1
388
E. N. W. Howe, M. Bhadbhade, and P. Thordarson
Experimental
dichloromethane (5 : 95 v/v) to remove polymeric compounds,
and the eluent was concentrated under vacuum. This fraction
was then further purified using column chromatography over
silica gel with a gradient elution of methanol in dichloromethane
General Methods and Materials
All starting materials were purchased from Sigma Aldrich.
Pyromellitoyl chloride 2 was synthesised from pyromellitic
dianhydride 1 according to a literature procedure.
(ranging from neat dichloromethane to methanol :
[
17]
Solvents
dichloromethane, 5 : 95 v/v). A less polar fraction (R ¼ 0.78)
f
and reagents were purchased from Sigma Aldrich, Merck, Ajax
Finechem, and Honeywell Burdick & Jackson and used without
further purification unless otherwise specified. Pyridine was
purified by distillation and dried over potassium hydroxide.
Anhydrous dichloromethane and tetrahydrofuran were dried
and deoxygenated using a PureSolv MD-7 solvent purification
system (Innovative Technology Inc.). Deuterated chloroform
for NMR was purchased from Cambridge Isotope Laboratories.
and a more polar fraction (R ¼ 0.27) were collected; TLC
f
(methanol : dichloromethane, 5 : 95 v/v).
The combined less polar fractions were evaporated to
yield crown-3-pyromellitimide 4 as a white solid (193.5 mg,
5
1
.3 %), m.p. 232–2348C; IR (Nujol) nmax: 3072 (w), 3044 (w),
765 (m), 1711 (s), 1461 (m), 1391 (m), 1093 (m), 726 (m)
ꢁ1
1
cm ; H NMR (300.17 MHz, CDCl ): d 1.93–2.05 (m, 4H,
3
(
(
3
NCH CH CH O) ), 2.77 and 3.03 (t,
J
OCH CH O) ), 3.47 (t, J 4.8 Hz, 4H, (NCH CH CH O) ),
4.9 Hz, 8H,
Ò
2
2
2
2
Column chromatography was performed using Davisil
2
2
2
2
2
2
2
13
chromatographic silica media (0.040–0.063 mm). Thin-layer
chromatography was carried out using Merck Kieselgel 60
F-254 precoated sheets (0.25 mm).
All synthetic reactions were carried out in an inert environ-
ment containing nitrogen. Melting points were determined on a
Mel-Temp II hot stage apparatus. Infrared spectra were recorded
on a Thermo Scientific Nicolet Avatar 370 FT-IR spectrometer
.95 (t, J 5.8 Hz, 4H, (NCH ) ), 8.26 (s, 2H, (ArH) );
2
C
2
2
NMR (75.5 MHz, CDCl ): d 27.0 (CH ), 37.8 (NCH ), 70.3
3
2
2
(
(
OCH ), 71.0 (OCH ), 71.1 (OCH ), 118.1 (ArCH), 138.0
2 2 2
þ
ArC), 167.4 (C ¼ O); MS (ESI): m/z 403.34 ([MþH] requires
þ
4
requires 403.1505); Anal. Calcd. for C H N O : C, 59.70;
03.15); HR-MS (ESI): m/z 403.1506 ([MþH] , C H N O
2
0
23
2
7
2
0 22 2 7
H, 5.51; N, 6.96; O, 27.83. Found: C, 60.09; H, 5.33; N, 6.86;
O, 27.72 %.
The combined more polar fractions were evaporated to
yield crown-6-bispyromellitimide 5 as a white solid (32.7 mg,
1
13
C
as a Nujol mull between sodium chloride plates. H and
NMR spectra were recorded on a Bruker Avance DPX 300
1
spectrometer operating at a frequency of 300.17 MHz for H and
1
5.49 MHz for C NMR respectively. NMR spectra were
3
7
0
.5 %) m.p. 250–2528C; IR (Nujol) nmax: 3069 (w), 3044 (w),
recorded at 298 K and samples were dissolved in CDCl3;
chemical shifts were referenced internally to residual solvent
ꢁ1
1781 (m), 1718 (s), 1456 (m), 1131 (m), 724 (m) cm
H NMR (300.17 MHz, CDCl ): d 1.92–2.03 (m, 8H,
;
1
1
13
3
resonances ( H: 7.26 ppm and C: 77.16 ppm). Low resolution
electrospray ionisation mass spectra were recorded on a Waters
Micromass ZQ 2000 ESCi Multi-Mode Ionisation Source mass
spectrometer equipped with MassLynx 4.0 instrument software.
High resolution ESI mass spectra were recorded on a Thermo
Scientific Linear Quadrupole Ion Trap with Orbitrap Mass
Analyser (LTQ ORBITRAP XL) mass spectrometer. Samples
were acquired in electrospray ionisation mode using in-house
made static glass nanospray tips inserted into a nanostage with
(
(
(
NCH CH CH O) ), 3.45–3.53 (m, 16H, (OCH CH O) , 3.55
2
2
2
2
4
2
4
t, J 5.8 Hz, 8H, (NCH CH CH O) ), 3.85 (t, J 7.0 Hz, 8H,
2
2
2
13
4
NCH ) ), 8.05 (s, 4H, (ArH) ); C NMR (75.5 MHz, CDCl3):
2
4
4
d 28.6 (CH ), 36.7 (NCH ), 69.0 (OCH ), 70.4 (OCH ), 70.7
2
2
2
2
(
OCH ), 117.9 (ArCH), 137.4 (ArC), 166.4 (C¼O); MS (ESI):
2
þ
m/z 843.62 ([M þ K] requires 843.89); HR-MS (ESI): m/z
þ
8
Calcd. for C H N O : C, 59.70; H, 5.51; N, 6.96; O, 27.83.
05.2904 ([M þ H] , C H N O requires 805.2932); Anal.
4
0 45 4 14
4
0 44 4 14
Found: C, 59.53; H, 5.53; N, 6.63; O, 28.31 %.
0
.9 kV capillary voltage and FTMS setting at 60000 resolution,
and the data then collected and processed with Xcalibur 2.0
instrument software. Microanalysis was performed by the
Research School of Chemistry, Australian National University,
Canberra, Australia.
X-Ray Structure Determination
The X-ray diffraction measurement for compound 4 was
carried out on a Bruker kappa APEX-II CCD diffractometer at
1
50 K by using graphite-monochromated Mo-Ka radiation
˚
(
l ¼ 0.71075 A). The crystal was mounted on the goniometer
Synthesis of Crown-3-Pyromellitimide 4 and
Crown-6-Bispyromellitimide 5
using cryo loops for intensity measurements, was coated with
paraffin oil, and then quickly transferred to the cold stream using
an Oxford Cryostream 700 system attachment. Upon obtaining
an initial refinement of unit cell parameters, the data collection
strategy was worked out to achieve a redundancy of at least four
[
17]
A solution of pyromellitoyl chloride 2 (2.98 g, 9.10 mmol) in
anhydrous tetrahydrofuran (50 mL) and a solution of 4,7,10-
trioxa-1,13-tridecanediamine 3 (4.02 g, 18.25 mmol) in anhy-
drous dichloromethane (50 mL) were added drop-wise into a
stirred solution of anhydrous pyridine (2.93 g, 37.09 mmol),
tetrahydrofuran (250 mL), and dichloromethane (250 mL) over
a period of 8 h, maintained at 08C in an ice bath. After addition
was complete, the reaction mixture was stirred for 16 h at room
temperature to afford a pale red solution with white precipitate.
The solvent was removed in vacuo and the resultant brown
residue was extracted with dichloromethane (3 ꢂ 30 mL) and
the combined organic extracts were washed with aqueous
hydrochloric acid (0.1 M, 50 mL), followed by water (50 mL)
and then saturated aqueous sodium chloride (50 mL). The
organic layer was dried over anhydrous magnesium sulfate,
filtered, and concentrated under vacuum to afford the crude
product as an orange residue. The crude product was purified by
column chromatography over silica gel with methanol in
˚
throughout the resolution range (inf – 0.80 A) at 10 s exposure
time per frame making use of the kappa off sets on the four circle
goniometer geometry. Data integration and reduction with the
multi-scan absorption correction method was carried out using
[
26]
Bruker APEX2 Suite software.
the Direct Methods program SHELXS-97 and refined by full-
The structure was solved by
[
27]
[
27]
matrix least-squares refinement program SHELXL.
All non-
hydrogen atoms were refined anisotropically and hydrogen
atoms were included by using a riding model. Further crystal and
refinement data are given in Table 4.
Crystallographic data (CCDC reference number 865686)
can be obtained on request, free of charge, by quoting
Cambridge Crystallographic Data Centre, 12 Union Road,