulfanyl substituent in 10 and 14 does not impede
catalysis. Compound 15 can be regarded as the first OPE
analogue with two ferrocene hinges obtained by alkyne
metathesis. The iodo substituents in biferrocene 13 allow
for further functionalization.
Bidirectional alkyne metathesis reactions starting from
1,1Ј-dialkynylferrocenes are highly attractive for the synthe-
sis of extended π systems with ferrocene hinges. Therefore,
we envisaged substrates 16 and 17 in addition to 6.
Compounds 16 and 17 were obtained in 90 and 72%
yield, respectively, by deprotonation and subsequent meth-
ylation of the respective terminal dialkynes. In addition to
the consistent spectroscopic data, compound 17 was crys-
Results and Discussion
Kotora et al. were the first to report alkyne homo tallized from hexane/dichloromethane (3:1) and subjected
metathesis with an alkynylferrocene, namely reaction of (1- to a crystal structure analysis.
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Table 1. Alkyne homo metathesis.
the planes of the respective cyclopentadienyl rings (by 18.2,
4.7, 5.0, and 7.3°, respectively). The distance between the
centers of the phenyl rings are 383.6 pm for the molecule
shown in Figure 1 and 361.5 pm for the other one. The con-
formational differences are likely a result of packing forces.
Although the structures of the substituted cyclopentadienyl
ligands are similar to one another, they are not identical.
Entry Starting material Product Yield [%][a]
Yield [%][b]
1
2
3
4
8
9
11[29]
13
40[26]
10
20
62
36
35
45
10
12
14
15
34
[a] Reaction conditions: Mo(CO)6 (10 mol-%), 4-chlorophenol
(0.3 equiv.), toluene, 120 °C, 12 h. [b] Mo(CO)6 (10 mol-%), 2-
fluorophenol (1.0 equiv.), chlorobenzene, 118–132 °C, 12–15 h.
In the crystal of 17, two crystallographically independent
molecules exist, one of which is shown in Figure 1. Both
molecules adopt eclipsed conformations with respect to the
cyclopentadienyl–iron–cyclopentadienyl axis and the cyclo-
pentadienyl substituents similar to the conformations ob-
served for some other 1,1Ј-disubstituted ferrocene deriva-
tives with extended π systems as substituents.[9,31,32] The cy-
clopentadienyl ligands of the independent molecules show
minor deviations from coplanarity (by 3.5 and 2.4°, respec-
Figure 1. Crystal structure of 17;[30] A. side view; B. top view. Se-
lected bond lengths [pm] and angles [°]: C1–C2 143.5(7), C1–C5
143.5(7), C1–C11 145.8(7), C2–C3 140.2(8), C3–C4 145.1(9), C4–
C5 141.5(9), C6–C7 143.3(8), C6–C10 140.2(7), C6–C20 147.1(7),
C7–C8 138.7(8), C8–C9 145.4(9), C9–C10 143.1(8), C17–C18
119.4(8), C26–C27 117.4(8); C14–C17–C18 179.2(6), C17–C18–
C19 176.6(6), C23–C26–C27 176.9(7), C26–C27–C28 178.2(7).
DFT calculations (B3LYP, 6-31G*, Spartan 14) result in
tively). The phenyl substituents are slightly twisted out of a geometry with deviation of the cyclopentadienyl ligands
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1,1Ј-Dialkynylferrocenes in Bidirectional Alkyne Metathesis Reactions
from coplanarity of 0.8° and a twisting of the phenyl rings
of 10.2 and 8.7° out of the cyclopentadienyl plane. The
HOMO energy of –5.2 eV and the LUMO energy of
–1.0 eV result in a HOMO–LUMO gap of 4.2 eV. In con-
trast to the LUMO, most of those occupied molecular or-
bitals predominantly located at the 4-(1-propynyl)phenyl
substituents show a symmetry that allows for attractive in-
teraction with no nodal plane between substituents (see
Supporting Information), which might, in addition to crys-
tal packing effects, be a reason for the observed eclipsed
conformation.
Because the Mortreux catalyst system gives [4]ferroceno-
phanes from 1,1Ј-dialkynylferrocenes instead of homo me-
tathesis products, nitridomolybdenum complex 18 was
tested as an alternative for the alkyne homo metathesis cat-
alyst. Compound 18, which is prepared from commercially
available sodium molybdate, was introduced by Fürstner et
al. and has been shown to be tolerant of many functional
groups and relatively stable in air for short periods of
time.[33]
with 1-tert-butyl-4-propynylbenzene (10; 2 equiv.) in the
presence of catalyst 18.
The cross metathesis of iodoalkynylferrocene 12 with
1 equiv. of alkyne 10 was tested. In the presence of catalyst
18 (20 mol-%) and by microwave heating at 130 °C for
120 min a 55% yield of metathesis product 23 was achieved,
which indicates that the catalyst is compatible with the iodo
as well as with the sulfanyl substituents. The yield is com-
parable to alkyne cross metatheses, which Stepnicka and
Kotora et al. reported with Mortreux catalyst.[35] Com-
pound 23 has been prepared by a Sonogashira coupling of
1-ethynyl-1Ј-iodoferrocene with 1-(tert-butylsulfanyl)-4-
iodobenzene in 95% yield.[10,36] Encouraged by this result
twofold cross metathesis reactions were tried with the men-
tioned diynes.
The reaction of 1,1Ј-dipropynylferrocene (6) with 18
(20 mol-%) afforded new triyne 19. The best yield (29%)
was achieved by microwave heating (250 W, 120 °C,
120 min) in toluene. Compound 19 is a promising starting
material for subsequent intramolecular homo metathesis
and would open access to [2.2]ferrocenophane-1,13-diyne
(20);[34] however, under the conditions formation of 19 not
20 was observed. Under similar reaction conditions 21 was
obtained in 14% yield, and 22 was isolated in only 11%
yield. In conclusion, catalyst 18 facilitates the alkyne homo
metathesis of 1,1Ј-dipropynylferrocene (6) and of more ex-
tended π systems such as diynes 16 or 17 to give ferrocene-
based triynes 19, 21, and 22, which are interesting com-
pounds in their own right. However, yields have to be im-
proved by searching for better catalysts.
Next, we turned our attention to the possibility of alkyne
cross metathesis. Stepnicka, Kotora et al. reported alkyne
cross metathesis of (1-propynyl)ferrocene (8) and methyl-
ated alkynes in 27–80% yield with Mortreux catalyst,[35]
which is not suitable for 1,1Ј-dialkynylferrocenes.[25] Mono-
and 1,1Ј-dialkynyl ferrocenes 6, 12, 16, and 17 were treated
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The reaction of 6 with 2 equiv. of 10 resulted in a mixture cross metathesis products 26 and 27[9] in 29 and 7% yield,
of homo metathesis product 11 (24%), single cross metathe- respectively, in addition to 9% of homo metathesis product
sis product 24 (30%), and double cross metathesis product 21, which indicates a preference for mono cross metathesis
25 (36%) with a high overall yield of 90%. In addition, under these conditions.
some starting material 10 was isolated. No homo metathesis
product 19 of diyne 6 was observed. This result indicates a tathesis products 28 and 29 in 11 and 12% yield, respec-
preference for cross versus homo alkyne metathesis. tively. Here one must take into account that 29 is the prod-
The reaction of 17 with 10 (2 equiv.) afforded cross me-
The reaction of diyne 16 with 10 (2 equiv.) under some- uct of a bidirectional reaction that gives an average yield of
what milder reaction conditions afforded single and double 35% per metathesis step.
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1,1Ј-Dialkynylferrocenes in Bidirectional Alkyne Metathesis Reactions
1-(tert-butylsulfanyl)-4-(trimethylsilylethynyl)benzene[28]
2.6 mmol) in THF (30 mL), and the mixture was stirred at 25 °C
for 20 h. After addition of iodomethane (0.3 mL, 5.3 mmol) at
(0.69 g,
Conclusions
The results indicate that alkyne cross metathesis may be
used as a tool for the bidirectional extension of 1,1Ј-dialk- –78 °C, the solution was stirred at 25 °C for 5 h. Water (20 mL)
was added, and, after stirring for 5 min, the layers were separated.
The aqueous layer was extracted with dichloromethane (3ϫ
20 mL). The collected organic layers were washed with brine
(20 mL) and dried with MgSO4. After solvent removal under re-
duced pressure, the residue was purified by column chromatog-
raphy (30ϫ3 cm, petroleum ether/dichloromethane, 4:1) to give 10
(0.49 g, 2.4 mmol, 91%) as a white solid, which was recrystallized
from hexane/dichloromethane (3:1). Colorless crystals (m.p. 82.0–
ynylferrocenes as building blocks for molecular wires. Iodo
and tert-butylsulfanyl substituents are compatible with
Mortreux catalyst systems as well as with nitridomolyb-
denum catalyst 18, which can compete with the Mortreux
catalyst system. Investigations with other catalysts intro-
duced by Fürstner et al. and by Tamm et al. are under in-
vestigation in our laboratory.[37,38] Remarkably, the yields
of the bidirectional double reaction are comparable or even
higher than those of the single reactions. However, so far
83.5 °C). IR (ATR): ν = 3041 (w), 2960 (m), 2921 (m), 2855 (m),
˜
2251 (w) 1692 (w), 1590 (w), 1486 (s), 1470 (m), 1363 (s), 1169 (m),
1
the yields obtained are not comparable to those of palla- 1151 (s), 845 (s) cm–1. H NMR (CDCl3, 400 MHz): δ = 1.30 [s, 9
H, C(CH3)3], 2.08 (s, 3 H, CCCH3), 7.35 + 7.46 (AAЈBBЈ, 4 H,
C6H4) ppm. 13C NMR (CDCl3, 100.6 MHz): δ = 4.4 (CCCH3),
30.9 [C(CH3)3], 46.2 [C(CH3)3], 79.2 (CϵC), 87.5 (CϵC), 124.5
(CArC), 131.4 (CArH), 132.2 (CArS), 137.2 (CArH) ppm. MS
(70 eV): m/z (%) = 204 (26) [M+], 149 (15), 148 (100) [M+ – C4H8],
147 (31), 115 (32), 57 (27) [tBu+]. HRMS: calcd. for C13H16S
204.0973; found 204.0974. C13H16S (204.3): calcd. C 76.41, H 7.89;
found C 76.45, H 7.67.
dium-catalyzed coupling reactions that lead to related prod-
ucts.
Experimental Section
General: All reactions were performed by using Schlenk techniques
with nitrogen or argon as the inert gas. All glassware was heated
at Ͻ 0.1 mbar with a heat gun prior to use to remove any oxygen or
water. Tetrahydrofuran (THF) and toluene were dried with sodium/
potassium alloy/benzophenone and distilled. Pentane and dichloro-
methane were dried with CaH2 and distilled. Starting materials
were either commercially acquired or were prepared according to
published procedures. Ferrocene was obtained as a donation from
Bis[(4-tert-butylsulfanyl)phenyl]ethyne
(11):[29]
(a) Hexacarb-
onylmolybdenum (26 mg, 0.1 mmol, 10 mol-%) and 4-chlorophenol
(38 mg, 0.3 mmol) were added to 1-(tert-butylsulfanyl)-4-(1-prop-
ynyl)benzene (10; 204 mg, 1.0 mmol) in toluene (10 mL), and the
solution was heated at 120 °C for 12 h. After solvent removal under
reduced pressure, the mixture was separated by column chromatog-
raphy (20ϫ2 cm, petroleum ether/dichloromethane, 4:1). I. 10
(129 mg, 0.6 mmol, 60%). II. 11 (21 mg, 0.05 mmol, 10%), orange
crystals (m.p. 128.4–130.1 °C). (b) After addition of Mo(CO)6
(13 mg, 0.05 mmol, 5 mol-%) and 2-fluorophenol (112 mg,
1.0 mmol) to 1-(tert-butylsulfanyl)-4-(1-propynyl)benzene (10;
0.20 g, 1.0 mmol) in chlorobenzene (20 mL), the solution was
heated at reflux (oil-bath temperature 132 °C) for 4 h. After cooling
to 25 °C and solvent removal under reduced pressure, the residue
was purified by column chromatography (30ϫ3 cm, petroleum
ether/dichloromethane, 4:1) to give 11 (63 mg, 0.2 mmol, 36%) as
colorless shiny crystals (m.p. 113.5–115.0 °C). Identified by com-
1
Innospec Deutschland GmbH. H and 13C NMR spectra were ob-
tained with Bruker AVS 200 (1H: 200 MHz) and AVS 400 (1H:
400 MHz, 13C: 100.6 MHz) instruments. Chemical shifts are refer-
enced to δTMS = 0 ppm or to residual solvent signals. Primary, sec-
ondary, tertiary and quaternary carbon atom signals were iden-
tified as such by APT and DEPT techniques. In some cases signal
assignments were based on 2D NMR spectra (HMC, HMBC). IR
spectra were obtained with Perkin–Elmer instruments FT-IR 580
and 1170 by using ATR techniques. Signal characteristics are ab-
breviated as s (strong), m (medium), w (weak), and br (broad).
Mass spectra were obtained with a Micromass LCT instrument
with lockspray source and direct injection and with a Q-TOF prem-
ier LC-MS/MS instrument with an Ionsabre APCI source (25 μA,
350 °C). In all cases dichloromethane was used as the solvent. Ana-
lytical TLC was performed with Merck 60F-254 silica gel thin layer
plates. Column chromatography was performed with J. T. Baker sil-
ica gel (60 μm) as the stationary phase by using the flash
chromatography method.[39] Elemental analyses were obtained with
an Elementar Vario EL instrument. Reactions under microwave ir-
radiation (μW) were performed with a CEM DiscoverTM Labmate
reactor under nitrogen (“open vessel”) in a 100 mL reaction flask
by using ChemDriverTM software. The temperature was monitored
by means of an IR sensor. Some reactions were performed by using
the PowerMaxTM method.
1
parison of the analytical data (IR, H NMR, and 13C NMR spec-
troscopy, and MS) with literature data.[29]
Bis(1Ј-iodoferrocenyl)ethyne (13): (a) Hexacarbonylmolybdenum
(26 mg, 0.1 mmol, 10 mol-%) and 4-chlorophenol (40 mg,
0.3 mmol) were added to 1-iodo-1Ј-(1-propynyl)ferrocene[25] (12;
350 mg, 1.0 mmol) in 1,4-dimethylbenzene (10 mL), and the solu-
tion was heated at 120 °C for 10 h. After solvent removal, the resi-
due was taken up with dichloromethane (20 mL), and the solution
was washed with aq. NaOH (1 m, 10 mL), brine (20 mL), and dried
with MgSO4. After solvent removal under reduced pressure, the
mixture was separated by column chromatography (30ϫ3 cm, pe-
troleum ether/dichloromethane, 4:1). I. 12 (57 mg, 0.2 mmol, 16%).
II. 13 (31 mg, 0.05 mmol, 10%), orange crystals (m.p. 128.4–
130.1 °C). (b) Hexacarbonylmolybdenum (26 mg, 0.1 mmol,
10 mol-%) and 2-fluorophenol (112 mg, 0.1 mmol) were added to
1-iodo-1Ј-(1-propynyl)ferrocene[25] (12; 350 mg, 1.0 mmol) in
chlorobenzene (10 mL), and the mixture was heated at 132 °C for
15 h. After solvent removal under reduced pressure, the residue was
purified by column chromatography (30ϫ3 cm, petroleum ether/
dichloromethane, 4:1) to give 13 (113 mg, 0.2 mmol, 35%) as
Diferrocenylethyne (9): (a) Ref.[26] (b) Hexacarbonylmolybdenum
(26 mg, 0.1 mmol, 10 mol-%) and 2-fluorophenol (112 mg,
1.0 mmol) were added to (1-propynyl)ferrocene[24] (8; 224 mg,
1.0 mmol) in chlorobenzene (20 mL) and heated at 118 °C (oil-bath
temperature) for 15 h. After solvent removal under reduced pres-
sure, the crude product was purified by column chromatography
(30ϫ2 cm, hexane/dichloromethane, 4:1) to give
9 (122 mg,
0.3 mmol, 62%), identified by1H NMR spectroscopy.[26]
orange crystals (m.p. 128.4–130.1 °C). IR (ATR): ν = 3101 (m),
˜
1-(tert-Butylsulfanyl)-4-(1-propynyl)benzene (10): At –78 °C MeLi
(1.6 m in diethyl ether, 2.5 mL, 3.9 mmol) was added dropwise to
2918 (m), 2849 (m), 2216 (w), 1631 (w), 1500 (w), 1403 (m), 1378
(m), 1347 (s), 1287 (m), 1202 (m), 1138 (m), 1057 (m), 1043 (m),
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J. Ma, N. Krauße, H. Butenschön
0128 (m), 1010 (s), 935 (s), 861 (s), 833 (s), 803 (s) cm–1. H NMR (CCpH), 85.5 (CCpCCCCp), 126.2 (CArH), 130.0 (CArC), 137.5
FULL PAPER
1
(CDCl3, 400 MHz): δ = 4.24 (m, 4 H, HCp), 4.44 (m, 4 H,
(CArH), 139.2 (CArS) ppm. MS (70 eV): m/z (%) = 725 (7), 724 (23),
HCp) ppm. 13C NMR (CDCl3, 100.6 MHz): δ = 40.9 (CI), 68.2
723 (52) [M + 1]+, 722 (100) [M+], 721 (6), 720 (13), 666 (8), 610
(CCpC), 71.0 (CCpH), 71.8 (CCpH), 74.1 (CCpH), 76.4 (CCpH), 84.0 (11), 608 (6), 438 (7), 437 (21), 436 (50), 434 (8), 305 (11), 57 (20).
(CCpCC) ppm. MS (70 eV): m/z (%) = 647 (11) [M + 1]+, 646 (100)
[M+], 644 (11), 350 (10), 336 (11), 290 (14), 288 (14), 216 (14), 215
(26), 189 (10), 85 (14), 83 (16), 71 (12), 57 (23), 56 (13) [Fe+].
HRMS: calcd. for C22H16Fe2I2 645.8040; found 645.8045.
C22H16Fe2I2 (645.8): calcd. C 40.91, H 2.50; found C 41.49, H 2.79.
HRMS: calcd. for C42H42Fe2S2 722.1427; found 722.1774.
1,1Ј-Bis{2-[5-(1-propynyl)]thiophenyl}ferrocene (16): At –78 °C BuLi
(1.6 m in hexane, 3.5 mL, 5.5 mmol) was added dropwise to 1,1Ј-
bis[2-(4-ethynyl)thiophenyl]ferrocene[9] (1.00 g, 2.5 mmol) in THF
(40 mL), and the mixture was stirred for 1 h. After addition of
iodomethane (1.3 mL, 20.1 mmol) at –78 °C, the solution was
stirred at 25 °C for 2 h. Water (20 mL) was added, and the mixture
was stirred for 5 min. The aqueous layer was extracted with di-
chloromethane (3ϫ 30 mL). The collected organic layers were
washed with brine (30 mL) and dried with MgSO4. After solvent
removal under reduced pressure, the residue was purified by col-
umn chromatography (30ϫ3 cm, silica gel deactivated with 5% tri-
ethylamine, petroleum ether/dichloromethane, 4:1) to give 16
(769 mg, 1.8 mmol, 72%) as a red solid (m.p. 118.5–120.0 °C). IR
1-(4-tert-Butylsulfanylphenyl)-1Ј-(1-propynyl)ferrocene (14): At
–78 °C butyllithium (1.6 m in hexane, 1.4 mL, 2.2 mmol) was slowly
added dropwise to 1-iodo-1Ј-(1-propynyl)ferrocene (12; 0.70 g,
2.0 mmol) in THF (30 mL), and the mixture was stirred at –78 °C
for 1 h. At 0 °C zinc chloride (0.33 g, 2.4 mmol) in THF (10 mL)
was added. The solution was stirred at 0 °C for 30 min, then at
25 °C for 1 h. 1-(tert-Butylsulfanyl)-4-iodobenzene[10,28] (0.64 g,
2.2 mmol) and Pd0 catalyst (5 mol-%) were added at 0 °C [the Pd0
catalyst was prepared in situ: at 0 °C diisobutylaluminium hydride
(20% in toluene, 0.2 mL, 0.2 mmol) was added to Pd(PPh3)2Cl2
(75 mg, 0.1 mmol) in THF (5 mL), and the mixture was stirred for
10 min]. The solution was stirred at 85 °C for 15 h. After cooling
to 25 °C, aq. NaOH (1 m, 10 mL) was added, and the mixture was
stirred for 5 min. The aqueous layer was separated and extracted
with dichloromethane (3ϫ 30 mL). The collected organic layers
were washed with brine (30 mL) and then dried with MgSO4. After
solvent removal under reduced pressure, the residue was purified
by column chromatography (30ϫ3 cm, petroleum ether/dichloro-
methane, 4:1) to give 14 (254 mg, 0.7 mmol, 33%) as a dark red
(ATR): ν = 3081 (w), 2908 (w), 2843 (m), 2340 (w), 2189 (w), 1427
˜
(m), 1029 (s), 973 (m), 929 (m), 865 (m), 811 (s), 784 (s) cm–1. H
1
NMR (CDCl3, 400 MHz): δ = 2.09 (s, 6 H, CH3), 4.21 (m, 4 H,
3
H
Cp), 4.41 (m, 4 H, HCp), 6.66 (d, J = 3.8 Hz, 2 H, SCCH), 6.88
(d, 3J = 3.8 Hz, 2 H, SCCH) ppm. 13C NMR (CDCl3, 100.6 MHz):
δ = 4.8 (CH3), 68.5 (CCpH), 70.8 (CCpH), 73.4 (CCpC), 80.8 (CϵC),
90.0 (CϵC), 121.4 (CArC), 122.1 (CArH), 131.5 (CArH), 142.3
(CArC) ppm. MS (70 eV): m/z (%) = 428 (14), 427 (29) [M + 1]+,
426 (100) [M+], 424 (6), 185 (13), 184 (7), 152 (10), 57 (7), 56 (7)
[Fe+]. HRMS: calcd. for C24H18FeS2 426.0199; found 426.0201.
C24H18FeS2 (426.4): calcd. C 67.61, H 4.26; found C 67.58, H 4.39.
solid (m.p. 86.1–87.8 °C). IR (ATR): ν = 3068 (w), 2966 (m), 2911
˜
(m), 2856 (m), 2359 (w), 1596 (s), 1508 (m), 1468 (m), 1455 (m),
1362 (s), 1166 (s), 1103 (m), 1036 (s), 1016 (s), 886 (s), 831 (s), 814
1,1Ј-Bis[4-(1-propynyl)phenyl]ferrocene (17): At –78 °C BuLi (1.6 m
in hexane, 3.3 mL, 5.3 mmol) was added dropwise to 1,1Ј-bis(4-
ethynylphenyl)ferrocene[9] (924 mg, 2.4 mmol) in THF (50 mL). Af-
ter stirring for 1 h, iodomethane (1.2 mL, 19.0 mmol) was added at
–78 °C, and the mixture was stirred at 25 °C for 3 h. Water (30 mL)
was added, and the mixture was stirred for 5 min. The aqueous
layer was extracted with dichloromethane (3ϫ 30 mL), and the col-
lected organic layers were washed with brine and dried with
MgSO4. After solvent removal under reduced pressure, the residue
was purified by column chromatography (30ϫ3 cm, petroleum
ether/dichloromethane, 3:1) to give 17 (894 mg, 2.2 mmol, 90%) as
1
(s) cm–1. H NMR (CDCl3, 400 MHz): δ = 1.30 [s, 9 H, SC(CH3)
3], 1.83 (s, 3 H, CCCH3), 4.02 (m, 2 H, HCp), 4.18 (m, 2 H, HCp),
4.37 (m, 2 H, HCp), 4.64 (m, 2 H, HCp), 7.44 (m, 4 H, C6H4) ppm.
13C NMR (CDCl3, 100.6 MHz): δ = 4.4 (CCCH3), 31.0 [SC(CH3)3],
45.9 [SC(CH3)3], 68.0 (CCpH), 69.7 (CCpH), 70.9 (CCpH), 72.5
(CCpH), 76.2 (CCpC), 77.2 (CCpC), 82.4 (CϵC), 85.4 (CϵC), 126.2
(CArH), 129.8 (CArC), 137.4 (CArH), 138.8 (CArS) ppm. MS
(70 eV): m/z (%) = 389 (22) [M + 1]+, 388 (100) [M+], 333 (24), 332
(100) [M+ – C4H8], 331 (8), 330 (8), 298 (9), 171 (8), 139 (12), 57
(45), 56 (10) [Fe+]. HRMS: calcd. for C23H24FeS 388.0948; found
388.0951. C23H24FeS (388.4): calcd. C 71.13, H 6.23; found C
70.99, H 6.48.
a red solid (m.p. 186.7–188.3 °C). IR (ATR): ν = 3084 (w), 2914
˜
(w), 2850 (m), 2243 (w), 1605 (w), 1523 (s), 1454 (m), 1415 (w),
1279 (m), 1106 (m), 1084 (m), 1032 (s), 888 (s), 848 (m), 832 (s),
Bis[1Ј-(4-tert-butylsulfanylphenyl)ferrocenyl]ethyne (15): After ad-
dition of hexacarbonylmolybdenum (6 mg, 0.03 mmol, 10 mol-%)
and 4-chlorophenol (10 mg, 0.08 mmol) to 1-(4-tert-butylsulfanyl-
phenyl)-1Ј-(1-propynyl)ferrocene (14, 97 mg, 0.3 mmol) in toluene
(10 mL), the solution was heated at reflux (oil-bath temperature
120 °C) for 20 h. After cooling to 25 °C, aq. NaOH (1 m, 10 mL)
was added, and the mixture was stirred for 5 min. After extraction
with dichloromethane (3ϫ 10 mL), the collected organic layers
were washed with brine (10 mL) and dried with MgSO4. After sol-
vent removal under reduced pressure, the residue was purified by
column chromatography (30ϫ3 cm, petroleum ether/dichloro-
methane, 2:1) to give 15 (31 mg, 0.04 mmol, 34%) as an orange
1
810 (s), 728 (w) cm–1. H NMR (CDCl3, 400 MHz): δ = 2.08 (s, 6
H, CH3), 4.22 (m, 4 H, HCp), 4.41 (m, 4 H, HCp), 7.18 (m, 4 H,
C6H4), 7.23 (m, 4 H, C6H4) ppm. 13C NMR (CDCl3, 100.6 MHz):
δ = 4.4 (CH3), 68.0 (CCpH), 70.7 (CCpH), 80.0 (CCpC), 85.2 (CϵC),
85.7 (CϵC), 121.3 (H3CCCCCH), 125.6 (H3CCCCCHCH), 131.4
(H3CCCCCH), 137.6 (CCpCCH) ppm. MS (70 eV): m/z (%) = 416
(9), 415 (48) [M + 1]+, 414 (100) [M+], 413 (6), 412 (11), 179 (29),
178 (17), 152 (11), 57 (9), 56 (7) [Fe+]. HRMS: calcd. for C28H22Fe
414.1071; found 414.1072. C28H22Fe (414.3): calcd. C 81.17, H
5.35; found C 80.96, H 5.35.
Crystal Structure Analysis of 17:[30] Single crystals of 17 were ob-
tained by crystallization from hexane/dichloromethane (1:3).
C28H16Fe, red needles, Mr = 408.26gmol–1, crystal system mono-
solid (m.p. 198.2–200.1 °C). IR (ATR): ν = 3068 (w), 2954 (s), 2920
˜
(s), 2853 (s), 2162 (w), 1597 (m), 1509 (m), 1449 (m), 1409 (w),
1364 (s), 1278 (m), 1167 (s), 1103 (m), 1049 (m), 1039 (s), 936 (s), clinic, space group P21/n, a = 12.8480(1), b = 7.4634(1), c =
885 (s), 831 (s), 808 (s) cm–1. 1H NMR (CDCl3, 400 MHz): δ = 43.1025(4) Å, β = 98.095(1), V = 4091.91(7) Å3, Z = 8, ρcalcd.
=
1.30 (s, 18 H, CH3), 4.10 (m, 4 H, HCp), 4.23 (m, 4 H, HCp), 4.40 1.325 gcm–3, μ = 5.968 mm–1, crystal size 0.25ϫ0.16ϫ0.08 mm;
(m, 4 H, HCp), 4.64 (m, 4 H, HCp), 7.46 (m, 8 H, C6H4) ppm. 13C F(000) = 1680, Bruker KAPPA APEX II diffractometer, T =
NMR (CDCl3, 100.6 MHz): δ = 31.0 (CH3), 45.9 [C(CH3)3], 67.1 213 K, Cu-Kα radiation (λ = 1.54187 Å), 3.48° Յ θ Յ 65.78°, reflec-
(CCpC), 68.5 (CCpH), 70.4 (CCpH), 71.3 (CCpH), 72.8 (CCpH), 84.0 tions collected/unique 23274/6884, R(int) = 0.065; index ranges –15
4516
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4510–4518

1,1Ј-Dialkynylferrocenes in Bidirectional Alkyne Metathesis Reactions
Յ h Յ 15, –4 Յ k Յ 8, –49 Յ l Յ 50, parameter/restraints 523/0, (CϵC), 85.4 (CϵC), 90.2 (CϵC), 120.7 (CArC), 120.8 (CArC),
structure solution and refinement with SHELXS-97 or SHELXL-
125.6 (CArC), 125.7 (CArH), 125.9 (CArH), 131.4 (CArH), 131.5
(CArH), 138.9 (CArC) ppm. MS (70 eV): m/z (%) = 776 (18), 775
(57) [M + 1]+, 774 (100) [M+], 772 (13), 388 (14), 387 (39), 386 (6),
179 (6), 178 (5), 84 (8). HRMS calcd. for C52H38Fe2 774.1672;
found 4774.1677. C52H38Fe2 (774.6): calcd. C 80.63, H 4.95; found
C 81.09, H 4.98.
97 (Sheldrick, 1997), respectively,[40] refinement method full-matrix
least squares, no absorption correction, goodness-of-fit on F2
=
1.038, R = 0.0912 [I Ͼ 2σ(I)], wR = 0.2890 (all data), final differ-
ence electron densities 1.585 and –0.759 eÅ–3. Positions of the
methyl hydrogen atoms were not determined.
General Procedure (GP): Catalyst 18[33] (50 mg, 0.05 mmol, 20 mol-
%) was dissolved in toluene (10 mL). After addition of the starting
material(s), the flask was subjected to microwave irradiation (Open
Vessel). After cooling to 25 °C, the solution was filtered through a
3 cm layer of silica gel and washed with dichloromethane. After
solvent removal under reduced pressure, the residue was purified
by column chromatography (30ϫ3 cm, silica gel deactivated with
5% triethylamine, petroleum ether/dichloromethane, 2:1).
Cross Metathesis Reaction with 10 and 12: GP, 1-iodo-1Ј-(1-prop-
ynyl)ferrocene[25] (12; 88 mg, 0.3 mmol) and 1-(tert-butylsulfanyl)-
4-(1-propynyl)benzene[29] (10; 51 mg, 0.3 mmol), µW (300 W),
130 °C, 30 min RAMP, 120 min HOLD. 1-{[4-(tert-Butylsulfanyl)-
phenyl]ethynyl}-1Ј-iodoferrocene (23; 69 mg, 0.1 mmol, 55%) was
obtained as a dark red solid, identified by 1H NMR spec-
troscopy.[10,36]
Cross Metathesis Reaction with 6 and 10: GP, 1,1Ј-bis(1-propynyl)-
ferrocene[24] (6; 66 mg, 0.25 mmol) and 1-(tert-butylsulfanyl)-4-(1-
propynyl)benzene (10; 102 mg, 0.5 mmol), µW (300 W), 130 °C,
30 min RAMP, 120 min HOLD. The product mixture was sepa-
Bis[1Ј-(1-propynyl)ferrocenyl]ethyne (19): GP, 1,1Ј-bis(1-propynyl)-
ferrocene (6; 66 mg, 0.3 mmol), µW (250 W), 120 °C, 30 min
RAMP, 120 min HOLD. Compound 19 (17 mg, 0.04 mmol, 29%)
was obtained as a red solid (m.p. 181.0–182.5 °C). IR (ATR): ν = rated by column chromatography (30 ϫ 2 cm, petroleum ether/
˜
3099 (w), 2966 (m), 2919 (s), 2850 (m), 2232 (w), 1719 (w), 1494
dichloromethane, 2:1 to 1:1). I. 10 (22 mg, 0.10 mmol, 20 %).
(m), 1463 (m), 1265 (m), 1202 (m), 1057 (m), 1043 (m), 1026 (s), II. 11[29] (21 mg, 0.06 mmol, 24%), identified by 1H NMR spec-
1
982 (m), 935 (s), 873 (m), 848 (s), 822 (s), 735 (m) cm–1. H NMR troscopy. III. 24[25] (30 mg, 0.07 mmol, 30 %), identified by 1H
(CDCl3, 400 MHz): δ = 1.91 (s, 6 H, CH3), 4.21 (m, 4 H, HCp), NMR spectroscopy. IV. 25[25] (50 mg, 0.09 mmol, 36%), identified
1
4.24 (m, 4 H, HCp), 4.37 (m, 4 H, HCp), 4.45 (m, 4 H, HCp) ppm. by H NMR spectroscopy.
13C NMR (CDCl3, 100.6 MHz): δ = 4.5 (CH3), 67.5 (CCCH3), 68.0
Cross Metathesis Reaction with 10 and 16: GP, 1,1Ј-bis{2-[5-(1-
(CCpC), 70.4 (CCpH), 70.5 (CCpH), 72.6 (CCpH), 72.7 (CCpH), 76.4
propynyl)]thiophenyl}ferrocene (16; 106 mg, 0.25 mmol) and 1-
(CCpC), 82.6 (CCCH3), 83.8 (CϵC) ppm. MS (70 eV): m/z (%) =
(tert-butylsulfanyl)-4-(1-propynyl)benzene (6; 102 mg, 0.50 mmol),
471 (37) [M + 1]+, 470 (100) [M+], 468 (14), 235 (8), 86 (10), 84
µW (200 W), 110 °C, 30 min RAMP, 120 min HOLD. The product
(14), 81 (9), 57 (11), 56 (16) [Fe+]. HRMS: calcd. for C28H22Fe2
mixture was separated by column chromatography (30ϫ 2 cm,
470.0420; found 470.0417. C28H22Fe2 (470.2): calcd. C 71.53, H
petroleum ether/dichloromethane, 3:1 to 2:1). I. 1-{5-[2-(4-tert-But-
4.72; found C 71.53, H 5.15.
ylsulfanylphenyl)ethynyl]-2-thiophenyl}-1Ј-[5-(1-propynyl)-2-thio-
Bis{2-[5-(1Ј-{2-[5-(1-propynyl)]thiophenyl}ferrocenyl)]thiophenyl}- phenyl]ferrocene (26) (42 mg, 0.07 mmol, 29%), orange solid (m.p.
ethyne (21): .GP, 1,1Ј-bis{2-[4-(1-propynyl)]thiophenyl}ferrocene
111.5–113.1 °C). II. 21 (9 mg, 0.01 mmol, 9%). III. 27[9](13 mg,
(16; 106 mg, 0.3 mmol), µW (200 W), 105 °C, 30 min RAMP, 0.02 mmol, 7%), identified by 1H NMR spectroscopy. 26: IR
120 min HOLD. Compound 21 (14 mg, 0.02 mmol, 14%) was ob-
(ATR): ν = 3081 (w), 2958 (w), 2920 (w), 2852 (w), 2189 (m), 1588
˜
tained as a red solid (m.p. 172.2–173.6 °C). IR (ATR): ν = 3081
(w), 1469 (m), 1427 (m), 1363 (m), 1214 (m), 1167 (m), 1030 (m),
˜
(w), 2959 (m), 2919 (m), 2851 (m), 2189 (w), 1753 (w), 1543 (w), 1014 (w), 973 (m), 838 (m), 811 (s), 770 (s), 730 (w) cm–1. 1H NMR
1428 (m), 1202 (m), 1044 (m), 1030 (s), 958 (s), 851 (m), 797 (s), (CDCl3, 400 MHz): δ = 1.31 [s, 9 H, C(CH3)3], 2.05 (s, 3 H,
743 (w) cm–1. 1H NMR (CDCl3, 400 MHz): δ = 2.08 (s, 6 H, CH3), CCCH3), 4.24 (m, 4 H, HCp), 4.44 (m, 4 H, HCp), 6.66 (d, J =
3
4.24 (m, 8 H, HCp), 4.44 (m, 8 H, HCp), 6.68 (d, J = 3.8 Hz, 2 H,
3.8 Hz, 1 H, arom. H), 6.73 (d, J = 3.8 Hz, 1 H, arom. H), 6.88 (d,
J = 3.8 Hz, 1 H, CϵCCSCCH), 7.05 (d, J = 3.8 Hz, 1 H,
3
3
SCCH), 6.73 (d, J = 3.8 Hz, 2 H, SCCH), 6.89 (d, J = 3.8 Hz, 2
H, SCCH), 7.04 (d, 3J = 3.8 Hz, 2 H, SCCH) ppm. 13C NMR CϵCCSCCHCH), 7.50 (m, 4 H, HAr) ppm. 13C NMR (CDCl3,
(CDCl3, 100.6 MHz): δ = 4.7 (CH3), 68.5 (CCpH), 68.6 (CCpH), 100.6 MHz): δ = 4.7 (CCCH3), 31.0 [C(CH3)3], 46.4 [C(CH3)3], 68.5
70.8 (CCpH), 71.0 (CCpH), 73.4 (CCpC), 80.6 (CCpC), 81.0 (CϵC), (CCpH), 68.6 (CCpH), 70.7 (CCpH), 70.9 (CCpH), 73.4 (CCpC), 80.5
87.1 (CϵC), 90.2 (CϵC), 120.3 (CArC), 121.5 (CArC), 122.2
(CCpC), 81.0 (CϵC), 85.0 (CϵC), 90.1 (CϵC), 92.7 (CϵC), 120.1
(CArH), 122.5 (CArH), 131.5 (CArH), 132.6 (CArH), 142.1 (CArC), (CArC or CTpC), 121.5 (CArC or CTpC), 122.2 (CArH or CTpH),
144.2 (CArC) ppm. MS (70 eV): m/z (%) = 577 (31), 576 (76), 520 122.4 (CArH or CTpH), 123.6 (CArC or CTpC), 131.1 (CArH or
(26), 388 (34), 330 (34), 186 (29), 185 (24), 111 (22), 97 (36), 95
CTpH), 131.5 (CArH or CTpH), 132.8 (CArH or CTpH), 133.1 (CArC
(26), 85 (28), 83 (38), 81 (26), 71 (40), 69 (43), 57 (100), 56 (46), or CTpC), 137.2 (CArH or CTpH), 142.0 (CArC or CTpC), 144.3
55 (53). HRMS: calcd. for C44H30Fe2S4 797.9929; found 797.9911.
C44H30Fe2S4 (798.7): calcd. C 66.17, H 3.79; found C 66.73, H 4.58.
(CArC or CTpC) ppm. MS (70 eV): m/z (%) = 578 (22), 577 (41) [M
+ 1]+, 576 (100) [M+], 521 (14), 520 (38), 57 (27). HRMS: calcd.
for C33H28FeS3 576.0703; found 576.0699. C33H28FeS3 (576.1):
calcd. C 68.74, H 4.89; found C 69.05, H 5.20.
Bis(4-{1Ј-[4-(1-propynyl)phenyl]ferrocenyl}phenyl)ethyne (22): GP,
1,1Ј-bis[4-(1-propynyl)phenyl]ferrocene (17; 103 mg, 0.3 mmol),
µW (200 W), 130 °C, 30 min RAMP, 120 min HOLD. Compound
22 (11 mg, 0.01 mmol, 11%) was obtained as an orange solid (m.p.
Cross Metathesis Reaction with 10 and 17: GP, 1,1Ј-bis[4-(1-prop-
ynyl)phenyl]ferrocene (17; 104 mg, 0.3 mmol) and 1-(tert-butyl-
258.0 °C, dec.). IR (ATR): ν = 3104 (w), 2921 (m), 2850 (m), 2223 sulfanyl)-4-(1-propynyl)benzene (10; 102 mg, 0.5 mmol), µW
˜
(w), 1910 (w), 1604 (w), 1524 (s), 1454 (m), 1280 (m), 1108 (m), (300 W), 130 °C, 30 min RAMP, 120 min HOLD. The product mix-
1
1084 (m), 1033 (s), 880 (s), 848 (s), 838 (s), 818 (s) cm–1. H NMR ture was separated by column chromatography (30ϫ2 cm, petro-
(CDCl3, 400 MHz): δ = 2.04 (s, 6 H, CH3), 4.25 (m, 8 H, HCp), leum ether/dichloromethane, 3:1 to 2:1). I. 1-{4-[2-(4-tert-Butyl-
4.45 (m, 8 H, HCp), 7.25 (m, 8 H, HAr), 7.38 (m, 8 H, HAr) ppm. sulfanylphenyl)ethynyl]phenyl}-1Ј-[4-(1-propynyl)phenyl]ferrocene
13C NMR (CDCl3, 100.6 MHz): δ = 4.4 (CH3), 68.0 (CCpH), 68.1 (28; 16 mg, 0.03 mmol, 11%). II. 1,1Ј-Bis{4-[2-(4-tert-butylsulfan-
(CCpH), 69.5 (CCpH), 69.6 (CCpH), 70.7 (CCpC), 70.8 (CCpC), 85.1 ylphenyl)ethynyl]phenyl}ferrocene (29;[9] 21 mg, 0.03 mmol, 12%),
Eur. J. Org. Chem. 2015, 4510–4518
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4517

J. Ma, N. Krauße, H. Butenschön
[15] R. R. Schrock, Chem. Commun. 2013, 49, 5529–5531.
[16] W. Zhang, J. S. Moore, Adv. Synth. Catal. 2007, 349, 93–120.
[17] R. R. Schrock, C. Czekelius, Adv. Synth. Catal. 2007, 349, 55–
77.
[18] A. Fürstner, P. W. Davies, Chem. Commun. 2005, 2307–2320.
[19] U. H. F. Bunz, Science 2005, 308, 216–217.
[20] O. R. Thiel in Transition Metals for Organic Synthesis (Eds.:
M. Beller, C. Bolm), Wiley-VCH, Weinheim, 2004, vol. 1. pp.
321–334.
FULL PAPER
identified by H NMR spectroscopy. 28: IR (ATR): ν = 3095 (w),
1
˜
2946 (s), 2921 (s), 2852 (s), 2216 (w), 1588 (w), 1524 (m), 1454 (s),
1260 (s), 1165 (m), 1082 (s), 1033 (s), 1016 (s), 878 (m), 824 (s), 811
1
(s), 797 (s), 784 (s) cm–1. H NMR (CDCl3, 400 MHz): δ = 1.31 [s,
9 H, C(CH3)3], 2.02 (s, 3 H, CH3), 4.25 (m, 4 H, HCp), 4.45 (m, 4
H, HCp), 7.16 (m, 2 H, HAr), 7.22 (m, 4 H, HAr), 7.34 (m, 2 H,
HAr) 7.53 (m, 4 H, HAr) ppm. 13C NMR (CDCl3, 100.6 MHz): δ =
4.4 (CH3), 31.0 [C(CH3)3], 46.4 [C(CH3)3], 67.9 (CCpH), 68.0
(CCpH), 70.6 (CCpH), 70.8 (CCpH), 80.0 (CϵC), 85.0 (CCpC), 85.4 [21] U. H. F. Bunz, Acc. Chem. Res. 2001, 34, 998–1010.
[22] A. Fürstner, Angew. Chem. Int. Ed. 2000, 39, 3012–3043; An-
gew. Chem. 2000, 112, 3140–3172.
[23] U. H. Bunz, L. Kloppenburg, Angew. Chem. Int. Ed. 1999, 38,
478–481; Angew. Chem. 1999, 111, 503–505.
[24] G. Doisneau, G. Balavoine, T. Fillebeen-Khan, J. Organomet.
Chem. 1992, 425, 113–117.
[25] J. Ma, B. Kühn, T. Hackl, H. Butenschön, Chem. Eur. J. 2010,
16, 1859–1870.
(CCpC), 85.8 (CϵC), 88.9 (CϵC), 91.4 (CϵC), 120.1 (CArC), 121.3
(CArC), 124.0 (CArC), 125.6 (CArH), 125.7 (CArH), 131.4 (CArH),
131.5 (CArH), 131.6 (CArH), 133.0 (CArC), 137.2 (CArH) 137.3
(CArC or CArS), 138.6 (CArC or CArS) ppm. MS (70 eV): m/z (%)
= 566 (17), 564 (43) [M + 1]+, 564 (100) [M+], 509 (13), 508 (34),
57 (33). HRMS: calcd. for C37H32FeS 564.1574; found 564.1570.
C37H32FeS (564.6): calcd. C 78.72, H 5.71; found C 78.22, H 5.95.
[26] M. Kotora, D. Necas, P. Stepnicka, Collect. Czech. Chem.
Commun. 2003, 68, 1897–1903.
Supporting Information (see footnote on the first page of this arti-
1
cle): Copies of H and 13C NMR spectra of all new compounds.
[27] V. Sashuk, J. Ignatowska, K. Grela, J. Org. Chem. 2004, 69,
7748–7751.
[28] M. Mayor, H. B. Weber, J. Reichert, M. Elbing, C. von Haen-
isch, D. Beckmann, M. Fischer, Angew. Chem. Int. Ed. 2003,
42, 5834–5838; Angew. Chem. 2003, 115, 6014–6018.
[29] V. Kaliginedi, P. Moreno-Garcia, H. Valkenier, W. Hong, V. M.
Garcia-Suarez, P. Buiter, J. L. H. Otten, J. C. Hummelen, C. J.
Lambert, T. Wandlowski, J. Am. Chem. Soc. 2012, 134, 5262–
5275.
[30] CCDC-1058260 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
N. K. thanks the Leibniz Universität Hannover for a graduate
fellowship. We thank Innospec Deutschland GmbH for a donation
of ferrocene. We thank Dr. Michael Wiebcke, Institut für An-
organische Chemie, Leibniz University of Hannover, for per-
forming the crystallographic analysis of 17.
[1] J. M. Tour, Molecular Electronics: Commercial Insights, Chem-
istry, Devices, Architecture and Programming, World Scientific, [31] N. Krauße, H. Butenschön, Eur. J. Org. Chem. 2014, 6686–
New Jersey 2003.
6695.
[2] R. L. Carroll, C. B. Gorman, Angew. Chem. Int. Ed. 2002, 41,
4378–4400; Angew. Chem. 2002, 114, 4556–4579.
[3] D. K. James, J. M. Tour, Top. Curr. Chem. 2005, 257, 33–62.
[4] D. K. James, J. M. Tour, Aldrichim. Acta 2006, 39, 47–56.
[5] J. M. Tour, Acc. Chem. Res. 2000, 33, 791–804.
[6] J.-J. Hwang, J. M. Tour, Tetrahedron 2002, 58, 10387–10405.
[7] D. L. Pearson, J. M. Tour, J. Org. Chem. 1997, 62, 1376–1387.
[8] A. Mishchenko, L. A. Zotti, D. Vonlanthen, M. Burkle, F.
Pauly, J. C. Cuevas, M. Mayor, T. Wandlowski, J. Am. Chem.
Soc. 2011, 133, 184–187.
[32] S. L. Ingham, M. S. Khan, J. Lewis, N. J. Long, P. R. Raithby,
J. Organomet. Chem. 1994, 470, 153–159.
[33] M. Bindl, R. Stade, E. K. Heilmann, A. Picot, R. Goddard, A.
Furstner, J. Am. Chem. Soc. 2009, 131, 9468–9470.
[34] M. Rosenblum, N. M. Brawn, D. Ciappenelli, J. Tancrede, J.
Organomet. Chem. 1970, 24, 469–477.
[35] T. Bobula, J. Hudlicky, P. Novak, R. Gyepes, I. Cisarova, P.
Stepnicka, M. Kotora, Eur. J. Inorg. Chem. 2008, 3911–3920.
[36] J. Ma, M. Vollmann, H. Menzel, S. Pohle, H. Butenschön, J.
Inorg. Organomet. Polym. 2012, 22, 1430.
[9] I. Baumgardt, H. Butenschön, Eur. J. Org. Chem. 2010, 1076–
1087.
[10] J. Ma, M. Vollmann, H. Menzel, S. Pohle, H. Butenschön, J.
Inorg. Organomet. Polym. 2008, 18, 41–50.
[11] N. Krauße, Dissertation, Leibniz University of Hannover,
2014.
[12] C. Engtrakul, L. R. Sita, Nano Lett. 2001, 1, 541–549.
[13] C. Engtrakul, L. R. Sita, Organometallics 2008, 27, 927–937.
[14] M. S. Inkpen, A. J. P. White, T. Albrecht, N. J. Long, Dalton
Trans. 2014, 43, 15287–15290.
[37] P. Persich, J. Llaveria, R. Lhermet, T. de Haro, R. Stade, A.
Kondoh, A. Fürstner, Chem. Eur. J. 2013, 19, 13047–13058.
[38] B. Haberlag, M. Freytag, C. G. Daniliuc, P. G. Jones, M.
Tamm, Angew. Chem. Int. Ed. 2012, 51, 13019–13022; Angew.
Chem. 2012, 124, 13159–13199.
[39] W. C. Still, M. Kahn, A. Mitra, J. Org. Chem. 1978, 43, 2923–
2925.
[40] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
Received: April 15, 2015
Published Online: June 2
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