9202 J. Am. Chem. Soc., Vol. 120, No. 36, 1998
Bazan et al.
stirring. The cooled reaction mixture was diluted with Et2O (20 mL)
and extracted with water (8 × 5 mL). The organic layer was then
dried (MgSO4) and purified by flash chromatography (hexanes) to yield
172 mg (75%) of colorless crystals. A single-crystal X-ray diffraction
experiment was carried out on one of these. 1H NMR (CDCl3): 7.58
(d, J ) 7 Hz, 2 H, o-phenyl); 7.41 (t, J ) 7.4 Hz, 2 H, m-phenyl); 7.30
(t, J ) 7.3 Hz, 1 H, p-phenyl); 7.20, 6.90 (AB spin system, J ) 16 Hz,
1 H each, vinyl); 6.71 (dd, J ) 7.8, 1.8 Hz, 1 H); 6.67 (d, J ) 1.4 Hz,
1 H); 6.55-6.43 (m, 5 H); 3.60 (m, 1 H); 3.17-2.81 (m, 7 H). 13C-
{1H} NMR (CDCl3): 139.9, 139.4, 139.3, 138.4, 137.9, 137.4 (quat.),
135.0, 133.0, 131.8, 131.75, 130.2, 129.8, 129.2, 128.8, 127.5, 126.9,
126.5, 35.5, 35.3, 34.9, 34.0. Calcd for C24H22: C, 92.9; H, 7.1.
Found: C, 92.97; H, 6.99.
4,16-Distyryl[2.2]paracyclophane (1a). A 100-mL round-bottom
flask was charged with a Teflon-coated stir bar, 4,16-dibromoparacy-
clophane (323 mg, 0.88 mmol), styrene (0.3 mL, 2.6 mmol), triethy-
lamine (2 mL), and DMF (25 mL). The reaction flask was fitted with
a Kontes vacuum line adapter and evacuated and back-filled with
nitrogen three times. This was transferred into an inert atmosphere
glovebox, where Pd(OAc)2 (4 mg, 0.018 mmol) and tris(o-tolyl)-
phosphine (21 mg, 0.07 mmol) were added to the flask. The flask
was then fitted with a septum (secured with wire) and heated to 100
°C for 2 days while stirring. The cooled reaction mixture was diluted
with water to afford a tan precipitate, which was filtered off and rinsed
with water. The solid was dissolved in chloroform, filtered into a clean
flask, and dried (MgSO4). After filtering off the MgSO4, the chloroform
solution was reduced in volume and layered with hexanes to afford
171 mg (47%) of colorless crystals upon standing overnight. 1H NMR
(CDCl3): 7.57 (d, J ) 7.2 Hz, 2 H, o-phenyl); 7.40 (t, J ) 7.4 Hz, 2
H, m-phenyl); 7.28 (t, J ) 7.4 Hz, 1 H, p-phenyl); 7.21, 6.87 (AB spin
system, J ) 16.1 Hz, 1 H each, vinyl); 6.68-6.61 (m, 2 H); 6.40 (d,
J ) 7.7 Hz, 1 H); 3.59 (m, 1 H); 3.11 (m, 1 H); 3.03-2.89 (m, 2 H).
13C{1H} NMR (CDCl3): 139.5, 138.2, 137.9, 137.4 (quat.), 133.6,
130.2, 129.5, 129.3, 128.7, 127.5, 127.0, 126.5, 34.5, 33.3. HREI Calcd
for C32H28 ) 412.2191. Found 412.2187. Calcd for C32H28: C, 93.2;
H, 6.8. Found: C, 92.26; H, 6.59.
4,12-Distyryl[2.2]paracyclophane (1b). A 50-mL round-bottom
flask was charged with a Teflon-coated stir bar, 4,12-dibromoparacy-
clophane (252 mg, 0.69 mmol), styrene (0.2 mL, 1.75 mmol),
triethylamine (2 mL), and DMF (10 mL). The reaction flask was fitted
with a Kontes vacuum line adapter and evacuated and back-filled with
nitrogen three times. This was transferred into an inert atmosphere
glovebox, where Pd(OAc)2 (3 mg, 0.013 mmol) and P(o-tol)3 (15 mg,
0.049 mmol) were added to the flask. The flask was then fitted with
a septum (secured with wire) and heated to 100 °C for 2 days with
stirring. The cooled reaction mixture was filtered through Celite and
diluted with chloroform. The solution was extracted with water (5 ×
10 mL) and then dried (MgSO4). After removing the volatiles under
vacuum, the crude product was purified by flash chromatography (5:1
hexanes:chloroform) to afford 130 mg (46%) of colorless crystals. These
can be recrystallized from warm pentane to obtain X-ray quality single
crystals. 1H NMR (CDCl3): 7.46 (d, J ) 7.6 Hz, 2 H, o-phenyl); 7.38
(t, J ) 7.9 Hz, 2 H, m-phenyl); 7.29 (t, J ) 7.3 Hz, 1 H, p-phenyl);
7.22, 6.87 (AB spin system, J ) 16.2 Hz, 1 H each, vinyl); 6.93 (d, J
) 1.5 Hz, 1 H); 6.56 (d, second order, J ) 7.8 Hz, 1 H); 6.52 (dd,
second order, J ) 7.9, 1.5 Hz, 1 H); 3.64 (m, 1 H); 3.18 (m, 1 H);
2.97-2.84 (m, 2 H). 13C{1H} NMR (CDCl3): 139.7, 138.0, 137.7,
136.8 (quat), 135.0, 131.8, 128.7, 127.5, 126.7, 126.6, 125.9, 34.5, 34.0.
Calcd for C32H28: C, 93.2; H, 6.8. Found: C, 93.13; H, 6.91.
2,5-Dimethylstilbene (1c). A 10-mL pear-shaped flask was charged
with a Teflon-coated stir bar, 2-bromo-p-xylene (0.37 mL, 1.49 mmol),
styrene (0.37 mL, 3.22 mmol), and triethylamine (5 mL). The flask
was fitted with a Kontes vacuum line adapter and evacuated and then
back-filled with nitrogen three times. The sealed assembly was
transferred into an inert atmosphere glovebox, where Pd(OAc)2 (6 mg,
0.027 mmol) and P(o-tol)3 (32 mg, 0.11 mmol) were added to the
reaction mixture. The flask was fitted with a rubber septum (secured
with wire) and then heated to 100 °C with stirring for 12 h. The cooled
reaction mixture was diluted with Et2O, and the insoluble triethylam-
monium bromide was filtered off. The mass of triethylammonium
bromide isolated (263 mg, 53%) and GC/MS analysis of the crude
reaction mixture indicated that only approximately half of the 2-bro-
moparaxylene starting material had been consumed. Purification by
flash chromatography (3:1 hexanes/chloroform) affords 136 mg (24%)
of white crystals following crystallization in the freezer overnight.
Bis-4,16-(4-carboxaldehyde-styryl)[2.2]paracyclophane (8). Work
was performed in an inert atmosphere glovebox. A 25-mL round-
bottom flask was charged with a Teflon-coated stir bar, 4,16-divinyl-
[2.2]paracyclophane (123 mg, 0.47 mmol), 4-bromobenzaldehyde (177
mg, 0.96 mmol), Pd(OAc)2 (3 mg, 0.013 mmol), NBu4Br (317 mg,
0.98 mmol), K2CO3 (149 mg, 1.08 mmol), and dimethylacetamide (6
mL). The resulting reaction mixture was heated for 2 days with stirring
at 105 °C. The crude product mixture was diluted with water and
filtered. A gray solid was collected and washed with two portions (15
mL) of chloroform and then transferred to a 100-mL Erlenmeyer flask.
The solid was warmed with 50 mL of chloroform and filtered hot. The
solid which remained on the fritted funnel was extracted again with
hot chloroform and repeated for a total of three extractions. The
combined filtrate was reduced in volume on a rotary evaporator to
obtain 96 mg (43%) of bright yellow crystals. 1H NMR (CDCl3): 10.00
(s, 1 H, CHO); 7.90, 7.70 (AA′BB′ pattern, J ) 8 Hz, 2 H each,
aromatic); 7.37, 6.92 (AB pattern, J ) 16.0 Hz, 1 H each, trans-alkene);
6.73 (d, J ) 1.5 Hz, 1 H, cyclophane); 6.64 (dd, J ) 1.5, 7.8 Hz, 1 H,
cyclophane); 6.43 (d, J ) 7.7 Hz, 1 H, cyclophane); 3.61, 3.15, 3.05-
2.92 (m, 4 H total, CH2). Calcd for C34H28O2: C, 87.15; H, 6.02; O,
6.83. Found: C, 87.07; H, 5.92; O, 6.75.
Bis-4,16-(4-vinyl-styryl)[2.2]paracyclophane (9). A THF solution
(10 mL) of the ylide reagent, CH2PPh3, was prepared upon dropwise
addition of LDA (2.0 M, 0.28 mL, 0.56 mmol) to a slurry of CH3-
PPh3Br (203 mg, 0.57 mmol) at 0 °C. This solution was allowed to
stir for 1.5 h at 0 °C and was then transferred via cannula to a second
THF slurry (10 mL) of bis-4,16-(4-carboxaldehyde-styryl)[2.2]-
paracyclophane (80 mg, 0.17 mmol). The mixture was gradually
warmed to ambient temperature and left to stir for 3 h upon which
time the reaction was quenched by adding an aqueous NH4Cl solution.
The THF solvent was removed using a rotary evaporator and then
chloroform was added and extracted with water (2 × 25 mL). The
organic phase was collected and dried (MgSO4) amd then purified by
column chromatography (3:1 hexanes:chloroform) to yield 35 mg (42%)
of bright lemon yellow microcrystals. 1H NMR (CDCl3): 7.53, 7.44
(AA′BB′ pattern, J ) 8.3 Hz, 2 H each, aromatic); 7.21, 6.86 (AB
pattern, J ) 16.2 Hz, 1 H each, trans-alkene); 6.73 (dd, J ) 10.9, 17.6
Hz, 1 H, vinyl); 6.67 (d, J ) 1.6 Hz, 1 H, cyclophane); 6.63 (dd, J )
1.7, 7.7 Hz, 1 H, cyclophane); 6.40 (d, J ) 7.7 Hz, 1 H, cyclophane);
5.78 (dd, J ) 0.7, 17.6 Hz, 1 H, vinyl); 5.26 (dd, J ) 0.7, 10.9 Hz, 1
H, vinyl); 3.59, 3.11, 3.01, 2.94 (m, 1 H each, CH2). 13C{1H} NMR
(CDCl3): 139.5, 138.2, 137.5, 137.3, 136.8 (quaternary), 136.4, 133.6,
130.1, 129.5, 128.9, 126.9, 126.64, 126.61, 113.7 (aromatic and vinyl),
34.5, 33.4 (CH2). Calcd. for C36H32: C, 93.06; H, 6.94. Found: C,
92.95; H, 6.77.
p-Vinylbenzylphosphonium Chloride. A toluene (50 mL) solution
of p-vinylbenzyl chloride (90%, 8.7 g, 51.3 mmol) and triphenylphos-
phine (13.1 g, 49.9 mmol) was heated with stirring to 110 °C for 12 h.
The resulting white crystalline solid was filtered off and washed with
toluene and then dried under vacuum. Yield 12.6 g (61%). 1H NMR
(CDCl3): 7.74 (m, 9H, PPh3); 7.60 (m, 6 H, PPh3); 7.12, 7.04 (AA′BB′
pattern, J ) 8 Hz, 2 H each, aromatic); 6.57 (dd, J ) 10.9 and 17.4
Hz, 1 H, vinyl); 5.65 (d, J ) 17.5 Hz, 1 H, vinyl); 5.52 (d, JPH ) 14.7
Hz, 2 H, benzylic); 5.20 (d, J ) 10.8 Hz, 1 H, vinyl).
trans-4,4′-tert-Butylvinylstilbene. To an Et2O suspension/solution
of p-vinylbenzylphosphonium chloride (3.99 g, 9.6 mmol) and 4-tert-
butylbenzaldehyde (1.7 mL, 10.1 mmol) was added LiOEt (1.0 M in
EtOH, 10 mL) dropwise over 30 min. The resulting homogeneous
solution was extracted with water and brine and then dried over MgSO4.
The crude product mixture was purified by column chromatography
(hexanes). The initial fractions containing the cis isomer were combined
and heated with a small amount of I2 to catalyze the isomerization to
the desired trans isomer. The later fractions containing pure trans
isomer were then combined with the isomerized fractions to afford 1.93
g (77%) of product. 1H NMR (CDCl3): 7.45, 7.38 (AA′BB′ pattern,
4 H each, aromatic); 7.09, 7.03 (AB pattern, 2H, J ) 16.4 Hz); 6.70