Butterfly topologies: New expanded carbon-rich organometallic scaffolds

Article abstract of DOI:10.1016/S0022-328X(03)00125-6

Starting from either (tetraethynylcyclobutadiene)cyclopentadienylcobalt or [1,2-diethynyl-3,4-(2-dioxanyl)cyclobutadiene]cyclopentadienylcobalt a sequence of copper and Pd-catalyzed couplings of the Eglinton and the Heck-Cassar-Sonogashira-Hagihara type furnishes five bow-tie shaped doubly annelated dehydroannulenes, the largest of which featuring a (formal) 7,8:13,14:25,26:31,32-tetra(4′alkyl- 1′,2′- benzo)tricyclo[18,16,0^2,19]hexatricosa- 3,5,9,11,15,17,21,23, 27,29,33,35-dodecayne-1,7,13,19,25,31-hexaene hydrocarbon ligand with a cyclopentadienyl-cobalt stabilized cyclobutadiene complex as its central unit. Single crystal X-ray structures of two of the smaller butterflies are reported and their surprising solid-state packing is discussed herein.

Full text of DOI:10.1016/S0022-328X(03)00125-6

Journal of Organometallic Chemistry 673 (2003) 13ꢀ24
/
www.elsevier.com/locate/jorganchem
Butterfly topologies: new expanded carbon-rich organometallic
scaffolds
Matthew Laskoski, Gaby Roidl, Holly L. Ricks, Jason G.M. Morton, Mark D. Smith,
Uwe H.F. Bunz *
Department of Chemistry and Biochemistry, USC NanoCenter, The University of South Carolina, Columbia, SC 29208, USA
Received 7 February 2003; received in revised form 10 February 2003; accepted 10 February 2003
Abstract
Starting from either (tetraethynylcyclobutadiene)cyclopentadienylcobalt or [1,2-diethynyl-3,4-(2-dioxanyl)cyclobutadiene]-
cyclopentadienylcobalt a sequence of copper and Pd-catalyzed couplings of the Eglinton and the Heckꢀ
/
Cassarꢀ
/
Sonogashiraꢀ
/
Hagihara type furnishes five bow-tie shaped doubly annelated dehydroannulenes, the largest of which featuring
a
(formal) 7,8:13,14:25,26:31,32-tetra(4?alkyl-1?,2?-benzo)tricyclo[18,16,02,19]hexatricosa-3,5,9,11,15,17,21,23,27,29,33,35-dodecayne-
1,7,13,19,25,31-hexaene hydrocarbon ligand with a cyclopentadienyl-cobalt stabilized cyclobutadiene complex as its central unit.
Single crystal X-ray structures of two of the smaller butterflies are reported and their surprising solid-state packing is discussed
herein.
# 2003 Published by Elsevier Science B.V.
Keywords: Alkynes; Dehydro[14]annulenes; Dehydro[18]annulenes; Cyclobutadiene complexes; Cobalt; Pd-catalysis; Copper
1. Introduction
synthetic sequences that involved multiple intermedi-
ates. A typical ‘pre-Pd-age’ sequence would have con-
verted an aromatic aldehyde in three steps under forcing
conditions and in only moderate yields into an alkyne.
The phenomenal success of the Pd-catalyzed couplings
was enhanced by other developments in alkyne chem-
We give herein a full account of the synthesis and
structural characterization of carbon-rich organometal-
lic butterflies that are based upon a central (tetraethy-
nylcyclobutadiene)cyclopentadienylcobalt unit [1a,1b].
The chemistry of carbon-rich-materials [2ꢀ7] has made
/
istry that play an important role [9ꢀ11].
/
great strides during the last 20 years. Molecules such as
the hexaethynylbenzenes [3], dreams once, are easily
accessible now and routinely incorporated into larger
carbon-rich structures [6]. The ‘quantum leap’ in meth-
odology occurred when the Pd-catalyzed reaction of aryl
halides to terminal alkynes was reported in 1975 by
Heck, Cassar, and Sonogashira and Hagihara [8]. This
procedure allows the direct attachment of alkyne units
to arenes, which prior was only possible via lengthy
Dehydroannulenes have commanded attention be-
cause of their attractive structures and their exciting
properties that include but are not restricted to supra-
molecular organization/aggregation, and their use as
electronic materials [6g,12ꢀ15]. While purely organic,
/
i.e. C,H,O,N-containing dehydroannulenes are wide-
spread, their organometallic congeners have found less
attention [16]. We have a long-standing interest in
carbon-rich organometallics [17] and report herein the
synthesis and characterization of large butterfly-shaped,
fused double dehydroannulenes that feature a central
tetraethynylated cyclobutadiene complex [18]. Such
butterfly topologies are speculated to be critically
important in the primary stages of the formation of
fullerenes in the gas phase [19].
* Corresponding author. Present address: School of Chemistry and
Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-
0400, USA. Tel.: ꢁ
E-mail
/
1-803-777-8436; fax: ꢁ
addresses:
/
1-803-929-0267.
bunz@mail.chem.sc.edu,
uwe.bunz@chemistry.gatech.edu (U.H.F. Bunz).
0022-328X/03/$ - see front matter # 2003 Published by Elsevier Science B.V.
doi:10.1016/S0022-328X(03)00125-6

14
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ24
/
2. Results and discussion
2.1. Syntheses
The parent butterfly 4 was made by the Pd-catalyzed
coupling of (tetraethynylcyclobutadiene)cyclopentadie-
nylcobalt (1) with diiodobenzene (2) to give the open
precursor (3) in an overall yield of 4.2% after a second
Pd-catalyzed coupling to trimethylsilylacetylene
(Scheme 1). Desilylation of 3 is followed by ring closing,
utilizing the Vogtle variant [20] of the Eglinlon coupling
¨
[10] and the title compound 4 forms in a 94% yield.
The complex 4 was only sparsely soluble in organic
solvents; a 13C-NMR spectrum could be obtained in
THF-d8, however, it was not possible to grow a single
crystalline specimen useful for X-ray diffraction. To
increase the solubility of the butterflies, and obtain
derivatives that would crystallize better, a second,
stepwise synthetic approach was developed. Diyne (5)
[18b] was transformed into 7 by standard Pd-methodol-
ogy. Desilylation and ring closure furnishes 7 in a 50%
overall yield (Scheme 2). The intermediate 7 was
Scheme 2. Synthesis of the butterflies 9a and 9b.
deprotected and subjected to reactions 1ꢀ3 with arene
/
6 (9a) or alkene 8 (9b). This sequence furnished the un-
symmetrical butterfly 9b (57%) and the symmetrical
butterfly 9a (16%). While the butterfly 9b was quite
unstable, 9a was stable and soluble in hexane, dichlor-
omethane, and THF. Crystallization from dichloro-
methane furnished
a
suitable single crystalline
specimen (vide infra). To obtain butterflies that incor-
porate the larger dehydro[18]annulenes, a similar step-
wise approach was utilized. A dehydroannulene moiety
was attached to 10 by coupling to 11 in a Cadiot
Chodciewicz [21] type protocol (Scheme 3). Subsequent
deprotection is followed by ring closure to afford the
dehydroannulenes (12a,b) with isopropyl (28%) or butyl
(38%) substituents. Deprotection of the acetal rings in
Scheme 3. Synthesis of the large butterfly precursor 14.
12 by para-toluenesulfonic acid (TsOH) was facile and
the formed intermediates were immediately subjected to
an Ohiraꢀ
/
TaberꢀBestmann [11] alkynylation with 13.
/
The tetraethynylcyclobutadiene complexes (14a,b) were
obtained in 17 and 18% overall yield starting from 10;
they were unstable when isolated and used immediately
in the following step.
The strategically important intermediates 14a,b al-
lowed the attachment of the second dehydroannulene
moiety as shown in Scheme 4. The synthesis of the larger
butterflies 15 commences with the coupling of 14a,b to
11. Deprotection and subsequent ring closure with
Cu(OAc)2 in acetonitrile furnishes the large butterflies
15a and 15b in 22 and 15% yield. For the synthesis of the
mixed butterfly 17 the diyne 14b (Rꢂbutyl) is coupled
/
to 16; the TMS-groups are cleaved off by K2CO3 and
the second ring is closed utilizing the Cu(OAc)2 coupling
to furnish 17 in an overall yield of 51% starting from 14b
Scheme 1. Synthesis of the parent cyclobutadiene (cyclopentadienyl)
cobalt based butterfly 4.

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ
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15
ligand have been discussed in depth in the preliminary
communication and will not be repeated here [1a,1b].
We investigated the solid state ordering of 9a and
were surprised to find a tetragonal packing of the
molecules with a space group I41, quite unusual for an
organometallic compound. Fig. 2 shows a packing
diagram of the small butterfly 9a. The molecules are
stacked in an AB scheme in the vertical c-axis. In two
different layers, the molecules are rotated by 908 with
respect to each other. In a single plane (Fig. 2) the
molecules are arranged as chessboard tiles in which
every second row of ‘tiling’ is missing.
The second layer above or below fills the ‘empty’
spaces above and below the squares in the middle. The
net effect is a striking supramolecular arrangement of 9a
in the solid state. All of the organometallic cyclobuta-
diene(cyclopentadienyl)cobalt units are arranged in a
square grid-like pattern that repeats the tetragonal
symmetry of the cyclobutadiene complex nicely. In
Fig. 3 the ORTEP representation of the unsymmetrical
butterfly 17 is shown. The molecular structure is the
expected combination of a dehydro[14]annulene and a
dehydro[18]annulene. The bond lengths and bond angles
are in excellent agreement with published values for the
corresponding sub-structures [1]. While 9a is signifi-
cantly bent, the large hydrocarbon ligand of 17 is
planar. It was of interest to see if the planarity has an
electronic reason or is due to a packing effect. Calcula-
tion of 17 utilizing PM3 TM (Wavefunction, Spartan
Pro, Windows 2000) shows that the large hydrocarbon
ligand is as bent (21.48 for the large dehydroannulene
and 17.58 for the small one) as the one in 9 for an
isolated molecule in the gas phase. Consequently, the
observed planarity in the solid-state structure of 17 must
be due to a packing effect.
Scheme 4. Synthesis of the enlarged butterflies 15 and 17.
(Rꢂbutyl). Attempts to obtain a single crystalline
/
specimen of either derivative of 15 failed, but it was
possible to obtain a suitable single crystal of 17 from
dichloromethaneꢀhexane mixtures. Crystalline samples
/
of the butterflies 15 and 17 are stable under ambient
conditions for several months.
2.2. Single crystal structures of 9a and 17
To gain a better understanding of the topology and
the supramolecular ordering of the butterflies in the
solid state we obtained a single crystal X-ray structure
showing that the large hydrocarbon ligand in 9a is bent
outwardly in the solid state. Fig. 1 displays the ORTEP of
9a. The structural details of the large hydrocarbon
The packing of 17 is somewhat similar to that of 9a,
insofar as the molecules are packed on top of each other
and rotated by 908. In Table 1 the cell parameters of the
two butterflies are listed; while the a and the b-axes of
9a and 17 are different, their c-axes are similar. The c-
axis is the ‘layer’ axis along which the molecules are
stacked on top of each other. The slightly larger c-axis
Table 1
Crystallographic data for 9a and 17
9a
17
Crystal system
Space group
Tetragonal
I41
Monoclinic
Cc
˚
a (A)
19.156(5)
19.156(5)
15.842(7)
90
32.447(3)
27.437(3)
14.042(1)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
90
90
108.354(2)
90
3
˚
5814(3)
4
11 865(2)
8
Fig. 1. ORTEP representation of 9a.

16
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ24
/
Fig. 3. ORTEP representation of 17.
hydrocarbon ligands, located in a common plane, are
oriented perpendicular to each other. The butyl ‘tails’ of
17 are tucked in-between two layers, into the interstitial
space. The main differences in the packing and in the
unit cells arise, therefore, from the differing dimensions
and shape of the large p-conjugated ligands in 9a and in
17 (Fig. 4).
Fig. 2. Packing of the organometallic butterfly 9a. The packing
pattern is such that the hydrocarbon ligands in two adjacent layers
are packed in a staggered fashion. The molecules in each layer are
rotated by 908 with respect to each other, which gives an overall
tetragonal symmetry to this packing arrangement.
of 9a is due to its larger tert-butyl substituents and the
upward bending of the whole hydrocarbon ligand. Both
factors contribute to the increased ‘thickness’ of 9a
compared with 17 that must be accommodated for by
the crystal lattice. In 17 as well as in 9a, the large
Fig. 4. Packing of the unsymmetrical butterfly 17 in the solid-state.
Top, view onto the large hydrocarbon ligand. Bottom, layered
˚
structure of 17, The layers are ca. 3.6 A spaced apart, with the CpCo
units and the butyl groups filling the interstitial interlayer spaces.

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ
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17
3. Conclusions
ambient temperature for 8 h. The reaction mixture was
quenched with water and extracted twice with ethyl
ether. The combined organic layers were dried over
MgSO4 and the solvent removed in vacuo. Column
chromatography (SiO2; hexanes:CH2Cl2, 10:1) furnished
I-1 (107 mg, 26%) as an orange oil. 1H-NMR (300 MHz,
A family of novel butterfly-shaped organometallic
double dehydro[14]annulenes and dehydro[18]annulenes
has been prepared by a combination of Pd- and Cu-
catalyzed reactions. These structures are attractive
synthetic targets on the way to an all-butadiyne bridged
organometallic wheel (see red sub-structure in Fig. 5)
[17c,17d]. More importantly, according to Jarrold [19]
all-carbon topologies of the butterfly-type described
here could play an important role in the first stages of
fullerene formation in the gas phase. The most surpris-
ing feature of these organometallic butterflies is their
supramolecular ordering in the solid state, the formation
of a very unusual tetragonal network. In future we will
investigate the self assembly of pyridine containing
butterflies and the covalent closure of organometallic
wheels.
CDCl3): d 7.91ꢀ
(m, 4H, aromatic-H), 7.38ꢀ
7.10ꢀ
7.06 (m, 8H, aromatic-H), 5.29 (s, 5H, Cp-H). 13C-
/
7.89 (m, 4H, aromatic-H), 7.57ꢀ
/7.56
/
7.34 (m, 8H, aromatic-H),
/
NMR (75 MHz, CDCl3): d 139.00, 132.61, 130.10,
129.80, 128.21, 100.71, 95.70, 84.30, 61.18. MS (EI) m/z;
Calc. for [Mꢁ] (C41H21CoI4) 1079.8, Found 1080.17.
4.2. Synthesis of 3
In a procedure analogous to the synthesis of I-1, I-1
(40, 1 mg, 37.1 mmol), (trimethylsilyl)acetylene (1.79 g,
5.88 mmol), (PPh3PdCl2 (2.0 mg, 2.9 mmol) and CuI (1.3
mg, 6.8 mmol) were reacted in piperidine (10 ml).
Column chromatography (SiO2; CH2Cl2:hexane, 9:1)
furnished 3 (23.2 mg, 16%) as a red oil. IR (Neat): n
(cmꢃ1) 2989, 2159, 1483, 1250, 1098. 1H-NMR (300
4. Experimental
4.1. Synthesis of 18
MHz, CDCl3): d 7.53ꢀ
/
7.51, 7.47ꢀ7.44 (m, 8H, aro-
/
In a 25 ml oven-dried Schlenk flask, (tetraethynylcy-
clobutadiene)cyclopentadienylcobalt (1) (105 mg, 0.391
mmol) was dissolved in 5 ml of dry piperidine. To the
solution was added (PPh3)2PdCl2 (14.1 mg, 20.1 mmol),
CuI (3.7 mg, 20 mmol) and 1,2-diiodobenzene (2) (5.00 g,
15.2 mmol). The resulting solution was stirred at
matic-H), 7.25ꢀ7.23 (m, 8H, aromatic-H), 5.12 (s, 5H,
/
Cp-H), 0.18 (s, 3611, TMS-H). 13C-NMR (75 MHz,
CDCl3): d 132.45, 132.29, 127.77, 127.55, 126.18,
124.85, 103.41, 98.92, 92.33, 87.78, 84.11, 61.53, 0.20.
MS (EI) m/z; Calc. for [Mꢁ] (C61H57CoSi4) 960.2,
Found 961.4.

18
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ24
/
Fig. 5. Hypothetical covalent network version of the supramolecular assembly formed by the butterfly 9a. The herein synthesized modules are
colored black, while the connectors are colored grey. The red center represents an organometallic wheel (Section 3).
4.3. Synthesis of 4
H), 5.01 (s, 5H, Cp-H). 13C-NMR (100 MHz, THF-d8):
d 131.81, 131.17, 129.99, 129.90, 128.57, 124.33, 93.48,
90.21, 84.61, 80.00, 68.21, 62.83. Elemental analysis:
Calc. C, 88.02; H, 3.17. Found: C, 87.15; H, 3.20%.
In a 50 ml round bottom flask was placed 3 (23.1 mg,
24.0 mmol) and K2CO3 (50.0 mg, 0.360 mmol) in
methanol (1 ml) and THF (2 ml). The resulting solution
was stirred at ambient temperature for 8 h before being
quenched with water and ethyl ether. The water layer
was separated and extracted with ethyl ether (50 ml).
The combined organic layers were dried over MgSO4
and the solvent removed in vacuo to yield a dark red oil.
To the oil, in a 500 ml round bottom flask, was added
Cu(OAc)2 (1.00 g, 5.51 mmol) and acetonitrile (200 ml).
The resulting mixture was heated to 80 8C for 6 h. The
solvent was removed in vacuo, the resulting mixture
redissolved in CH2Cl2 and filtered through a silica gel
plug. The solvent was removed in vacuo and column
chromatography (SiO2; CH2Cl2:hexanes, 1:1) furnished
4 (14.1 mg, 94%) as a dark red micro-crystalline solid.
Melting point (m.p.): decomposition was observed
before melting. IR (Neat): n (cmꢃ1) 2924, 2361, 2342,
4.4. Synthesis of 19
In a procedure analogous to the synthesis of 3, 5 (85.0
mg, 0.146 mmol), 3-trimethylsilylethynyl)-4-iodo-tert-
butylbenzene (6) (140 mg, 0.393 mmol), (PPh3)2PdCl2
(2.1 mg, 2.9 mmol), CuI (1.3 mg, 6.8 mmol) were reacted
in piperidine (1 ml). Column chromatography (SiO2;
hexanes:CH2Cl2, 9:1) furnished 19 (92.1 mg, 61%) as an
orange oil. IR (Neat): n (cmꢃ1) 2924, 2844, 2367, 2333,
1461, 1237. 1H-NMR (300 MHz, CDCl3): d 7.44 (d, 2H,
3
4JH,H
ꢂ
/
1.9 Hz, aromatic-H), 7.35 (d, 2H, JH,H
8.1 Hz, 4JH,H
ꢂ8.1
/
Hz, aromatic-H), 7.24 (dd, 2H, 3JH,H
ꢂ
/
ꢂ
/
1.9 Hz, aromatic-H), 4.95 (s, 5H, Cp-H), 1.23 (s, 18H, t-
butyl), 1.10 (s, 42H, TIPS-H), 0.19 (s, 18H, TMS-H).
13C-NMR (75 MHz, CDCl3): d 151.04, 132.23, 129.42,
125.44, 124.36, 123.59, 104.09, 100.84, 97.87, 96.69,
92.02, 87.01, 83.81, 61.76, 61.50, 34.72, 30.98, 18.69,
11.09, 0.07. MS (EI) m/z; Calc. for [Mꢁ] (C65H89CoSi4)
1458. 1H-NMR (400 MHz, CDCl3): d 7.73 (dd, 4H,
4
7.3 Hz, JH,H
3JH,H
ꢂ
/
ꢂ
/
1.7 Hz, aromatic-H), 7.52 (dd,
1.7 Hz, aromatic-H), 7.42
3
4H, JH,H
4
7.3 Hz, JH,H
ꢂ
/
ꢂ
/
3
(quint, 8H, JH,H
4
7.3 Hz, JH,H
ꢂ
/
ꢂ
/
1.7 Hz, aromatic-
1040.5373, Found: 1040.5380 (Eꢂ2.3 ppm).
/

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ
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19
4.5. Synthesis of 7
(1.2 mg, 1.7 mmol), and CuI (1.0 mg, 5.3 mmol) in
piperidine (1 ml). Column chromatography (SiO2;
CH2Cl2:hexanes, 4:1) furnished 20b (40.4 mg, 65%) as
a red oil. IR (Neat): n (cmꢃ1) 2944, 2855, 2133, 1461,
In a procedure analogous to the synthesis of 4, 19
(0.128 g, 0.960 mmol) and K2CO3 (0.240 g, 1.74 mmol)
were reacted in methanol (2 ml) and THF (5 ml). After
aqueous workup and isolation of the desilylated inter-
mediate, Cu(OAc)2 (0.480 g, 5.51 mmol) and CH3CN
(50 ml) were added and the resulting mixture heated to
1244, 1000. 1H-NMR (400 MHz, CDCl3): d 7.55 (d, 2H,
4
3JH,H
ꢂ
/
8.0 Hz, aromatic-H), 7.50 (d, 2H, JH,H
ꢂ1.8
/
Hz, aromatic-H), 7.36 (dd, 2H, 3JH,H
1.8 Hz, aromatic-H), 6.00 (d, 2H, JH,H
ꢂ
/
8.0 Hz, 4JH,H
ꢂ
/
3
ꢂ
/11.0 Hz,
3
alkene-H), 5.94 (d, 2H, JH,H
80 8C for
8
h. Column chromatography (SiO2;
CH2Cl2:hexanes, 4:1) furnished 7 (87.1 mg, 82%) as a
ꢂ
/
11.0 Hz, alkene-H),
4.98 (s, 5H, Cp-H), 1.32 (s, 18H, t-butyl), 0.23 (s, 18H,
TMS-H). 13C-NMR (100 MHz, CDCl3): d 151.00,
130.90, 127.13, 126.39, 126.17, 123.40, 120.89, 118.44,
103.73, 102.49, 92.78, 92.26, 91.27, 88.55, 84.23, 83.96,
78.94, 62.27, 61.32, 34.91, 33.99, 0.06. MS (EI) m/z;
Calc. for [Mꢁ] (C55H51CoSi2) 826.2861, Found:
826.2898.
dark red oil. IR (Neat): n (cmꢃ1) 2943, 2852, 2338,
1
2143, 1462, 1246. H-NMR (400 MHz, CDCl3): d 7.49
3
(d, 2H, JH,H
ꢂ8.2 Hz, aromatic-H), 7.44 (d, 2H,
/
3
1.9 Hz, aromatic-H), 7.38 (dd, 2H, JH,H
4JH,H
ꢂ
/
ꢂ8.2
/
4
Hz, JH,H
ꢂ
/
1.9 Hz, aromatic-H), 4.93 (s, 5H, Cp-H),
1.31 (s, 18H, t-butyl), 1.14 (s, 42H, TIPS-H). 13C-NMR
(100 MHz, CDCl3): d 150.80, 130.48, 127.13, 126.64,
126.32, 123.40, 100.78, 96.97, 92.21, 84.13, 83.81, 83.60,
61.96, 61.38, 34.90, 30.99, 18.70, 11.11. MS (EI) m/z;
Calc. for [Mꢁ] (C59H71CoSi2) 894.4426, Found:
894.4401%.
4.8. Synthesis of 9a
In a procedure analogous to the synthesis of 4, 20a
(34.1 mg, 33 mmol) was deprotected with K2CO3 (100
mg, 0.720 mmol) in methanol (2 ml) and THF (5 ml).
The resulting product was reacted with Cu(OAc)2 (200
mg, 1.10 mmol) in CH3CN (50 ml). Chromatography
(SiO2; CH2Cl2:hexanes, 1:1) furnished 9a (16.2 mg, 55%)
as a dark red crystalline solid. M.p.: 220 8C (dec.). IR
(Neat): n (cmꢃ1) 2943, 2855, 2333, 2144, 1667, 1461,
4.6. Synthesis of 20a
In a 100 ml round bottom flask, 7 (98.0 mg, 0.110
mmol) and Me4NꢁFꢃ (0.300 g, 10.9 mmol) were
dissolved in DMSO (5 ml) and ethyl ether (10 ml).
The resulting solution was stirred at ambient tempera-
ture for 2 h. The reaction was quenched with water and
extracted with ethyl ether. The combined organic layers
were dried over MgSO4 and the solvent removed in
vacuo to yield a dark red oil. In a procedure analogous
to the synthesis of 18, the oil was placed in a 25 ml
Schlenk flask and reacted with 6 (90.2 mg, 0.253 mmol),
(PPh3)2PdCl2 (1.5 mg, 2.1 mmol), CuI (1.0 mg, 5.3 mmol)
in piperidine (5 ml). Column chromatography (SiO2;
CH2Cl2:hexanes, 1:1) furnished I-3a (34.2 mg, 30%) as a
1244. 1H-NMR (400 MHz, CDCl3): d 7.65 (d, 4H,
4
3JH,H
ꢂ
/
8.3 Hz, aromatic-H), 7.53 (d, 4H, JH,H
8.3 Hz, 4JH,H
ꢂ1.8
/
Hz, aromatic-H), 7.43 (dd, 4H, 3JH,H
ꢂ
/
ꢂ
/
1.8 Hz, aromatic-H), 4.97 (s, 5H, Cp-H), 1.34 (s, 36H, t-
butyl-CH3). 13C-NMR (100 MHz, CDCl3): d 151.18,
130.96, 127.45, 126.83, 126.52, 123.68, 92.98, 89.25,
84.52, 83.91, 79.23, 62.31, 35.17, 31.26. UVꢀvis
/
(CHCl3): l 296 (oꢂ
/
27 530 cmꢃ1 Mꢃ1), 323 (oꢂ
/
22 787 cmꢃ1 Mꢃ1). MS could not be determined due
to decomposition.
red oil. IR (Neat); n (cmꢃ1) 2960, 2872, 2293, 2141,
1
1460, 1240. H-NMR (400 MHz, CDCl3): d 7.58ꢀ
/
7.44
8.2 Hz,
4.9. Synthesis of 9b
3
(m, 8H, aromatic-H), 7.35 (d, 2H, JH,H
ꢂ
/
3
aromatic-H), 7.30 (d, 2H, JH,H
4
8.2 Hz, JH,H
ꢂ
/
ꢂ
/
2.0
Hz, aromatic-H), 5.05 (s, 5H, Cp-H), 1.30 (s, 18H, t-
In a procedure analogous to the synthesis of 4, 20b
(40.2 mg, 48.7 mmol), and K2CO3 (20.1 mg, 0.140 mmol)
were reacted in methanol (2 ml) and THF (5 ml). The
resulting oil was reacted with Cu(OAc)2 (190 mg, 1.05
mmol) in CH3CN (50 ml). Column chromatography
(SiO2; CH2Cl2:hexanes, 1:1) furnished 9b (29.1 mg, 88%)
as a dark red crystalline solid that was only stable in
dilute solutions at ambient temperature. IR (Neat): n
(cmꢃ1) 2956, 2333, 2167, 1644, 1584, 1450, 1400, 1100,
butyl), 1.32 (s, 18H, t-butyl), 1.31 (s, 18H, TMS-H).
1
(Note: Due to the low amount of 20a, only a H-NMR
was obtained before continuing on with the synthesis.)
MS (EI) m/z; Calc. for [Mꢁ] (C71H71CoSi2) 1038.4,
Found: 1038.4.
4.7. Synthesis of 20b
1017. 1H-NMR (400 MHz, CDCl3):
d 7.65 (d,
In a procedure analogous to the synthesis of 20a, 7
(68.0 mg, 76.1 mmol) and Me4NꢁFꢃ (0.300 g, 10.9
mmol) were reacted in DMSO (5 ml) and ethyl ether (10
ml). The resulting oil was placed in a 25 ml Schlenk flask
and reacted with cis-1-chloro-2-(trimethylsilylethyny-
l)ethylene (8) (30.0 mg, 0.190 mmol), (PPh3)2PdCl2
2H,3JH,H
ꢂ
/
8.2 Hz, aromatic-H), 7.52 (d, 2H,4JH,H
ꢂ
/
3
1.8 Hz, aromatic-H), 7.42 (dd, 2H, JH,H
ꢂ
/
8.2 Hz,
9.9
9.9 Hz, alkene-H),
4JH,H
Hz, alkene-H), 6.34 (d, 2H, JH,H
ꢂ
/
1.8 Hz, aromatic-H), 6.72 (d, 2H, JH,H
ꢂ
/
3
3
ꢂ
/
4.95 (s, 5H, Cp-H), 1.33 (s, 18H, t-butyl-CH3). 13C-
NMR (100 MHz, CDCl3): d 151.39, 130.98, 127.47,

20
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ24
/
126.56, 126.3, 123.51, 123.79, 116.87, 96.46, 94.01,
93.31, 88.68, 88.19, 84.44, 84.08, 83.68, 79.20, 63.33,
3JH,H
ꢂ
7.1 Hz, butyl-CH3). 13C-NMR (75 MHz,
/
CDCl3): d 143.46, 132.21, 131.97, 128.21, 126.39,
122.57, 104.86, 97.47, 94.99, 82.40, 80.30, 78.81, 78.11,
77.41, 66.82, 55.09, 45.78, 32.98, 25.65, 22.13, 18.58,
13.74, 11.16, 10.94. Elemental Analysis; Calc.: C, 75.24;
H, 8.01. Found: C, 76.11; H, 7.95%. MS (EI) m/z Calc.
for Mꢁ (C67H85CoO4Si2) 1068.5318. Found 1068.6.
62.99, 35.19, 31.80. UVꢀ/vis (CHCl3): lmax
ꢂ333 nm
/
(oꢂ313). MS could not be determined due to decom-
/
position.
4.10. Synthesis of 21
To a 50 ml oven-dried Schlenk flask was added 10
(200 mg, 0.505 mmol) and dry THF (25 ml) under
4.11. Synthesis of 12a
nitrogen. The flask was cooled to ꢃ
/
78 8C and lithium
To a 50 ml round bottom flask was added 21a (707
mg, 0.680 mmol), Bu4NꢁFꢃ (2.0 ml, 1.0 M in THF)
and THF (7 ml). The resulting solution was stirred at
ambient temperature for 1 h before being quenched with
water and ethyl ether. The water layer was separated
and extracted with ethyl ether (50 ml). The combined
organic layers were dried over MgSO4 and the solvent
removed in vacuo to yield a dark red oil. To the oil, in a
500 ml round bottom flask, was added Cu(OAc)2 (2.70
g, 14.8 mmol) and acetonitrile (400 ml). The resulting
solution was heated to 80 8C for 6 h. The solvent was
removed in vacuo, the crude product dissolved in
CH2Cl2 and filtered through a silica gel plug. Removal
of the solvent in vacuo and column chromatography
diisopropylamide (0.140 g, 1.28 mmol) in THF was
added drop-wise over 10 min. Stirring was continued for
10 min and the solution was brought to 0 8C at which
time the solution turned cloudy. After stirring at 0 8C
for 30 min, CuI (240 mg, 1.26 mmol), was added, the
solution turned transparent and was stirred for an
additional 15 min. Following cooling to ꢃ78 8C, 4-
/
(bromoethynyl)-3-(triisopropylsilylethynyl)isopropyl-
benzene (11a) (450 mg, 1.12 mmol) or 4-(bromoethy-
nyl)-3-(triisopropylsilylethynyl)butylbenzene (11b) (682
mg, 1.64 mmol) and dry propylamine (6.5 ml) were
added successively. The resulting solution was stirred for
5 min, warmed to ambient temperature and stirred for 1
h before being quenched with water and ethyl ether. The
water layer was separated and extracted with ethyl ether
(200 ml). The combined organic layers were dried over
MgSO4 and the solvent removed in vacuo. Column
(SiO2; hexanes:CH2Cl2, 2:1 ꢁ
(228 mg, 46%) as a dark orange oil. IR (Neat): n (cmꢃ1
2954, 2924, 2854, 2324, 2185, 1731, 1454, 1093, 1001.
/10% NEt3) furnished 12a
)
1H-NMR (300 MHz, CDCl3): d 7.38 (d, 2H, 3JH,H
ꢂ/8.0
chromatography (SiO2; hexanes:CH2Cl2, 3:1 ꢁ
/
10%
Hz, aromatic-H), 7.32 (d, 2H, 4JH,H
ꢂ
/
1.6 Hz, aromatic-
3 4
H), 7.13 (dd, 2H, JH,H 8.0 Hz, JH,H
aromatic-H), 5.14 (s, 2H, acetal-CH), 5.07 (s, 5H, Cp-
NEt3) furnished 21a (315 mg, 60%) or 21b (310 mg,
57%) as dark orange oils. Compound 21a: IR (Neat): n
(cmꢃ1) 2947, 2854, 2316, 2193, 2147, 1554, 1101, 993.
ꢂ
/
ꢂ1.6 Hz,
/
H), 4.16ꢀ
acetal-CH2), 2.83 (sept, 2H, JH,H
CH), 2.10ꢀ
acetal-CH2), 1.20 (d, 12H, JH,H
CH3). 13C-NMR (75 MHz, CDCl3): d 149.43, 131.68,
131.42, 127.54, 125.19, 122.88, 97.29, 82.43, 81.23,
80.49, 79.59, 79.14, 78.44, 77.24, 66.92, 66.90, 56.49,
33.92, 25.74, 23.42. MS (EI) m/z Calc. for Mꢁ
(C47H39CoO4) 726.2180, unable to determine due to
decomposition.
/
4.08 (m, 4H, acetal-CH2), 3.85ꢀ
/
3.67 (m, 4H,
1H-NMR (300 MHz, CHCl3): d 7.38 (d, 2H, 3JH,H
ꢂ/8.0
ꢂ
/
6.9 Hz, isopropyl-
1.31 (m, 2H,
3
Hz, aromatic-H), 7.27 (d, 2H, 4JH,H
ꢂ
/1.6 Hz, aromatic-
/
2.03 (m, 2H, acetal-CH2), 1.40ꢀ
/
3
H), 7.07 (dd, 2H, JH,H
aromatic-H), 5.13 (s, 2H, acetal-CH), 5.03 (s, 5H, Cp-
4
8.0 Hz, JH,H
3
ꢂ
/
ꢂ/1.6 Hz,
ꢂ
/
6.9 Hz, isopropyl-
H), 4.15ꢀ
acetal-CH2), 2.82 (sept, 2H, JH,H
CH), 2.09ꢀ
acetal-CH2), 1.20 (d, 12H, JH,H
CH3), 1.15 (s, 42H, TIPS-H). 13C-NMR (75 MHz,
CDCl3): d 149.40, 132.54, 130.28, 126.58, 126.37,
122.92, 105.06, 97.6, 95.12, 82.55, 80.47, 78.86, 78.19,
77.60, 66.93, 66.92, 55.29, 33.97, 25.76, 23.50, 18.71,
11.30. MS (EI) m/z Calc. for Mꢁ (C65H81CoO4Si2)
/
4.10 (m, 4H, acetal-CH2), 3.82ꢀ
/3.78 (m, 4H,
3
ꢂ/6.9 Hz, isopropyl-
/
1.98 (m, 2H, acetal-CH2), 1.35ꢀ
/1.23 (m, 2H,
3
ꢂ
/
6.9 Hz, isopropyl-
4.12. Synthesis of 12b
In a procedure analogous to the synthesis of 12a, 21b
(1.36 g, 1.27 mmol) and Bu4NꢁFꢃ (3.2 ml, 1.0 M in
THF) were reacted for 1 h in THF (10 ml). The resulting
dark oil was reacted with Cu(OAc)2 (5.10 g, 28.1 mmol)
for 6 h at 80 8C in acetonitrile. Aqueous workup
followed by column chromatography (SiO2; hexa-
1040.5005. Found: 1040.5015 (Eꢂ2.4 ppm). Compound
/
21b: IR (Neat): n (cmꢃ1) 2949, 2905, 2850, 2319, 2193,
1
2134, 1533, 1101, 880. H-NMR (300 MHz, CDCl3): d
3
7.35 (d, 2H, JH,H
ꢂ8.0 Hz, aromatic-H), 7.24 (d, 2H,
/
4JH,H
ꢂ
/
1.6 Hz, aromatic-H), 7.02 (dd, 2H, JH,H
1.6 Hz, aromatic-H), 5.13 (s, 2H, acetal-
4.12 (m, 4H, acetal-
3.75 (m, 4H, acetal-CH2), 2.61ꢀ2.51 (m, 4H,
butyl-CH2), 2.10ꢀ1.99 (m, 2H, acetal-CH2), 1.60ꢀ1.50
(m, 4H, butyl-CH2), 1.38ꢀ1.20 (m, 4H, buryl-CH2,
acetal-CH2), 1.15 (s, 42H, TIPS-H), 0.89 (t, 6H,
ꢂ/8.0
3
4
Hz, JH,H
ꢂ
/
nes:CH2Cl2, 2:1 ꢁ
66%) as a dark orange oily solid. IR (Neat): n (cmꢃ1
2955, 2927, 2855, 2120, 1717, 1559, 1489, 1107, 1003.
/10% NEt3) furnished 12b (635 mg,
CH), 5.03 (s, 5H, Cp-H), 4.17ꢀ
/
)
CH2), 3.84ꢀ
/
/
/
/
1H-NMR (300 MHz, CDCl3): d 7.41 (d, 2H, 3JH,H
ꢂ/8.0
/
Hz, aromatic-H), 7.39 (d, 2H, 4JH,H
ꢂ
/
1.6 Hz, aromatic-
3
H), 7.13 (dd, 2H, JH,H
4
8.0 Hz, JH,H
ꢂ
/
ꢂ1.6 Hz,
/

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ
/24
21
aromatic-H), 5.15 (s, 2H, acetal-CH), 5.10 (s, 5H, Cp-
methanol (5 ml) and dry THF (2 ml). Aqueous workup
followed by column chromatography (SiO2; hexa-
H), 4.18ꢀ
acetal-CH,), 2.59 (t, 4H, JH,H
2.14ꢀ
butyl-CH2), 1.39ꢀ
/
4.13 (m, 4H, acetal-CH2), 3.85ꢀ
/
3.67 (m, 4H,
3
ꢂ/7.1 Hz, butyl-CH2),
nes:CH2Cl2 3:1 ꢁ10% NEt3) furnished 14b (254 mg,
/
/
2.01 (m, 2H, acetal-CH2), 1.62ꢀ
/1.54 (m, 4H,
48%) as an unstable yellow crystalline solid. M.p.:
unable to determine due to rapid decomposition at
ambient temperatures. IR (Neat): n (cmꢃ1) 3335, 2924,
2955, 2855, 1747, 1558, 1508, 1373, 1010. 1H-NMR (300
/
1.26 (m, 4H, butyl-CH2, acetal-
3
CH2), 0.93 (t, 6H, JH,H
ꢂ
/
7.1 Hz, butyl-CH3). 13C-
NMR (75 MHz, CDCl3): d 143.62, 133.38, 131.67,
129.34, 125.22, 122.85, 97.37, 82.51, 82.48, 81.16, 80.56,
79.58, 79.24, 78.55, 77.23, 66.95, 56.64, 35.38, 32.98,
25.79, 22.20, 13.88. MS (EI) m/z Calc. for Mꢁ
(C49H43CoO4) 754.2493, unable to determine due to
decomposition.
MHz, CDCl3): d 7.42 (d, 2H, 3JH,H
ꢂ8.0 Hz, aromatic-
/
4
H), 7.39 (d, 2H, JH,H
ꢂ
/
1.6 Hz, aromatic-H), 7.14 (dd,
1.6 Hz, aromatic-H), 5.09
(s, 5H, Cp-H), 3.30 (s, 2H, alkyne-H), 2.59 (t, 4H,
3JH,H
7.1 Hz, butyl-CH2), 1.64ꢀ1.51 (m, 4H, butyl-
CH2), 1.38ꢀ1.24 (m, 4H, butyl-CH2), 0.92 (t, 6H,
3JH,H 7.1 Hz, bulyl-CH3). 13C-NMR (75 MHz,
3
4
2H, JH,H
ꢂ/8.0 Hz, JH,H
ꢂ
/
ꢂ
/
/
/
4.13. Synthesis of 14a
ꢂ
/
CDCl3): d 144.18, 133.53, 131.76, 129.42, 125.47,
122.10, 84.10, 83.96, 82.25, 81.82, 81.08, 80.05, 78.36,
77.61, 76.94, 61.94, 59.60, 35.41, 32.94, 22.67, 13.90. MS
(EI) m/z Calc. for Mꢁ (C45H31Co) 630.1758, unable to
determine Mꢁ due to decomposition.
In a 100 ml round bottom flask was placed 12a (220
mg, 0.302 mmol), p-toluenesulfonic acid (200 mg, 1.05
mmol), THF (3 ml) and H2O (2 ml). The resulting
mixture was stirred for 12 h under the exclusion of light.
The mixture was quenched with water and extracted
with ethyl ether (100 ml). Removal of the solvent and
drying under vacuum (10ꢃ1 mbar) yielded a dark red
oil. To the red oil was added finely powdered K2CO3
(270 mg, 1.96 mmol), dry methanol (5 ml) and dry THF
4.15. Synthesis of 22a
In a 25 ml, oven-dried Schlenk flask was placed 14a
(58.5 mg, 97.2 mmol) and dry THF (10 ml) under
(2 ml). The flask was cooled to ꢃ10 8C and dimethyl-(1-
/
nitrogen. The flask was cooled to ꢃ78 8C and lithium
/
diazo-2-oxopropyl)-phosphonate (13) (270 mg, 1.41
mmol) was added drop-wise. The resulting reaction
mixture was stirred for 8 h under exclusion of light.
The reaction was quenched with aqueous NaHCO3 and
extracted with ethyl ether (200 ml). The combined
organic layers were dried over MgSO4 and the solvent
was removed in vacuo. Column chromatography (SiO2;
diisopropylamide (23.0 mg, 0.213 mmol) in THF was
added drop-wise over 5 min. Stirring was continued for
10 min. The solution was brought to 0 8C and turned
cloudy. After stirring at 0 8C for 30 min, CuI (65.0 mg,
0.342 mmol), was added and the solution turned
transparent. The resulting solution was stirred for 15
min. Following cooling to ꢃ78 8C, 11a (117 mg, 0.291
/
hexanesꢁ
/
10% NEt3) furnished 14a (117 mg, 61%) as an
mmol) and dry propylamine (1.8 ml) were added
successively. The resulting solution was stirred for 5
min, before being warmed to ambient temperature,
stirred for 1 h and then quenched with water and ethyl
ether. The water layer was separated and extracted with
ethyl ether (200 ml). The combined organic layers were
dried over MgSO4 and the solvent removed in vacuo.
Column chromatography (SiO2; hexanes:EtOAc, 1:1)
furnished 22a (35.0 mg, 29%) as a dark orange oil. IR
(Neat): n (cmꢃ1) 2954, 2916, 2862, 2316, 1770, 1554,
1416, 1062. 1H-NMR (300 MHz, CDCl3): d 7.47 (d, 2H,
unstable yellow crystalline solid. M.p.: unable to deter-
mine due to rapid decomposition at ambient tempera-
tures. IR (Neat): n (cmꢃ1) 3326, 2962, 2916, 2847, 2308,
1693, 1646, 1540, 1416, 1093. 1H-NMR (300 MHz,
4
CDCl3): d 7.45 (d, 2H, JH,H
ꢂ1.6 Hz, aromatic-H),
/
3
7.41 (d, 2H, JH,H
ꢂ
/
8.0 Hz, aromatic-H), 7.19 (dd, 2H,
8.0 Hz, JH,H 1.6 Hz, aromatic-H), 5.09 (s,
5H, Cp-H), 3.30 (s, 2H, alkyne-H), 2.90 (sept, 2H,
3JH,H 6.9 Hz, isopropyl-CH), 1.24 (d, 12H, 3JH,H
6.9
3JH,H
ꢂ
/
ꢂ
/
4
ꢂ
/
ꢂ
/
Hz, isopropyl-CH}). 13C-NMR (75 MHz, CDCl3): d
150.00, 131.85, 131.66, 127.65, 125.56, 122.24, 83.96,
82.24, 81.80, 81.19, 80.05, 78.30, 77.62, 77.58, 76.93,
61.91, 59.61, 34.01, 23.46. MS (EI) m/z Calc. for Mꢁ
(C43H27Co) 602.1445, unable to determine Mꢁ due to
decomposition.
4JH,H
Hz, aromatic-H), 7.40 (d, 2H, 3JH,H
H), 7.39 (s, 2H, aromatic-H), 7.20 (dd, 2H, JH,H
ꢂ
/
1.4 Hz, aromatic-H), 7.41 (d, 2H,3JH,H
ꢂ8.0
/
ꢂ
/
8.0 Hz, aromatic-
3
ꢂ
/
8.0
1.6 Hz, aromatic-H), 7.11 (dd, 2H, JH,H
8.2 Hz, 4JH,H
1.6 Hz, aromatic-H), 5.13 (s, 5H, Cp-H),
2.92ꢀ2.84 (m, 4H, isopropyl-CH), 1.24 (d, 2H, JH,H
8.0 Hz, isopropyl-CH3), 1.20 (d, 2H, JH,H
isopropyl-CH3), 1.19 (s, 42H, TIPS-H). 13C-NMR (75
MHz, CDCl3): d 150.08, 150.02, 132.48, 131.91, 131.73,
130.44, 127.67, 127.18, 126.49, 125.69, 122.37, 122.29,
104.84, 95.69, 83.93, 82.21, 81.98, 81.24, 80.48, 79.35,
78.42, 77.92, 77.63, 77.25, 76.37, 63.48, 60.27, 34.65,
34.07, 23.53, 23.50, 18.81, 11.39. MS (EI) m/z Calc. for
3
Hz, 4JH,H
ꢂ
/
ꢂ
/
ꢂ
/
3
/
ꢂ
/
3
4.14. Synthesis of 14b
ꢂ8.0 Hz,
/
In a procedure analogous to the synthesis of 14a, 12b
(635 mg, 0.841 mmol) and p-toluenesulfonic acid (500
mg, 2.63 mmol) were reacted in THF (3 ml) and H2O (2
ml). The resulting dark oil was reacted with K2CO3 (740
mg, 5.36 mmol) and 13 (740 mg, 3.85 mmol) in dry

22
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ24
/
Mꢁ (C87H87CoSi2) 1246.5678, unable to determine Mꢁ
due to decomposition.
NMR (75 MHz, CDCl3): d unable to determine due to
limited solubility as well as a minimal quantity of
material. MS (EI) m/z Calc. for Mꢁ (C69H45Co),
decomposition before Mꢁ was recorded.
4.16. Synthesis of 22b
In a procedure analogous to the synthesis of 22a, 14b
(155 mg, 0.245 mmol), lithium diisopropylamide (64.2
mg, 0.541 mmol) in THF, CuI (120 mg, 0.632 mmol),
11b (400 mg, 960 mmol) and dry propylamine (3.0 ml)
were reacted in THF (50 ml). Aqueous workup followed
by column chromatography (SiO2; hexanes:EtOAc, 1:1)
furnished 22b (104 mg, 33%) as a dark orange oil. IR
(Neat): n (cmꢃ1) 2924, 2855, 2115, 1717, 1558, 1543,
4.18. Synthesis of 15b
In a procedure analogous to the synthesis of 15a, 22b
(102 mg, 81.8 mmol), and Bu4NꢁFꢃ (0.23 ml, 1.0 M in
THF) were reacted for 1 h in THF (3 ml). The resulting
dark oil was reacted with Cu(OAc)2 (310 mg, 1.71
mmol) in acetonitrile (200 ml). Aqueous workup fol-
lowed by preparative TLC using EtOAc:hexane (1:1) as
the eluent, 15b (35.0 mg, 46%) was isolated as an orange
solid. M.p.: 230 8C (dec.). IR (Neat): n (cmꢃ1) 2955,
1
1458, 1396, 1025. H-NMR (300 MHz, CDCl3): d 7.43
4
(d, 2H, JH,H
ꢂ1.4 Hz, aromatic-H), 7.39 (d, 2H,
/
3
8.0 Hz, aromatic-H), 7.38 (d, 2H, JH,H
1
3JH,H
Hz, aromatic-H), 7.28 (s, 2H, aromatic-H), 7.20 (dd, 2H,
ꢂ
/
ꢂ
/
8.0
2950, 2820, 2235, 1725, 1555, 1075, 997. H-NMR (300
MHz, CDCl3): d 7.44 (d, 4H, 4JH,H
3
H), 7.41 (d, 4H, JH,H
ꢂ1.6 Hz, aromatic-
8.0 Hz, aromatic-H), 7.15 (dd,
/
4
3JH,H
ꢂ
/
8.1 Hz, JH,H
ꢂ
/
1.6 Hz, aromatic-H), 7.11 (dd,
8.0 Hz, JH,H 1.6 Hz, aromatic-H), 5.12
2.53 (m, 8H, butyl-CH2), 1.62ꢀ1.53
(m, 8H, butyl-CH2), 1.38ꢀ1.27 (m, 8H, butyl-CH2), 1.19
ꢂ
/
3
4
3
4
2H, JH,H
ꢂ
/
ꢂ
/
4H, JH,H
(s, 5H, Cp-H), 2.60 (t, 8H, JH,H
1.66ꢀ
CH2), 0.93 (t, 12H, JH,H
ꢂ
/
8.0 Hz, JH,H
ꢂ
/
1.6 Hz, aromatic-H), 5.17
3
(s, 5H, Cp-H), 2.62ꢀ
/
/
ꢂ7.1 Hz, butyl-CH2),
1.23 (m, 8H, butyl-
7.1 Hz, butyl-CH3). 13C-
/
/
/
1.53 (m, 8H, butyl-CH2), 1.43ꢀ
/
(s, 42H, TIPS-H), 0.92 (m, 12H, butyl-CH3). 13C-NMR
(75 MHz, CDCl3): d 144.24, 144.20, 133.57, 132.28,
132.24, 131.76, 129.43, 128.40, 127.09, 125.56, 122.16,
122.05, 104.74, 95.77, 83.89, 82.20, 81.97, 81.08, 80.45,
79.31, 78.43, 77.96, 77.70, 76.58, 76.36, 63.49, 60.28,
35.48, 35.43, 33.14, 32.96, 29.70, 29.35, 22.31, 22.22,
18.80, 11.38. MS (EI) m/z Calc. for Mꢁ (C87H87CoSi2)
1246.5678, unable to determine Mꢁ due to decomposi-
tion.
ꢂ
/
3
NMR (75 MHz, CDCl3): d 144.28, 133.61, 131.90,
129.47, 125.59, 122.18, 82.92, 82.12, 81.12, 80.35, 78.38,
77.72, 77.69, 62.09, 35.46, 33.00, 22.24, 13.90. MS (EI)
m/z Calc. for Mꢁ (C73H53Co) 988.3479, unable to
determine due to decomposition.
4.19. Synthesis of 23
In a dry 100 ml Schlenk flask, 14b (110 mg, 0.174
mmol) was dissolved in 1 ml of dry piperidine. To the
solution was added (PPh3)2PdCl2 (4.0 mg, 5.7 mmol),
CuI (1.3 mg, 6.8 mmol) and 1,2-dimethoxy-3-iodo-4-
(trimethylsiylethynyl)benzene (16) (200 mg, 0.561
mmol). The resulting solution was stirred at ambient
temperature for 8 h. The reaction mixture was quenched
with water and extracted twice with ethyl ether. The
combined organic layers were dried over MgSO4 and the
solvent removed in vacuo. Column chromatography
(SiO2; EtOAc:hexanes, 4:1) furnished 23 (110 mg, 58%)
as an orange oil. IR (Neat): n (cmꢃ1) 2955, 2932, 2858,
4.17. Synthesis of 15a
To a 25 ml, round bottom flask was added 22a (35.1
mg, 28.1 mmol), Bu4NꢁFꢃ (0.120 ml, 1.0 M in THF)
and THF (3 ml). The resulting solution was stirred at
ambient temperature for 1 h before being quenched with
water and ethyl ether. The water layer was separated
and extracted with ethyl ether (20 ml). The combined
organic layers were dried over MgSO4 and the solvent
removed in vacuo to yield a dark red oil. To the oil, in a
100 ml round bottom flask, was added Cu(OAc)2 (160
mg, 0.881 mmol) and acetonitrile (100 ml). The resulting
solution was heated to 80 8C for 6 h. The solvent was
removed in vacuo, the resulting mixture redissolved in
CHCl3 and filtered through a silica gel plug. Removal of
the solvent in vacuo and column chromatography (SiO2;
hexanes:CHCl3, 1:1) furnished 15a (20.2 mg, 77%) as
orange needles after crystallization from CHCl3. M.p.:
214 8C (dec.). IR (Neat): n (cmꢃ1) 2954, 2908, 2847,
2149, 1508, 1261, 1219, 845. 1H-NMR (300 MHz,
4
CDCl3): d 7.40 (d, 2H, JH,H
ꢂ1.6 Hz, aromatic-H),
/
3
7.37 (d, 2H, JH,H
ꢂ
/
8.0 Hz, aromatic-H), 7.14 (dd, 2H,
4
8.0 Hz, JH,H 1.6 Hz, aromatic-H), 6.95 (s,
3JH,H
2H, OMe-aromatic-H), 6.93 (s, 2H, OMe-aromatic-H),
5.13 (s, 5H, Cp-H), 3.90 (s, 6H, OMe), 3.89 (s, 6H,
ꢂ
/
ꢂ
/
3
OMe), 2.58 (t, 4H, JH,H
ꢂ
/
7.1 Hz, butyl-CH2), 1.61ꢀ
1.30 (m, 4H, butyl-CH2),
7.1 Hz, butyl-CH3), 0.30 (s, 18H,
/
1.54 (m, 4H, butyl-CH2), 1.38ꢀ
/
3
2324, 1693, 1554, 1416, 1093. 1H-NMR (300 MHz,
4
CDCl3): d 7.50 (d, 4H, JH,H
0.91 (t, 4H, JH,H
ꢂ
/
ꢂ
/
1.5 Hz, aromatic-H),
TMS-H). 13C-NMR (75 MHz, CDCl3): d 149.33,
149.26, 144.33, 133.81, 131.95, 129.70, 129.63, 125.68,
122.66, 119.16, 118.63, 114.92, 114.33, 103.74, 97.69,
93.01, 86.16, 84.22, 81.86, 81.40, 80.47, 79.03, 77.95,
62.58, 61.38, 56.33, 56.25, 35.68, 33.24, 22.48, 14.15,
3
7.46 (d, 4H, JH,H
ꢂ
/
8.0 Hz, aromatic-H), 7.13 (dd, 4H,
8.0 Hz, JH,H 1.5 Hz, aromatic-H), 5.17 (s,
5H, Cp-H), 2.90 (sept, 2H, JH,H
CH), 1.24 (d, 12H, 3JH,H 7.2 Hz, isopropyl-CH3). 13C-
4
3JH,H
ꢂ
/
ꢂ
/
3
ꢂ7.2 Hz, isopropyl-
/
ꢂ
/

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 13ꢀ
/24
23
0.50. MS (EI) m/z Calc. for Mꢁ (C71H63CoO4Si2)
1094.3597, unable to determine Mꢁ due to decomposi-
tion.
was applied (mꢂ
/
0.424 mmꢃ1). Data refinement pro-
2s(I))ꢂ0.1031; GoFꢂ
1.019; 4807 data with 359 parameters were refined
duced R1ꢂ0.0491, wR2 (I ꢀ
/
/
/
/
with seven restraints. Max/min residual electron density
ꢃ3
˚
0.206 e A
4.20. Synthesis of 17
was determined to 0.450/ꢃ
/
.
In a procedure analogous to the synthesis of 15a, 23
(110 mg, 100 mmol) and Bu4NꢁFꢃ (0.30 ml, 1.0 M in
THF) were reacted for 1 h in THF (3 ml). The resulting
dark oil was reacted with Cu(OAc)2 (364 mg, 2.00
mmol) in acetonitrile (200 ml). Aqueous workup fol-
lowed by column chromatography (SiO2; hexanes:
EtOAc, 1:1) furnished 17 (76.5 mg, 88%) as orange
coffin shaped crystals after crystallization from CHCl3.
M.p.: 205 8C (dec.). IR (Neat): n (cmꢃ1) 2954, 2924,
4.21.2. Crystal data for 17a
The cyclobutadiene complex C45H44CoO4 of the
FWꢂ947.26 was isolated as red block-like crystal,
(0.36ꢄ0.26ꢄ
0.12 mm3). The unit cell was monoclinic
featuring the space group Cc with cell dimensions of
/
/
/
˚
˚
˚
aꢂ
908, bꢂ
/
32.447(3) A, bꢂ
/
27.437(3) A, cꢂ
/
14.042(1) A, aꢂ
/
3
˚
/
108.354(2)8, gꢂ
/
908, Vꢂ
/
11 865(2) A and Zꢂ
/
8 molecules in the unit cell. The calculated density,
Dcalc
1.377 g cmꢃ3. Intensity data covering the full
sphere of reciprocal space were measured to Uꢂ1.95ꢀ
ꢂ
/
1
2855, 2155, 1504, 1269, 1215, 853. H-NMR (300 MHz,
4
CDCl3): d 7.42 (d, 2H, JH,H
/
/
ꢂ1.6 Hz, aromatic-H),
/
24.248; 32 639 reflections were collected, of which 13 840
were independent. Semiempirical absorption correction
was applied with maximum and minimum transmission
of 0.8309 and 0.5449, respectively. Data refinement
3
7.41 (d, 2H, JH,H
ꢂ
/
8.0 Hz, aromatic-H), 7.17 (dd, 2H,
4
8.0 Hz, JH,H 1.6 Hz, aromatic-H), 7.13 (s,
3JH,H
2H, OMe aromatic-H), 6.95 (s, 2H, OMe aromatic-H),
5.10 (s, 5H, Cp-H), 3.98 (s, 6H, OMe), 3.91 (s, 6H,
ꢂ
/
ꢂ
/
produced R1ꢂ
/
0.0491, wR2 (I ꢀ
/
2s(I))ꢂ0.2582;
/
3
OMe), 2.60 (t, 4H, JH,H
ꢂ
/
7.1 Hz, butyl-CH2), 1.61ꢀ
1.30 (m, 4H, butyl-CH2),
7.1 Hz, butyl-CH3). 13C-NMR (75
/
GoFꢂ1.049; 1461 parameters were refined, with 52
/
1.54 (m, 4H, butyl-CH2), 1.39ꢀ
/
restraints. Max/min residual electron density was deter-
ꢃ3
3
0.92 (t, 4H, JH,H
˚
0.775 e A
ꢂ
/
mined to 1.873/ꢃ
/
.
MHz, CDCl3): d 149.84, 148.82, 144.15, 133.59, 131.64,
129.45, 125.48, 122.39, 122.22, 116.83, 113.56, 111.99,
92.91, 90.17, 87.44, 83.97, 83.64, 81.99, 81.11, 80.16,
78.85, 78.56, 77.70, 62.17, 61.50, 56.14, 56.04, 35.40,
31.54, 22.19, 13.86. MS (EI) m/z Calc. for Mꢁ
(C65H45CoO4) 948.2650, unable to determine due to
decomposition.
5. Supporting information
Crystallographic information files (CIFs for 9a
(CCDC No. 154093) and 17 (CCDC No. 198703)).
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: ꢁ44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
4.21. Experimental details for the crystal structure
determinations of 9a and 17
/
X-ray intensity data for 9a and 17 were measured in v
scan mode using a Bruker SMART APEX CCD-based
diffractometer system with Moꢀ
/
Ka radiation at lꢂ
/
Acknowledgements
˚
0.71073 A, at 190(2) K. Raw data frame integration
and Lorentz and polarization corrections were per-
We thank the National Science Foundation (PI Bunz,
CAREER, CHE 9981765) and the USC NanoCenter for
generous funding. U.H.F.B. is a Camille Dreyfus
formed with SAINT
ꢁ
/
. Structure solution (direct meth-
ods in all cases) and refinement against F2 using all data
was performed with SHELXTL
.
Teacher-Scholar (2000ꢀ2004).
/
4.21.1. Crystal data for 9a
The cyclobutadiene complex (C65H53Co)(CH2Cl2) of
the FWꢂ977.93 was isolated as red plate crystal with a
dimension of 0.25ꢄ0.20ꢄ
0.08 mm3). The unit cell was
tetragonal featuring the space group I41 with cell
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˚
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