A practical and efficient synthesis of 5′-substituted m-terphenyls

Article abstract of DOI:10.1055/s-2007-983722

Outlined is a simple, convenient, scalable procedure for the synthesis of a variety of 5′-substituted m-terphenyl compounds from commercially available materials. A series of novel compounds were generated based on the m-terphenyl scaffold. In addition we

Full text of DOI:10.1055/s-2007-983722

PAPER
1979
A Practical and Efficient Synthesis of 5¢-Substituted m-Terphenyls
A
P
ractica
o
l
and
E
fficie
a
nt Synthesi
n
s
of
5
¢
-Subst
n
ituted
m
-Ter
e
phenyls D. Kehlbeck,a Eric J. Dimise,a Sarah M. Sparks,a Skylar Ferrara,c Joseph M. Tanski,b Craig M. Anderson*c
a
b
c
Department of Chemistry, Union College, Schenectady, NY 12308, USA
Department of Chemistry, Vassar College, Poughkeepsie, NY 12604, USA
Department of Chemistry, Bard College, Annandale-on-Hudson, NY 12504, USA
Fax +1(845)7587628; E-mail: canderso@bard.edu
Received 28 February 2007
The synthetic work described in Scheme 1 can be realized
using 2,4,6-tribromoaniline as the starting material. Sand-
meyer chemistry converts 2,4,6-tribromoaniline into
1,3,5-tribromo-2-iodobenzene (1). When treated with
Abstract: Outlined is a simple, convenient, scalable procedure for
the synthesis of a variety of 5¢-substituted m-terphenyl compounds
from commercially available materials. A series of novel com-
pounds were generated based on the m-terphenyl scaffold. In addi-
tion we present a full and complete characterization, including the phenylmagnesium bromide, 1 readily forms a reactive
crystal structure, of 3,5-diphenylbenzaldehyde (1,1¢:3¢,1¢¢-terphe-
nyl-5¢-carbaldehyde).
benzyne species that affords 1-bromo-3,5-diphenylben-
zene (2) as outlined by Hart.6 The brominated 1-position
of the 3,5-diphenylbenzene is left available for conversion
to 3,5-diphenylphenylmagnesium bromide (3), which can
then be used in a variety of reactions to afford the desired
products 4. Grignard 3 is readily prepared by refluxing 2
in tetrahydrofuran with a slight excess of magnesium met-
al initiated by dibromoethane. With 3 in hand, a series of
reactions were employed to give formyl- (5), acetyl- (6),
pyridyl- (7), and pyrimidyl- (8) substituted products at the
1-position (Figure 1). In addition, a number of Schiff
bases 9–13 were prepared from 5 and their characteriza-
tion is reported.
Key words: imine, Kumada, pyridine, heterocycle, biaryl
The m-terphenyl unit exists in numerous natural prod-
ucts,1 pharmaceuticals,2 and plays an important role as a
sterically crowded protecting group,3 a ligand for asym-
metric catalysis,4 and as a building block in material
science5 due to its unique molecular architecture and po-
tential for interesting electronics. Here, we outline an ex-
peditious synthetic route to an unexplored class of new m-
terphenyl compounds.
I
NH2
Br
Br
Br
Br
Br
i,ii
iv, v
iii
Br
Br
R
X
1
2
4
Scheme 1 Reaction conditions: (i) NaNO2, concd HCl, 0 °C, 30 min; (ii) KI, r.t., 1 h; (iii) PhMgBr, THF, reflux, 1 h, then r.t. 12 h; (iv) Mg,
THF, reflux, 1 h; (v) various reagents.
R
O
N
N
N
H
N
R
5 R = H
6 R = Me
9 R = Ph
10 R = Bn
8
7
11 R = CH2CH2NH2
12 R = CH2CH2NMe2
13 R = [CH2CH2]
Figure 1
SYNTHESIS 2007, No. 13, pp 1979–1983
x
x.
x
x
.
2
0
0
7
Advanced online publication: 18.06.2007
DOI: 10.1055/s-2007-983722; Art ID: M01407SS
© Georg Thieme Verlag Stuttgart · New York

1980
J. D. Kehlbeck et al.
PAPER
Olah and co-workers7 have outlined a series of formyla- seen at approximately 38°. Both results are in agreement
tion reactions using N-formylmorpholine as a formylating with the X-ray diffraction results and indicate that the
agent. We employed this chemistry in, what is to date, the nonplanarity is not solely a result of crystal packing. The
most expeditious route to compound 5. A prior reported structure is consistent with the IR spectrum and with our
synthesis of 5 employed a lithium aluminum hydride re- new NMR peak assignments. Selected bonds and angles
duction of the corresponding carboxylic acid, followed by are given in Table 1.
manganese dioxide oxidation to the aldehyde, which gave
modest yields (43% from the carboxylic acid).8 The
Table 1 Selected Bond Lengths and Angles for Compound 5
formylation outlined here gives 5 (Scheme 2) in one step
Bonds
Valuea
from 2 in good yield (73%). In addition full characteriza-
tion of the aldehyde is described and we report 1H NMR
data different from that previously reported by Ohemeng
and Nguyen. The X-ray diffraction analysis of the alde-
hyde has confirmed its structure and our new assignments.
O1–C1
C1–C2
C6–C8
C4–C14
1.204(2) Å
1.483(3) Å
1.479(6) Å
1.498(6) Å
1.39(2) Å
124.8(2)°
118.6(2)°
120.3(3)°
120(1)°
b
C
aryl–Caryl
1) Mg, THF
2) N-formylmorpholine
O1–C1–C2
C1–C2–C3
C1–C2–C7
3) HCl
Br
H
O
2
5
Scheme 2
b
C
aryl–Caryl–Caryl
a Estimated standard deviation in the least significant figure are given
X-ray quality crystals of 3,5-diphenylbenzaldehyde (5)
were grown from a concentrated dichloromethane solu-
tion by slow diffusion of hexane. The crystal structure is
composed of discrete molecules separated by van der
Waals forces only. There is no apparent p-stacking of any
phenyl rings. A view of the molecule showing the labeling
scheme is seen in Figure 2. The molecule adopts a nonpla-
nar arrangement of the meta-substituted phenyl rings and
the angles of phenyl groups to the benzaldehyde ring are
37.5(3)° (C8–C13 ring) and 37.8(3)° (C14–C19 ring). A
DFT study using Gaussian 039 was performed on 3,5-
diphenylbenzaldehyde with geometry optimization and
no constraints. The phenyl rings were shown to be nonpla-
nar at 37.1° (C8–C13 ring) and 38.0° (C14–C19 ring). An
energy profile was determined using the Spartan 0410
semi-empirical molecular modeling package for rotation
about one phenyl–benzaldehyde bond; a minimum was
in parentheses.
b Average.
3,5-Diphenylacetophenone (6) (Scheme 3) was prepared
by the reaction of 3 with acetic anhydride. This reaction
gives modest yields (59%) but provides a quick and easy
route to the acetylated terphenyl.
1) Mg, THF
2) Ac2O, 0 °C
Br
H3C
O
2
6
Scheme 3
We employed an inverse addition technique outlined by
Leazer et al. whereby 3 was slowly added to a large excess
of acetic anhydride.11 When these measures are taken, the
bisubstituted product expected from the direct addition of
acetic anhydride to 3 is not produced.
A Kumada-like nickel-catalyzed coupling (Scheme 4)
was used to prepare 2-(3,5-diphenylphenyl)pyridine (7).
Herrmann and co-workers reported the success of several
high yield coupling reactions of halogenated aromatic het-
erocycles to aryl Grignards using imidizolium ligands in
the presence of bis(acetylacetonato)nickel(II).12 Here, 3 is
coupled to 2-chloropyridine in the presence of bis(acetyl-
acetonato)nickel(II) and 1,3-bis(2,4,6-trimethylphe-
nyl)imidizolium to afford 7 in 82% yield. The m-
terphenylpyrimidine 8 was prepared by an analogous
route.
Figure 2 ORTEP of 3,5-diphenylbenzaldehyde
Synthesis 2007, No. 13, 1979–1983 © Thieme Stuttgart · New York

PAPER
A Practical and Efficient Synthesis of 5¢-Substituted m-Terphenyls
1981
3,5-Diphenylphenylmagnesium Bromide ( 3)
1)
2)
Mg, THF
N
Cl
R
A soln of 2 (3.09 g, 10 mmol) in anhyd THF (10 mL) was added
dropwise to a stirred, refluxing mixture of Mg turnings (0.27 g, 11
mmol) in anhyd THF (10 mL). 1,2-Dibromoethane (2 drops) was
added to initiate the reaction. Reflux was continued for 1 h after
complete addition of 2.
3 mol% Ni(acac)2
Br
R
N
3 mol%
N
N
2
3,5-Diphenylbenzaldehyde (5)
7, R = CH, 82%
8, R = N, 49%
A soln of N-formylmorpholine (10 mmol) in anhyd THF (10 mL)
was slowly transferred via cannula to the stirring soln of 3 and the
mixture was stirred at r.t. for 30 min. Excess Grignard was
quenched with 3 M HCl to a pH of 2. The aqueous layer was washed
with Et2O and the combined organic layers were washed with sat.
NaHCO3 and sat. NaCl. The product was purified by flash chroma-
tography (silica gel 200–425 mesh, 30% CH2Cl2–hexane) and re-
crystallized (30% CH2Cl2–hexane) to give pure product (1.88 g,
73%); mp 101–102 °C; Rf = 0.36 (50% CH2Cl2–hexane).
IR (neat): 1697 cm–1 (C=O).
1H NMR (200 MHz, CDCl3,): d = 7.42–7.55 (m, 6 H), 7.66–7.71
(m, 4 H), 8.01 (s, 3 H), 10.15 (s, 1 H).
Scheme 4
We have outlined a convenient, scalable procedure for the
generation of a new set of compounds based on the terphe-
nyl scaffold. We have used the terphenyl Grignard as a
useful intermediate, coupling the scaffold to a variety of
electrophiles, demonstrating the utility of the approach.
Molecules possessing a terphenyl scaffold possess unique
architecture and may find use in a variety of applications
including catalysis and material science.
13C NMR (50 MHz, CDCl3): d = 192.52, 142.97, 139.93, 137.65,
132.04, 129.26, 128.35, 127.46, 127.38.
1H NMR and 13C NMR spectra were obtained using a Varian Gem-
ini 2020 200 MHz spectrometer or Varian Mercury 300 MHz with
CDCl3 as the solvent and TMS as an internal standard unless other-
wise noted. GC-MS analysis was performed on an Agilent 6890N
gas chromatograph equipped with an N10149 autosampler coupled
to an Agilent 5973 mass spectrometer. UV-Visible absorption stud-
ies were completed using an HP 8453 spectrophotometer. All reac-
tions were run under an atmosphere of dry N2 except in the
preparation of 1,3,5-tribromo-2-iodobenzene (1). Anhydrous
MgSO4 or Na2SO4 was used as the drying agent in all reactions. All
reagents and solvents were purchased from Sigma-Aldrich and
were used without additional purification. Elemental analyses were
performed by Atlantic Microlab Inc. (Norcross, GA).
UV (MeOH): lmax (e) = 202 (sh, 39200), 205 (41600), 248 nm
(37200).
Anal. Calcd for C19H14O: C, 88.34; H, 5.46. Found: C, 88.05; H,
5.47.
3¢,5¢-Diphenylacetophenone (6)
The m-terphenyl Grignard 3 (3.24 mmol) was slowly transferred via
cannula to a stirred soln of Ac2O (6 mL, 63.5 mmol) at 0 °C. The
mixture was stirred at 0 °C for 2 h and the reaction was quenched
with H2O. The aqueous layer was washed with Et2O and the com-
bined organic layers were washed with 10% NaOH and sat. NaCl
and dried. The product was purified by flash chromatography (silica
gel, 200–425 mesh, 20% CH2Cl2–hexane) and recrystallized (20%
CH2Cl2–hexane) to give pure product (0.524 g, 59%); mp 99–
101 °C; Rf = 0.16 (50% CH2Cl2–hexanes).
1,3,5-Tribromo-2-iodobenzene (1)
Prepared similar to the method described by Hart and co-workers.6
A soln of NaNO2 (3.28 g, 47.5 mmol) in H2O (15 mL) was added
dropwise to a mechanically stirred slurry of 2,4,6-tribromoaniline
(15 g, 45.5 mmol) in concd HCl (23 mL) at 0 °C. Stirring was con-
tinued for 30 min after complete addition of NaNO2. The diazonium
salt was slowly transferred through a glass wool filter to a soln of
KI (75.53 g, 0.455 mol) in H2O (114 mL). The soln was stirred vig-
orously with both magnetic and mechanical stirring at r.t. for 1 h.
CH2Cl2 (200 mL) and 0.5 M Na2SO3 (20 mL) were added succes-
sively. The aqueous layer was separated and washed with CH2Cl2.
The combined organic layers were washed with 10% NaOH and sat.
NaCl and dried. A red solid was isolated upon solvent removal. Re-
crystallization (25% hexane–CH2Cl2) afforded pure product (14.2
g, 71%); mp 101–103 °C (Lit.13 104–105); Rf = 0.61 (10% CH2Cl2–
hexane).
IR (neat): 1678 cm–1 (C=O).
1H NMR (200 MHz, CDCl3): d = 2.71 (s, 3 H), 7.41–7.54 (m, 6 H),
7.66–7.70 (m, 4 H), 7.99–8.01 (t, 1 H), 8.15–8.16 (d, 2 H).
13C NMR (50 MHz, CDCl3): d = 27.12, 126.14, 127.52, 128.16,
129.19, 130.78, 138.40, 140.43, 142.55, 198.26.
UV (MeOH): lmax (e) = 204 (946), 249 nm (794).
Anal. Calcd for C20H16O: C, 88.20; H, 5.92. Found: C, 87.94; H,
5.98.
2-(3,5-Diphenylphenyl)pyridine (7)
The m-terphenyl Grignard (4.17 mmol) was added dropwise by can-
nula transfer to a stirred soln of 2-chloropyridine (2.84 mmol),
Ni(acac)2 (0.085 mmol, 3 mol%), and 1,3-bis(2,4,6-trimethylphe-
nyl)imidizolium (0.085 mmol, 3 mol%) in anhyd THF (3 mL) at r.t.
and the mixture was allowed to stir. After 18 h the reaction was
quenched with 0.5 M HCl. The aqueous layer was washed with
Et2O and the combined organic layers were washed with sat. NaCl
and dried. The product was purified by flash chromatography (silica
gel, 200–425 mesh, 25% CH2Cl2–hexane) and recrystallized (40%
CH2Cl2–hexane) to give pure product (0.7150 g, 82%); mp 137–
139 °C; Rf = 0.46 (100% CH2Cl2).
1H NMR (200 MHz, CDCl3): d = 7.25–7.32 (m, 1 H), 7.39–7.53 (m,
6 H), 7.70–7.87 (m, 7 H), 8.20–8.21 (d, 2 H), 8.74–8.77 (m, 1 H).
13C NMR (50 MHz, CDCl3): d = 121.06, 122.59, 125.08, 126.97,
127.61, 127.78, 129.03, 137.05, 140.69, 141.26, 142.56, 149.99,
157.57.
1H NMR (200 MHz, CDCl3): d = 7.71 (s, 2 H).
1-Bromo-3,5-diphenylbenzene (2)
Prepared by a modification of the procedure described by Hart and
co-workers.6 A soln of 1 (10.0 g, 22.7 mmol) in anhyd (200 mL)
was added dropwise over 1 h to a stirred, refluxing soln of 1 M
PhMgBr in THF (227 mL). Reflux was continued for 1 h after com-
plete addition of 1. Stirring was continued at r.t. for 12 h. Excess Ph-
MgBr was quenched with sat. NH4Cl. The aqueous layer was
washed with Et2O. The combined organic layers were washed with
sat. NaCl and dried. A white solid was isolated after solvent remov-
al. Recrystallization (40% CH2Cl2–hexane) gave pure product (5.41
g, 77%); mp 103–105 °C (Lit.13 107.5–109 °C); Rf = 0.57 (30%
CH2Cl2–hexane).
Synthesis 2007, No. 13, 1979–1983 © Thieme Stuttgart · New York

1982
J. D. Kehlbeck et al.
PAPER
UV (MeOH): lmax (e) = 200 (40800), 202 (sh, 37400), 250 nm
(35200).
HRMS-ESI: m/z [M + H]+ calcd for C21H21N2: 301.1699; found:
301.1692.
Anal. Calcd for C23H17N: C, 89.87; H, 5.57; N, 4.56. Found: C,
89.90; H, 5.43; N, 4.43.
Bis(3,5-Diphenylbenzaldehyde) N-Ethylenediimine (13)
Relatively pure diimine was generated by placing the monoimine
under vacuum for 24 h. Alternatively a 2:1 amine/aldehyde mixture
was refluxed for 48 h; yield: 25%.
IR (neat): 1645 cm–1 (C=N).
1H NMR (200 MHz, CDCl3): d = 4.06 (s, 4 H), 7.36–7.50 (m, 12 H),
7.60–7.81 (m, 8 H), 7.83 (t, 2 H), 7.91 (d, 4 H), 8.41 (s, 2 H).
13C NMR (75 MHz, CDCl3): d = 163.03, 142.39, 140.74, 137.35,
128.04, 128.53, 127.87, 127.52, 126.03, 61.75.
HRMS-ESI: m/z [M + H]+ calcd for C40H33N2: 541.2638; found:
541.2619.
2-(3,5-Diphenylphenyl)pyrimidine (8)
The m-terphenyl Grignard 3 (4.17 mmol) was added dropwise to a
stirred soln of 2-chloropyrimidine (2.84 mmol), Ni(acac)2, (0.085
mmol, 3 mol%), and 1,3-bis(2,4,6-trimethylphenyl)imidizolium
(0.085 mmol, 3 mol%) in anhyd THF (3 mL) at r.t. and the mixture
was allowed to stir for 18 h. The reaction was quenched with 0.5 M
HCl. The aqueous layer was washed with Et2O and the combined
organic layers were washed with sat. NaCl and dried. The product
was purified by flash chromatography (silica gel, 200–425 mesh,
25% CH2Cl2–hexane) and recrystallized (40% CH2Cl2–hexane) to
give pure product (0.4291 g, 49%); mp 145–147 °C; Rf = 0.34 (80%
CH2Cl2–hexanes).
3,5-Diphenylbenzaldehyde N-2-(Dimethylamino)ethylimine
1H NMR (200 MHz, CDCl3): d = 7.21–7.24 (m, 1 H), 7.35–7.54 (m,
6 H), 7.75–7.80 (m, 4 H), 7.94–7.97 (m, 1 H), 8.70–8.71 (m, 2 H),
8.84–8.87 (m, 2 H).
(12)
Yield: 85%.
IR (neat): 1647 cm–1 (C=N).
13C NMR (50 MHz, CDCl3): d = 119.55, 126.14, 127.58, 127.78,
1H NMR (300 MHz, acetone-d6): d = 2.33 (s, 6 H), 2.68 (t, 2 H),
3.81 (t, 2 H), 7.34–7.51 (m, 6 H), 7.65–7.71 (m, 4 H), 7.86 (t, 1 H),
7.94 (d, 2 H), 8.46 (s, 1 H).
13C NMR (75 MHz, CDCl3): d = 162.10, 142.41, 140.78, 137.39,
129.08, 128.55, 127.92, 127.54, 126.07, 60.29, 60.15, 46.09.
128.59, 129.01, 138.76, 141.08, 142.39, 157.51, 164.77.
UV/Vis (MeOH): lmax (e) = 202 (48400), 252 (57900), 310 nm
(1450).
Anal. Calcd for C22H16N2: C, 85.69; H, 5.23; N, 9.08. Found: C,
85.36; H, 5.22; N, 8.98.
HRMS-ESI: m/z [M + H]+ calcd for C23H25N2: 329.2012; found:
329.2011.
Imines; General Procedure
Imine syntheses were performed by two methods: (1) Reactions be-
tween a volatile amine (1.2–1.6 equiv) and 5 (0.500 g, 1.93 mmol)
in CH2Cl2. Mixtures were magnetically stirred and brought to re-
flux. Molecular sieves were added for removal of H2O. Removal of
the excess amine was accomplished under vacuum and products
isolated in excellent yields and purities. (2) A 1:1 molar ratio of
amine and 5 (0.500 g) were mixed in CH2Cl2 at r.t. for several hours.
Na2SO4 was added to remove H2O. The mixture was filtered and the
solvent removed by evaporation. Products were isolated in excellent
yields and purity.
X-ray Structure Determination of 5
X-ray diffraction data were collected on a Bruker APEX 2 CCD
platform diffractometer [Mo-Ka (l = 0.71073 Å)] at 115 K.14
A
suitable crystal was mounted in a nylon loop with Paratone-N cryo-
protectant oil. The structure was solved using direct methods and
standard difference map techniques, and was refined by full-matrix
least-squares procedures on F2 with SHELXTL (Version 6.14).15
All nonhydrogen atoms were refined anisotropically. Hydrogen at-
oms were included in calculated positions and were refined using a
riding model, except for the aldehyde hydrogen, which was includ-
ed in a calculated position and refined semi-freely with the help of
a distance restraint. The structure exhibits a twofold whole mole-
cule disorder about the crystallographic mirror plane; each atom of
every disordered atom pair was assigned an occupancy of 0.5. The
disorder was refined with the help of similarity restraints on 1–2 and
1–3 distances and displacement parameters and rigid bond restraints
for anisotropic displacement parameters. Selected data is found in
Table 2.
3,5-Diphenylbenzaldehyde N-Phenylimine (9)
Yield: 98%.
IR (neat): 1627 cm–1 (C=N).
1H NMR (200 MHz, CDCl3): d = 7.24–7.31 (m, 3 H), 7.35–7.53 (m,
8 H), 7.69–7.76 (m, 4 H), 7.94 (t, 1 H), 8.12 (d, 2 H), 8.59 (s, 1 H).
HRMS-ESI: m/z [M + H]+ calcd for C25H20N: 334.1590; found:
34.1585.
Computational Details
3,5-Diphenylbenzaldehyde N-Benzylimine (10)
A molecular model of 3,5-diphenylbenzaldehyde was created using
Gaussian 03’s GaussView building tools.9 This model was then
minimized using Density Functional Theory at the B3LYP level
with a 6-31G basis set using the Gaussian 03 package.9 The subse-
quent checkpoint output file was then obtained to view the opti-
mized parameters. Evaluation of rotational energy barriers
(semiempirical calculations): A molecular model of 3,5-diphenyl-
benzaldehyde was created using Spartan 04 entry model kit (Wave-
function Inc., Irvine, CA.).10 The dihedral angle containing the
aldehyde constituent was constrained to 5° and the dihedral angle of
the phenyl-benzaldehyde bond [C(phenyl)–C(benzaldehyde)] fur-
thest from the oxygen atom in the molecule was constrained to
37.8°. These constraints were placed to mimic the X-ray crystallo-
graphic data. The other phenyl–benzaldehyde bond [C(benzalde-
hyde)–C(phenyl)] closest to the oxygen atom was constrained at 0°
and set to rotate 180° during the subsequent job. An energy profile
(DrelE) was then created as Hartree–Fock molecular orbital calcu-
Yield: 97%.
IR (neat): 1645 cm–1 (C=N).
1H NMR (200 MHz, CDCl3): d = 4.89 (s, 2 H), 7.26–7.53 (m, 11 H),
7.65–7.74 (m, 4 H), 7.88 (t, 1 H), 8.00 (d, 2 H), 8.53 (s, 1 H).
HRMS-ESI: m/z [M + H]+ calcd for C26H22N: 348.1749; found:
348.1743.
3,5-Diphenylbenzaldehyde N-2-Aminoethylimine (11)
The monoimine was generated by using excess ethylenediamine
and by allowing the reaction to reflux overnight; yield: 85%.
IR (neat): 1654 cm–1 (C=N).
1H NMR (200 MHz, CDCl3): d = 1.33 (s, 2 H), 3.07 (t, 2 H), 3.74 (t,
2 H), 7.35–7.52 (m, 6 H), 7.62–7.84 (m, 4 H), 7.87 (t, 1 H), 7.95 (d,
2 H), 8.45 (s, 1 H).
Synthesis 2007, No. 13, 1979–1983 © Thieme Stuttgart · New York

PAPER
A Practical and Efficient Synthesis of 5¢-Substituted m-Terphenyls
1983
Table 2 Selected Crystal Data for Compound 5
(5) (a) Fang, Y.; Hanan, G. S. Synlett 2003, 852. (b) Wang, J.;
Hanan, G. S. Synlett 2005, 1251. (c) Shi, J.; Chen, C. H.;
Klubek, K. P. US 5,972,247, 1999. (d) Dickie, D. A.;
Schatte, G.; Jennings, M. C.; Jenkins, H. A.; Khoo, S. Y. L.;
Clyburne, J. A. C. Inorg. Chem. 2006, 45, 1646.
Property
Value
formula
C19H14O
(e) Rajakumar, P.; Srinivasan, K. Tetrahedron 2004, 60,
10285. (f) Riddle, J. A.; Lathrop, S. P.; Bollinger, J. C.; Lee,
D. J. Am. Chem. Soc. 2006, 128, 10986.
habit, color
parallelepiped, colorless
orthorhombic
Cmc21
lattice type
(6) Du, C. J. F.; Hart, H.; Ng, K. K. D. J. Org. Chem. 1986, 51,
space group
3162.
(7) Olah, G. A.; Ohannesian, L.; Arvanaghi, M. J. Org. Chem.
1984, 49, 3856.
a
23.647(3) Å
6.9588(8) Å
8.3389(9) Å
1372.2(3) Å3
4
(8) Ohemeng, K. A.; Nguyen, V. N. US 5,942,532, 1999.
(9) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A. Jr.;
Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.;
Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi,
M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.;
Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.;
Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.;
Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.;
Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V.
G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.;
Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman,
J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.;
Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.;
Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith,
T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
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b
c
V
Z
lations using a 6-31G* basis set resulting in relative energies in
kcal/mol–1 calculated for successive 20° rotation about the specified
bond. These relative energies were then plotted against their defined
angle of rotation. Within this energy profile, energy maxima occur
near the planar 0° and 180° rotamers and energy minima occur ap-
proximately at 38° and 137°.
Acknowledgment
We sincerely thank The Andrew W. Mellon Foundation (C.M.A.),
The National Science Foundation [NSF 0521237 to J.M.T. (P.I.)
and C.M.A.], Research Corporation (CC5836 to J.D.K.), and Bard,
Union, and Vassar Colleges for generous financial support. We also
thank Profs James Adrian and Davit Zargarian for helpful discussi-
ons.
(10) Spartan 04, Wavefunction Inc.: Irvine, CA, 2004.
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Synthesis 2007, No. 13, 1979–1983 © Thieme Stuttgart · New York