136
M.J. Alco´n et al. / Journal of Organometallic Chemistry 655 (2002) 134ꢂ145
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27.6 (CH2CH2NH); 26.4 (C3); 23.2 (C4); 18.3 (CH3);
14.6 (CH2CH2Si); 7.8 (CH2Si). MSꢁ(m/z): 460 (Mꢁ);
254 (Mꢁ/Si(OCH2CH3)3).
2.2.2. N,N?-bis[(S)-benzylprolyl]-N-(2-aminoethyl-3-
aminopropyl)triethoxysilylethylenediamine (2b)
2.2.2.1. Procedure A. To a solution of (S)-N-benzylpro-
line (2 g, 10.4 mmol) and triethylamine (1.05 g, 1.45 ml,
10.4 mmol) in tetrahydrofurane (80 ml) ice-cooled, ethyl
chloroformate (1.1 g, 10.4 mmol) was added dropwise
with vigorous stirring, when the addition is finished the
pasty reaction mixture is stirred for 30 min (temperature
5ꢂ10 8C), obtaining a very reactive mixed anhydride.
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To the anhydride solution, N-(2-aminoethyl-3-amino-
propyl)triethoxysilane (1.37 g, 1.42 ml, 5.2 mmol) in
tetrahydrofurane (5 ml), was added dropwise for 15 min
and the mixture was stirred at 0 8C for 1 h, and filtered.
The solvent was evaporated and the residue extracted
with ethyl acetate and washed successively with water,
aqueous NaHCO3 and brine. The organic layer was
dried over magnesium sulphate and evaporated in vacuo
Scheme 1. Synthesis of ligands.
OCH2CH3); 3.57ꢂ
CH2CH2CH2Si); 3.30ꢂ
1.96 (m, 4H, H3); 1.96ꢂ
2H, CH2CH2Si) 1.19 (t, 9H,6.4 Hz, OCH2CH3); 0.55ꢂ
0.49 (m, 2H, CH2Si). 13C-NMR (CDCl3, 50 8C) d
(ppm): 172.5 (CꢀOamide); 158.2 (CꢀOCbz); 136.5 (Carom
R); 128.3ꢂ127.7 (Carom H); 66.9 (CH2Cbz); 59.2 (C2);
58.3 (CH2CH3); 47.2ꢂ46.3 (CH2CH2CH2Si,
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3.49 (m, 4H, H5); 3.47ꢂ
3.16 (m, 4H, CH2ꢁ
1.82 (m, 4H, H4); 1.66ꢂ
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3.31 (m, 2H,
NH); 2.17ꢂ
1.57 (m,
to give 6.01 g (90%) of product. [a]2D0ꢀ
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ꢃ50.3 (1,
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EtOH). C35H54N4O5Si (639): Calc. C, 64.1; H, 8.2; N,
8.5. Found: C, 63.7; H, 8.4; N, 8.9%. IR (KBr, cmꢃ1):
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nꢀ
(Cꢁ
1H, NH); 7.40ꢂ
3.80 (q, 6H, 8.3 Hz, OCH2CH3); 3.50 (d, 2H, CH2Ph);
3.45 (m, 3H, CH2N, H5’); 3.34ꢂ3.26 (m, 2H, CH2N);
3.20ꢂ2.95 (m, 5H, CH2CH2CH2Si, H5’, H2?); 2.50ꢂ2.25
(m, 2H, H5); 2.23ꢂ2.05 (m, 2H, H3?); 1.85ꢂ1.74 (m, 2H,
H3); 1.76ꢂ1.50 (m, 4H, H4); 1.55 (m, 2H, CH2CH2Si);
1.19 (t, 9H, CH3); 0.52ꢂ
0.44 (m, 2H, CH2Si). 13C-NMR
(CDCl3, 40 8C) d (ppm): 175.16 (CꢀO); 138.36, 138.32
(C1Ph); 128.69, 128.54, 128.43, 128.40, (Co ꢁPh); 127.24,
127.16, (Cp ꢁPh); 67.16 (C2’); 62.44 (C2?); 59.87 (Ch2Ph);
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3400 (NH); 1700 (amide I); 1530 (amide II); 1098
1
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ꢁ
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Si). H-NMR (CDCl3, 40 8C) dꢀ
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7.70ꢂ
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7.50 (d, br,
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ꢁ
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7.28 (m, 10H, Ph); 3.91 (d, 2H, CH2Ph);
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CH2CH2NH,C5); 30.8 (CH2CH2NH); 26.4 (C3); 23.4
(C4); 18.1 (CH3); 13.9 (CH2CH2Si); 7.5 (CH2Si).
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2.2.1.2. N,N?-bis[(S)-prolyl]N-(2-aminoethyl-3-ami-
nopropyl)triethoxysilylethylenediamine. A mixture of
N,N?-bis[(S)-N-benzyloxycarbonylprolyl]-N-(2-ami-
noethyl-3-aminopropyl)triethoxysilylethylenediamine (1
g, 1 mmol), cyclohexene (0.31 g, 3.8 mmol) and 130 mg
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of commercial PdꢂC (10%) in 20 ml of ethanol was
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58.42 (OCH2); 57.78 (Ch2Ph); 54.10 (C5?); 52.90 (C5);
50.28 (CH2CH2CH2Si), 45.58, 38.77, 37.33 (CH2N);
30.74 (C3?); 29.48 (C3); 24.14 (C4?); 23.94 (C4); 22.90
(CH2CH2CH2Si); 18.27 (CH3); 7.70 (CH2Si). MSꢁ(m/
heated under reflux for 1 h in argon, cooled and filtered
over celite. The catalyst was washed with ethanol, and
filtrate and wash liquids were evaporated under reduced
pressure to give 620 mg of 1b. Yield: (98%). [a]2D0ꢀ
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ꢃ
/
z): 639 (Mꢁ); 435 (Mꢁ
/Si(OCH2CH3)3).
64.3 (1, EtOH). C21H42N4O5Si (459): Calc. C, 54.9; H,
9.1; N, 12.2. Found: C, 54.7; H, 9.4; N, 11.9%. IR (KBr,
cmꢃ1): nꢀ
(amide II); 1099 (Cꢁ
dꢀ7.87ꢂ7.80 (s br, 1H, NH); 5.54ꢂ
NH); 4.18ꢂ4.08 (m, 2H, H2); 3.70 (c, 6H, 8.3 Hz,
OCH2CH3); 3.49ꢂ3.20 (m, 4H, H5); 3.35ꢂ2.95 (m, 2H,
CH2CH2CH2Si); 2.97ꢂ2.88 (m, 4H, CH2ꢁNH); 2.17ꢂ
1.991 (m, 2H, H3); 1.97ꢂ1.41 (m, 8H, H3?, H4,
CH2CH2Si); 1.19 (t, 9H, 8.3 Hz, OCH2CH3); 0.68ꢂ
0.38 (m, 2H, CH2Si). 13C-NMR (CDCl3, 50 8C) d
(ppm): 166.3 (CꢀOamide); 61.3 (C2); 58.1 (CH2CH3);
47.0ꢂ46.5 (CH2CH2CH2Si, CH2CH2NH); 45.1 (C5);
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3428, 3342 (NH); 1692 (amide I); 1521
Si). 1H-NMR (CDCl3, 50 8C)
5.27 (s br, 1H,
2.2.2.2. Procedure B. To a solution of N,N?-bis[(S)-
prolyl]N-(2-aminoethyl-3-aminopropyl)triethoxysilyl-
ethylenediamine 1b (2 mmol) and triethylamine (1
mmol) in ice-cooled THF (25 ml), benzyl bromide (1
mmol), was added dropwise with vigorous stirring.
When the addition was finished the reaction mixture
was stirred for 6 h at 0 8C. The solvent was evaporated
and the residue extracted with chloroform and washed
successively with water, aqueous NaHCO3 and brine.
The organic layer was dried over magnesium sulphate
and evaporated in vacuo to give 2b. The product was
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