to the mixture. The solid that formed was filtered and dissolved
in a dilute solution of aq KOH. After removal of the solid
impurities by filtration, the filtrate was acidified with dilute HCl.
The solid which separated was recrystallized from EtOH/water
yielding 0.27 g (27%) of 4 (lit: 30%): mp 176 °C (lit. mp 185
1
°C); H NMR (400 MHz, DMSO-d6, rt) δ 14.56 (s, 3H), 7.65 (d,
J ) 7.3 Hz, 6H), 7.55 (t, J ) 7.2 Hz, 3H), 7.45 (t, J ) 7.1 Hz,
6H).
P r ep a r a tion of 5. To a solution of 0.5 g of 4 (1.14 mmol) in
30 mL of acetonitrile was added K2CO3 (1.57 g, 11.4 mmol). After
90 min reflux, dimethyl sulfate was added (0.18 mL, 1.90 mmol),
and the reflux was continued with stirring for an additional 17
h. After evaporation of the solvent, 20 mL of ammonium
hydroxide was added to the residue, and the solution was
extracted three times with CH2Cl2. After evaporation of the
organic solvent, the residue was recrystallized from EtOH,
F IGURE 2. Four basic arrangements of a given peripheral
aryl ring of 9b viewed along the anisyl-CH2 bond. The black
rectangle represents a side view of the anisyl ring while the
label “Ar” represents the central ring. Conformations i and ii
represent “perpendicular” arrangements. In conformations iii
and iv, the anisyl ring is eclipsed with one of the groups
attached to the methylene carbon.
1
yielding brown needles of 5 (0.15 g, 27%): mp 180-185 °C; H
NMR (400 MHz, CDCl3, rt) δ 7.92 (d, J ) 7.3 Hz, 6H,), 7.59 (t,
J ) 7.4 Hz, 3H), 7.48 (t, J ) 7.6 Hz, 6H,), 3.52 (s, 9H).
Red u ction of 5 w ith LiAlH4. A 480 mg (1 mmol) portion of
5 was dissolved in 70 mL of dry THF, and to the solution was
slowly added LiAlH4 (0.76 g, 20 mmol). After being stirred for 3
h under an inert atmosphere, the mixture was quenched with a
few drops of water and the stirring continued for an additional
90 min. The mixture was filtered and the filtrate evaporated.
The residue was purified by recrystallization from CHCl3,
yielding 310 mg (64%) 6: mp 120 °C; 1H NMR (400 MHz, C6D6,
rt) δ 7.49 (d, J ) 8.1 Hz, 2H), 7.40 (d, J ) 8.2 Hz, 4H), 7.13-
7.08 (m, 6H), 7.02-6.99 (m, 3H), 6.23 (d, J ) 11.4 Hz, 1H), 6.16
(d, J ) 10.0 Hz, 2H), 4.02 (d, J ) 11.6 Hz, 1H), 3.51 (d, J ) 10.5
Hz, 2H), 2.96 (s, 6H), 2.93 (s, 3H); 13C NMR (100 MHz, CDCl3,
rt) δ 157.6, 157.5, 144.8, 144.7,129.0, 128.5, 128.3, 128.2, 127.0,
127.0, 125.5, 125.1, 68.7, 68.6, 63.2, 63.1; CI MS (+DCI) m/z 469
(MH+ - H2O).
P r ep a r a tion of 1,3,5-Tr iben zyl-2,4,6-tr im eth oxyben zen e
(7). Compound 6 (200 mg 0.41 mmol) was dissolved in 20 mL of
dry CH2Cl2, and to the solution was added 0.38 mL (4.9 mmol)
of trifluoroacetic acid followed by 1.56 mL of triethylsilane (9.8
mmol), and the mixture was stirred at rt for 70 h. After
neutralization with a saturated solution of NaHCO3, the phases
were separated and the organic phase was dried (MgSO4) and
evaporated. The residue was recrystallized from CHCl3/ether to
yield 146 mg (81%) 7: mp 115 °C (lit.9 mp 101 °C); 1H NMR
(400 MHz, CDCl3, rt) δ 7.35 (d, J ) 7.0 Hz, 6H), 7.18 (t, J ) 7.2
Hz, 6H), 7.06 (t, J ) 7.2 Hz, 3H), 4.15 (s, 6H), 3.27 (s, 9H); 13C
NMR (100 MHz, CDCl3, rt) δ 157.8, 142.0, 128.61, 128.57, 126.1,
124.4, 62.0, 30.8; CI MS m/z 439.2 (MH+).
P r ep a r a tion of 9b. To 2 mL of dry anisole were added CaCO3
(1.5 g) and anhydrous AgClO4 (1.3 g) (CAUTION, anhydrous
AgClO4 can explode when struck.) The mixture (protected from
light) was stirred under an inert atmosphere for 15 min. 1,3,5-
Tris(bromomethyl)-2,4,6-triethylbenzene (0.73 g, 1.65 mmol) was
then added to the mixture, which resulted in the immediate
precipitation of yellow AgBr. The mixture was stirred at rt for
4 h. After the mixture was poured into 20 mL of water, the solid
that precipitated was filtered and the filtrate was extracted twice
with dichloromethane and once with ether. The organic phase
was dried (MgSO4) and the solvent evaporated. Recrystallization
of the residue from CHCl3/EtOH yielded 0.16 g (18%) of 9b: mp
170 °C; 1H NMR (400 MHz, CDCl3, rt) 6.92 (d, J ) 8.4 Hz, 6H),
6.80 (d, J ) 8.5 Hz, 6H), 4.07 (s, 6H), 3.77 (s, 9H), 2.45 (q, J )
7.4 Hz, 6H), 1.08 (t, J ) 7.4 Hz, 9H); 13C NMR (100 MHz, CDCl3,
rt) δ 157.6, 141.1, 134.2, 133.4, 128.6, 113.7, 55.2, 33.7, 23.6,
15.2; CI MS m/z 1057.3 (MH+).
F IGURE 3. Crystal structure of 9b (side view).
armed compound 9b adopts in the crystal a conformation
of crystallographic C3 symmetry with full up-down
alternation of the sidearms and therefore with the three
p-methoxybenzyl groups pointing toward the same face
of the central ring (Figure 3). The three peripheral rings
are oriented in the H-perpendicular arrangement.19
In summary, two hexasubstituted benzene derivatives
(7 and 9b) have been synthesized starting from 3 and
8b. X-ray crystallography indicates that 9b adopts in the
crystal a conformation with facial segregation of substit-
uents with the peripheral rings oriented in the H-
perpendicular conformation.
Exp er im en ta l Section
P r ep a r a tion of 4. The compound was prepared according
to the literature procedure.10 Phloroglucin tribenzoate (3, 1.0 g,
2.3 mmol) and 1 g of AlCl3 were mixed together in a three-necked
flask under an inert atmosphere until a homogeneous mixture
was obtained, which was heated at 150-160 °C for 3 h. After
cooling, a dilute solution of aq HCl (50 mL) was carefully added
Ack n ow led gm en t. We thank Dr. Shmuel Cohen for
the crystal structure determinations and the USA-
Israel Binational Science Foundation for support of this
work.
(18) Crystal data for 9b: C36H42O3, space group R3h, a ) 18.555(1)
Å, c ) 15.113(1) Å, V ) 4506.0(3) Å3, Z ) 6, Fcalcd ) 1.11 g cm-3, µ(Mo
KR) ) 0.72 cm-1, no. of unique reflections ) 1696, no. of reflections
with I g 3σI ) 1128, R ) 0.048, Rw ) 0.068.
(19) According to MM3 calculations (Alchemy 2000 program), the
conformation with all rings oriented in the Ar-perpendicular arrange-
ment is a local maximum (with three negative eigenvalues in the
vibrational matrix) lying 12.3 kcal mol-1 above the H-perpendicular
conformation. Inspection of the calculated Ar-perpendicular form
indicates that close contacts are present between the aromatic protons
and the methylene protons of the ethyl group.
Su p p or tin g In for m a tion Ava ila ble: NMR spectra for
4-7 and 9b and crystal data for 6 and 9b. This material is
J O034016U
J . Org. Chem, Vol. 68, No. 9, 2003 3701