The Journal of Organic Chemistry
Note
were divided by the total number of moles of pyrene-d10 (0.0573
mmol), providing the percent residual hydrogen (4.8% H).
Chromatography was performed with Sorbent Technologies silica
gel (porosity = 60 Å, particle size = 32−63 μm).
75% yield with 94.4% deuterium incorporation (Table 1, entry
3). The method was further applied to less generic PAHs,
specifically, geodesic polyarenes, which have been utilized as
building blocks for organic electronic materials. Applying this
simple and convenient method to these larger, curved
polycyclic aromatic hydrocarbons enabled the synthesis of
perdeuterated compounds that were not previously accessible
so easily by other methods.9 The perdeuteration of two
geodesic polyarenes was explored. Corannulene10 and dibenzo-
[a,g]corannulene11 are both curved polycyclic aromatic hydro-
carbons that have attracted widespread interest for a variety of
synthetic and materials applications. Accessing these molecules
in their perdeuterated form will allow further studies of these
molecules as synthetic intermediates. Applying the potassium
tert-butoxide/DMF-d7/microwave irradiation conditions to
both corannulene (Table 1, entry 4) and dibenzo[a,g]-
corannulene (Table 1, entry 5) affords the corresponding
perdeuterated geodesic polyarenes in good yields with high
deuterium incorporation. All compounds were again analyzed
by EI-MS (Figure 3), and the degree of deuterium
Pyrene-1,2,3,4,5,6,7,8,9,10-d10 (7). To a flame-dried, nitrogen-
purged 10 mL microwave vessel equipped with a magnetic stir bar
were added 50.0 mg (0.248 mmol) of pyrene and 1.00 mL of
dimethylformamide-d7. The mixture was stirred, and sublimed
potassium tert-butoxide was added (0.555 g, 4.95 mmol). The
microwave vessel was capped and placed in a microwave reactor for
1 h at 170 °C. The mixture was cooled to room temperature and
immediately flushed through a short pad of silica gel with
dichloromethane as the eluent. Evaporation of the solvent provided
1
49.9 mg (95%) of deuterated pyrene as a tan solid. H NMR analysis
(500 MHz, CDCl3) with 1,3,5-trimethoxybenzene as an internal
standard showed 95.2% deuterium incorporation. 1H NMR (500
MHz, CDCl3) δ (ppm): 8.21 (s, 4H), 8.10 (s, 4H), 8.03 (s, 2H). 13C
NMR (125 MHz, CDCl3, no proton decoupling, 300 pulses, 60 s pulse
delay) δ (ppm): 130.9 (s), 126.8 (t, J = 24.0 Hz), 125.3 (t, J = 24.5
Hz), 124.6 (s), 124.4 (t, J = 24.0 Hz). See Figure 1 for EI-MS data.
HRMS (DART-TOF): calcd for C16HD10 (M + 1)+ 213.1488, found
213.1490. DART-TOF % deuterium incorporation: 45% d10:38%
d9:8.5% d8.12
Fluoranthene-1,2,3,4,5,6,7,8,9,10-d10 (8). The same general
procedure above was used with fluoranthene (50.0 mg, 0.248 mmol),
1.00 mL of dimethylformamide-d7, and sublimed potassium tert-
butoxide (0.555 g, 4.95 mmol) to afford 39.0 mg (75%) of deuterated
fluoranthene as a tan solid. 1H NMR analysis (500 MHz, CDCl3) with
1,3,5-trimethoxybenzene as an internal standard showed 94.4%
deuterium incorporation. 1H NMR (500 MHz, CDCl3) δ (ppm):
7.99−7.97 (m), 7.95 (s), 7.93−7.92 (m), 7.85 (s), 7.64 (s), 7.39 (s).
13C NMR (125 MHz, CDCl3, no proton decoupling, 376 pulses, 60 s
1
incorporation was determined by H NMR analysis with the
same internal standard.
Thus, a convenient and relatively inexpensive method for the
preparation of perdeuterated polycyclic aromatic hydrocarbons
has been developed. Using commercially available reagents and
short reaction times, both common and exotic perdeuterated
PAHs are now easily accessible. Most importantly, this method
affords efficient H/D exchange, delivering deuterium incorpo-
ration levels comparable to those found in commercially
available perdeuterated standards (Figure 1). The ease,
convenience, short reaction times, and accessibility of reagents
presage a wide variety of applications of this method in the
future.
pulse delay) δ (ppm): 139.1 (s), 136.6 (s), 132.2 (s), 129.6 (s), 127.2
(t, J = 23.9 Hz), 126.9−126.6 (m), 125.9 (t, J = 24.0 Hz), 121.2−120.8
(m), 119.2 (t, 24.0 Hz). See Figure 3 for EI-MS data. HRMS (DART-
TOF): calcd for C16D10 (M+) 212.1410, found 212.1418.
Corannulene-1,2,3,4,5,6,7,8,9,10-d10 (9). The same general
procedure above was used with 20.0 mg (0.0800 mmol) of
corannulene, 0.40 mL of dimethylformamide-d7, and sublimed
potassium tert-butoxide (0.179 g, 1.60 mmol) to afford 16.7 mg
(80%) of deuterated corannulene as a tan solid. 1H NMR analysis (500
MHz, CDCl3) with 1,3,5-trimethoxybenzene as an internal standard
showed >98% deuterium incorporation. 1H NMR (500 MHz, CDCl3)
δ (ppm): 7.77 (s, 10H). 13C NMR (125 MHz, CDCl3, no proton
decoupling, 3184 pulses, 60 s pulse delay) δ (ppm): 134.9 (s), 129.7
(s), 125.6 (t, J = 22.0 Hz). See Figure 3 for EI-MS data. HRMS
(DART-TOF): calcd for C20D10 (M+) 260.1410, found 260.1411.
Dibenzo[a,g]corannulene-1,2,3,4,5,6,7,8,9,10,11,12,13,14-
d14 (10). The same general procedure above was used with 20.0 mg
(0.0571 mmol) of dibenzo[a,g]corannulene, 0.30 mL of dimethylfor-
mamide-d7, and sublimed potassium tert-butoxide (0.128 g, 1.14
mmol) to afford 14.7 mg (71%) of deuterated dibenzo[a,g]-
corannulene as a tan solid. 1H NMR analysis (500 MHz, CDCl3)
with 1,3,5-trimethoxybenzene as an internal standard showed 95.5%
deuterium incorporation. 1H NMR (500 MHz, CDCl3) δ (ppm):
8.73−8.66 (m), 8.34 (s), 8.26 (m), 7.98 (m), 7.78 (s). 13C NMR (125
MHz, CDCl3, no proton decoupling, 2696 pulses, 60 s pulse delay) δ
(ppm): 135.8 (s), 134.8 (s), 134.1 (s), 133.0 (s), 132.9 (s), 130.0 (s),
128.5 (s), 128.3 (s), 126.8−126.2 (m), 125.6−125.3 (m), 124.7−123.9
(m). See Figure 3 for EI-MS data. HRMS (APPI): calcd for C28D14
(M+) 364.1968, found 364.1959.
EXPERIMENTAL SECTION
■
All chemicals were purchased and used without further purification
unless otherwise noted. Deuterated materials, N,N-dimethylforma-
mide-d7 (99.5% D) and pyrene-d10 (98% D), were purchased from
Cambridge Isotope Laboratories; independent analysis of these
1
materials by H NMR integration with an internal standard and EI-
MS confirmed the percent deuterium incorporation. Potassium tert-
butoxide (sublimed grade, 99.99% trace metals basis) was purchased
from Aldrich and stored sealed under nitrogen in a desiccator.
Exposure to moisture resulted in diminished deuterium incorporation.
Potassium tert-butoxide that was freshly sublimed in our laboratory
worked just as well as freshly opened, sublimed grade potassium tert-
butoxide purchased from Aldrich. Microwave irradiation was
performed with a CEM Discover LabMate reactor with the IntelliVent
pressure control system; temperatures of the reaction mixtures were
monitored by a vertically focused IR temperature sensor and not by an
internal temperature probe. EI-MS data were obtained with a unit
resolution quadrupole mass spectrometer. High-resolution mass
spectrometry was performed using a DART time-of-flight mass
spectrometer. NMR shifts are referenced in parts per million downfield
from TMS, using chloroform-d1 (δH = 7.26 ppm, δC = 77.23 ppm). 13
C
NMR spectra were recorded at 125 MHz with no proton decoupling
and a 60 s pulse delay. Deuterium incorporation was determined by
1H NMR integration (500 MHz) with 1,3,5-trimethoxybenzene as an
internal standard. For example, pyrene-d10 (0.0573 mmol) and 1,3,5-
trimethoxybenzene (0.00238 mmol) were mixed in 0.70 mL of CDCl3.
The residual hydrogen signals from pyrene-d10 were integrated (8.5
per 1H) versus the internal standard (7.34 per 1H). From the
integration, the number of moles of residual hydrogen present in the
pyrene-d10 sample was calculated based on the known moles of the
internal standard and found to be 0.00276 mmol. The moles of
residual hydrogen present in the pyrene-d10 sample (0.00276 mmol)
ASSOCIATED CONTENT
■
S
* Supporting Information
1
All H NMR and 13C spectra. This material is available free of
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dx.doi.org/10.1021/jo301903m | J. Org. Chem. 2013, 78, 2139−2143