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TOPUZYAN et al.
1
-aminobutyric acid (IIb), 0.85 g (8.42 mmol) of
IR spectrum, , cm : 1778 (C O), 1765 (C N),
1642 (C C). Found, %: C 74.53; H 5.89; N 4.21.
C19H17NO3. Calculated, %: C 74.25; H 5.57; N 4.56.
triethylamine, and 0.87 g (4.21 mmol) of reagent I.
1
Yield 81%. IR spectrum, , cm : 3255 (N H), 1750
1
(C O, ester), 1685 (C O, amide). H NMR spec-
4-p-Methoxybenzylidene-2-phenyl-4,5-dihydro-
1,3-oxazol-5-one (Vd). mp 157 159; published data
[3]: mp 159 161 C. IR spectrum, , cm : 1780
trum (CDCl3), , ppm: 1.16 t (3H, CH3, J = 7.2 Hz),
1.71 q (2H, -CH2, -Abu, J = 7.1 Hz), 2.20 t (2H,
-CH2, -Abu, J = 7.5 Hz), 3.06 t (2H, -CH2, -Abu,
J = 6.5 Hz), 4.03 q (2H, OCH2, J = 7.1 Hz), 5.00 s
(2H, ArCH2O), 5.86 br.s (1H, NH), 7.25 m (5H,
1
(C O), 1767 (C N), 1647 (C C).
b. To a solution of 1 g (2.4 mmol) of N-benzoyl-
O-isopropyl- , -dehydrotyrosine (IIc) and 0.49 g
(4.8 mmol) of triethylamine in 15 ml of acetonitrile
we added 0.5 g (2.4 mmol) of 3-ethoxycarbonylbenzo-
triazole 1-oxide (I), and the mixture was left to stand
for 24 h at 18 20 C. It was then treated as described
above in a. The residue was ground with ether
(3 10 ml), and the precipitate was filtered off and
washed with ether. The product was a colorless
amorphous substance which was a mixture of two
compounds (according to the TLC data) with Rf 0.24
H
arom). Found, %: N 5.04. C14H19NO4. Calculated, %:
N 5.28.
N-Benzoyl-O-isopropyl- , -dehydrotyrosine
ethyl ester (IIIc). A mixture of 1 g (2.4 mmol) of
N-benzoyl-O-isopropyl- , -dehydrotyrosine (IIc) and
0.2 ml of sulfuric acid in 7 ml of ethyl acetate was
stirred for 24 h at room temperature. The light yellow
solution was diluted with ethyl acetate (50 ml), treated
with a 5% solution of sodium hydrogen carbonate
(2 25 ml) and with water until neutral reaction, and
dried over sodium sulfate. The solvent was removed
under reduced pressure, the residue was ground with
ether (2 10 ml), and the precipitate was filtered off
and washed with ether. Yield 0.6 g (56%). mp 107
1
and 0.44. The H NMR spectrum of this mixture is
shown in Fig. 1. After removal of the solvent, we
isolated 0.1 g of yellow oxazolone Vc. mp 150
153 C. IR spectrum, , cm : 1778 (C O), 1765
1
(C N), 1642 (C C).
1
108 C. Rf 0.45. IR spectrum, , cm : 3235 (N H),
N-(N-Benzoyl-O-isopropyl- , -dehydrotyrosyl)-
-butyrolactam (IVc). Acetic anhydride, 0.49 g
(4.8 mmol), was added to a solution of 1 g (2.4 mmol)
of dipeptide IIc and 0.49 g (4.8 mmol) of triethyl-
amine in 10 ml of acetonitrile, and the mixture was
left to stand for 24 h at 18 20 C. The mixture was
then treated as described above in a. The residue was
ground with ether (2 10 ml), and the precipitate was
filtered off and washed with ether. Yield 0.57 g
(78%). mp 147 148 C (from acetonitrile). Rf 0.27.
1H NMR spectrum (DMSO-d6), , ppm: 1.26 d (6H,
CH3, J = 6.0 Hz), 1.91 m (2H, -CH2, Abu), 2.42 t
(2H, -CH2, Abu, J = 7.7 Hz), 3.70 t (2H, -CH2,
Abu, J = 7.2 Hz), 4.66 m (1H, CHO, J = 6.0 Hz),
6.67 s (1H, -CH, -Tyr), 6.94 d (2H, m-H, -Tyr,
J = 9.0 Hz), 7.59 d (2H, o-H, -Tyr, J = 9.0 Hz),
7.94 d (2H, o-H, Bz, J = 8.2 Hz), 7.50 m (2H, m-H,
Bz, J = 8.0 Hz), 7.59 m (1H, p-H, Bz, J = 8.0 Hz),
10.10 s (1H, NH). 13C NMR spectrum (DMSO-d6,
1750 (C O, ester), 1650 (C O, amide), 1615 (C C).
1H NMR spectrum (CDCl3), , ppm: 1.17 t (3H, CH3,
J = 7.2 Hz), 1.25 d (6H, CMe2, J = 6.6 Hz), 1.75 q
(2H, -CH2, -Abu, J = 7.1 Hz), 2.32 t (2H, -CH2,
-Abu, J = 7.4 Hz), 3.20 q (2H, -CH2, -Abu, J =
6.5 Hz), 4.06 q (2H, OCH2, J = 7.2 Hz), 4.63 m
(1H, OCH), 7.20 s (1H, -CH, -Tyr), 6.85 8.20 m
(9H, Harom), 7.86 t (1H, NH, -Abu, J = 6.0 Hz),
9.62 s (1H, NH, -Tyr). From the ether solution we
isolated 0.09 g (12%) of oxazolone Vc. mp 151
153 C. Rf 0.89.
Reaction of N-substituted , -dehydrodipeptides
IIc and IId with 3-ethoxycarbonylbenzotriazole
1-oxide (I). a. A mixture of 2.5 mmol of N-benzoyl-
, -dehydrodipeptide IIc or IId, 5 10 mmol of tri-
ethylamine, 2.5 mmol of compound I, and 10 ml of
acetonitrile was refluxed for 3 5 h on a water bath.
The solvent was removed, the residue was dissolved
in 50 ml of chloroform, and the solution was washed
with a 5% solution of sodium hydrogen carbonate
(2 25 ml), water (25 ml), 1 N hydrochloric acid
(2 25 ml), and water again (until neutral reaction).
The organic phase was dried with calcium chloride
and evaporated, and the residue was recrystallized
from ethanol.
75.46 MHz), C, ppm: 45.03 (C3); 17.14 (C2); 31.81
(C3); 60.40 (C4); 21.09 (C5); 114.50 (C6); 130.85
(C7); 127.15 (C8); 127.91 (C9); 127.32 (C10); 131.05
(C11); 157.28 (C13); 125.39, 128.07, 132.54 (C12, C13,
C14, C15); 164.95, 167.12, 172.35 (CO).
Removal of the solvent from the ether solution
gave 0.1 g (14%) of oxazolone Vc with mp 152
154 C. Rf 0.89.
4-p-Isopropoxybenzylidene-2-phenyl-4,5-di-
hydro-1,3-oxazol-5-one (Vc). mp 151 153 C [2].
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 3 2001