PYRIDYLPHENOL LIGANDS
1137
(1.03 g, 2.7 mmol, 68%) was obtained after rotary evaporation. Rf ¼ 0.60
1
(hexanes/E.A. ¼ 6:1); H NMR ꢀ 1.14 (s, 9 H), 1.34 (s, 9 H), 3.63 (s, 3 H),
6.83 (s, 1 H), 7.20 (s, 1, H), 7.27 (d, 1 H, J ¼ 7.5 Hz), 7.41 (d, 1 H,
J ¼ 7.3 Hz), 7.51 (unresolved dd, 1 H); 13C NMR ꢀ 31.33, 32.46, 35.13,
36.88, 106.22, 116.50, 125.67, 126.04, 137.28, 140.40, 148.70, 151.97,
157.34, 160.23; IR (KBr, cmÀ1) n 665, 1070, 1237, 1432, 1545, 1604,
2954, 3036; FABMS: m/z (relative intensity) 378 {[(MþH)þþ2], 81}, 376
{[(MþH)þ, 100}; HRMS (ESIMS): Calc. for (C20H27BrNO)þ: m/z
376.1276. Found: m/z 376.1271.
Preparation of 6-(20,40-Di-tert-butyl-60-methoxyphenyl)pyridine-
2-carboxyaldehyde (9)
3,5-Di-tert-butyl-2-[20-(60-bromo)pyridyl]anisole
(8)
(500 mg,
1.33 mmol) and TMEDA (300 mL, 1.99 mmol) were dissolved in
n
THF (5 mL) under N2. 1.6 M BuLi (1.25 mL, 1.99 mmol( was then added
at À 78ꢀC by syringe under N2. The mixture turned from colorless to deep
yellow. After 1 h, DMF (1.0 mL, 13.3 mmol) was added. The solution deco-
lorized and some white precipitate appeared. After 1 h, water was added and
the crude product was extracted with ether (3 times). The organic layer was
then washed with water (3 times), brine, dried (MgSO4), filtered, and rotary-
evaporated to dryness. The crude product was then separated by column
chromatography on silica gel (230–400 mesh) using hexanes/E.A. (10:1) as
the eluent. A white solid (355 mg, 1.09 mmol, 82%) was obtained after
1
rotary evaporation. Rf ¼ 0.37 (hexanes/E.A. ¼ 9:1); H NMR ꢀ 1.13 (s, 9
H), 1.37 (s, 9 H), 3.64 (s, 3 H), 6.89 (d, 1 H, J ¼ 1.6 Hz), 7.26 (d, 1 H),
7.27 (d, 1 H, J ¼ 1.6 Hz), 7.54 (dd, 1 H, J ¼ 1.2, 7.3 Hz), 7.85 (unresolved dd,
1 H), 7.93 (dd, 1 H, J ¼ 1.2, 7.6 Hz), 10.11 (s, 1 H); 13C NMR ꢀ 31.35, 32.48,
35.19, 36.87, 55.76, 106.20, 116.64, 119.48, 131.68, 135.91, 148.80, 151.82,
152.11, 157.31, 160.44, 194.18; IR (KBr, cmÀ1) n 724, 1066, 1709, 2959,
3392; FABMS: m/z 326 [(MþH)þ]; HRMS (ESIMS): Calc. for
(C21H27NO2)þ: m/z 326.2120. Found: m/z 326.2112.
Preparation of bis-2-[6-(20,60-Di-tert-butyl-60-methoxyphenyl)pyridyl]-
methanol (10)
3,5-Di-tert-butyl-2-[20-(60-bromo)pyridyl]anisole
(58)
(350 mg,
0.93 mmol) and TMEDA (154 mL, 1.02 mmol) were dissolved in THF
(5 mL) under N2. nBuLi (1.6 M, 0.64 mL, 1.02 mmol) was then added at
À78ꢀC via syringe. The solution turned from colorless to deep yellow.