Ring-Opening Polymerization of a Racemic Lactide
FULL PAPER
Mg2SO4, the volatiles were evaporated to afford the product (1.6 g,
9.54 mmol) in 93% yield.
OH), 8.44 (s, 2H; ArCHN), 7.65–7.24 (m, 14H; ArH), 6.96 (t, J=7.8 Hz,
2H; ArH), 3.74 (t, J=6.6 Hz, 4H; CH2CH2CH2), 2.10 ppm (quin, J=
6.3 Hz, 2H; CH2CH2CH2); 13C NMR (75 MHz, CDCl3): d=165.79,
158.64, 137.80, 133.32, 130.79, 129.84, 129.36, 128.17, 127.15, 118.86,
118.60 (Ar and ArCHN), 56.48 (CH2CH2CH2), 31.51 ppm (CH2CH2CH2).
Bis([N-(tert-butoxycarbonyl)aminomethyl]dimethylsilane: A mixture of
bis(azidomethyl)dimethylsilane (919 mg, 5.4 mmol), PtO (98 mg,
0.43 mmol), and (Boc)2O (2.3 mL, 10.8 mmol) in EtOH (30 mL) was stir-
red at room temp. for 28 h under H2. After filtration of the reaction mix-
ture, the crude product was purified by flash column chromatography
(hexane/EtOAc=4/1) to afford the desired product (257 mg, 0.81 mmol,
15%).
1,3-Diamino-N,N’-bis(3,5-di-tert-butylsalicylidene)propane:
Yellow
powder (68% yield). 1H NMR (300 MHz, CDCl3): d=13.8 (s, 2H; OH),
8.39 (s, 2H; ArCHN), 7.39 (d, J=2.4 Hz, 2H; ArH), 7.09 (d, J=2.4 Hz,
2H; ArH), 3.71 (t, J=6.6 Hz, 4H; CH2CH2CH2), 2.12 (quin, J=6.6 Hz,
2H; CH2CH2CH2), 1.46 (s, 18H; C
C
N
Bis(aminomethyl)dimethylsilane dihydrochloride: Concentrated aqueous
HCl (30 mL) was added to bis([N-(tert-butoxycarbonyl)aminomethyldi-
methylsilane (257 mg, 0.81 mmol) and the mixture was stirred at room
temperature for 1 h. The reaction mixture was then heated to reflux for
12 h and the volatiles were subsequently evaporated to afford the desired
product (162 mg, quantitative) as a white solid.
A
A
1,3-Diamino-N,N’-bis(3-tert-butyl-5-chlorosalicylidene)propane:
Pale
yellow powder (91% yield). 1H NMR (300 MHz, CDCl3): d=13.99 (s,
2H; OH), 8.32 (s, 2H; ArCHN), 7.26 (d, J=2.1 Hz, 2H; ArH), 7.09 (d,
J=2.4 Hz, 2H; ArH), 3.74 (t, J=6.6 Hz, 4H; CH2CH2CH2), 2.16 (quin,
Ligand synthesis: All ligands were prepared by condensation of two
equivalents of the corresponding salicylaldehyde with the diamine in
EtOH.
J=6.8 Hz, 2H; CH2CH2CH2), 1.42 ppm (s, 18H; C
(75 MHz, CDCl3): d=165.18, 159.16, 139.80, 129.66, 128.45, 122.60,
119.24 (Ar and ArCHN), 56.80 (CH2CH2CH2), 35.01 (C(CH3)3), 31.47
(CH2CH2CH2), 29.03 ppm (C(CH3)3).
1,3-Diamino-N,N’-bis[3-(trimethylsilyl)salicylidene]propane:
A
General procedure: synthesis of N,N’-bis-[3-(tert-butyldimethylsilyl)sali-
AHCTREUNG
cylidene]-2,2-dimethyl-1,3-propanediamine:
1,3-Diamino-2,2-dimethyl-
AHCTREUNG
propane was added to a solution of 3-(tert-butyldimethylsilyl)-2-hydroxy-
benzaldehyde (1.5 g, 6.35 mmol) in EtOH (10 mL) at room temperature
and the mixture was stirred for several hours to afford a yellow suspen-
sion. After filtration, the product was recrystallized from EtOH/CHCl3 to
give a yellow, crystalline solid (1.67 g, 3.10 mmol, 98% yield). M.p. 113–
1148C; 1H NMR (400 MHz, CDCl3): d=13.58 (s, 2H; OH), 8.33 (s, 2H;
ArCHN), 7.43 (dd, J=2.0, 7.2 Hz, 2H; ArH), 7.28 (dd, J=2.0, 7.2 Hz,
2H; ArH), 6.89 (t, J=7.4 Hz, 2H; ArH), 3.48 (s, 4H; CH2CMe2CH2),
Yellow
1
powder (99% yield). H NMR (300 MHz, CDCl3): d=13.55 (s, 2H; OH),
8.37 (s, 2H; ArCHN), 7.42 (dd, J=1.8, 7.2 Hz, 2H; ArH), 7.25 (dd, J=
1.8, 7.5 Hz, 2H; ArH), 6.88 (t, J=7.2 Hz, 2H; ArH), 3.71 (t, J=6.6 Hz,
4H; CH2CH2CH2), 2.14 (quin, J=6.6 Hz, 2H; CH2CH2CH2), 0.33 ppm (s,
18H; Si
132.67, 127.26, 118.36, 117.61 (Ar and ArCHN), 56.92 (CH2CH2CH2),
31.61 (CH2CH2CH2), ꢁ1.22 ppm (Si(CH3)3).
A
AHCTREUNG
1.10 (s, 6H; CH2C
N
N
tBu(CH3)2Si); (400 MHz, C6D6): d=14.08 (s, 2H; OH), 7.90 (s, 2H;
R
1,3-Diamino-N,N’-bis[5-phenyl-3-(trimethylsilyl)salicylidene]propane:
Yellow powder (93% yield). 1H NMR (300 MHz, CDCl3): d=13.62 (s,
2H; OH), 8.45 (s, 2H; ArCHN), 7.63 (d, J=2.4 Hz, 2H; ArH), 7.55–7.51
(m, 4H; ArH), 7.46 (d, J=2.4 Hz, 2H; ArH), 7.44–7.38 (m, 4H; ArH),
7.34–7.28 (m, 2H; ArH), 3.76 (t, J=6.5 Hz, 4H; CH2CH2CH2), 2.18
ArCHN), 7.61 (dd, J=1.7, 7.2 Hz, 2H; ArH), 7.15 (dd, J=1.7, 7.5 Hz,
2H; ArH), 6.95 (t, J=7.4 Hz, 2H; ArH), 3.10 (s, 4H; CH2CMe2CH2),
1.23 (s, 18H; C
tBu
(CH3)2Si); 13C NMR (100 MHz, CDCl3): d=166.15, 166.09, 139.30,
132.80, 124.93, 117.99, 117.77 (Ar and ArCHN), 68.36 (CH2CMe2CH2),
36.34 (CH2CMe2CH2), 27.12 (C(CH3)3), 24.57 (CH2C(CH3)2CH2), 17.68
(C (CH3)2Si); (100 MHz, C6D6): d=166.56,
(CH3)3), ꢁ4.73 ppm (tBu
166.20, 139.57, 133.02, 125.02, 118.31, 118.16 (Ar and ArCHN), 67.96
(CH2CMe2CH2), 35.67 (CH2CMe2CH2), 27.23 (C(CH3)3), 24.07 (CH2C-
(CH3)2CH2), 17.77 (C (CH3)2Si); elemental analy-
A
G
ACHTREUNG
(quin, J=6.6 Hz, 2H; CH2CH2CH2), 0.37 ppm (s, 18H; Si(CH3)3);
A
N
13C NMR (75 MHz, CDCl3): d=165.87, 165.55, 140.91, 136.66, 131.57,
131.20, 128.83, 127.91, 126.72, 117.67 (Ar and ArC(Ph)N), 56.96
A
ACHTREUNG
(CH2CH2CH2), 31.51 (CH2CH2CH2), ꢁ1.17 ppm (Si
(CH3)3).
AHCTREUNG
1,3-Diamino-N,N’-bis[3-(3,5-di-tert-butylphenyl)-5-methylsalicylidene]-
1
A
(CH3)3), ꢁ4.60 ppm (tBu
ACHTREUNG
propane: Sticky solid (99% yield). H NMR (300 MHz, CDCl3): d=13.66
sis calcd (%) for C31H50N2O2Si2: C 69.09, H 9.35, N 5.20; found: C 69.10,
H 9.32, N 5.01.
(s, 2H; OH), 8.38 (s, 2H; ArCHN), 7.46 (d, J=1.8 Hz, 4H; Ar
tBu)H), 7.41 (t, J=2.0 Hz, 2H; Ar(di-tBu)H), 7.23 (d, J=2.1 Hz, 4H;
(di-
AHCTREUNG
1,3-Diamino-N,N’-bis(salicylidene)propane: Yellow, crystalline solid
(99% yield). 1H NMR (300 MHz, CDCl3): d=13.45 (s, 2H; OH), 8.38 (s,
2H; ArCHN), 7.35–7.23 (m, 4H; ArH), 6.98–6.85 (m, 4H; ArH), 3.72 (t,
J=6.6 Hz, 4H; CH2CH2CH2), 2.12 ppm (quin, J=6.9 Hz, 2H;
CH2CH2CH2); 13C NMR (75 MHz, CDCl3): d=165.54, 161.19, 132.33,
131.31, 118.76, 118.67, 117.01 (Ar and ArCHN), 56.76 (CH2CH2CH2),
31.60 ppm (CH2CH2CH2).
ArH), 7.03 (d, J=1.8 Hz, 2H; ArH), 3.71 (t, J=6.3 Hz, 4H;
CH2CH2CH2), 2.34 (s, 6H; ArCH3), 2.09 (quin, J=6.6 Hz, 2H;
CH2CH2CH2) 2.38 ppm (s, 36H; C
(CH3)); 13C NMR (75 MHz, CDCl3):
A
d=165.78, 156.27, 150.21, 136.89, 134.35, 130.67, 130.56, 127.50, 123.82,
121.23, 118.60 (Ar and ArCHN), 56.60 (CH2CH2CH2), 34.85
(CH2CH2CH2, C
N
N
1,3-Diamino-N,N’-bis(3,5-dibromosalicylidene)propane: Yellow powder
(66% yield). 1H NMR (300 MHz, CDCl3): d=14.51 (s, 2H; OH), 8.28 (s,
2H; ArCHN), 7.71 (d, J=7.7 Hz, 2H; ArH), 7.34 (d, J=2.4 Hz, 2H;
ArH), 3.78 (t, J=6.6 Hz, 4H; CH2CH2CH2), 2.14 ppm (quin, J=6.5 Hz,
2H; CH2CH2CH2); 13C NMR (75 MHz, CDCl3): d=164.10, 158.23,
137.88, 132.78, 119.81, 112.42, 109.62 (Ar and ArCHN), 55.72
(CH2CH2CH2), 31.09 ppm (CH2CH2CH2).
1,3-Diamino-N,N’-bis(3,5-dimethylsalicylidene)propane: Yellow powder
(89% yield). 1H NMR (300 MHz, CDCl3): d=13.46 (s, 2H; OH), 8.30 (s,
2H; ArCHN), 7.01 (s, 2H; ArH), 6.88 (s, 2H; ArH), 3.70 (t, J=6.6 Hz,
4H; CH2CH2CH2), 2.26 (s, 6H; CH3), 2.25 (s, 6H; CH3), 2.09 ppm (quin,
J=6.6 Hz, 2H; CH2CH2CH2); 13C NMR (75 MHz, CDCl3): d=165.66,
157.20, 134.31, 128.91, 127.13, 125.65, 117.66 (Ar and ArCHN), 56.71
(CH2CH2CH2), 31.67 (CH2CH2CH2), 20.23, 15.32 ppm (CH3).
1,3-Diamino-2,2-dimethyl-N,N’-bis(salicylidene)propane: Yellow, needle-
shaped crystals (99% yield). 1H NMR (300 MHz, CDCl3): d=13.58 (s,
2H; ArOH), 8.34 (s, 2H; ArCHN), 7.32 (t, J=7.5 Hz, 2H; ArH), 7.28
(d, J=7.8 Hz, 2H; ArH), 6.94 (d, J=8.1 Hz. 2H; ArH), 6.89 (t, J=
7.4 Hz, 2H; ArH), 3.49 (s, 4H; CH2CMe2CH2), 1.08 ppm (s, 6H; CH2C-
1,3-Diamino-N,N’-bis(3-isopropylsalicylidene)propane: Yellow syrup
(99% yield). 1H NMR (300 MHz, CDCl3): d=13.77 (s, 2H; OH), 8.38 (s,
2H; ArCHN), 7.29–7.28 (m, 2H; ArH), 7.12–7.09 (m, 2H; ArH), 6.86 (t,
J=7.5 Hz, 2H; ArH), 3.73 (t, J=6.6 Hz, 4H; CH2CH2CH2), 3.41 (sext,
J=7.2 Hz, 2H; CH
1.26 ppm (d, J=6.9 Hz, 12H; CH
d=165.91, 158.64, 136.36, 128.90, 118.35, 118.12 (Ar and ArCHN), 56.69
(CH2CH2CH2), 31.67 (CH2CH2CH2), 26.32 (CH(CH3)2), 22.37 ppm (CH-
(CH3)2).
G
ACHTREUNG
AHCTREUNG
AHCTREUNG
AHCTREUNG
1,3-Diamino-2,2-dimethyl-N,N’-bis(3-phenylsalicylidene)propane: Yellow,
crystalline solid (99% yield). M.p. 150–1518C; 1H NMR (300 MHz,
CDCl3): d=14.03 (s, 2H; ArOH), 8.40 (s, 2H; ArCHN), 7.65–7.27, 6.96
(m, 16H; ArH), 3.51 (s, 4H; CH2CMe2CH2), 1.06 ppm (s, 6H; CH2C-
ACHTREUNG
1,3-Diamino-N,N’-bis(3-phenylsalicylidene)propane: Deep yellow, crystal-
line solid (98% yield). 1H NMR (300 MHz, CDCl3): d=14.07 (s, 2H;
Chem. Eur. J. 2007, 13, 4433 – 4451
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4447