Alkynylboronates and -boramides in CoI- and Rh I-Catalyzed [2+2+2] cycloadditions: Construction of oligoaryls through selective Suzuki couplings

Article abstract of DOI:10.1002/ejoc.201100371

Oligoaryls were prepared through transition-metal-catalyzed [2+2+2] cycloadditions of borylated alkynes, followed by Suzuki cross-couplings with aryl halides. Ethynylboryl pinacolate took part in cobalt-catalyzed [2+2+2] cycloadditions of all types invest

Full text of DOI:10.1002/ejoc.201100371

FULL PAPER
DOI: 10.1002/ejoc.201100371
Alkynylboronates and -boramides in CoI- and RhI-Catalyzed [2+2+2]
Cycloadditions: Construction of Oligoaryls through Selective Suzuki Couplings
Laura Iannazzo,[a] K. Peter C. Vollhardt,[b] Max Malacria,[a] Corinne Aubert,*[a] and
Vincent Gandon*[a,c]
Keywords: Boron / Cobalt / Cross-coupling / Cycloaddition / Rhodium
Oligoaryls were prepared through transition-metal-catalyzed
[2+2+2] cycloadditions of borylated alkynes, followed by Su-
zuki cross-couplings with aryl halides. Ethynylboryl pinacol-
ate took part in cobalt-catalyzed [2+2+2] cycloadditions of all
types investigated (i.e., all-intermolecular cyclotrimerization,
diyne-yne cocyclization, and all-intramolecular triyne cyclo-
isomerization). The resulting platforms gave rise to linear
and angular ter- and quateraryls after Pd-catalyzed cross-
coupling. In addition, the first [2+2+2] cycloadditions involv-
ing alkynyl naphthaloboramides were developed. These de-
rivatives could be cocyclized with diynes in the presence of
a rhodium complex as catalyst. Because the boramide group
is inactive under Suzuki coupling conditions, but can be
readily deprotected to afford an active one, an iterative func-
tionalization of a boronate-/boramide-substituted benzene
could be achieved.
Introduction
Transition-metal-catalyzed [2+2+2] cycloadditions[1] of
borylated alkynes represent a powerful tool for formation
of functionalizable six-membered rings in a highly selective
fashion.[2] In particular, these transformations allow the ra-
pid construction of borylated platforms ready for Suzuki–
Miyaura cross-coupling reactions to give conjugated prod-
ucts.[3] We[2b,2g,2j] and others[2c,2f,2h] have used such se-
quences for the construction of biaryl linkages [Scheme 1,
Equation (1)], and aryl-substituted cyclohexa-1,3-dienes
[Equation (2)] or 1,3,5-trienes [Equation (3)].
Applications of this strategy for the preparation of oli-
goaryls (Figure 1), however, are unknown,[4] although mul-
tiple couplings to oligoborylated arenes prepared by other
routes have been reported. In particular, double Suzuki
couplings based on 1,4-diborylbenzenes have been carried
out frequently, notably for the construction of rod-like ma-
terials.[5] On the other hand, the use of 1,2-diborylbenzenes
is rare,[6] and only a few double Suzuki couplings involving
1,3-diborylbenzenes have been reported.[7] Triple Suzuki
couplings are also rare and are limited to the 1,3,5-substitu-
tion pattern.[8]
Scheme 1. Examples of previously described cobalt-catalyzed co-
oligomerizations involving borylated alkynes, followed by Suzuki
couplings. BPin = boryl pinacolate.
So far, only boronates [R–CϵC–B(OR)2] and the corre-
sponding sulfur derivatives [R–CϵC–B(SR)2] have been
used as [2+2+2] cycloaddition partners.[2] In this study we
have scrutinized other types of substrates, such as trifluoro-
borates and boramides.
Boramides appeared particularly interesting, because it
had been shown that the naphthaloboramide group is inac-
tive under Suzuki coupling conditions and can thus serve
as a masked boron reagent for iterative functionalization
[a] UPMC Univ Paris 06, IPCM UMR CNRS 7201,
4 place Jussieu, 75005 Paris, France
Fax: +33-1-44277360
E-mail: corinne.aubert@upmc.fr
[b] Department of Chemistry, University of California at Berkeley,
Berkeley, California 94720-1460, USA
[c] Univ Paris-Sud, UMR CNRS 8182,
91405 Orsay, France
E-mail: vincent.gandon@u-psud.fr
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FULL PAPER
Figure 1. Oligoaryls potentially accessible by sequential [2+2+2] cycloaddition/Suzuki coupling.
after deprotection (Scheme 2).[9] Even certain boronates,
such as those derived from N-methyliminodiacetic acid, are
only sluggishly reactive and can be used as protected boron
groups.[10] Here we report our efforts to generate oligobor-
ylated arenes from these species and their conversion into
oligoaryls.
Scheme 3. Synthesis of the boramide 5.
The alkynes 1 and 2 were addressed first; their use as
[2+2+2] cycloaddition partners had not been reported pre-
viously and, if successful, should lead directly to potassium
aryltrifluoroborates, the relative superiority of which (over
boronates) in Suzuki cross-coupling reactions is well estab-
lished.[14] Unfortunately, all our attempts to cyclotrimerize
or to cocyclize the potassium trifluoroborate 1 or the more
soluble tetrabutylammonium trifluoroborate 2 proved un-
successful. Various catalysts were tried, including
CpCo(CO)2, CpCo(C2H4)2,[15] CpCo(CO)(dimethyl fumar-
ate),[16] Cp*Ru(cod)Cl, Ni(cod)2, RhCl(PPh3)3, and
[Rh(cod)2]BF4/Tol-BINAP. With the first three it was pos-
sible to observe a new cobalt complex. On inspection of 1H,
13C, and 19F NMR spectra, its structure was assigned as
[Cp2Co][BF4] (Scheme 4).[17] The substrate is thus able to
oxidize CoI into CoIII, which is inactive for [2+2+2] cyclo-
additions.[18] It is likely that the other potential catalysts
also suffered decomposition.
Scheme 2. Use of protected borylated groups for iterative Suzuki
couplings.
Results and Discussion
We first focused on monoborylated alkynes as substrates
for [2+2+2] cycloadditions (Figure 2). Compounds 1,[11]
2,[12] 3,[13] and 4[2g] were prepared by previously reported
procedures.
Scheme 4. Catalyst oxidation by the trifluoroborate salt.
We turned to the N-coordinated boronate 3, but it also
proved reluctant to undergo cyclotrimerization, and we
were unable to determine the origin of the catalyst deactiva-
tion or depletion. On the other hand, the derivative 4 gave
rise to the expected regioisomeric cyclotrimerization prod-
Figure 2. Monosubstituted borylated alkynes tested in [2+2+2]
cycloadditions.
The previously unknown boramide 5 was prepared from ucts in good yield (Scheme 5).[2g] As a first illustration of
4 by pinacol/naphthalene-1,8-diamine exchange in toluene the topic of this paper, 7 was subjected to triple Suzuki
at reflux (Scheme 3). This approach provided the product cross-couplings,[8] both with electron-rich and with elec-
in quantitative yield after conventional flash chromatog- tron-poor aryl halides, to furnish the (m,mЈ)-quateraryl de-
raphy on silica gel without specific precautions.
rivatives 9–14 in moderate to excellent yields.
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Oligoaryls through Selective Suzuki Couplings
Scheme 5. Cyclotrimerization of 4 and triple Suzuki cross-couplings of the triborylbenzene 7. BPin = boryl pinacolate. [a] THF, reflux,
CsF. [b] Toluene/EtOH/H2O, 80 °C, Na2CO3.
Finally, compound 5 failed to autocyclize in the presence complexes. Unfortunately, attempted stoichiometric reac-
of the above catalysts and was recovered unchanged. Again, tions between 5 and CpCo(CO)2, CpCo(C2H4)2, or CpCo-
the fates of the catalysts could not be determined, but in (CO)(dimethyl fumarate) led to intractable materials.
view of the successful reactions described in Table 1, below,
To investigate cocyclizations of borylated diynes, we pre-
it is possible that 5, on its own, leads to unreactive metal pared compound 15, containing two pinacol boronate
Scheme 6. [2+2+2] Cycloadditions involving the diborylated diyne 15 and subsequent Suzuki cross-couplings. BPin = boryl pinacolate;
E = CO2Me. [a] DMF, microwaves, 200 °C, 10 min. [b] o-Xylene, reflux, 1 h.
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FULL PAPER
groups (Scheme 6). With CpCo(CO)(dimethyl fumarate) as Table 1. Cocyclizations of the borylated alkyne 5 with the diynes
catalyst,[19] we obtained the expected diborylated cycload-
25a–j.
ducts 16–18, on using 3-methoxypropyne, phenyacetylene,
and methyl propiolate, respectively. The quite heat-sensitive
substrate 15 rapidly deteriorates during the course of the
reaction, preventing yields higher than 41–48%. The tribo-
rylated cycloadduct 19 (from 15 and 4) could also be pre-
pared, but only in 11% yield, because autotrimerization of
4 is already fast at room temperature[2g] and could not be
suppressed, even under high-dilution conditions (slow ad-
Entry Diyne
X
R1
R2
Product Yield [%][a]
dition of 4).[20] Monocoupling at the less hindered bor-
ylated site in 17 or in 18 produced the biaryls 20 and 22 in
63% and 46% yields, respectively. Bis(coupling) also proved
possible with 18 and p-(trifluoromethyl)phenyl bromide,
with the p-teraryl 23 being isolated in 73% yield. On the
other hand, the presence of a BPin group adjacent to Ph
proved incompatible with a second coupling: compound 20,
for instance, was isolated in the same 63% yield with either
1 or 2 equiv. of p-iodoanisole. Protodeborylation[21] can
also occur, as demonstrated by the formation of 21 from
17 and p-(trifluoromethyl)phenyl bromide (1 or 2 equiv.).
Coupling of 17 (2 equiv.) with 1,4-diiodobenzene led to the
expected product 24, albeit in a modest 22% yield.
1
2
3
4
5
6
7
8
9
25a
25b
25c
25d
25e
25f
25g
25h
25i
CH2
CH2
CH2
Me
Ph
Me
Ph
26a
26b
26c
26d
26e
26f
26g
26h
26i
62
65
67
24
60
CO2Et CO2Et
CH2
BPin
Me
H
BPin
Me
H
Ph
H
(CH2)2
C(CO2Me)2
C(CO2Me)2
74
Ph
76
C(CO2Me)2 CO2Me
89[b]
51
O
NTs
Ph
Me
Ph
Me
10
25j
26j
28
[a] Isolated yields. [b] Mixture (3:1) of ortho and para isomers (26h1
and 26h2, respectively). BPin = boryl pinacolate.
The lack of success in effecting autotrimerization of 3
and 5 notwithstanding, these compounds were next mixed
The linear teraryl derivative 26b was deprotected (sulf-
with diynes in the presence of catalytic amounts of uric acid) to afford 27 (Scheme 7), prior to Suzuki coupling
CpCo(CO)2, CpCo(C2H4)2, CpCo(CO)(dimethyl fumar- with p-iodoanisole to give the (o,p)-quateraryl 28 in 71%
ate), Cp*Ru(cod)Cl, Ni(cod)2, RhCl(PPh3)3, or [Rh(cod)2]- yield over the two steps. More importantly, the triborylated
BF4/Tol-BINAP in order to promote their cocyclizations. platform 26d (Scheme 7) could be employed in iterative
None of these combinations worked, except in the case of couplings. It was first subjected to a selective reaction with
5 and the last of these catalytic systems (Table 1).[22] Grati- p-iodoanisole at its pinacol boronate moieties, giving 29 in
fyingly, in this case, both hepta-1,6- and octa-1,7-diynes, 47% yield. As expected, the boramide functionality was in-
variously bearing H atoms or methyl, phenyl, alkoxycarb- ert to the Suzuki conditions. Deprotection to the intermedi-
onyl, or even BPin groups at their termini, could be used. ate boronic acid, followed by treatment with 1-iodo-4-(tri-
These cocyclizations provided the borylated benzenes 26a– fluoromethyl)benzene, PdCl2(dppf), and K2CO3 then gave
j in moderate to high yields.
the (o,p)-quateraryl 30 in 60% yield.
Scheme 7. Deprotection and Suzuki coupling of 26b and 26d.
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Oligoaryls through Selective Suzuki Couplings
An all-intramolecular cyclization topology was tested
with the triyne 31 (Scheme 8), also bearing two pinacol
boronate moieties. This compound could be fully converted
into the expected tricyclic framework. Because of protode-
borylation;[21] however, the product 32a was accompanied
in the crude mixture by the corresponding monoborylated
32b, as well as non-borylated 32c.[16]
Experimental Section
General Methods: Reactions were carried out under argon. Solvents
were purified as follows: DCE was distilled from calcium hydride,
toluene, xylenes, and hexane from NaK2.8, and THF from sodium
benzophenone ketyl. Solvents were degassed (Ar) prior to use of
CpCo(C2H4)2. CpCo(C2H4)2 was prepared by a known pro-
cedure.[15] Reaction mixtures employing CpCo(CO)2 were irradi-
ated (visible light) with a halogen lamp (300 W). Microwave heating
was carried out with a Biotage microwave synthesizer (400 W max).
Thin layer chromatography (TLC) was performed on Merck
60 F254 silica gel. Merck Gerudan SI silica gel (35–70 μm, 60 Å)
was used for column chromatography. H, 19F, 11B, and 13C NMR
1
spectra were recorded at 20 °C at 400, 377, 128, and 100 MHz,
respectively, with a Bruker AVANCE 400 spectrometer. 13C NMR
signals for carbon atoms attached to boron atoms are very broad
and were not observed. Chemical shifts (δ) are given in ppm, for 1H
NMR referenced to the residual proton resonance of the solvents (δ
= 7.26 ppm for CDCl3; δ = 7.16 ppm for C6D6), for 13C NMR to
the corresponding carbon resonance (δ = 77.16 ppm for CDCl3; δ
= 128.06 ppm for C6D6). Coupling constants (J) are given in Hertz
(Hz). The terms m, s, d, t, q, and quint, refer to multiplet, singlet,
doublet, triplet, quartet, quintet; br. stands for broad. When pos-
sible, NMR signals were assigned on the basis of NOE, DEPT, and
2D-NMR (COSY, HMBC) experiments. Infrared spectra (IR) were
recorded with a Bruker Tensor 27 spectrometer. High-resolution
mass spectral data (HRMS) were obtained by ESI. Melting points
were measured with an SMP3 Stuart Scientific melting point appa-
ratus and were not corrected.
Compound 2:[23] 1H NMR (400 MHz, CDCl3): δ = 0.81 (t, J =
7.3 Hz, 12 H), 1.25 (quint, J = 9.1 Hz, 8 H), 1.42–1.49 (m, 8 H),
1.96 (s, 1 H), 3.01–3.09 (m, 8 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 13.1 (CH3), 19.1 (CH2), 23.3 (CH2), 57.9 (CH2) ppm;
CϵC signal not observed. 19F NMR (377 MHz, CDCl3): δ =
–134.2 (q, J = 26 Hz) ppm.
Scheme 8. Intramolecular [2+2+2] cycloaddition of the triyne 31
and Suzuki coupling of the resulting 1,2-diborylated benzene 32a.
BPin = boryl pinacolate.
Compound 32a could be purified by column chromatog-
raphy on silica and was obtained in 24% yield. Satisfyingly,
a cross-coupling experiment with p-iodoanisole (3 equiv.)
provided the o-teraryl 33 in 62% yield. With just 1 equiv.
of p-iodoanisole, an inseparable mixture containing 33, 32a,
and the expected monocoupling product was obtained. It is
likely that the monocoupling product is actually more reac-
tive than 32a under Suzuki coupling conditions.
Compound 5: 1,8-Diaminonaphthalene (1.66 mmol, 263 mg) was
added to a solution of ethynylpinacolboronic ester (4, 2.5 mmol,
380 mg) in toluene (50 mL). The mixture was heated at reflux for
24 h and then allowed to cool to room temperature. After evapora-
tion of the solvent, the residue was purified by flash column
chromatography on silica gel with pentane/Et2O (8:2) as eluent to
afford 5 (100%, 285 mg) as a white solid (m.p. 92 °C). 1H NMR
(400 MHz, CDCl3): δ = 2.60 (s, 1 H), 5.84 (br. s, 2 H), 6.29 (d, J
= 7.2 Hz, 2 H), 7.07–7.12 (m, 4 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 106.1 (CH), 118.4 (CH), 119.8 (C), 127.6 (CH), 136.3
(C), 140.3 (C) ppm; CϵC signal not observed. 11B NMR
Conclusions
(128 MHz, CDCl ): δ = 22 ppm. IR (neat): νmax = 1578, 2178, 1674,
˜
3
The alkynyl boronate 4 and boramide 5 proved to be
compatible with [2+2+2] cycloaddition reactions, allowing
the formation of complex oligoborylated frameworks.
Whereas compound 4 required a cobalt-based catalyst,
preferably CpCo(CO)(dimethyl fumarate), for reactions to
take place, the [Rh(cod)2]BF4/Tol-BINAP catalytic system
proved to be the best choice with the naphthaloboramide
5. On the other hand, we could not devise any reaction
condition compatible with the use of borylated alkynes con-
3024 cm–1.
Procedure A for Suzuki Couplings: A dried flask was charged under
argon with Pd(PPh3)4 (0.05 equiv.) and anhydrous THF. Com-
pound 7 (1 equiv.), the halide derivative (3 equiv.), and CsF
(9 equiv.) were added to the solution. The reaction mixture was
heated at reflux for 48 h and then allowed to cool to room tempera-
ture. Water and CH2Cl2 were added, and the aqueous layer was
extracted with CH2Cl2. The combined organic extracts were
washed with water, dried with MgSO4, and concentrated. The resi-
taining sp3 boron centers. Most of the cyclization products due was purified by flash column chromatography on silica gel with
a gradient mixture of pentane and EtOAc.
converted to oligoaryls under Suzuki cross-coupling condi-
tions. In particular, the interesting ability of the naphthalo-
boramide group to function as a masked boron reagent
could be exploited for the iterative construction of a quater-
aryl derivative.
Procedure B for Suzuki Couplings: A dried flask was charged under
argon with Pd(PPh3)4 (0.05 equiv.) and a mixture of toluene/etha-
nol (5:2). Compound 7 (1 equiv.) and the halide derivative (3 equiv.)
were added to the solution, followed by K2CO3 (9 equiv.) and
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FULL PAPER
water. The reaction mixture was heated at reflux for 48 h and al-
lowed to cool to room temperature. Water and CH2Cl2 were added,
and the aqueous layer was extracted with CH2Cl2. The combined
organic extracts were washed with water, dried with MgSO4, and
concentrated. The residue was purified by flash column chromatog-
raphy with a gradient mixture of pentane and EtOAc.
fied by flash column chromatography on silica gel with a gradient
mixture of pentane and Et2O to give the corresponding product.
Compound 16: White solid. M.p. 173 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.32 (s, 12 H), 1.37 (s, 12 H), 1.73–1.77 (m, 4 H), 2.85–
2.89 (m, 2 H), 2.96–3.03 (m, 2 H), 3.23 (s, 3 H), 4.46 (s, 2 H), 7.40
(s, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 23.2 (CH2), 23.3
(CH2), 25.0 (CH3), 25.2 (CH3), 29.8 (CH3), 30.2 (CH2), 57.2 (CH3),
74.7 (CH2), 83.4 (C), 83.6 (C), 132.7 (CH), 138.2 (C), 140.7 (C),
142.2 (C) ppm; C–B signal not observed. 11B NMR (128 MHz,
Compound 9:[24] Yellow solid. M.p. 161 °C. 1H NMR (400 MHz,
CDCl3): δ = 7.37–7.42 (m, 3 H), 7.47–7.51 (m, 6 H), 7.70–7.73 (m,
6 H), 7.80 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 125.3
(CH), 127.5 (CH), 127.6 (CH), 128.9 (CH), 141.3 (C), 142.5 (C)
CDCl ): δ = 31 ppm. IR (neat): νmax = 974, 1192, 1371, 1470, 2927,
˜
3
2977 cm–1. HRMS: calcd. for C24H38B2O5Na 451.27976; found
ppm. IR (neat): νmax = 1610, 2973 cm–1. HRMS: calcd. for C24H19
˜
451.28127.
307.14813 [M + H]; found 307.14840.
Compound 17: White solid. M.p. 78 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.12 (s, 12 H), 1.38 (s, 12 H), 1.83–1.88 (m, 4 H), 2.91–
2.95 (m, 2 H), 3.10–3.16 (m, 2 H), 7.29–7.44 (m, 5 H), 7.53 (s, 1
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 14.3 (CH2), 14.4 (CH2),
24.9 (CH3), 25.2 (CH3), 29.7 (CH2), 30.3 (CH2), 83.4 (C), 83.7 (C),
126.6 (CH), 127.8 (CH), 129.4 (CH), 133.5 (CH), 139.3 (C), 141.2
(C), 142.8 (C), 143.9 (C) ppm; C–B signal not observed. 11B NMR
1
Compound 10:[25] Yellow solid. M.p. 131 °C. H NMR (400 MHz,
CDCl3): δ = 3.86 (s, 9 H), 7.00 (d, J = 9.0 Hz, 6 H), 7.62 (d, J =
8.8 Hz, 6 H), 7.65 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ
= 55.5 (CH3), 114.4 (CH), 124.0, (CH), 128.5 (CH), 134.0 (C),
141.9 (C), 159.4 (C) ppm. IR (neat): νmax = 1252, 1512, 2929 cm–1.
˜
HRMS: calcd. for C27H25O3 396.17254 [M + H]; found 396.17248.
1
Compound 11:[26] Yellow solid. M.p. 203 °C. H NMR (400 MHz,
(128 MHz, CDCl ): δ = 30 ppm. IR (neat): νmax = 1135, 1300, 1598,
˜
3
2926, 2976 cm–1. HRMS: calcd. for C28H38B2O4Na 483.28484;
CDCl3): δ = 3.96 (s, 9 H), 7.76 (d, J = 8.1 Hz, 6 H), 7.86 (s, 3 H),
8.16 (d, J = 8.5 Hz, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
52.3 (CH3), 126.2 (CH), 127.4 (CH), 129.5 (C), 130.4 (CH), 141.7
found 483.28546.
Compound 18: White solid. M.p. 197 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.34 (s, 12 H), 1.44 (s, 12 H), 1.75–1.77 (m, 4 H), 2.86–
2.90 (m, 2 H), 3.02–3.05 (m, 2 H), 3.87 (s, 3 H), 8.11 (s, 1 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 22.8 (CH2), 22.9 (CH2), 25.0
(CH3), 25.5 (CH3), 29.6 (CH2), 30.2 (CH2), 52.0 (CH3), 83.7 (C),
83.9 (C), 129.7 (C), 133.3 (CH), 138.9 (C), 140.1 (C), 169.0 (C=O)
ppm; C–B signal not observed. 11B NMR (128 MHz, CDCl3): δ =
(C), 145.1 (C), 167.0 (C=O) ppm. IR (neat): ν
= 1277, 1726,
˜
max
2953 cm–1.
1
Compound 12:[27] Yellow solid. M.p. 231 °C. H NMR (400 MHz,
CDCl3): δ = 7.74–7.82 (m, 12 H), 7.83 (s, 3 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 126.0 (CH), 126.2 (CH), 127.7 (CH), 130.0
(C), 130.3 (C), 141.6 (C), 144.1 (C) ppm. 19F NMR (377 MHz,
31 ppm. IR (neat): ν
= 1135, 1283, 1712, 2932, 2977 cm–1.
˜
CDCl ): δ = –62 ppm. IR (neat): ν
= 1127, 1331 cm–1.
˜
max
3
max
HRMS: calcd. for C24H36B2O6Na 465.25902; found 465.26042.
Compound 13:[28] Yellow oil. 1H NMR (400 MHz, CDCl3): δ =
7.61–7.65 (m, 12 H), 7.10 (s, 3 H), 7.91–7.95 (m, 6 H), 8.30 (d, J
= 8.1 Hz, 3 H), 8.74 (d, J = 7.8 Hz, 3 H), 8.81 (d, J = 8.3 Hz, 3 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 122.7 (CH), 123.1 (CH),
126.7 (CH), 126.8 (CH), 127.0 (CH), 127.1 (CH), 127.4 (CH), 128.1
(CH), 128.8 (CH), 129.0 (C), 130.1 (C), 130.9 (CH), 131.1 (C),
Compound 19: Yellow solid. M.p. 95 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.30 (s, 12 H), 1.31 (s, 12 H), 1.41 (s, 12 H), 1.72 (m,
4 H), 2.87 (m, 2 H), 2.99 (m, 2 H), 7.95 (s, 1 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 23.1 (CH2), 23.3 (CH2), 24.9 (CH3), 25.0
(CH3), 25.6 (CH3), 29.8 (CH2), 30.3 (CH2), 83.3 (C), 83.7 (C), 83.8
(C), 133.5 (CH), 139.8 (C), 145.4 (C) ppm; C–B signal not ob-
131.7 (C), 138.4 (C), 141.0 (C) ppm. IR (neat): ν
= 1228, 1366,
˜
max
served. IR (neat): ν
= 835, 1139, 2929 cm–1.
˜
1738, 2970 cm–1. HRMS: calcd. for C48H30Na 606.23475; found
max
Procedure for Suzuki Couplings of Diborylated Tetrahydronaphtha-
lenes: PdCl2(dppf) (0.013 mmol) and the halide derivative (0.013 or
0.27 mmol) were added to solutions of compounds 16–18
(0.13 mmol) in dry THF (10 mL). K2CO3 (0.81 mmol) and water
were added, and the reaction mixture was heated at reflux for 72 h.
After having cooled to room temperature, the solution was treated
with water and CH2Cl2, and the aqueous layer was extracted with
CH2Cl2. The combined organic extracts were washed with water,
dried with MgSO4, and concentrated. The residue was purified by
flash column chromatography on silica gel with a gradient mixture
of pentane and Et2O.
606.23529.
Compound 14:[29] Brown oil. 1H NMR (400 MHz, CDCl3): δ =
7.11–7.15 (m, 3 H), 7.33–7.43 (m, 6 H), 7.75 (s, 3 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 122.8 (CH), 123.9 (CH), 125.5 (CH),
128.2 (CH), 135.8 (C), 143.6 (C) ppm. IR (neat): ν
= 693,
˜
max
1592 cm–1. HRMS: calcd. for C18H13S3 325.01738 [M + H]; found
325.01739.
Procedure for Cocyclizations of the Diborylated Diyne 15 with Alk-
ynes Under Standard Conditions: A solution of the diyne 15
(0.68 mmol), the alkyne (3.4 mmol), and CpCo(CO)(dimethyl fum-
arate) (0.06 mmol) in o-xylene (10 mL) was heated at reflux for 1 h.
After having cooled to room temperature, the crude product was
purified by flash column chromatography on silica gel with a gradi-
ent mixture of pentane and Et2O to give the corresponding prod-
uct.
1
Compound 20: Yellow oil. H NMR (400 MHz, CDCl3): δ = 1.16
(s, 12 H), 1.66–1.74 (m, 2 H), 1.81–1.87 (m, 2 H), 2.63 (t, J =
6.2 Hz, 2 H), 2.97 (t, J = 6.3 Hz, 2 H), 3.84 (s, 3 H), 6.92–6.94 (m,
2 H), 7.02 (s, 1 H), 7.22–7.47 (m, 7 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 23.2 (CH2), 23.4 (CH2), 25.0 (CH3), 28.6 (CH2), 30.2
(CH2), 55.3 (CH3), 83.8 (C), 113.4 (CH), 126.8 (CH), 127.8 (CH),
128.0 (CH), 129.2 (CH), 130.3 (CH), 133.1 (C), 134.6 (C), 140.5
(C), 142.2 (C), 143.6 (C), 143.7 (C), 158.5 (C) ppm; C–B signal not
observed. 11B NMR (128 MHz, CDCl3): δ = 30 ppm. IR (neat):
Procedure for Cocyclizations of the Diborylated Diyne 15 with Alk-
ynes Under Microwave Conditions: In a microwave vial, a solution
of the diyne 15 (0.68 mmol), the alkyne (3.4 mmol), and CpCo(CO-
)(dimethyl fumarate) (0.06 mmol) in DMF (4 mL) was heated at
200 °C for 10 min. After having cooled to room temperature, the
reaction mixture was extracted with Et2O and washed several times
with water. The combined organic extracts were dried with MgSO4,
and the solvent was removed in vacuo. The crude product was puri-
ν
= 1098, 1442, 2929 cm–1. HRMS: calcd. for C29H33BO3Na
˜
max
463.24150; found 463.24149.
1
Compound 21: Yellow oil. H NMR (400 MHz, CDCl3): δ = 1.73
(m, 4 H), 2.50 (m, 2 H), 2.69 (m, 2 H), 7.05–7.15 (m, 5 H), 7.29–
3288
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 3283–3292

Oligoaryls through Selective Suzuki Couplings
7.53 (m, 4 H), 7.61–7.71 (m, 2 H) ppm. 13C NMR (100 MHz, 7.06 (m, 4 H), 7.40–7.52 (m, 10 H), 7.55 (s, 1 H) ppm. 13C NMR
CDCl3): δ = 22.7 (CH2), 23.0 (CH2), 28.8 (CH2), 29.5 (CH2), 124.9 (100 MHz, CDCl3): δ = 25.7 (CH2), 32.9 (CH2), 33.4 (CH2), 105.6
(CH), 125.2 (CH), 127.8 (CH), 128.8 (CH), 129.7 (CH), 129.8
(CH), 117.3 (CH), 119.5 (C), 127.1 (CH), 127.4 (CH), 127.5 (CH),
(CH), 130.9 (CH), 134.4 (C), 136.0 (C), 138.9 (C), 140.6 (C), 141.1 128.4 (CH), 128.5 (CH), 128.6 (CH), 129.1 (CH), 131.4 (CH), 136.3
(C), 144.2 (C), 145.5 (C) ppm. 19F NMR (277 MHz, CDCl3): δ = (C), 137.4 (C), 141.3 (C), 141.9 (C), 142.0 (C), 143.7 (C), 144.1 (C)
–62.8 ppm. IR (neat): ν
= 1107, 1323, 1736, 2937 cm–1.
ppm; one C signal not observed, C–B signal not observed. 11B
˜
max
NMR (128 MHz, CDCl ): δ = 30 ppm. IR (neat): ν
= 1248,
˜
3
max
Compound 22: White solid. M.p. 237 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.45 (s, 12 H), 1.70–1.75 (m, 2 H), 1.79–1.85 (m, 2 H),
2.78–2.81 (m, 2 H), 2.93–2.96 (m, 2 H), 3.87 (s, 3 H), 6.99–7.00 (m,
1 H), 7.06–7.08 (m, 1 H), 7.33 (dd, J = 1.3, 5 Hz, 1 H), 7.79 (s, 1
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 22.8 (CH2), 22.9 (CH2),
25.5 (CH3), 29.3 (CH2), 29.8 (CH2), 52.3 (CH3), 84.0 (C), 125.5
(CH), 127.0 (CH), 128.3 (CH), 130.5 (C), 135.0 (CH), 140.4 (C),
141.3 (C), 142.3 (C), 154.6 (C), 168.9 (C=O) ppm; C–B signal not
observed. 11B NMR (128 MHz, CDCl3): δ = 31 ppm. IR (neat):
1507, 3029, 3153 cm–1. HRMS: calcd. for C31H25BN2Na
459.20030; found 459.19927.
1
Compound 26c: Yellow oil. H NMR (400 MHz, CDCl3): δ = 1.20
(t, J = 7.0 Hz, 3 H), 1.41 (t, J = 7.2 Hz, 3 H), 2.05–2.13 (m, 2 H),
3.15 (t, J = 7.6 Hz, 2 H), 3.29 (t, J = 7.6 Hz, 2 H), 4.30 (q, J =
7.0 Hz, 2 H), 4.37 (q, J = 7.2 Hz, 2 H), 5.89 (br. s, 2 H), 6.34 (d, J
= 7.2 Hz, 2 H), 7.03–7.05 (m, 2 H), 7.10–7.14 (m, 2 H), 8.00 (s, 1
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 14.1 (CH3), 14.4 (CH3),
24.7 (CH2), 33.0 (CH2), 33.8 (CH2), 61.1 (CH2), 61.5 (CH2), 105.9
(CH), 117.7 (CH), 119.7 (C), 127.6 (CH), 128.7 (C), 132.3 (C),
134.0 (C), 136.3 (C), 141.2 (CH), 146.7 (C), 148.9 (C), 166.7 (C=O),
168.5 (C=O) ppm; C–B signal not observed. 11B NMR (128 MHz,
ν
=
1138, 1308, 1715, 2926 cm–1. HRMS: calcd. for
˜
max
C22H27BO4SNa 421.16153; found 421.16184.
Compound 23: White solid. M.p. 165 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.69 (t, J = 3.0 Hz, 4 H), 2.35–2.38 (m, 2 H), 2.62–
2.68 (m, 2 H), 3.56 (s, 3 H), 7.32 (d, J = 8.1 Hz, 2 H), 7.47 (d, J =
8.1 Hz, 2 H), 7.66 (s, 1 H), 7.68–7.72 (m, 4 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 22.4 (CH2), 22.7 (CH2), 29.0 (CH2), 29.2
(CH2), 51.9 (CH3), 123.0 (C), 125.1 (CH), 125.4 (CH), 127.9 (CH),
128.3 (CH), 129.6 (CH), 129.8 (C), 137.0 (C), 139.7 (C), 140.5 (C),
CDCl ): δ = 31 ppm. IR (neat): νmax = 1021, 1321, 1627, 3376 cm–1.
˜
3
HRMS: calcd. for C25H25BN2O4Na 451.17996; found 451.17962.
Compound 26d: Colorless oil. 1H NMR (400 MHz, CDCl3): δ =
1.34 (s, 12 H), 1.35 (s, 12 H), 2.04 (quint, J = 8.0 Hz, 2 H), 3.02 (t,
J = 8. 0 Hz, 2 H), 3.13 (t, J = 8.0 Hz, 2 H), 6.24 (br. s, 2 H), 6.32
(d, J = 7.2 Hz, 2 H), 7.00–7.02 (m, 2 H), 7.10–7.14 (m, 2 H), 7.82
(s, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 24.8 (CH3), 25.0
(CH2), 25.1 (CH3), 33.4 (CH2), 33.9 (CH2), 83.6 (C), 84.3 (C), 105.7
(CH), 117.3 (CH), 127.7 (CH), 136.5 (2 C), 136.7 (CH), 141.7 (C),
148.1 (C), 151.8 (C) ppm; C–B signal not observed. 11B NMR
140.9 (C), 141.4 (C), 144.4 (2 C), 144.7 (C), 167.7 (C=O) ppm. 19
F
NMR (377 MHz, CDCl ): δ = –62.9, –62.7 ppm. IR (neat): ν
˜
3
max
= 1165, 1323, 1729, 2938 cm–1. HRMS: calcd. for C26H20F6O2Na
478.13675; found 478.13648.
Compound 24: White solid. M.p. 290 °C. 1H NMR (400 MHz,
CDCl3): δ = 1.15 (s, 24 H), 1.69–1.75 (m, 4 H), 1.82–1.88 (m, 4 H),
2.66–2.70 (t, J = 6.1 Hz, 4 H), 2.96–3.00 (t, J = 6.3 Hz, 4 H), 7.08
(s, 4 H), 7.17–7.29 (m, 6 H), 7.31–7.48 (m, 6 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 23.2 (CH2), 23.4 (CH2), 25.0 (CH3), 28.6
(CH2), 30.2 (CH2), 83.8 (C), 126.8 (CH), 127.8 (CH), 128.0 (CH),
128.9 (CH), 129.2 (CH), 133.0 (C), 140.5 (C), 140.6 (C), 142.7 (C),
143.6 (C), 143.7 (C) ppm; C–B signal not observed. 11B NMR
(128 MHz, CDCl ): δ = 32 ppm. IR (neat): νmax = 985, 1357, 1689,
˜
3
3089 cm–1. HRMS: calcd. for C31H39B3N2O4Na 559.30812; found
559.30801.
Compound 26e: Brown oil. 1H NMR (400 MHz, CDCl3): δ = 1.86–
1.88 (m, 4 H), 2.26 (s, 3 H), 2.37 (s, 3 H), 2.68–2.72 (m, 4 H), 5.81
(br. s, 2 H), 6.35 (d, J = 7.2 Hz, 2 H), 7.07–7.18 (m, 5 H) ppm. 13
C
NMR (100 MHz, CDCl3): δ = 19.4 (CH3), 19.5 (CH3), 22.9 (CH2),
23.2 (CH2), 27.6 (CH2), 27.7 (CH2), 105.9 (CH), 117.8 (CH), 119.8
(C), 127.7 (CH), 130.7 (CH), 133.8 (C), 135.8 (C), 136.5 (C), 136.8
(C), 137.0 (C), 141.3 (C) ppm; C–B signal not observed. 11B NMR
(128 MHz, CDCl ): δ = 30 ppm. IR (neat): ν
= 1145, 1380,
˜
3
max
2954 cm–1. HRMS: calcd. for C50H56B2O4Na 765.42569; found
765.42594.
(128 MHz, CDCl ): δ = 31 ppm. IR (neat): νmax = 1373, 1599, 2925,
˜
3
Procedure for Cocyclizations of the Diynes 25a–j with the Alkynyl-
naphthaloboramide 5: [Rh(cod)2]BF4 (0.015 mmol) and Tol-BINAP
(0.021 mmol) were dissolved in 1,2-dichloroethane (2 mL) under
argon, and the mixture was stirred at 80 °C for 15 min. A solution
of the alkyne 5 (0.31 mmol) and a diyne 25a–j (0.31 mmol) in 1,2-
dichloroethane (1 mL) was added at 80 °C, and the reaction mix-
ture was stirred at this temperature overnight. After evaporation of
the solvent, the residue was purified by flash column chromatog-
raphy on silica gel with a gradient mixture of pentane and Et2O.
3398 cm–1. HRMS: calcd. for C22H23BN2 326.19528; found
326.19563.
Compound 26f: Colorless oil. 1H NMR (400 MHz, CDCl3): δ =
3.46 (s, 4 H), 3.76 (s, 6 H), 6.01 (br. s, 2 H), 6.40 (d, J = 7.2 Hz, 2
H), 7.04–7.16 (m, 4 H), 7.27 (s, 1 H), 7.45–7.48 (m, 2 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 40.6 (CH2), 40.8 (CH2), 53.2 (CH3),
60.3 (C), 106.1 (CH), 117.8 (CH), 124.3 (CH), 127.3 (CH), 127.7
(CH), 130.0 (CH), 136.1 (C), 136.4 (C), 140.0 (C), 141.2 (C), 142.4
(C), 172.1 (C=O) ppm; C–B signal not observed. 11B NMR
Compound 26a: Yellow oil. 1H NMR (400 MHz, CDCl3): δ = 2.10–
2.13 (m, 2 H), 2.27 (s, 3 H), 2.38 (s, 3 H), 2.90 (t, J = 12.0 Hz, 4
H), 5.81 (br. s, 2 H), 6.35 (d, J = 7.2 Hz, 2 H), 7.12–7.16 (m, 5 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 19.0 (CH3), 19.3 (CH3),
24.2 (CH2), 31.9 (CH2), 32.1 (CH2), 105.9 (CH), 117.7 (CH), 119.8
(C), 127.7 (CH), 131.0 (C), 131.4 (CH), 133.5 (C), 136.4 (C), 141.3
(C), 143.2 (C), 144.3 (C) ppm; C–B signal not observed. 11B NMR
(128 MHz, CDCl ): δ = 29 ppm. IR (neat): νmax = 1333, 1599, 1730,
˜
3
2953, 3404 cm–1. HRMS: calcd. for C23H21BN2O4Na 423.14866;
found 423.14838.
1
Compound 26g: Brown oil. H NMR (400 MHz, CDCl3): δ = 3.54
(s, 2 H), 3.73 (s, 6 H), 3.80 (s, 2 H), 5.43 (br. s, 2 H), 6.05 (d, J =
7.2 Hz, 2 H), 7.96–7.06 (m, 4 H), 7.42–7.58 (m, 11 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 40.4 (CH2), 40.8 (CH2), 53.0 (CH3),
60.1 (C), 105.7 (CH), 117.4 (CH), 119.4 (C), 127.4 (CH), 127.6
(CH), 127.7 (CH), 128.5 (CH), 128.6 (CH), 128.7 (CH), 129.0
(CH), 132.4 (CH), 136.2 (C), 137.3 (C), 139.4 (C), 139.5 (C), 140.4
(C), 141.1 (C), 141.2 (C), 141.9 (C) ppm; C–B signal not observed.
(128 MHz, CDCl ): δ = 31 ppm. IR (neat): νmax = 1236, 1599, 2931,
˜
3
3403 cm–1. HRMS: calcd. for C21H21BN2Na 312.17923; found
312.17906.
Compound 26b: Colorless oil. 1H NMR (400 MHz, CDCl3): δ =
2.05 (quint, J = 8.0 Hz, 2 H), 2.85 (t, J = 6.0 Hz, 2 H), 3.10 (t, J
= 8.0 Hz, 2 H), 5.44 (br. s, 2 H), 6.05 (d, J = 7.2 Hz, 2 H), 6.96–
11B NMR (128 MHz, CDCl ): δ = 30 ppm. IR (neat): νmax = 1270,
˜
3
Eur. J. Org. Chem. 2011, 3283–3292
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3289

L. Iannazzo, K. P. C. Vollhardt, M. Malacria, C. Aubert, V. Gandon
FULL PAPER
1410, 1628, 1732, 2952, 3425 cm–1. HRMS: calcd. for
C35H29BN2O4Na 575.21187; found 575.21163.
Compound 28: PdCl2(dppf) (0.005 mmol, 4.4 mg) and para-iodoan-
isole (0.08 mmol, 19 mg) were added to a solution of compound
27 (0.05 mmol, 17 mg) in THF (3 mL). After addition of K2CO3
(0.32 mmol, 45 mg) and water, the reaction mixture was heated at
reflux for 48 h. After the mixture had cooled to room temperature,
water and EtOAc were added, and the aqueous layer was extracted
with EtOAc. The combined organic extracts were washed with
water, dried with MgSO4, and concentrated. The residue was puri-
fied by flash column chromatography on silica gel with pentane/
Compound 26h1: Colorless oil. 1H NMR (400 MHz, CDCl3): δ =
3.63 (s, 2 H), 3.71 (s, 6 H), 3.83 (s, 3 H), 3.91 (s, 2 H), 5.70 (br. s,
2 H), 6.31 (d, J = 7.02 Hz, 2 H), 7.02–7.13 (m, 4 H), 7.37 (s, 2 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 40.3 (CH2), 41.7 (CH2),
52.3 (CH3), 53.2 (CH3), 59.7 (C), 105.8 (CH), 117.6 (CH), 119.6
(C), 127.6 (2 CH), 130.0 (C), 131.7 (CH), 136.5 (C), 141.3 (C),
141.4 (C), 142.3 (C), 168.5 (C=O), 172.1 (C=O) ppm; C–B signal
not observed. 11B NMR (128 MHz, CDCl3): δ = 30 ppm. IR (neat):
1
Et2O (96:4) as eluent to afford 28 (89%, 17 mg) as a yellow oil. H
NMR (400 MHz, CDCl3): δ = 2.04–2.09 (m, 2 H), 2.85–2.88 (m, 2
H), 3.09–3.12 (m, 2 H), 3.74 (s, 3 H), 6.70 (d, J = 8.8 Hz, 2 H),
7.06 (d, J = 8.8 Hz, 2 H), 7.12–7.23 (m, 5 H), 7.31–7.49 (m, 4 H),
7.54–7.56 (m, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 26.1
(CH2), 33.3 (CH2), 33.5 (CH2), 55.2 (CH3), 113.2 (CH), 126.4
(CH), 127.0 (CH), 127.9 (CH), 128.4 (CH), 128.7 (CH), 129.3
(CH), 130.3 (CH), 131.1 (CH), 134.1 (C), 136.1 (C), 137.3 (C),
139.3 (C), 140.4 (C), 141.0 (C), 141.2 (C), 144.5 (C), 158.1 (C) ppm.
ν
= 1273, 1523, 1736, 3041, 3412 cm–1. HRMS: calcd. for
˜
max
C25H23BN2O6Na 481.15459; found 481.15450.
Compound 26h2: Colorless oil. 1H NMR (400 MHz, CDCl3): δ =
3.63 (s, 2 H), 3.78 (s, 6 H), 3.91 (s, 3 H), 3.99 (s, 2 H), 6.11 (br. s,
2 H), 6.40 (d, J = 7.0 Hz, 2 H), 7.01–7.15 (m, 4 H), 7.59 (s, 1 H),
8.08 (s, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 40.1 (CH2),
41.1 (CH2), 52.1 (CH3), 53.2 (CH3), 65.95 (C), 106.2 (CH), 117.9
(CH), 119.9 (C), 126.3 (C), 127.7 (CH), 131.4 (CH), 132.3 (CH),
136.4 (C), 141.3 (C), 141.5 (C), 141.6 (C), 167.1 (C=O), 172.1
(C=O) ppm; C–B signal not observed. 11B NMR (128 MHz,
IR (neat): ν
= 1245, 1673, 1789, 2972 cm–1. HRMS: calcd. for
˜
max
C28H24ONa 399.17194; found 399.17180.
CDCl ): δ = 30 ppm. IR (neat): νmax = 1215, 1547, 1759, 3250 cm–1.
Compound 29: PdCl2(dppf) (0.013 mmol, 10 mg) and para-iodo-
anisole (0.26 mmol, 61 mg) were added to a solution of compound
26d (0.065 mmol, 35 mg) in THF (5 mL). After addition of K2CO3
(0.78 mmol, 108 mg) and water, the reaction mixture was heated at
reflux for 48 h. After the mixture had cooled to room temperature,
water and EtOAc were added, and the aqueous layer was extracted
with EtOAc. The combined organic extracts were washed with
water, dried with MgSO4, and concentrated. The residue was puri-
fied by flash column chromatography on silica gel with pentane/
˜
3
1
Compound 26i: Brown oil. H NMR (400 MHz, CDCl3): δ = 5.07
(s, 2 H), 5.30 (s, 2 H), 5.48 (br. s, 2 H), 6.08 (d, J = 7.0 Hz, 2 H),
6.98–7.07 (m, 4 H), 7.39–7.51 (m, 10 H), 7.66 (s, 1 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 73.7 (CH2), 74.0 (CH2), 105.8 (CH),
117.6 (CH), 119.5 (C), 127.6 (CH), 127.8 (CH), 128.0 (CH), 128.1
(CH), 128.7 (CH), 128.8 (CH), 128.9 (CH), 132.6 (CH), 135.0 (C),
136.2 (C), 139.0 (C), 139.1 (C), 139.2 (C), 139.9 (C), 140.5 (C),
141.0 (C) ppm; C–B signal not observed. 11B NMR (128 MHz,
1
Et2O (8:2) as eluent to afford 29 (47%, 15 mg) as a yellow oil. H
CDCl ): δ = 30 ppm. IR (neat): ν
= 1113, 1315, 1572, 1639,
˜
3
max
NMR (400 MHz, CDCl3): δ = 2.06 (m, 2 H), 2.87 (t, J = 9.4 Hz,
2 H), 3.10 (t, J = 9.4 Hz, 2 H), 3.88 (s, 3 H), 3.90 (s, 3 H), 5.51 (br.
s, 2 H), 6.10 (d, J = 8.8 Hz, 2 H), 6.98–7.09 (m, 8 H), 7.34 (d, J =
12 Hz, 2 H), 7.48–7.53 (m, 3 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 25.7 (CH2), 33.0 (CH2), 33.5 (CH2), 55.4 (CH3), 105.7
(CH), 113.9 (CH), 117.3 (CH), 117.4 (CH), 119.4 (C), 127.6 (CH),
129.8 (CH), 130.3 (CH), 131.4 (CH), 133.7 (C), 134.1 (C), 136.3
(C), 136.7 (C), 141.1 (C), 141.3 (C), 143.9 (C), 158.7 (C), 158.9
3137 cm–1. HRMS: calcd. for C30H23ON2B 438.19032; found
438.18994.
1
Compound 26j: Yellow oil. H NMR (400 MHz, CDCl3): δ = 2.18
(s, 3 H), 2.29 (s, 3 H), 2.42 (s, 3 H), 4.57 (s, 4 H), 5.77 (br. s, 2 H),
6.33 (d, J = 7.0 Hz, 2 H), 7.04–7.14 (m, 5 H), 7.34 (d, J = 8.0 Hz,
2 H), 7.80 (d, J = 8.0 Hz, 2 H) ppm. 13C NMR (100 MHz, CDCl3):
δ = 18.3 (CH3), 18.7 (CH3), 30.4 (CH3), 53.6 (CH2), 53.8 (CH2),
106.1 (CH), 118.0 (CH), 119.8 (C), 127.7 (CH), 127.8 (CH), 129.6
(C), 130.0 (CH), 132.5 (C), 133.0 (CH), 133.8 (C), 135.3 (C), 136.1
(C), 136.4 (C), 141.0 (C), 143.8 (C) ppm; C–B signal not observed.
(C) ppm. IR (neat): ν
= 945, 1178, 1689, 2963 cm–1. 11B NMR
˜
max
(128 MHz, CDCl3): δ = 31 ppm. HRMS: calcd. for C33H29O2N2B
496.23166; found 496.23121.
11B NMR (128 MHz, CDCl ): δ = 30 ppm. IR (neat): νmax = 1214,
˜
3
1
1521, 2934, 3150 cm–1. HRMS: calcd. for C27H26BN3O2SNa
Compound 30: H NMR (400 MHz, CDCl3): δ = 2.07 (quint, J =
7.3 MHz, 2 H), 2.89 (t, J = 7.4 Hz, 2 H), 3.11 (t, J = 7.2 Hz, 2 H),
3.81 (s, 3 H), 3.88 (s, 3 H), 6.81 (d, J = 7.8 Hz, 2 H), 6.79–7.70
(m, 4 H), 7.28–7.30 (m, 3 H), 7.44–7.50 (m, 4 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 26.1 (CH2), 33.4 (CH2), 33.5 (CH2), 55.2
(CH3), 55.4 (CH3), 113.4 (CH), 113.8 (CH), 124.6 (CH), 124.7 (C),
128.9 (CH), 129.6 (CH), 130.2 (CH), 131.2 (CH), 132.0 (C), 133.4
(C), 135.3 (C), 137.0 (C), 138.4 (C), 142.1 (C), 145.0 (C), 145.8
(C), 158.3 (C), 158.9 (C) ppm. 19F NMR (277 MHz, CDCl3): δ =
490.17359; found 490.17311.
Compound 27: The protected boronic acid 26b (0.13 mmol, 59 mg)
was dissolved in THF (10 mL), and H2SO4 (2 m) was added. The
solution was heated at 60 °C for 24 h and was then allowed to cool
to room temperature and extracted with EtOAc. The combined
organic extracts were washed with satd. NaHCO3 and brine, dried
with MgSO4, and concentrated. The crude product was purified by
flash column chromatography on silica gel with pentane/Et2O (7:3)
to afford 27 as a yellow oil (80%, 34 mg) in equilibrium with the
corresponding boroxine.[30] 1H NMR (400 MHz, CDCl3): δ = 1.98
(m, 4 H), 2.70 (m, 4 H), 2.96 (m, 1.5 H), 3.06 (m, 3 H), 6.58 (m,
0.5 H), 6.78 (s, 1 H), 6.91 (m, 1.5 H), 7.27–7.50 (m, 17 H), 7.86 (s,
1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 25.5 (CH2), 25.6
(CH2), 29.8 (CH2), 32.6 (CH2), 32.8 (CH2), 33.3 (CH2), 33.5 (CH2),
127.0 (C), 127.8 (C), 128.0 (C), 128.1 (C), 128.3 (CH), 128.7 (CH),
128.9 (CH), 129.1 (CH), 129.2 (C), 134.5 (CH), 135.5 (C), 136.7
–62 ppm. IR (neat): ν
= 1056, 1789, 3024 cm–1. HRMS: calcd.
˜
max
for C30H25F3O2Na 497.16989; found 497.17035.
Compound 31:[31] Yellow oil. 1H NMR (400 MHz, CDCl3): δ = 1.22
(s, 24 H), 4.22 (s, 4 H), 4.24 (s, 4 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 24.6 (CH3), 56.7 (CH2), 56.8 (CH2), 82.1 (C), 84.4 (C)
ppm; CϵC signal with boron not observed. IR (neat): νmax = 1114,
˜
2156, 2232 cm–1.
(C), 137.3 (C), 141.2 (C), 141.5 (C), 141.7 (C), 142.5 (C), 142.6 (C), Compound 32a: Colorless oil. 1H NMR (400 MHz, CDCl3): δ =
143.2 (C), 143.6 (C), 145.1 (C) ppm. 11B NMR (128 MHz, CDCl3): 1.35 (s, 24 H), 5.00 (s, 4 H), 5.19 (s, 4 H) ppm. 13C NMR
δ = 30 ppm. IR (neat): ν
= 1065, 1789, 2963 cm–1. HRMS:
(100 MHz, CDCl3): δ = 25.1 (CH3), 72.1 (CH2), 74.5 (CH2), 84.2
˜
max
calcd. for C23H23BO2Na 365.16833; found 365.16866.
(C), 133.2 (C), 144.4 (C) ppm; C–B signal not observed. IR (neat):
3290
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 3283–3292

Oligoaryls through Selective Suzuki Couplings
1215, 1532 cm–1. HRMS: calcd. for C22H32B2O6Na
Auvinet, J. P. A. Harrity, G. Hilt, J. Org. Chem. 2010, 75, 3893;
l) M. Danza, G. Hilt, Adv. Synth. Catal. 2011, 353, 303.
For reviews, see: a) N. Miyaura, A. Suzuki, Chem. Rev. 1995,
95, 2457; b) N. Miyaura, Top. Curr. Chem. 2002, 219, 11; c) N.
Miyaura in Metal-Catalyzed Cross-Coupling Reactions, vol. 1
(Eds.: A. de Meijere, F. Diederich), Wiley-VCH, Weinheim,
2004, pp. 41–124; d) J. Sakamoto, M. Rehahn, G. Wegner,
A. D. Schlüter, Macromol. Rapid Commun. 2009, 30, 653.
Oligoaryls are important organic materials, see: F. Babudri,
G. M. Farinola, F. Naso, Synlett 2009, 2740, and references
therein.
See, among many others: a) D. Hinderberger, O. Schmelz, M.
Rehahn, G. Jeschke, Angew. Chem. 2004, 116, 4716; Angew.
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O. J. Dautel, M. Robitzer, J.-C. Flores, D. Tondelier, F. Serein-
Spirau, J.-P. Lère-Porte, D. Guérin, S. Lenfant, M. Tillard, D.
Vuillaume, J. J. E. Moreau, Chem. Eur. J. 2008, 14, 4201.
a) M. Shimizu, Y. Tomioka, I. Nagao, T. Hiyama, Synlett 2009,
3147; b) H. Yoshida, K. Okada, S. Kawashima, K. Tanino, J.
Ohshita, Chem. Commun. 2010, 46, 1763.
See, inter alia: a) E. Perret-Aebi, A. von Zelewsky, Synlett 2002,
773; b) I. Eryazici, P. Wang, C. N. Moorefield, M. Panzer, S.
Durmus, C. D. Shreiner, G. R. Newkome, Dalton Trans. 2007,
626; c) A. M. Müller, Y. S. Avlasevich, W. W. Schoeller, K.
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ν
=
˜
max
437.22772; found 437.22776.
[3]
1
Compound 30b: Yellow oil. H NMR (400 MHz, CDCl3): δ = 1.32
(s, 12 H), 5.02 (s, 4 H), 5.11 (s, 2 H), 5.24 (s, 2 H), 7.58 (s, 1 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 25.0 (CH3), 71.9 (CH2),
72.4 (CH2), 73.4 (CH2), 74.8 (CH2), 84.0 (C), 126.6 (CH), 131.8
(C), 135.6 (C), 138.2 (C), 146.2 (C) ppm; C–B signal not observed.
[4]
[5]
IR (neat): ν
= 888, 1059, 1380, 2973 cm–1. HRMS: calcd. for
˜
max
C16H21O4BNa 311.14251; found 311.14268.
Compound 33: Colorless oil. 1H NMR (400 MHz, CDCl3): δ = 3.74
(s, 6 H), 4.99 (s, 4 H), 5.12 (s, 4 H), 6.73 (d, J = 8.4 Hz, 4 H), 6.94
(d, J = 8.4 Hz, 4 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 55.1
(CH3), 72.8 (CH2), 73.8 (CH2), 113.5 (CH), 130.6 (CH), 130.9 (C),
131.0 (C), 134.0 (C), 139.0 (C), 158.3 (C) ppm. IR (neat): ν
=
˜
max
1123, 1289, 2956 cm–1.
[6]
[7]
Acknowledgments
We thank the Université Pierre et Marie Curie (UPMC), the Uni-
versité Paris-Sud (UPS), the Ministère de la Recherche, the Centre
National de la Recherche Scientifique (CNRS), the Institut Uni-
versitaire de France (IUF), and the National Science Foundation
(NSF) (CHE 0907800, K. P. C. V.) for financial support of this
work. We also thank Guillaume Bertrand for technical assistance
during the synthesis of CpCo(CO)(dimethyl fumarate).
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Eur. J. Org. Chem. 2011, 3283–3292
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3291

L. Iannazzo, K. P. C. Vollhardt, M. Malacria, C. Aubert, V. Gandon
FULL PAPER
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the [2+2+2] cycloaddition product of 15 with ethene (see
ref.[1g]).
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Received: March 17, 2011
Published Online: May 12, 2011
3292
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 3283–3292