oP(A)7-OTf as an off-white foam: m.p. 205.2 °C; 1H NMR
complex due to slow conformational exchange, see the ESI;‡
MS (ESI) calcd for C43H28F3NNaO5S (M + Na+) 750.2, found
750.2.
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General procedure: A Schlenk vacuum tube was charged with
oP(A)n−1-OTf (1.00 mmol), 4-(dimethylamino)phenylboronic
acid (198 mg, 1.20 mmol), Pd(OAc)2 (44.9 mg, 0.20 mol),
SPhos (98.5 mg, 0.24 mmol), and K3PO4 (849 mg, 4.00 mmol),
then evacuated and backfilled with argon (3×). Anhydrous THF
(2.0 mL) was added followed by deionized water (0.5 mL). The
reaction mixture was degassed by three freeze–pump–thaw
cycles, then sealed and heated at 80–85 °C overnight. The reac-
tion mixture was then cooled, diluted with EtOAc (20 mL), and
washed with water, acidifying the aqueous layer with 1 M HCl
(15 mL). The aqueous layer was extracted with EtOAc and the
combined organic layers washed with water and brine, dried
over MgSO4, filtered, and concentrated.
oP(DA)4: Purification by flash chromatography (CH2Cl2) gave
210 mg (0.53 mmol, 53%) of oP(DA)4 as a red solid, which was
recrystallized from abs. ethanol prior to further analysis:
m.p. 229.0 °C; 1H NMR (CDCl3, 500 MHz) δ 2.90 (s, 6H), 6.39
(m, 4H), 6.71 (m, 2H), 7.14 (m, 2H), 7.34 (m, 2H), 7.39 (td, 1H,
J = 7.6, 1.3 Hz), 7.43 (m, 1H), 7.49 (td, 1H, J = 7.3, 1.3 Hz,),
7.53 (dd, 1H, J = 7.5, 1.3 Hz,), 7.84 (m, 2H); 13C NMR (CDCl3,
125 MHz) δ 40.8, 112.1, 122.6, 126.7, 127.7, 128.2, 128.8,
129.7, 129.8, 129.96, 130.03, 131.6, 132.0, 138.7, 138.9, 141.0,
146.1, 148.2, 149.3; MS (MALDI) calcd for C26H21N2O2 (M −
H) 393.16, found 392.88; HRMS (ESI) calcd for C26H23N2O2
(M + H+) 395.1681, found 395.1691.
oP(DA)6: Purification by flash chromatography (toluene) gave
284 mg (0.52 mmol, 52%) of oP(DA)6 as a deep yellow solid,
which was recrystallized from abs. ethanol prior to further analy-
sis: m.p. 224.7 °C; 1H NMR complex due to slow conformation-
al exchange, see the Results and discussion section and the
ESI;‡ MS (MALDI) calcd for C38H29N2O2 (M − H) 545.22,
found 545.14; HRMS (ESI) calcd for C38H31N2O2 (M+H+)
547.2386, found 547.2393.
oP(DA)8: Purification by flash chromatography (CHCl3) gave
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211 mg (0.54 mmol, 54%) of oP(DA)8 as a light yellow solid:
1
m.p. 303.8 °C; H NMR complex due to slow conformational
exchange, see the ESI;‡ MS (MALDI) calcd for C50H37N2O2
(M − H) 697.29, found 697.28; HRMS (ESI) calcd for
C50H38N2NaO2 (M + Na+) 721.2831, found 721.2854.
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Acknowledgements
36 oP(DA)8 exhibits insufficient solubility for 2D NMR experiments in
deuterated chloroform, benzene, acetone, DMSO, and trifluoroethanol.
37 R. Ditchfield, Mol. Phys., 1974, 27, 789–807.
Primary support from the National Science Foundation
(CHE-0910477) is gratefully acknowledged. Gaussian 09 was
purchased with the assistance of the Air Force Office of Scien-
tific Research (FA9550-10-1-0377), and the MALDI mass
spectrometer was purchased with the assistance of the NSF
(CHE-0839233).
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is the slope and b is the intercept from the plot of δcalc vs. δexp
.
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Notes and references
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3404 | Org. Biomol. Chem., 2012, 10, 3398–3405
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