Synthesis and Properties of Nitrogen-Containing Curved Heterosuperbenzene

Article abstract of DOI:10.1055/s-0036-1590872

A novel nitrogen-functionalized curved superbenzene was prepared via oxidative cyclodehydrogenation of a suitable hexaarylbenzene precursor under mild conditions. The spectroscopic and electrochemical properties are detailed here and compared with those o

Full text of DOI:10.1055/s-0036-1590872

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2017, 49, A–E
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Y. Shi et al.
Paper
Synthesis
Synthesis and Properties of Nitrogen-Containing Curved Hetero-
superbenzene
Yubai Shi*
Cheng Li
Shaohua Ma
Yin Zhang
School of Medical Technology, Ningbo College of
Health Sciences, Xuefu Road No. 51, Ningbo 315100,
P. R. of China
syb@pku.org.cn
Received: 15.05.2017
Accepted after revision: 19.07.2017
Published online: 16.08.2017
fy the self-assembly and electronic properties.2 Draper et al.
reported S-fused hexa-peri-hexabenzocoronene (S-fused
HBC) 1 (Figure 1),3 which showed concentration-dependent
optical properties due to the extraordinary solid-state
packing arrangement with an intrinsic carbon–sulfur
framework. Draper and co-workers also introduced a four-
nitrogen-containing ‘superbenzene’ molecule 2.4 The pres-
ence of nitrogen atoms increased the overall electron-
accepting properties in comparison to the all-carbon
analogue and offered the possibility of making novel
PAH-based bidentate coordination complexes.
DOI: 10.1055/s-0036-1590872; Art ID: ss-2017-h0327-op
Abstract A novel nitrogen-functionalized curved superbenzene was
prepared via oxidative cyclodehydrogenation of a suitable hexaarylben-
zene precursor under mild conditions. The spectroscopic and electro-
chemical properties are detailed here and compared with those of per-
methoxylated hexa-peri-hexabenzocoronene. The crystal structure
analysis confirmed that the molecule has an unequal ‘double-concave’
aromatic core due to the inclusion of a pyrimidine subunit and the ste-
ric encumbrance of the methoxy groups at the periphery.
Recently, there has been increasing interest in curved
PAHs, which may force aromatic rings to adopt unusual in-
termolecular contacts that are typically unavailable to pla-
nar molecules and that could form the basis for supramo-
lecular self-assembled systems5 and even self-healing elec-
tronic materials.6 Whereas hexa-peri-hexabenzocoronene
(HBC),7 a representative example of PAHs, is planar, perme-
Key words polycyclic aromatic hydrocarbons, double-concave,
heterosuperbenzene, hexa-peri-hexabenzocoronene, cyclodehydroge-
nation
Polycyclic aromatic hydrocarbons (PAHs), which can be
regarded as two-dimensional graphite sections, have
aroused increasing attention in view of their prospective
utilization in charge-carrier field-effect transistors, photo-
voltaic devices, and light-emitting diodes.1 Their planarity
is often deemed to be their most significant geometric
characteristic. The attachment of heteroatoms, such as sul-
fur and nitrogen, into the PAH skeleton is expected to modi-
thoxylated HBC
3 is a remarkable ‘double-concave’
graphene molecule due to the steric encumbrance of the
substituents at the bay regions. The nonplanar HBC 3 is a
good supramolecular host for fullerene and electron-
deficient perfluorobenzene. However, to the best of our
O
N
N
O
O
O
O
N
S
O
O
N
O
O
O
O
O
O
O
O
O
O
3
1
2
O
Figure 1 Structures of S-fused HBC 1, N-containing ‘superbenzene’ 2, and permethoxylated HBC 3
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

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Y. Shi et al.
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knowledge, reports on heteroatom-containing curved PAHs,
which are expected to display special supramolecular self-
assembly and electronic properties, are rare.
the outer perimeter by methoxy groups successfully pre-
vents chlorination of the core. Accurate MALDI-TOF mass
spectrum data, elemental analysis, 13C and 1H NMR spectra
(in CDCl3) were obtained of 9. All data were supportive of
the structure and no signals other than those expected for 9
were observed. The 1H NMR spectrum of 9 shows only one
aromatic proton signal for the hydrogen atom located be-
tween the imine nitrogen atoms (see Supporting Informa-
tion) corresponding to the six pairs of equivalent methoxy
protons. The methoxy groups of each phenyl ring rendered
them equivalent on the NMR timescale. The electron-
donating methoxy groups result in a downfield shift of the
aromatic proton.
N-HSB 9 was soluble in common organic solvents such
as dichloromethane, tetrahydrofuran, and toluene. The
UV-vis spectrum of 9 recorded in chloroform (Figure 2)
shows a pattern of absorption bands characteristic of HBCs,
but bathochromically shifted 15 nm relative to the unsub-
stituted HBC (λmax = 359 nm)7 with λmax = 374 nm (ε = 9.9 ×
104 M–1·cm–1) due to 15 electron-withdrawing methoxy
substituents. However, in comparison with 3 (λmax = 397
nm, Figure 2C), the absorption spectrum of compound 9 is
hypsochromically shifted by 23 nm, which may be contrib-
uted to the reduced number of methoxy groups and the
electron-deficient pyrimidine ring. The emission spectrum
The synthesis of the twisted nitrogen-containing het-
erosuperbenzene (N-HSB) 9 is based on the functionalized
hexaarylbenzene precursor 8, and retains the arrangement
of five trimethoxylated phenyl rings and two ortho-imine
nitrogen atoms (Scheme 1). The synthesis protocol consists
of the following steps: (a) multiple bond oxidization of 1,2-
bis(3,4,5-trimethoxyphenyl)acetylene in iodine and di-
methyl sulfoxide;8 (b) decarboxylation of two molecules of
(3,4,5-trimethoxyphenyl)acetic acid in the presence of 4-
(N,N-dimethylamino)pyridine and N-ethyl-N′-(3-dimethyl-
aminopropyl)carbodiimide hydrochloride; (c) a two-fold
Knoevenagel condensation9 of compounds 4 and 5; (d) a
Pd(II)-catalyzed Sonogashira reaction10 between 1-ethynyl-
3,4,5-trimethoxybenzene and 5-bromopyrimidine; and (e)
a Diels–Alder cycloaddition reaction between compounds 6
and 72a to afford precursor 8. An intramolecular Scholl reac-
tion11 was then carried out to produce the resulting
strained N-HSB 9, by using FeCl3 as oxidant until the quan-
titative removal of the hydrogen atoms had occurred.12 The
crude product was purified by column chromatography
over silica gel, and obtained as a red-brown solid in 59%
yield for the last step.
The additive effect of 15 donor groups to the outer phe-
nyl rings and the pyrimidyl subunit should facilitate an oxi-
dative ring closure, whereas the complete substitution of
of 9 in chloroform exhibits a Stokes shift of 148 nm (λmax =
522 nm). Due to the existence of the imine nitrogen atoms,
N-HSB 9 is expected to show weak alkalescence. Further-
more, in chloroform solution, the fluorescence quantum
yields of 9 were measured to be 0.32 by the optically dilute
method with quinine bisulfate (Φf = 0.55 in 1.0 M H2SO4) as
the reference.13 Accordingly, it is observed that protonation
of the peripheral nitrogen atoms by the gradual addition of
trifluoroacetic acid changes the absorption spectrum (Fig-
ure 2A) and quenches the fluorescence (Figure 2B). The de-
crease in intensity of the 374 and 417 nm absorption bands
and the appearance of the new 584 nm band in the UV-vis
spectrum show that nitrogen protonation has a profound
electronic effect on the π-electron density throughout the
system.
Cyclic voltammetry on 9 in CH2Cl2, using a silver wire as
quasi-reference electrode and ferrocene as an internal po-
tential marker, reveals two irreversible oxidation waves
with E1/2 = 0.62 and 0.80 V vs Ag/AgCl, ca. 60~180 mV high-
er than that of 3, indicating that N-HSB 9 is somewhat more
difficult to oxidize than 3, as expected (Figure 3). According
to the onset potential of the first oxidation and the optical
band gap in the film, the HOMO and LUMO levels of 9 are
estimated to be –5.20 and –3.89 eV.
O
O
O
O
O
O
O
O
O
O
COOH
O
d)
O
O
N
N
a)
b)
O
O
7
O
O
O
+
O
O
O
O
O
O
O
c)
O
O
O
O
O
O
O
O
O
O
O
4
O
O
O
O
O
5
O
O
6
e)
N
N
O
O
O
N
O
O
O
O
N
O
O
O
f)
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Single crystals suitable for X-ray diffraction structure
analysis were obtained by slow evaporation of a solution of
9 in methanol at room temperature.14 The molecular core is
found to be markedly non-planar as a consequence of the
presence of pronounced peri-interactions (Figure 4). The six
8
O
O O
O
O
9
Scheme 1 Reagents and conditions: (a) DMSO, I2, 145 °C, 18 h; (b) EDC·HCl,
DMAP, CH2Cl2, 24 h; (c) n-Bu4N+OH–, EtOH, 30 min, 80 °C; (d) 5-bromo-
pyrimidine, Pd(PPh3)2Cl2, CuI, Et3N, n-Bu4N+I–, 70 °C, 12 h; (e) Ph2O, 220
°C, 9 h; (f) FeCl3, CH2Cl2, r.t., 30 min.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

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Figure 3 Cyclic voltammogram conducted on a Zahner IM6e electro-
chemical workstation (0.25 M solution of 9 and Bu4N+PF6– in CH2Cl2
with a scan rate of 0.1 V/s). A glassy carbon coating was used as the
working electrode, a Pt wire and Ag/AgCl used as counter electrode and
reference electrode.
ternating manner with respect to the inner ring. The intro-
duction of the nitrogen atoms result in the molecule dis-
playing double concave faces and adopting a centroasym-
metric conformation. In contrast to permethoxylated HBC 3
which exhibits only a significant distortion (β = 16.8°,
where β is the angle between the central aromatic ring and
the distorted outer rings), 9 displays an inconsistent devia-
tion from the planar geometry, with a slight distortion in
the pyrimidyl ring (β = 4.8°) and a variational distortion in
the five outer aromatic rings (β1 = 13.5°, β2 = 27.1°, β3 =
24.3°, β4 = 22.6°, β5 = 18.0°). The molecules pack as dimer
Figure 2 UV-vis (A) and fluorescence (B) spectra of 9 (1.0 × 10–5 M,
CHCl3, 25 °C) at increasing concentrations of TFA: (a) solid line, 0 μM
TFA, (b) dashed line, 1.0 μM TFA, (c) dotted line, 4.0 μM TFA, (d)
dashed/dotted line, 10 μM TFA, and (e) dashed/dotted/dotted line, 20
μMTFA; UV-vis spectrum (C) of 3 (1.0 × 10–5 M, CHCl3, 25 °C).
Figure 4 Single-crystal structure of 9: (A) ORTEP drawing with 30%
probability ellipsoids; (B) molecular packing viewed down the a-axis.
The hydrogen atoms have been omitted for clarity.
carbon atoms of the central benzene ring are coplanar to
within 0.0063 Å. The steric congestion in the bay region
forces the outer aromatic rings to flip up and down in an al-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

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Y. Shi et al.
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pairs, which exhibit close offset face-to-face contacts be-
tween the pyrimidyl rings; the inter-ring separation is 3.27
Å, while permethoxylated HBC 3 exhibits a large interpla-
nar distance of 13.05 Å. This curved conformation provides
a small cavity on the pyrimidyl ring side and a larger cavity
in the other side that are expected to be geometrically com-
plementary to guest molecules of different sizes and
shapes.
In summary, we have presented details about the syn-
thesis of novel, non-planar, nitrogen-containing heterosu-
perbenzene 9 and described its structural, optical, and elec-
trochemical properties. X-ray single-crystal diffraction
analysis revealed that the unequal twisted conformation is
dominated by the infection of the fifteen flexible methoxy
groups at the periphery and pyrimidine subunit. Investiga-
tions of both conformational flexibilities of the core and
double different concave have shown that the design of the
molecule is well-suited for a host–guest system, potentially
with facial selectivity. Further functionalization and inves-
tigation of its supramolecular properties are in progress, in
order to understand the implications of this feature of
curved nitrogen-functionalized graphene molecules.
Anal. Calcd for C20H22O8: C, 61.53; H, 5.68. Found: C, 61.24; H, 5.81.
1,3-Bis(3,4,5-trimethoxyphenyl)propan-2-one (5)
A solution of (3,4,5-trimethoxyphenyl)acetic acid (3.00 g, 13.3 mmol)
in CH2Cl2 (20 mL) was added slowly to a solution of EDC·HCl (3.05 g,
15.9 mmol) and DMAP (2.43 g, 19.9 mmol) in CH2Cl2 (50 mL). The re-
action mixture was kept at r.t. for 24 h. The mixture was washed with
2 N aq HCl (30 mL) and brine (20 mL) and then dried over anhydrous
Na2SO4. After the solvent had been removed in vacuo, the residue was
purified by column chromatography (silica gel, EtOAc–PE, 1:1) to af-
ford 5.
Yield: 1.81 g (70%); white solid; mp 88–90 °C; Rf = 0.42 (EtOAc–PE,
1:1).
1H NMR (400 MHz, CDCl3): δ = 6.33 (s, 2 H), 6.32 (s, 2 H), 3.83 (m, 18
H), 3.66 (s, 4 H).
13C NMR (100 MHz, CDCl3): δ = 205.7, 153.4, 137.2, 129.5, 106.6, 60.8,
56.1, 49.3..
GCMS: m/z (%) = 390 (40) [M]+, 181 (100).
Anal. Calcd for C21H26O7: C, 64.60; H, 6.71. Found: C, 64.19; H, 6.72.
2,3,4,5-Tetrakis(3,4,5-trimethoxyphenyl)cyclopenta-2,4-dien-1-
one (6)
To a solution of 4 (50 mg, 0.13 mmol) and 5 (50 mg, 0.14 mmol) in
EtOH (15 mL) under an argon atmosphere, a 0.8 M n-Bu4N+OH– solu-
tion in MeOH (0.09 mL, 0.07 mmol) was added dropwise at r.t. The
mixture was heated to 80 °C for 30 min, and then quenched by addi-
tion of H2O (20 mL). The product was extracted with CH2Cl2 (20 mL)
and concentrated, and the residue was purified by column chroma-
tography (silica gel, EtOAc–PE, 1:1) to afford 6.
The 1H and 13C NMR spectra were recorded at room temperature on a
Bruker AVANCE 400 NMR spectrometer. MALDI-TOF-MS spectra were
obtained on a Bruker BIFLEX III mass spectrometer. HRMS was carried
out on an IonSpec 4.7 Tesla Fourier transform mass spectrometer. Ab-
sorption spectra were measured on a Hitachi UV-vis spectrophotom-
eter (model U-3010) and fluorescence measurements were carried
out on a Hitachi spectrophotometer (model F-4500) with a 1 cm
quartz cell. Elemental analyses were performed on a Vario EL elemen-
tal analyzer. The X-ray diffraction data collection was carried out on a
Rigaku Saturn CCD area detector with graphite monochromated Mo-
Kα radiation (0.71070 Å) at 113 K. All calculations were performed by
using the SHELXL-9715 and the CrystalStructure crystallographic soft-
ware packages.16 Reagents used in the synthesis were obtained from
Aldrich and were of analytical grade. Compounds 1,2-bis(3,4,5-trime-
thoxyphenyl)acetylene and 1-ethynyl-3,4,5-trimethoxybenzene were
synthesized according to literature methods.7,17
Yield: 65 mg (67%); black solid (unstable, stored in refrigerator); mp
175–177 °C; Rf = 0.32 (EtOAc–PE, 1:1).
1H NMR (400 MHz, CDCl3): δ = 6.57 (s, 4 H), 6.24 (s, 4 H), 3.83 (s, 6 H),
3.81 (s, 6 H), 3.66 (s, 12 H), 3.50 (s, 12 H).
13C NMR (100 MHz, CDCl3): δ = 200.5, 153.4, 152.8, 138.6, 137.9,
128.3, 125.9, 124.5, 107.4, 107.2, 61.0, 60.9, 56.1, 55.9.
MS (MALDI-TOF): m/z [M]+ calcd for C41H44O13: 744.3; found: 743.9.
HRMS: m/z [M + H]+ calcd for C41H45O13: 745.2860; found: 745.2878.
5-[2-(3,4,5-Trimethoxyphenyl)ethynyl]pyrimidine (7)
A
stirred solution of 5-bromopyrimidine (1.60 g, 10.1 mmol),
Pd(PPh3)2Cl2 (0.35 g, 0.51 mmol), CuI (0.29 g, 1.53 mmol), and
n-Bu4N+I– (11.20 g, 30.3 mmol) in DMF–Et3N (5:1; 24 mL) under an
argon atmosphere at 70 °C was treated with 1-ethynyl-3,4,5-tri-
methoxybenzene (2.32 g, 12.1 mmol) in DMF–Et3N (5:1; 12 mL) over
12 h. The resulting mixture was allowed to stir for an additional 30
min before it was cooled to r.t., then poured into brine (30 mL), and
extracted with CH2Cl2 (30 mL). The organic layer was dried over anhy-
drous Na2SO4. After the solvent had been removed in vacuo, the resi-
due was purified by column chromatography (silica gel, EtOAc–PE,
1:4) to afford 7.
1,2-Bis(3,4,5-trimethoxyphenyl)ethanedione (4)
A solution of 1,2-bis(3,4,5-trimethoxyphenyl)acetylene (0.15 g, 0.42
mmol) and I2 (0.07 g, 0.29 mmol) in DMSO (20 mL) was heated at 145
°C for 18 h under an argon atmosphere. The reaction mixture was
poured into an Na2S2O3 solution and extracted with CH2Cl2 (20 mL).
The organic layer was washed with brine (20 mL), dried over anhy-
drous Na2SO4, and concentrated under reduced pressure. The residue
was purified by column chromatography (silica gel, EtOAc–PE, 1:3) to
give 4.
Yield: 2.23 g (82%); white solid; mp 134–136 °C (Lit.2a 136–140 °C);
Rf = 0.32 (EtOAc–PE, 1:4).
1H NMR (400 MHz, CDCl3): δ = 9.10 (s, 1 H), 8.81 (s, 2 H), 6.76 (s, 2 H),
3.85 (s, 9 H).
13C NMR (100 MHz, CDCl3): δ = 158.4, 156.5, 153.1, 139.7, 119.8,
116.5, 109.0, 96.4, 81.3, 60.9, 56.1.
GC-MS: m/z (%) = 270 (100) [M]+.
Yield: 0.14 g (86%); yellow crystals; mp 193–195 °C; Rf = 0.22 (EtOAc–
PE, 1:3).
1H NMR (400 MHz, CDCl3): δ = 7.20 (s, 4 H), 3.93 (s, 6 H), 3.87 (s, 12
H).
13C NMR (100 MHz, CDCl3): δ = 192.9, 153.3, 144.3, 127.9, 107.3, 60.9,
56.3.
GCMS m/z (%) = 390 (40) [M]+, 195 (100).
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Anal. Calcd for C15H14N2O3: C, 66.66; H, 5.22; N, 10.36. Found: C,
66.35; H, 5.36; N, 10.06.
References
(1) (a) Jiang, W.; Li, Y.; Wang, Z. Acc. Chem. Res. 2014, 47, 3135.
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2015, 44, 6616. (c) Matsuo, K.; Saito, S.; Yamaguchi, S. Angew.
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(2) (a) Wijesinghe, L. P.; Lankage, B. S.; Ó Máille, G. M.; Perera, S. D.;
Nolan, D.; Wang, L.; Draper, S. M. Chem. Commun. 2014, 50,
10637. (b) Jiang, W.; Li, Y.; Wang, Z. Chem. Soc. Rev. 2013, 42,
6113.
5-[2,3,4,5,6-Pentakis(3,4,5-trimethoxyphenyl)phenyl]pyrimidine
(8)
A mixture of 6 (0.53 g, 0.71 mmol) and 7 (0.25 g, 0.92 mmol) in Ph2O
(2 mL) was heated at reflux for 9 h under an argon atmosphere. After
cooling to r.t., the residue was purified by column chromatography
(silica gel, EtOAc–PE, 6:1); this afforded 8.
Yield: 0.33 g (47%); white solid; mp 218–220 °C; Rf = 0.31 (EtOAc–PE,
6:1).
1H NMR (400 MHz, CDCl3): δ = 8.75 (s, 1 H), 8.24 (s, 2 H), 6.08 (s, 2 H),
(3) Martin, C. J.; Gil, B.; Perera, S. D.; Draper, S. M. Chem. Commun.
2011, 47, 3616.
(4) (a) Draper, S. M.; Gregg, D. J.; Schofield, E. R.; Browne, W. R.;
Duati, M.; Passaniti, J. G. V. P. J. Am. Chem. Soc. 2004, 126, 8694.
(b) Gregg, D. J.; Fitchett, C. M.; Draper, S. M. Chem. Commun.
2006, 29, 3090.
(5) Ball, M.; Zhong, Y.; Wu, Y.; Schenck, C.; Steigerwald, F. N. M.;
Xiao, S.; Nuckolls, C. Acc. Chem. Res. 2015, 48, 267.
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Myers, M.; Miao, Q.; Sanaur, S.; Pang, K.; Steigerwald, M. L.;
Nuckolls, C. Angew. Chem. Int. Ed. 2005, 44, 7390.
(7) (a) Wang, Z.; Dötz, F.; Enkelmann, V.; Müllen, K. Angew. Chem.
Int. Ed. 2005, 44, 1247. (b) Piot, L.; Marie, C.; Dou, X.; Feng, X.;
Müllen, K.; Fichou, D. J. Am. Chem. Soc. 2009, 131, 1378.
(8) Yusybov, M. S.; Filimonov, V. D. Synthesis 1991, 2, 131.
(9) Jones, D. J.; Purushothaman, B.; Ji, S.; Holmes, A. B.; Wong, W.
W. H. Chem. Commun. 2012, 48, 8066.
(10) (a) Yi, T.; Mo, M.; Fu, H. Y.; Li, R. X.; Chen, H.; Li, X. J. Catal. Lett.
2012, 142, 594. (b) Pan, X.; Bannister, T. D. Org. Lett. 2014, 16,
6124.
(11) (a) Chaolumen Murata, M.; Sugano, Y.; Wakamiya, A.; Murata,
Y. Angew. Chem. Int. Ed. 2015, 54, 9308. (b) Nagarajan, S.;
Barthes, C.; Gourdon, A. Tetrahedron 2009, 65, 3767.
(12) Cao, J.; Liu, Y. M.; Jing, X.; Yin, J.; Li, J.; Xu, B.; Tan, Y. Z.; Zheng, N.
J. Am. Chem. Soc. 2015, 137, 10914.
6.05 (s, 4 H), 5.99 (s, 4 H), 3.62 (s,15 H), 3.37 (s, 30 H).
13C NMR (100 MHz, CDCl3): δ = 157.2, 155.5, 152.4, 152.2, 141.4,
140.5, 136.7, 136.4, 135.4, 135.2, 135.0, 134.2, 132.7, 109.3, 109.1,
109.0, 60.7, 57.0.
MS (MALDI-TOF): m/z calcd (%) = 986.4 (100.0), 987.4 (60.7), 988.4
(21.2), 989.4 (5.4); m/z found (%) = 987.0 (70.8), 988.0 (100), 989.0
(42.9), 990.0 (21.4).
Anal. Calcd for C55H58N2O15: C, 66.93; H, 5.92; N, 2.84. Found: C,
66.76; H, 5.92; N, 3.00.
Nitrogen-Containing Heterosuperbenzene (N-HSB) 9
Compound 8 (80 mg, 0.081 mmol) was dissolved in CH2Cl2 (60 mL) in
a Schlenk flask under an argon atmosphere. Throughout the whole re-
action, a constant stream of argon was bubbled through the mixture
to remove the HCl formed in situ. A solution of FeCl3 (0.21 g, 1.62
mmol) in MeNO2 (5 mL) was added dropwise and the mixture was
stirred for 30 min at r.t. MeOH (50 mL) was added, and a yellow solid
precipitated; it was purified by column chromatography (silica gel,
EtOAc–PE, 1:1); this afforded 9.
Yield: 45 mg (59%); red-brown solid; mp >280 °C; Rf = 0.33 (EtOAc–PE,
1:1).
1H NMR (400 MHz, CDCl3): δ = 10.14 (s, 1 H), 4.39 (s, 6 H), 4.34 (s, 6
(13) Olmsted, J. J. Phys. Chem. 1979, 83, 2581.
(14) Crystal data of 9: C55H46N2O15, M = 974.94, red-brown prisms,
crystal dimensions 0.14 × 0.10 × 0.08 mm3, monoclinic, space
group P21/n1, a = 14.5921(14), b = 15.9903(16), c = 20.660(2) Å,
α = 90.00, β = 110.228 (8), γ = 90.00°, V = 4523.2(8) Å3, Z = 4, ρ =
1.432 g/cm3, μ = 0.105 mm–1, θ range 1.65–25.00°. Of the 7962
H), 4.24 (s, 3 H), 4.12 (s, 12 H), 4.09 (s, 6 H), 4.08 (s, 12 H).
13C NMR (100 MHz, CDCl3): δ = 155.0, 153.8, 153.1, 152.2, 152.0,
151.8, 147.4, 147.1, 146.6, 126.2, 124.6, 121.6, 118.9, 117.0, 116.6,
115.9, 115.1, 114.6, 114.5, 62.0, 61.8, 61.7, 61.5, 61.3, 61.1.
MS (MALDI-TOF): m/z calcd (%) = 974.3 (100.0), 975.3 (59.5), 976.3
(17.4), 977.3 (3.3), 976.3 (3.1), 977.3 (1.8); m/z found (%) = 975.1
(17.4), 976.1 (100), 977.1 (56.8), 978.1 (26.4), 979.1 (11.3), 980.1
(3.5).
reflections that were collected, 5913 were unique (Rint
=
0.1154), GOF = 1.254. CCDC 654508 contains the supplemen-
tary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
(15) Sheldrick, G. M. SHELXL-97: Program for structure refinement;
University of Göttingen: Germany, 1997.
Anal. Calcd for C55H46N2O15: C, 67.76; H, 4.76; N, 2.87. Found: C,
67.23; H, 4.71; N, 3.18.
(16) Crystal structure analysis package, Rigaku and Rigaku/MSC
(2000–2005). 9009 New Trails Dr.,The Woodlands, TX 77381,
USA.
Funding Information
(17) Lawrence, N. J.; Ghani, F. A.; Hepworth, L. A.; Hadfield, J. A.;
McGown, A. T. Synthesis 1999, 1656.
This work was supported by the Soft Science Fund Project of the
Ningbo Science and Technology Bureau, China (2015A10052).
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Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0036-1590872.
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E