Article
Organometallics, Vol. 29, No. 21, 2010 5633
(0.724 g, 7.16 mmol, 1.09 equiv) were added to 2-hydroxy-3-
methoxybenzaldehyde (1.00 g, 6.57 mmol, 1.0 equiv) in MeOH
(30 mL). Compound 1b was obtained as a yellow powder in 87%
yield. 1H NMR (300 MHz, CDCl3): δ 1.38, 1.62, 1.81, 2.08
(bm, 8H, CH(CH2)4CH), 3.03 (m, 1H, NCHCH2), 3.66 (m, 1H,
OCHCH2), 3.90 (s, 3H, OCH3) 6.78, 6.81, 6.84, 6.88, 6.91, 6.94
(m, 3H, C6H3), 8.42 (s, 1H, CHdN), 13.84 (s, 1H, OH). 13C
NMR (300 MHz, CDCl3): δ 24.12 (NCHCH2CH2CH2), 24.28
(OCHCH2CH2CH2), 32.58 (NCHCH2CH2), 32.62 (OCHCH2-
CH2), 73.59 (NCHCH2), 74.76 (OCHCH2), 114.08, 117.97,
118.42, 123.00, 148.50, 151.94 (Ar), 165.41 (CdN). Anal. Calcd
for C14H19NO3: C, 67.45; H, 7.68; N, 5.62. Found: C, 67.63; H,
7.73; N, 5.60. HRMS (ESI): m/z 250.1515 [M þ Hþ], calcd for
C14H19NO3 249.14.
(E)-2-(((trans-2-Hydroxycyclohexyl)imino)methyl)-4-methyl-
6-(triphenylsilyl)phenol (1c; L3-H). Following the general pro-
cedure for the synthesis of tridentate Schiff base ligands 1a-d,
trans-2-aminocyclohexanol (0.338 g, 2.23 mmol, 1.1 equiv) and
triethylamine (0.223 g, 2.21 mmol, 1.09 equiv) were added to
2-hydroxy-5-methyl-3-(triphenylsilyl)benzaldehyde16d (0.800 g,
2.02 mmol, 1.0 equiv) in MeOH (30 mL). Compound 1c was
obtained as a yellow powder in 90% yield. 1H NMR (300 MHz,
CDCl3): δ 1.31, 1.56, 1.75, 2.03 (bm, 8H, CH(CH2)4CH), 2.19 (s,
3H, CCH3), 2.97 (m, 1H, NCHCH2), 3.59 (m, 1H, OCHCH2),
3.90 (s, 3H, OCH3) 7.07-7.64 (m, 18H, Ar), 8.41 (s, 1H,
CHdN), 13.20 (s, 1H, OH). 13C NMR (300 MHz, CDCl3): δ
20.43 (CCH3), 24.25 (NCHCH2CH2CH2), 24.40 (OCHCH2-
CH2CH2), 32.59 (NCHCH2CH2), 32.76 (OCHCH2CH2),
73.42 (NCHCH2), 75.71 (OCHCH2), 117.73, 121.32, 127.40,
127.67, 129.24, 129.76, 134.23, 134.68, 135.16, 135.42, 136.35,
142.04, 163.98 (Ar), 165.54 (CdN). Anal. Calcd for C32H33NO2-
Si: C, 78.17; H, 6.76; N, 2.85. Found: C, 76.99; H, 6.67; N, 2.16.
HRMS (ESI): m/z 492.2625 [M þ Hþ], calcd for C32H33NO2Si
491.23.
(E)-2-(tert-Butyldimethylsilyl)-6-(((trans-2-hydroxycyclohexyl)-
imino)methyl)-4-methylphenol (1d; L4-H). Following the general
procedure for synthesis of tridentate Schiff base ligands 1a-d,
trans-2-aminocyclohexanol (0.166 g, 1.09 mmol, 1.1 equiv) and
triethylamine (0.110 g, 1.08 mmol, 1.09 equiv) were added to
2-hydroxy-5-methyl-3-(triphenylsilyl)benzaldehyde16d (0.250 g,
0.99 mmol, 1.0 equiv) in MeOH (30 mL). Compound 1d was
obtained as a yellow powder in 81% yield. 1H NMR (300 MHz,
CDCl3): δ 0.32 (s, 6H, Si(CH3)2), 0.92 (s, 9H, C(CH3)3), 1.37,
1.63, 1.80, 2.08 (bm, 8H, CH(CH2)4CH), 2.97 (m, 1H, NCH-
CH2), 3.69 (m, 1H, OCHCH2), 7.05 (d, J = 1.78 Hz, 1H, C6H2),
7.20 (d, J = 2.09 Hz, 1H, C6H2), 8.37 (s, 1H, CHdN), 12.98 (s,
1H, OH). 13C NMR (300 MHz, CDCl3): δ -4.71 (Si(CH3)2),
17.61 (SiC(CH3)3), 20.43 (CCH3), 24.28 (NCHCH2CH2CH2),
24.45 (OCHCH2CH2CH2), 27.11 (SiC(CH3)3), 32.53 (NCH-
CH2CH2), 32.83 (OCHCH2CH2), 73.62 (NCHCH2), 75.74
(OCHCH2), 117.42, 124.72, 126.81, 133.06, 140.20, 163.73
(Ar), 165.90 (CdN). Anal. Calcd for C20H33NO2Si: C, 69.11;
H, 9.57; N, 4.03. Found: C, 69.34; H, 9.81; N, 4.01. HRMS
(ESI): m/z 348.2482 [M þ Hþ], calcd for C20H33NO2Si, 347.23.
General Procedure for Synthesis of Tridentate Schiff Base
Ligands 1e-h. The corresponding benzaldehyde (1.0 equiv)
was added to the corresponding amino alcohol (1.0 equiv) in
MeOH (30 mL). The solution mixture was heated to reflux
overnight and dried over Na2SO4 followed by filtration. The
volatile component was removed in vacuo to give tridentate
Schiff base ligands in quantitative yield.
C(CH3)3), 1.37 (s, 9H, C(CH3)3), 3.68 (m, 2H, OCH2CH2), 3.86
(m, 2H, NCHCH2), 7.03 (d, J = 2.68 Hz, 1H, C6H2), 7.32 (d,
J = 2.68 Hz, 1H, C6H2), 8.35 (s, 1H, CHdN), 13.49 (s, 1H, OH).
13C NMR (300 MHz, CDCl3): δ 29.40 (C(pCH3)3), 31.48
(C(oCH3)3), 34.35 (pCCH3), 35.01 (oCCH3), 61.82 (OCH2CH2),
62.33 (NCH2CH2), 117.73, 126.05, 127.14, 136.71, 140.21,
157.95 (Ar), 168.14 (CdN). Anal. Calcd for C17H27NO2: C,
73.61; H, 9.81; N, 5.05. Found: C, 73.94; H, 10.16; N, 4.70.
HRMS (ESI): m/z 278.2213 [M þ Hþ], calcd for C17H27NO2,
277.20.
(E)-2,4-Di-tert-butyl-6-(((3-hydroxypropyl)imino)methyl)-
phenol (1f; L6-H). Following the general procedure for synthesis
of tridentate Schiff base ligands 1e-h, 3,5-di-tert-butyl-2-hy-
droxybenzaldehyde (0.800 g, 3.41 mmol, 1.0 equiv) was added to
3-amino-1-propanol (0.256 g, 3.41 mmol, 1.0 equiv) in MeOH
(30 mL). The solution mixture was heated to reflux overnight
and dried over Na2SO4, followed by filtration. The volatile
component was removed in vacuo to give the tridentate Schiff
base ligand 1f in quantitative yield. 1H NMR (300 MHz,
CDCl3): δ 1.31 (s, 9H, C(CH3)3), 1.45 (s, 9H, C(CH3)3), 1.97
(m, 2H, CH2CH2CH2), 3.71 (t, J = 6.84 Hz, 2H, OCH2CH2),
3.76 (t, J = 6.25 Hz, 2H, NCHCH2), 7.09 (d, J = 2.38 Hz, 1H,
C6H2), 7.38 (d, J = 2.38 Hz, 1H, C6H2), 8.39 (s, 1H, CHdN),
13.85 (s, 1H, OH). 13C NMR (300 MHz, CDCl3): δ 29.40
(C(pCH3)3), 31.48 (C(oCH3)3), 33.50 (CH2CH2CH2) 34.11 (pC-
CH3), 35.00 (oCCH3), 55.84 (OCH2CH2), 60.31 (NCH2CH2),
117.77, 125.78, 126.83, 136.65, 139.97, 158.08 (Ar), 166.35
(CdN). Anal. Calcd for C18H29NO2: C, 74.18; H, 10.03; N,
4.81. Found: C, 74.05; H, 10.20; N, 4.84. HRMS (ESI): m/z
292.2394 [M þ Hþ], calcd for C18H29NO2, 291.22.
(E)-2,4-Di-tert-butyl-6-(((4-hydroxybutyl)imino)methyl)phenol
(1g; L7-H). Following the general procedure for synthesis of
tridentate Schiff base ligands 1e-h, 3,5-di-tert-butyl-2-hydro-
xybenzaldehyde (1.00 g, 4.26 mmol, 1.0 equiv) was added to
4-amino-1-butanol (0.380 g, 4.26 mmol, 1.0 equiv) in MeOH
(30 mL). The solution mixture was heated to reflux overnight
and dried over Na2SO4, followed by filtration. The volatile
component was removed in vacuo to give the tridentate Schiff
base ligand 1g in quantitative yield. 1H NMR (300 MHz,
CDCl3): δ 1.31 (s, 9H, C(CH3)3), 1.45 (s, 9H, C(CH3)3), 1.70
(m, 2H, CH2CH2CH2), 1.79 (m, 2H, CH2CH2CH2), 3.62 (t, J =
6.55 Hz, 2H, OCH2CH2), 3.70 (t, J = 6.24 Hz, 2H, NCHCH2),
7.08 (d, J = 2.38 Hz, 1H, C6H2), 7.37 (d, J = 2.38 Hz, 1H,
C6H2), 8.36 (s, 1H, CHdN), 13.90 (s, 1H, OH). 13C NMR (300
MHz, CDCl3): δ 27.19 (CH2CH2CH2), 29.39 (C(pCH3)3),
30.29 (CH2CH2CH2), 31.48 (C(oCH3)3), 34.08 (pCCH3), 34.98
(oCCH3), 59.17 (OCH2CH2), 62.56 (NCH2CH2), 117.77, 125.70,
126.72, 136.62, 139.88, 158.13 (Ar), 166.83 (CdN). Anal. Calcd
for C19H31NO2: C, 74.71; H, 10.23; N, 4.59. Found: C, 74.73; H,
10.32; N, 4.58. HRMS (ESI): m/z 306.2501 [M þ Hþ], calcd for
C19H31NO2, 305.24.
(E)-2,4-Di-tert-butyl-6-(((5-hydroxypentyl)imino)methyl)phenol
(1h; L8-H). Following the general procedure for synthesis of
tridentate Schiff base ligands 1e-h, 3,5-di-tert-butyl-2-hydro-
xybenzaldehyde (1.00 g, 4.26 mmol, 1.0 equiv) was added to
5-amino-1-pentanol (0.440 g, 4.26 mmol, 1.0 equiv) in MeOH
(30 mL). The solution mixture was heated to reflux overnight
and dried over Na2SO4, followed by filtration. The volatile
component was removed in vacuo to give the tridentate Schiff
base ligand 1h in quantitative yield. 1H NMR (300 MHz,
CDCl3): δ 1.31 (s, 9H, C(CH3)3), 1.45 (s, 9H, C(CH3)3), 1.48
(m, 2H, CH2CH2CH2), 1.63 (m, 2H, CH2CH2CH2), 1.74 (m,
2H, CH2CH2CH2), 3.59 (t, J = 6.84 Hz, 2H, OCH2CH2), 3.67
(t, J = 6.54 Hz, 2H, NCHCH2), 7.07 (d, J = 2.38 Hz, 1H,
C6H2), 7.37 (d, J = 2.38 Hz, 1H, C6H2), 8.34 (s, 1H, CHdN),
13.95 (s, 1H, OH). 13C NMR (300 MHz, CDCl3): δ 23.39
(CH2CH2CH2), 29.40 (C(pCH3)3), 30.66 (CH2CH2CH2), 31.49
(C(oCH3)3), 33.44 (CH2CH2CH2), 34.10 (pCCH3), 35.00 (oC-
CH3), 59.43 (OCH2CH2), 62.80 (NCH2CH2), 117.80, 125.67,
126.70, 136.63, 139.86, 158.17 (Ar), 158.17 (CdN). Anal. Calcd
(E)-2,4-Di-tert-butyl-6-(((2-hydroxyethyl)imino)methyl)phenol
(1e; L5-H). Following the general procedure for synthesis of
tridentate Schiff base ligands 1e-h, 3,5-di-tert-butyl-2-hydro-
xybenzaldehyde (1.00 g, 4.26 mmol, 1.0 equiv) was added to
ethanolamine (0.260 g, 4.26 mmol, 1.0 equiv) in MeOH (30 mL).
The solution mixture was heated to reflux overnight and dried
over Na2SO4, followed by filtration. The volatile component
was removed in vacuo to give the tridentate Schiff base ligand 1e
in quantitative yield. 1H NMR (300 MHz, CDCl3): δ 1.24 (s, 9H,