Page 13 of 15
ACS Catalysis
g, 92% yield). Despite appearing >97% pure by 1H NMR
203.01, 137.27, 131.58, 131.06, 129.85, 128.72, 127.66,
1
2
3
4
5
6
7
8
spectroscopy, diminishing quenchꢀlabeling at higher
quench loadings suggested that significant impurities
remain in this sample that led to unlabeledꢀquenching.
Successive recrystallizations with toluene/hexanes evenꢀ
tually furnished a light brown semiꢀsoft solid that perꢀ
formed more favorably (2.2 g, 56% yield). This highꢀ
lights the challenge associated with 2; since sample staꢀ
bility precludes chromatography, consistent and reliable
purification will require further optimization. 1HꢀNMR
(500 MHz, CDCl3): δ 7.92ꢀ7.87 (m, 3H), 7.84ꢀ7.80 (m,
2H), 7.78ꢀ7.72 (m, 3H), 7.47 (d, J = 7.7 Hz, 1H), 2.92 (t,
J = 7.6 Hz, 2H), 2.62 (t, J = 6.5 Hz, 2H), 1.55 (p, J = 6.6
Hz, 2H). 13C{1H}ꢀNMR (125 MHz, CDCl3): δ 134.79,
131.50, 130.93, 130.20, 128.72, 127.66, 127.55, 127.35,
126.94, 126.03, 125.21, 125.17, 125.04, 124.98, 124.95,
123.03, 122.26, 42.57, 32.95, 30.28. ESIꢀMS calculated
for C20H15NO 285.1154, found 285.1146. Spectra data
are consistent with those previously reported.49
127.37, 127.26, 126.65, 125.91, 125.22, 125.19, 124.94,
124.91, 124.77, 123.60, 44.03, 33.70, 31.98, 29.69,
29.46, 29.27, 22.19. ESIꢀMS calculated for C24H24O
328.1827, found 328.1826.
7-Iodoheptylpyrene (10). 9ꢀBorabicyclo[3.3.1]nonane
(9ꢀBBN) was generated in situ by treating BH3ꢀTHF (1.0
M, 1.60 mL, 1.60 mmol) with cyclooctadiene (2.00 × 102,
1.63 mmol) in a dried Schlenk flask and heating gently to
30ꢀ40 oC for 2 hours. Immediate bubbling was noted
upon addition of cyclooctadiene. The solution was then
treated with a solution of 9 (473 mg, 1.59 mmol) in THF
(2 mL) and stirred overnight at ambient temperature. A
small amount of methanol (5 ꢂL) was added to quench
excess hydride, and then solid I2 (221 mg, 1.74 mmol)
was added in a single portion. The resulting purple soluꢀ
tion was treated with sodium methoxide (0.8 M solution
in methanol) dropwise until the purple color dissipated; in
this instance, ca. 800 ꢂL was added over 10 minutes.
Excess iodine was quenched by pouring the reaction
into aqueous sodium thiosulfate (1.0 M, 10 mL). Crude
product was extracted by washing with diethyl ether (3x,
10 mL) and dried over anhydrous magnesium sulfate.
Purification by column chromatography on silica gel usꢀ
ing CH2Cl2: hexanes (1:15) eluent afforded a white fluffy
solid (145.6 mg, 22% yield). 1HꢀNMR (500 MHz, CDCl3):
δ 8.28 (d, J = 9.2 Hz, 1H), 8.16 (dd, J = 7.3, 4.8 Hz, 2H),
8.11 (dd, J = 8.5, 3.3 Hz, 2H), 8.06 – 7.96 (m, 3H), 7.87
(d, J = 7.8 Hz, 1H), 3.34 (t, J = 7.8 Hz, 2H), 3.18 (t, J =
7.0 Hz, 2H), 1.93 – 1.78 (m, 4H), 1.53 – 1.46 (m, 2H),
1.46 – 1.37 (m, 4H). 13C{1H}ꢀNMR (125 MHz, CDCl3): δ
137.25, 131.59, 131.07, 129.87, 128.74, 127.67, 127.39,
127.28, 126.66, 125.92, 125.23, 125.20, 124.95, 124.92,
124.78, 123.61, 33.69, 33.66, 31.95, 30.60, 29.70,
28.64, 7.42. ESIꢀMS calculated for C23H23I 426.0844,
found 426.0840.
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24
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60
1-Pyrenylheptene (9). Pyreneꢀ1ꢀcarbaldehyde (7) and
1ꢀmethylpyrene (8) were synthesized as described preꢀ
viously.50 In a flameꢀdried flask, a stirring solution of 8
(8.26 g, 38.2 mmol) in dry THF (38 mL) was chilled to 0
oC and treated with nꢀBuLi (16.8 mL, 2.5 M solution in
hexanes, 42.1 mmol). After stirring for 1 hour, the soluꢀ
tion was cooled to ꢀ78 oC with dry ice/acetone and treatꢀ
ed with 6ꢀbromoꢀhexene (6.13 mL, 45.9 mmol). For
convenience, the solution was allowed to warm to ambiꢀ
ent temperature overnight. Excess base was neutralized
by the addition of dilute aqueous ammonium chloride.
Crude product was extracted with ether (3 × 50 mL),
washed with brine (50 mL), dried over anhydrous
MgSO4, and concentrated to a vibrant yellow solid in
vacuo. Recrystallization in hot hexanes afforded white to
paleꢀyellow crystals (7.98 g, 74% yield). If further purifiꢀ
cation is required, good separation has been achieved
by column chromatography with 1:40 ethyl acetate to
hexanes eluent. Characterization data are consistent
with those previously reported.
8-Pyrenyloctanenitrile (4). A dry flask was charged
with 10 (244.7 mg, 0.574 mmol), potassium cyanide
(47.8 mg, 0.734 mmol), and magnetic stir bar. After disꢀ
solving the solids in DMF (5.0 mL), the solution was
heated to 70 oC for 6 hours. Product was precipitated by
addition of water (10 mL) and collected by vacuum filtraꢀ
tion. Purification by column chromatography on silica gel
with hexanes/CH2Cl2 (2:1) eluent afforded a pale yellow
to white crystalline solid (140.1 mg, 0.430 mmol, 75%
8-Pyrenyloctanal (3). In a glovebox, a pressure tube
was charged with 9 (113.2 mg, 0.379 mmol), (acetyꢀ
lacetonato)dicarbonylrhodium(I) (29 ꢂL of a 2.0 × 10 mM
stock solution in THF, 5.8 × 10ꢀ4 mmol), a Dow proprieꢀ
tary linearꢀselective phosphorusꢀbased ligand (14 ꢂL of a
82 mM stock solution in acetone, 1.2 × 10ꢀ3 mmol), toluꢀ
ene (4 mL), and a magnetic stir bar. The tube was fitted
with a regulator and charged with 145 psi of synthesis
gas (H2/CO), which included purging the nitrogen atꢀ
mosphere by pressurizing with synthesis gas to 145 psi
and venting to ambient pressure (3x). The vessel was
heated to 80 oC and agitated with lively stirring overnight.
The crude material was concentrated to dryness in vac-
uo and purified by column chromatography on silica gel
using CH2Cl2: hexanes (1.1 : 1) eluent to afford a fluffy
white solid (85.1 mg, 0.259 mmol, 68% yield). The
branched isomer was not detectable by NMR. 1HꢀNMR
(400 MHz, CDCl3): δ 9.75 (s, 1H), 8.27 (d, J = 9.3 Hz,
1H), 8.18ꢀ8.09 (m, 4H), 8.05ꢀ7.97 (m, 3H), 7.86 (d, J =
7.8 Hz, 1H), 3.34 (t, J = 7.8 Hz, 2H), 2.41 (t, J = 7.1 Hz,
2H), 1.86 (p, J = 7.7 Hz, 2H), 1.63 (p, J = 7.2 Hz, 2H),
1.52ꢀ1.32 (m, 6H). 13C{1H}ꢀNMR (100 MHz, CDCl3): δ
1
yield). HꢀNMR (400 MHz, CDCl3): δ 8.27 (d, J = 9.3 Hz,
1H), 8.19ꢀ8.10 (m, 4H), 8.08 – 7.95 (m, 3H), 7.86 (d, J =
7.8 Hz, 1H), 3.38 (t, J = 7.8 Hz, 2H), 2.28 (t, J = 7.1 Hz,
2H), 1.85 (p, J = 7.6 Hz, 2H), 1.62 (p, J = 7.2 Hz, 2H),
1.54 – 1.31 (m, 6H). 13C{1H}ꢀNMR (100 MHz, CDCl3): δ
137.05, 131.54, 131.01, 129.84, 128.68, 127.62, 127.33,
127.26, 126.64, 125.89, 125.18, 125.14, 124.93, 124.88,
124.76, 123.51, 119.94, 33.58, 31.82, 29.50, 28.83,
28.73, 25.42, 17.19. ESIꢀMS calculated for C24H23N
325.1830, found 325.1834.
ASSOCIATED CONTENT
Supporting Information. More details on the quench effiꢀ
ciency, time evolution weightꢀaverage molecular weight, RI
and UV trace comparisons, error analysis, catalyst death
verses unlabeled quenching, data fits with optimized rate
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