Bonvallet et al.
bonded ipso-2H produces an upfield shift of ∼0.3 ppm (to lower
frequency), and each ortho-2H contributes an additional upfield
shift of ∼0.1 ppm. meta-2H makes little contribution.
temperature, added to water (200 mL), and extracted with benzene
(2 × 200 mL). The benzene extracts were washed with brine (250
mL) and dried with MgSO4, and solvent was removed to give a
light yellow oil (5.83 g). This material was purified by column
chromatography (silica, 8:1 hexane/CH2Cl2, Rf ) 0.58) to yield 12
Summary
1
as a white solid (2.49 g, 65% yield): mp 120-121 °C; H NMR
Molecular glass-forming materials 1,3-bis(1-naphthyl)-5-(2-
naphthyl)benzene (2) and 1,3-bis(1-naphthyl-d7)-5-(2-naphthyl)-
benzene (2-d14) have been synthesized in gram quantity and
high purity using Suzuki coupling chemistry. Sophisticated triple
resonance and two-dimensional NMR measurements permit the
detailed assignment of 1H, 2H, and 13C NMR spectra. Dynamic
averaging of the atropisomers of these tris(naphthyl)benzene
derivatives is rapid on the NMR time scale at room temperature.
The availability of both protio- and deuterio-isotopomers of tris-
(naphthyl)benzene 2 has enabled a series of important investiga-
tions concerning diffusion in glasses and the physical properties
of glassy materials.13-15
(CDCl3) δ 7.52 (m, 2H), 7.64 (m, 2H), 7.77 (d, J ) 2 Hz, 2H),
7.88 (m, 3H), 7.97 (s (br), 1H); 13C NMR δ 123.6, 125.1, 126.5,
126.86, 126.9, 127.9, 128.5, 129.1, 129.4, 132.9, 133.3, 133.7,
135.8, 145.0; mass spectrum m/z (rel intensity) 364 (M+, 50), 362
(M+, 100), 360 (M+, 51), 354(19), 282 (11), 202 (84), 176(11),
152 (10), 101 (42); HRMS calcd for C16H1079Br2 359.9149, found
359.9162.
1,3-Bis(1-naphthyl-d7)-5-(2-naphthyl)benzene (2-d14).12
A
solution of 1,3-dibromo-5-(2-naphthyl)benzene (12) (1.69 g, 5
mmol), 1-naphthylboronic acid-d7 (9-d7) (1.98 g, 11 mmol), 2 M
Na2CO3 (10 mL), EtOH (15 mL), and toluene (60 mL) was
stirred under N2. After 20 min, Pd(PPh3)4 (405 mg, 0.35 mmol,
7.0 mol %) was added and the solution was refluxed at 87 °C for
23 h. The solution was allowed to cool to room temperature and
added to water (160 mL) and CH2Cl2 (150 mL). The organic phase
was separated, and the aqueous phase was extracted three more
times with CH2Cl2 (1 × 100 mL, 2 × 75 mL). The organic extracts
were combined and dried with MgSO4, and solvent was re-
moved (30 °C under reduced pressure) to give 4.02 g of a light
brown solid. This material was purified via flash column chroma-
tography26,27 (silica, hexane/CH2Cl2, solvent gradient: 100:0 to 9:1,
Rf ) 0.07) and recrystallized from hexane to yield 1,3-bis(1-
naphthyl-d7)-5-(2-naphthyl)benzene (2-d14) as a white solid (1.16
Experimental Section
CuBr2 Adsorbed on Alumina.18 Alumina (80 g, neutral, Activity
I) and water (120 mL) were combined with CuBr2 (41 g, 183
mmol). The green suspension was mixed for 4 h using a rotary
evaporator (without vacuum). The water was then removed, first
by rotary evaporation at 80 °C under aspirator vacuum, followed
by mechanical vacuum (0.1 mmHg) at 65 °C overnight to obtain
the reagent as a black solid.
1-Bromonaphthalene-d7 (6-d7).18 Naphthalene-d8 (5-d8) (4.99
g, 36.6 mmol) and CuBr2 adsorbed to alumina (120 g) were added
to CCl4 (250 mL). The solution was stirred (mechanical stirrer)
for 9 days at 25-29 °C, and the reaction progress was followed
by GC/mass spectrometry (single ion method). The mixture was
filtered, the filter cake was rinsed with CCl4 (100 mL), and the
filtrate was concentrated to a pale yellow oil by rotary evaporation.
Residual naphthalene was removed by sublimation. Distillation
afforded a short forerun, followed by the desired product 6-d7 as a
pale yellow oil at 78 °C (head temperature, 0.1 mmHg). 6.02 g
(77%). 2H NMR (76.74 MHz, CHCl3) δ 7.32 (s, 1D), 7.57 (d, 2D),
7.82 (m, 3D), 8.25 (s, 1D).
1
g, 53% yield): mp 192-193 °C; H NMR (500 MHz, CDCl3) δ
7.49 (m, 2H), 7.69 (t, J ) 1.4 Hz, 1H), 7.87 (m, 3H), 7.94 (d, J )
8.5 Hz, 1H), 7.97 (d, J ) 1.7 Hz, 2H), 8.18 (d, J ) 1 Hz, 1H). 2H
NMR (76.8 MHz, CHCl3) δ 7.70 (m, 14D); 13C NMR (125 MHz,
CDCl3) δ 125.6, 126.049, 126.051, 126.4, 127.6, 128.0, 128.2,
128.6, 130.7, 131.5, 132.7, 133.69, 133.73, 138.1, 139.8, 141.0,
141.4; mass spectrum m/z (rel intensity) 470 (M+, 51), 446 (8),
393 (21), 322 (77), 238 (57), 236 (56), 210 (24), 208 (25), 157
(66), 129 (100), 128 (75); HRMS calcd for C36H10D14 470.2757,
found 470.2752.
In one instance, the mass spectrum of the product contained a
high-mass peak at m/z ) 602, in addition to the expected parent
ion for 2-d14 at m/z ) 470.
1-Naphthylboronic Acid-d7 (9-d7).25 1-Bromonaphthalene-d7
(6-d7) (6 g, 28 mmol) was added to THF (41 mL), and the sol-
ution was cooled to -78 °C under N2. n-BuLi (2.35 M in hexanes,
13.1 mL, 30.9 mmol) was added dropwise, maintaining the
temperature below -60 °C. After the solution had stirred for 50
min, a separate solution of B(OMe)3 (6.6 mL, 57.8 mmol) and THF
(32 mL) was cooled to -78 °C and then added slowly, maintaining
the temperature below -60 °C. The solution was allowed to warm
to room temperature overnight while stirring. The next day the
reaction mixture was cooled to 5 °C, and concentrated HCl (11.1
mL) was added slowly. The solution was stirred at room temperature
for 1 h. Water (165 mL) was added, and the solution was extracted
with ether (3 × 280 mL). The combined ether extracts were dried
with MgSO4, and the solvent was removed using rotary evaporation
to yield an off-white solid. The solid was collected into a filter
funnel and washed with benzene (4 × 55 mL). After air-drying for
1.5 h, 1-naphthylboronic acid-d7 (9-d7) was collected as a
white solid (3.13 g, 62% yield): 1H NMR (Me2SO-d6) δ 8.38
(s, 2H); 2H NMR (38.4 MHz, Me2CO) δ 7.47 (s (br), 3D), 7.89 (s
(br), 3D), 8.61 (s (br), 1D).
We speculate that the peak at m/z ) 602 arises from the binaphthyl-
containing structure 13, which may ultimately result from carrying
a minor impurity of 1,4-dibromonaphthalene-d6 through the syn-
thetic sequence.
1,3-Dibromo-5-(2-naphthyl)benzene (12).12 A solution of 2-naph-
thylboronic acid (11) (1.86 g, 10.8 mmol), 1,3,5-tribromobenzene
(10) (3.40 g, 10.8 mmol), 2 M Na2CO3 (10.8 mL), EtOH (11 mL),
and toluene (65 mL) was stirred under N2. After 20 min, Pd(PPh3)4
(540 mg, 4.33 mol %) was added and the solution was refluxed at
85 °C for 22 h. The solution was allowed to cool to room
(26) Because of the poor solubility of the sample in the solvent
used for column chromatography, an alternate method of loading the
sample was used. The sample was dissolved in CH2Cl2 and mixed
with a portion of silica gel (1:5 ratio of sample to silica gel). The
mixture was evaporated to dryness and loaded atop the chromatography
column.
(25) Ford, A.; Sinn, E.; Woodward, S. J. Organomet. Chem. 1995, 493,
115-220.
(27) Leonard, J.; Lygo, B.; Procter, G. AdVanced Practical Organic
Chemistry, 2nd ed.; Chapman and Hall: New York, 1995.
10056 J. Org. Chem., Vol. 72, No. 26, 2007