M. J. Reyes et al. / Tetrahedron Letters 45 (2004) 8713–8715
8715
´
Alvarez-Builla, J.; Fajardo, M.; Gomez-Sal, P.; Gago, F.
´
Tetrahedron 1994, 50, 4995–5012; (c) Burgos, C.; Delgado,
(ppm) 8.81 (2H, dd, J = 7.0 and 1.2Hz); 8.05 (1H, tt,
J = 7.7 and 1.2Hz); 7.99 (1H, dd, J = 2.6 and 0.8Hz); 7.84
(2H, dd, J = 7.7 and 7.0Hz); 7.72 (1H, dd, J = 8.9 and
2.6Hz); 7.52 (2H, dd, J = 8.3 and 1.3Hz); 7.40 (2H, dd,
J = 8.3 and 7.3Hz); 7.26 (1H, tt, J = 7.3 and 1.3Hz); 6.63
(1H, dd, J = 8.9 and 0.8Hz); 13C NMR (75MHz CD3OD):
d (ppm) 164.9, 144.9, 144.5, 140.0, 137.7, 137.0, 129.9,
128.5, 127.3, 126.4, 125.5, 112.3; MS (EI, m/z) 247 (44,
M+1), 246 (100, M), 140 (48), 114 (25). Hydrobromide:
Beige solid, mp 234–235°C (EtOH–AcOEt). Anal. Calcd
for C16H14BrN3Æ1/4H2O: C, 57.76; H, 4.39; N, 12.63.
Found: C, 58.03; H, 4.37; N, 12.75.
´
F.; Garcıa-Navıo, J. L.; Izquierdo, M. L.; Alvarez-Builla,
´
´
J. Tetrahedron 1995, 31, 8649–8654; (d) Garcıa de Viedma,
´
A.; Martinez-Barrasa, V.; Burgos, C.; Izquierdo, M. L.;
´
Alvarez-Builla, J. J. Org. Chem. 1999, 64, 1007–1010; (e)
De la Rosa, R.; Martinez-Barrasa, V.; Burgos, C.;
Alvarez-Builla, J. Tetrahedron Lett. 2000, 41, 5837–5840;
´
(f) Martınez-Barrasa, V.; Delgado, F.; Burgos, C.; Garcıa-
Navıo, J. L.; Izquierdo, M. L.; Alvarez-Builla, J. Tetra-
´
´
´
hedron 2000, 56, 2481–2490; (g) Reyes, M. J.; Delgado, F.;
Izquierdo, M. L.; Alvarez-Builla, J. Tetrahedron 2002, 58,
´
´
8573–8579; (h) Nun˜ez, A.; Garcıa de Viedma, A.; Martın-
ez-Barrasa, V.; Burgos, C.; Alvarez-Builla, J. Synlett 2002,
7, 1093–1096.
11. General procedure for double coupling: the aminide 5
(1mmol) and the corresponding boronic acid (3mmol)
were dissolved in a toluene–ethanol mixture (20:1, 15mL).
Then, Cs2CO3 (4mmol) was added, followed by Pd(PPh3)4
(57mg, 5%mmol). After the addition, the mixture was
kept under argon with vigorous stirring for 5min, and
then refluxed until no starting material was detected. At
the end, the mixture was filtered through Celite, and the
residue washed with acetonitrile until no colour was
observed in the filtrate. The filtrates were combined and
evaporated to dryness, and the residue purified by flash
chromatography through a silica gel column, using
ethanol as the mobile phase. Compound 6b was isolated
as a yellow oil, compound 6d was recrystallized from
ethanol and compounds 6a and 6c were transformed into
the corresponding hydrobromides, and then recrystallized
from a suitable solvent.
7. (a) Zoltewicz, J. A.; Cruskie, M. P., Jr.; Dill, C. D. J. Org.
Chem. 1995, 60, 264–267; (b) Zoltewicz, J. A.; Cruskie, M.
P., Jr. J. Org. Chem. 1995, 60, 3487–3493.
´
8. (a) Garcıa-Cuadrado, D.; Cuadro, A. M.; Alvarez-Builla,
J. Synlett 2002, 11, 1904–1906; (b) Barchın, B. M.;
Valenciano, J.; Cuadro, A. M.; Alvarez-Builla, J.; Vaqu-
ero, J. J. Org. Lett. 1999, 1, 545–546.
9. Reyes, M. J.; Burgos, C.; Izquierdo, M. L.; Alvarez-Builla,
J. Tetrahedron 2004, 60, 1093–1097.
´
10. General procedure for cross-coupling: Pd(PPh3)4 (57mg,
5%mmol), the corresponding boronic acid (1.5mmol), the
corresponding aminide 3 (1mmol) were dissolved in a
toluene–ethanol mixture (20:1, 15mL). Then, Cs2CO3
(2mmol) was added, and the mixture was stirred under
argon and refluxed for the reaction time indicated in Table
1. The course of the reaction was followed by TLC, HPLC
and/or 1H NMR. Once the starting material had been
consumed, the catalyst was filtered off through Celite and
washed with acetonitrile until no colour was observed in
the filtrate. The filtrates were combined and evaporated to
dryness. The crude product was purified by flash chroma-
tography on a silica gel column with ethanol as the mobile
phase, and recrystallized from a suitable solvent. Com-
pound 4f was isolated as a yellow oil, while compounds 4a
and 4h were transformed into the corresponding hydro-
bromides before purification.
N-(30,50-Diphenylpyridin-20-yl)pyridinium aminide (6a):
yellow solid (204mg, 63%), IR (KBr) mmax (cmꢀ1): 1592,
1420, 1385, 1311, 1144, 698cmꢀ1 1H NMR (300MHz,
;
CD3OD): d (ppm) 8.63 (2H, dd, J = 7.1 and 1.3Hz); 7.98
(1H, d, J = 2.6Hz); 7.97 (1H, tt, J = 7.7 and 1.3Hz); 7.72
(4H, m); 7.60 (1H, d, J = 2.6Hz); 7.49 (2H, dd, J = 7.4and
1.3Hz); 7.42 (2H, ap. t, J = 7.4Hz); 7.36 (2H, ap. t,
J = 7.4Hz); 7.32 (1H, tt, J = 7.4and 1.3Hz); 7.23 (1H, tt,
J = 7.4and 1.3Hz); 13C NMR (75MHz CD3OD): d (ppm)
161.6, 145.3, 144.2, 140.4, 139.6, 138.4, 137.6, 130.4, 130.0,
129.7, 128.3, 128.1, 127.4, 126.5, 126.4, 124.9; MS (CI,
m/z) 324 (100, M+1), 323 (47), 247 (39), 245 (46), 80 (48).
Hydrobromide: Beige solid, mp 155–156°C (EtOH–Et2O).
Anal. Calcd for C22H17N3Æ2HBrÆ1H2O: C, 52.51; H, 4.21;
N, 8.35. Found: C, 52.36; H, 4.17; N, 8.39.
N-(50-Phenylpyridin-20-yl)pyridinium aminide (4a): orange
solid (299mg, 90%), IR (KBr) mmax (cmꢀ1): 1594, 1466,
1378, 119, 768cmꢀ1 1H NMR (300MHz, CD3OD): d
;