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B.G. Park et al. / Journal of Organometallic Chemistry 696 (2011) 4039e4045
4.6. Synthesis of methyl 5-((5-tert-butyl-2-
(trifluoromethylsulfonyloxy)phenyl)ethynyl)picolinate 5
1022, 836, 702. HRMS (CI) calcd for C21H20NO2 [M þ H]þ 318.1489,
found 318.1485.
A mixture of 4 (1.70 g, 4.16 mmol), 3 (0.670 g, 4.16 mmol),
PdCl2(PPh3)2 (60 mg, 0.083 mmol), and CuI (24 mg, 0.012 mmol) in
NEt3/THF (20 mL, 1:1, v/v) was stirred at room temperature under
nitrogen atmosphere for 18 h. The crude reaction mixture was
filtered through a pack of Celite, and the filtrate concentrated under
reduced pressure. The residual brown solid was purified by flash
column chromatography on SiO2 (hexanes:EtOAc ¼ 4:1, v/v) to
afford 5 as a yellow solid (1.57 g, 86%). 1H NMR (400 MHz, CDCl3,
4.9. Synthesis of dimethyl 5,50-(6,60-(buta-1,3-diyne-1,4-diyl)bis(3-
tert-butyl-6,1-phenylene)bis(ethyne-2,1-diyl))dipicolinate 8
A 100-mL round bottom flask was loaded with 7 (0.77 g,
3.2 mmol), PdCl2(PPh3)2 (44 mg, 0.063 mmol), and Cu(OAc)2
(29 mg, 0.16 mmol). A mixture of THF/iPr2NH (10 mL, 1:1, v/v) and
pyridine (2 mL) was added, followed by I2 (0.40 g, 1.6 mmol). After
stirring at room temperature for 2 h under air, the reaction was
completed as judged by TLC. The crude reaction mixture was
filtered through a pack of Celite and the isolated solid material was
extracted with CHCl3 (3 ꢂ 150 mL). The organic layer was washed
with water (3 ꢂ 100 mL), dried over anhydrous MgSO4, filtered, and
concentrated under reduced pressure. The crude solid was washed
with Et2O (100 mL) and concentrated under reduced pressure to
afford 8 as a pale yellow solid (0.64 g, 64%). 1H NMR (400 MHz,
298 K):
d
8.91 (s, 1H), 8.15 (d, J ¼ 8.0 Hz, 1H), 8.02 (dd, J ¼ 8.0, 2.0 Hz,
1H), 7.67 (d, J ¼ 2.4 Hz, 1H), 7.48 (dd, J ¼ 8.8, 2.4 Hz, 1H), 7.24 (d,
J ¼ 8.8 Hz, 1H), 4.03 (s, 3H), 1.35 (s, 9H); 13C NMR (100 MHz, CDCl3,
298 K):
d 165.3, 152.2, 152.0, 147.8, 146.8, 139.7, 131.0, 128.4, 124.7,
123.2, 121.4, 116.6, 91.5, 89.2, 53.2, 35.0, 31.2. FT-IR (thin film on
NaCl, cmꢀ1): 2962, 1746, 1725, 1584, 1552, 1493, 1425, 1368, 1310,
1278, 1213, 1140, 1119, 1077, 1023, 927, 875, 638, 617. HRMS (CI)
calcd for C20H19F3NO5S [M þ H]þ 442.0931, found 442.0938.
CDCl3, 298 K):
d
8.87 (d, J ¼ 1.6 Hz, 2H), 8.03 (d, J ¼ 8.0 Hz, 2H), 7.98
(dd, J ¼ 8.0, 2.0 Hz, 2H), 7.61 (d, J ¼ 2.0 Hz, 2H), 7.54 (d, J ¼ 8.4 Hz,
2H), 7.42 (dd, J ¼ 8.4, 2.0 Hz, 2H), 4.00 (s, 6H), 1.36 (s, 18H); 13C NMR
4.7. Synthesis of methyl 5-((5-tert-butyl-2-((triisopropylsilyl)
ethynyl)phenyl)ethynyl)picolinate 6
(100 MHz, CDCl3, 298 K):
d 165.4, 153.0, 152.2, 146.2, 139.7, 132.9,
129.3, 126.8, 125.6, 124.6, 124.0, 122.1, 94.7, 89.5, 81.3, 77.7, 53.1,
35.2, 31.1. FT-IR (thin film on NaCl, cmꢀ1): 2958, 1745, 1723, 1586,
1436, 1366, 1308, 1276, 1259, 1234, 1194, 1163, 1131, 1023, 832, 750,
701. HRMS (ESI) calcd for C42H37N2O4 [M þ H]þ 633.2753, found
633.2721.
A 100-mL round bottom flask was loaded with 5 (1.57 g,
3.65 mmol), PdCl2(dppf)$CH2Cl2 (90 mg, 0.11 mmol), and CuI
(40 mg, 0.21 mmol) under nitrogen atmosphere. A mixture of
DMF/iPr2NH (30 mL, 1:1, v/v) was added under nitrogen, followed
by ethynyltriisopropylsilane (1.60 mL, 7.11 mmol). The solution was
stirred at 70 ꢁC for 48 h under nitrogen, and filtered through a pack
of Celite. The filtrate was diluted with Et2O (100 mL), and washed
with water (3 ꢂ 100 mL) and brine (100 mL). The organic layer was
dried over anhydrous MgSO4, filtered, and concentrated under
reduced pressure. The residual material was purified by flash
column chromatography on SiO2 (hexanes:EtOAc ¼ 10:1, v/v) to
afford 6 as a brown viscous oil (1.49 g, 88%). 1H NMR (400 MHz,
4.10. Synthesis of 5,50-(6,60-(buta-1,3-diyne-1,4-diyl)bis(3-tert-
butyl-6,1-phenylene)bis(ethyne-2,1-diyl))dipicolinic acid 9
To a stirred solution of 8 (0.22 g, 0.34 mmol) in CH2Cl2/CH3OH
(30 mL, 3:2, v/v) was added a solution of NaOH (41 mg, 1.0 mmol) in
CH3OH (4 mL). After stirring at 40 ꢁC for 3 h, the reaction was
completed as judged by TLC. The reaction mixture was diluted with
water (50 mL), and an aqueous solution of HCl (1 M) was added to
adjust the pH to 4. The mixture was diluted with EtOAc (150 mL).
The organic layer was separated, washed with water (3 ꢂ 30 mL),
dried over anhyd MgSO4, filtered, and concentrated under reduced
pressure. The residual solid material was washed with Et2O
(50 mL), and dried in vacuo to afford 9 as a brown solid (144 mg,
CDCl3, 298 K):
d
8.85 (d, J ¼ 1.2 Hz, 1H), 8.12 (d, J ¼ 8.0 Hz, 1H), 7.95
(dd, J ¼ 8.0, 2.0 Hz, 1H), 7.57 (d, J ¼ 1.6 Hz, 1H), 7.47 (d, J ¼ 8.4 Hz,
1H), 7.35 (dd, J ¼ 8.0, 2.0 Hz, 1H), 4.03 (s, 3H), 1.32 (s, 9H), 1.10 (s,
21H); 13C NMR (100 MHz, CDCl3, 298 K):
d 165.3, 152.2, 151.8, 146.2,
139.6, 132.8, 129.4, 126.5, 124.5, 124.3, 124.2, 123.4, 105.2, 95.2, 95.1,
88.2, 53.2, 35.0, 31.2, 18.8, 11.4. FT-IR (thin film on NaCl, cmꢀ1):
2956, 2865, 1748, 1725, 1491, 1462, 1436, 1308, 1234, 1162, 1131,
1072, 1022, 883, 828, 672. HRMS (CI) calcd for C30H40NO2Si
[M þ H]þ 474.2823, found 474.2804.
70%). 1H NMR (400 MHz, CDCl3, 298 K):
d 8.91 (s, 2H), 8.06 (d,
J ¼ 8.0 Hz, 2H), 8.00 (dd, J ¼ 8.0, 1.6 Hz, 2H), 7.68 (s, 2H), 7.54 (d,
J ¼ 8.4 Hz, 2H), 7.45 (dd, J ¼ 8.4, 2.0 Hz, 2H), 1.40 (s, 18H); 13C NMR
(100 MHz, CDCl3, 298 K):
d 164.9, 153.3, 149.9, 146.4, 141.1, 131.9,
4.8. Synthesis of methyl 5-((5-tert-butyl-2-ethynylphenyl)ethynyl)
picolinate 7
129.3, 126.8, 126.3, 124.8, 124.2, 122.4, 95.2, 89.3, 81.5, 78.0, 35.2,
31.1. FT-IR (thin film on NaCl, cmꢀ1): 3422, 1697, 1583, 1554, 1413,
1362, 1307, 1260, 1232, 1166, 1146, 1118, 1030, 833, 796, 729, 695.
HRMS (CI) calcd for C40H33N2O4 [M þ H]þ 605.2435, found
605.2441.
To a stirred solution of 6 (1.49 g, 3.14 mmol) in THF/H2O (30 mL,
10:1, v/v) was added TBAF (9.0 mL, 1.0 M solution in THF) in
a dropwise fashion. The mixture was stirred for 3 h, diluted with
water (50 mL), and extracted with CH2Cl2 (3 ꢂ 50 mL). The
combined organic extracts were washed with water (3 ꢂ 30 mL),
dried over anhydrous MgSO4, filtered, and concentrated under
reduced pressure. The residual material was purified by flash
column chromatography on SiO2 (hexanes:EtOAc ¼ 4:1 to 2:1, v/v)
to afford 7 as a brown solid (0.93 g, 93%). 1H NMR (400 MHz, CDCl3,
Acknowledgment
This work was supported by the National Science Foundation
(CHE 0547251) and Grant No. 00035484 from the SMBA of Korea.
298 K):
d
8.88 (d, J ¼ 2.0 Hz, 1H), 8.12 (d, J ¼ 8.0 Hz, 1H), 7.97 (dd,
J ¼ 8.0, 2.0 Hz, 1H), 7.58 (d, J ¼ 1.6 Hz, 1H), 7.49 (d, J ¼ 8.4 Hz, 1H),
Appendix A. Supplementary material
7.37 (dd, J ¼ 8.0, 2.0 Hz,1H), 4.02 (s, 3H), 3.33 (s,1H),1.33 (s, 9H); 13C
NMR (100 MHz, CDCl3, 298 K):
d
165.4, 152.3, 152.2, 146.3, 139.5,
CCDC 822961 contains the supplementary crystallographic data
for this paper. This data can be obtained free of charge from The
132.7, 129.2, 126.6, 124.7, 124.6, 124.1, 122.3, 94.8, 88.7, 82.0, 81.0,
53.1, 35.0, 31.1. FT-IR (thin film on NaCl, cmꢀ1): 3285, 2959, 2906,
1743,1723,1584,1435,1366,1308,1276,1259,1234,1194,1163,1131,