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thionylchloride were removed by distillation. The solid prod-
uct hydrochloride salt of the above methyl ester of L-
phenylalanine (33.8 g, 0.157 mol) was stirred in sodium car-
bonate solution (33.0 g, 0.314 mol, 330 mL H2O, 150 mL of
DCM) at 5 8C in open atmosphere. At 0 8C, methyl chlorofor-
mate (24.0 mL, 0.310 mol) was added drop wise and the
reaction was continued for 12 h at 25 8C. The reaction mix-
ture was extracted with dichloromethane and the organic
layer was dried over anhydrous Na2SO4. The liquid was fur-
ther purified by passing through silica gel column using
ethyl acetate and pet ether (1:4 v/v) as eluent. Yield 5 35.1g
(93%). 1H NMR (400MHz, CDCl3) d ppm: 7.32–7.24 (m, 3H,
ArH), 7.12 (d, 2H, ArH), 5.12 (b, 1H, ANH), 4.64 (q, 1H,
CHCH2Ar), 3.73 (s, 3H, COOCH3), 3.67 (s, 3H, NHCOOCH3),
3.11 (d, 2H, CH2Ar). 13C-NMR (100MHz, CDCl3) d ppm:
172.95, 156.24, 135.69, 129.15 (2C), 128.52 (2C), 127.06,
54.69, 52.24(2C), 38.13. FT-IR (cm21): 3338, 2954, 1705,
1518, 1444, 1355, 1253, 1210 and 1057. HR-MS (ESI1): m/
z [M1Na1] calcd. for C12H15NO4 [M1]: 260.0898; Found:
260.0899.
the similar procedure the details are provided in the Sup-
porting Information.
Model Reaction for Entries 1–11
Herein, the reaction is described for 1-decanol with the L-
valine monomer. L-Valine monomer (0.50 g, 0.003 mol) and
1-decanol (0.43 g, 0.003 mol) were taken in a test tube
shaped apparatus and melted by placing in an oil bath at
100 8C with constant stirring. The condensation apparatus
was made oxygen and moisture free by purging with nitro-
gen under constant stirring. After degassing Titanium tetra-
butoxide (0.018 g, 0.05 mmol) was added and the
condensation was carried out at 120 8C under nitrogen
purge for 4 h. At the end of the condensation reaction, the
product was obtained as colorless liquid. Yield 5 0.69 g
1
(83%) H NMR (400 MHz, CDCl3) d ppm: 5.21 (b, 1H, ANH),
4.29 (m, 1H, CH), 4.14 (m, 2H, COOCH2), 3.69 (s, 3H,
NHCOOCH3), 2.15 (m, 1H, CH), 1.64 (d, 2H, CH2), 1.27 (m,
14H, CH2), 0.97 (d, 3H, CH3), and 0.88 (m, 6H, CH3) 13C-
NMR (100 MHz, CDCl3) d ppm: 172.3, 157.0, 65.5, 59.0, 52.4,
31.9, 29.6, 29.4, 28.6, 25.9, 22.8, 19.0, 17.5, and 14.2. FT-IR
(cm21): 3742, 3357, 2925, 2856, 2360, 1714, 1525, 1456,
1343, 1304, 1257, 1206, 1178, and 1073. HRMS (ESI): m/z
[M 1 H]1 calcd. For C17H34NO4: 316.2489; found: 316.2486.
Dual ester-urethane monomers of other amino acids: glycine,
b-alanine, L-valine, D-valine, L-leucine, L-alanine, D-alanine,
and D-phenyl alanine were prepared as described above and
details are provided in the Supporting Information.
Model Reaction for Entries 12–16
Herein, the model reactions were carried out at 120 8C;
amino acid monomer and diol were taken as the ratio of 1.0:
0.5 equivalents. The rest of the procedure are similar as pro-
vided in the model reaction entries 1–11. Herein, described
for L-valine monomer (0.91 g, 0.048 mol) with 1,5-pentane-
diol (0.26 g, 0.024 mol) at 120 8C in presence of Ti(OBu)4
catalyst (0.018 g, 0.052 mmol, 1 mol %). Yield 5 0.74 g
Synthesis of Poly(ester-urethane)s Via Dual
Ester-Urethane Melt Polycondensation
Herein, we described for dual ester-urethane melt polymer-
ization procedure for L-Phenylalanine monomer with 1,12-
dodecanediol. Equimolar amounts of amino acid monomer L-
Phenylalanine monomer (0.53 g, 0.002 mol) and 1, 12-
dodecanediol (0.45 g, 0.002 mol) were taken in a test tube-
shaped polymerization vessel and melted by placing the tube
in oil bath at 100 8C. The polycondensation apparatus was
made oxygen and moisture free by purging with nitrogen
and subsequent evacuation by vacuum under constant stir-
ring. Titanium isopropoxide (6.3 mg, 0.02 mmol, 1.0 mol %)
was added as catalyst and the melt polycondensation was
carried out at 150 8C for 4 h with constant stirring under
nitrogen purge. During this stage, the methanol was removed
along with the purge gas and the polymerization mixture
became viscous. The viscous melt was further subjected to
high vacuum (0.01 mmHg) at 150 8C for 2 h under stirring.
At the end of the polycondensation, poly(ester-urethane),
was obtained as a viscocus product. It was purified by dis-
solving in tetrahydrafuran, filtered and precipitated into
1
(71%). Colorless oil; eluent (30% ethyl acetate in hexane) H
NMR (400MHz, CDCl3) d ppm: 5.31 (b, 2H, ANH), 4.21 (m,
1H, CH), 4.07 (t, 4H, COOCH2), 3.61 (s, 6H, NHCOOCH3), 3.61
(m, 2H, ACH), 1.62 (m, 4H, CH2), 1.36 (m, 2H, CH2), and
0.91–0.82 (d, 12H, CH3). 13C-NMR (100MHz, CDCl3) d ppm:
172.2, 156.9, 64.9, 59.1, 52.3, 31.2, 28.1, 22.4, 19.0, and 17.5.
FT-IR (cm21): 3340, 2962, 1706, 1519, 1461, 1351, 1309,
1238, 1189, 1096, and 1031. HRMS (ESI): m/z [M 1 H]1
calcd. for C19H35N2O8: 419.2394; found: 419.2393.
The other model compounds were synthesised by similar
procedure the details are provided in the Supporting
Information.
Model Reaction for Entries 17–19
1
The model reaction is described for 1-decanol with the L-
valine monomer at 150 8C. 1-Decanol (2.01 g, 0.013 mol)
and L-valine monomer (1.21 g, 0.006 mol) were taken in
polymerization apparatus and melted by placing in an oil
bath at 100 8C with constant stirring. After degassing, Tita-
nium tetrabutoxide (0.023 g, 0.006 mmol) was added and
the condensation was carried out at 150 8C under nitrogen
purge for 4 h. Further, controlled vacuum (1 mm of Hg) was
applied at 150 8C for 1 h. Yield52.32 g (83%). Colorless oil;
Eluent (5% ethyl acetate in hexane) 1H NMR (400MHz,
CDCl3) d ppm: 5.14 (b, 1H, ANH), 4.25 (m, 1H, CH), 4.10
methanol to obtain fibrous product. Yield 5 0.63 g (75%). H
NMR (400 MHz, CDCl3) d ppm: 7.31–7.12 (m, 5H, ArH), 5.13
(b, 1H, NH), 4.62 (m, 1H, CH), 4.10–4.04 (m, 4H, COOCH2,
NHCOOCH2), 3.10 (t, 2H, CH2Ar), 1.56–1.25 (m, 20H, CH2).
13C-NMR (100MHz, CDCl3) d ppm: 171.74, 155.93, 135.85,
129.25, 128.46, 126.98, 65.56, 65.29, 54.65, 38.35, 29.50,
29.16, 28.89, 28.38, and 25.76. FT-IR (cm21): 3348, 2924,
2853, 1717, 1505, 1458, 1397, 1346, 1249, 1196, and 1057.
All other amino acid based linear poly(ester-urethane) with
various amino acid monomers and catalysts were done using
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