Z. Liang et al. / European Journal of Medicinal Chemistry 46 (2011) 2011e2021
2019
Ocean Chemical Company, China). IR spectra were recorded on
Shimadzu FTIR-8400S spectrometer. 1H and 13C NMR spectra were
measured on a Bruker AV-300 spectrometer. Chemical shifts are
CH2Cl2 (10 mL) was added p-nitrobenzoyl chloride (0.81 g,
4.40 mmol). After stirring at room temperature overnight, the
reaction mixture was filtered, and the filtrate was diluted with
water (20 mL), and extracted with CH2Cl2 (3 ꢂ10 mL). The
combined organic layers were washed with water and brine, dried
(Na2SO4), filtered, and concentrated. Purification by flash column
chromatography (petroleum ether/AcOEt 90:1, v/v) afforded P23
(0.48 g, 79%) as a light yellow solid. M.p.182e184 ꢁC. IR (KBr, cmꢀ1):
reported as
d values from an internal tetramethylsilane standard.
Mass spectral data were obtained on Agilent 1100 LC/DAD/MSD or
Q-Tof Micro MS/MS.
4.4.1. Benzyl 3b-(2-chloroacetoxy)olean-12-en-28-oate (P20)
To a mixture of benzyl oleanolate 2 (5.00 g, 9.20 mmol), K2CO3
(25.00 g, 0.18 mol) and DMAP (0.12 g, 0.92 mmol) in CH2Cl2
(200 mL) was added dropwise chloroacetyl chloride (14.30 mL,
0.18 mol) over a period of 30 min. After stirring at 0 ꢁC for 24 h, the
reaction mixture was filtered, and the filtrate was diluted with
water (300 mL), and extracted with CH2Cl2 (3 ꢂ 200 mL). The
combined organic layers were washed with water and brine, dried
(Na2SO4), filtered, and concentrated. Purification by flash column
chromatography (petroleum ether/AcOEt 200: 1, v/v) afforded P20
(5.80 g, 89%) as a white solid. M.p. 174e176 ꢁC. IR (KBr, cmꢀ1): 2947,
2946, 1721, 1529, 1102. 1H NMR (CDCl3, 300 MHz)
d 0.64, 0.91, 0.93,
0.94, 0.97, 1.02, 1.15 (each 3H, s), 2.92 (1H, dd, J ¼ 4.0, 14.1 Hz),
4.75e4.80 (1H, m), 5.05 (1H, d, J ¼ 12.3 Hz), 5.11 (1H, d, J ¼ 12.3 Hz),
5.30 (1H, br s), 7.30e7.35 (5H, m), 8.19 (2H, d, J ¼ 8.7 Hz), 8.29 (2H, d,
J ¼ 8.7 Hz). 13C NMR (CDCl3, 75 MHz)
d 177.3; 164.3; 150.4; 143.7;
130.5; 128.3; 127.9; 127.8; 123.4; 122.3; 82.9; 77.4; 76.9; 76.5; 65.9;
55.3; 47.5; 46.7; 45.9; 41.7; 41.4; 39.3; 38.1; 36.9; 33.8; 33.0; 32.6;
32.3; 30.6; 28.2; 27.6; 25.8; 23.6; 23.5; 23.4; 23.0; 18.2; 17.0; 16.9;
15.3. ESIMS m/z: [M þ Na]þ calcd for C44H57NNaO6: 718.4; found:
718.3.
1727, 1462, 1174. 1H NMR (CDCl3, 300 MHz)
d 0.61, 0.87, 0.88, 0.90,
0.91, 0.92,1.12 (each 3H, s), 2.92 (1H, dd, J ¼ 4.2,14.1 Hz), 4.04 (2H, s),
4.55e4.60 (1H, m), 5.04 (1H, d, J ¼ 12.3 Hz), 5.10 (1H, d,
J ¼ 12.3 Hz), 5.28 (1H, t, J ¼ 3.5 Hz), 7.29e7.36 (5H, m). ESIMS m/
z: [M þ Na]þ calcd for C39H55ClNaO4: 645.4; found: 645.2.
4.4.5. Benzyl 3b-(4-aminobenzoyloxy)olean-12-en-28-oate (P24)
A solution of P23 (42 mg, 0.06 mmol) in methanol (5 mL) was
cooled to 0 ꢁC and added dropwise hydrazine (1 mL). After addition
of Raney nickel (20 mg), the suspension was heated to reflux for 4 h
and then stirred at 40 ꢁC overnight. The mixture was filtered, and
the filtrate was concentrated. Purification by flash column chro-
matography (petroleum ether/AcOEt 90:1, v/v) afforded P24 (7 mg,
4.4.2. Benzyl 3b-(2-azidoacetoxy)olean-12-en-28-oate (P21)
A solution of P20 (0.18 g, 0.29 mmol) in DMF (10 mL) was added
sodium azide (0.03 g, 0.45 mmol) in three portions during 30 min.
The mixture was stirred for 4 h at 75 ꢁC before it was quenched
with water (20 mL). The mixture was extracted with EtOAc
(3 ꢂ 10 mL). The combined organic layers were washed with water
and brine, dried (Na2SO4), filtered, and concentrated. Purification
by flash column chromatography (petroleum ether/AcOEt 50: 1, v/v)
afforded P21 (0.17 g, 92%) as a white solid. M.p. 135e137 ꢁC. IR
(KBr, cmꢀ1): 2947, 2106, 1730, 1462. 1H NMR (CDCl3, 300 MHz)
18%). M.p. 204e206 ꢁC. 1H NMR (CDCl3, 300 MHz)
d 0.63, 0.90, 0.92,
0.94, 0.98, 1.14, 1.29 (each 3H, s), 2.91 (1H, d, J ¼ 10.7 Hz), 4.12 (2H,
br s), 4.65e4.70 (1H, m), 5.05 (1H, d, J ¼ 12.6 Hz), 5.11 (1H, d,
J ¼ 12.6 Hz), 5.30 (1H, t, J ¼ 3.4 Hz), 6.66 (2H, d, J ¼ 8.7 Hz),
7.29e7.36 (5H, m), 7.85 (2H, d, J ¼ 8.7 Hz). 13C NMR (CDCl3, 75 MHz)
d
177.4; 166.3; 150.5; 143.7; 136.5; 131.5; 128.0; 127.8; 122.5; 120.8;
113.8; 80.7; 65.9; 55.4; 47.6; 46.8; 45.9; 41.7; 41.4; 39.4; 38.2; 38.1;
37.0; 33.9; 33.0; 32.7; 32.4; 30.7; 29.6; 28.3; 27.6; 25.8; 23.7; 23.6;
23.4; 23.1; 22.6; 18.2; 17.0; 16.9; 15.3. ESIMS m/z: [M þ H]þ calcd for
C44H60NO4: 666.5; found: 666.4.
d
0.61, 0.88, 0.89, 0.90, 0.92, 1.13, 1.55 (each 3H, s), 2.90 (1H, dd,
J ¼ 4.3, 13.8 Hz), 3.85 (2H, s), 4.658e4.64 (1H, m), 5.04 (1H, dd,
J ¼ 12.6, 17.3 Hz), 5.09 (1H, dd, J ¼ 12.6, 17.3 Hz), 5.29 (1H, t,
J ¼ 3.5 Hz), 7.29e7.36 (5H, m). ESIMS m/z: [M þ Na]þ calcd for
C39H55N3NaO4: 652.4; found: 652.3.
4.4.6. Propargyl phenylacetate (6)
To a solution of phenylacetic acid (0.46 g, 3.40 mmol) in DMF
(10 ml) were added propargyl bromide (0.45 g, 3.80 mmol) and
K2CO3 (0.94 g, 6.80 mmol). The reaction mixture was stirred at
room temperature overnight and then filtered. The filtrate was
diluted with water (20 ml), and extracted with EtOAc (3 ꢂ 10 mL).
The combined organic layers were washed with water and brine,
dried (Na2SO4), filtered, and the filtrate was evaporated under
vacuum to give 6, which was used for next reaction without further
purification.
4.4.3. Benzyl 3b-(2-(diethylamino)acetoxy)olean-12-en-28-oate
(P22)
To a mixture of P20 (0.30 g, 0.48 mmol) and K2CO3 (0.13 g,
0.96 mmol) in DMF (15 mL) was added diethylamine (0.11 mL,
0.96 mmol). The mixture was stirred at room temperature over-
night and then the reaction mixture was filtered, and the filtrate
was diluted with water (30 mL), and extracted with EtOAc
(3 ꢂ 15 mL). The combined organic layers were washed with water
and brine, dried (Na2SO4), filtered, and concentrated. Purification
by flash column chromatography (petroleum ether/AcOEt 10:1, v/v)
afforded P22 (0.22 g, 68%) as a white solid. M.p. 53e55 ꢁC. IR (KBr,
4.4.7. Benzyl 3b-(2-{4-[(2-phenylacetoxy)methyl]-1H-1,2,3-triazol-
1-yl}acetoxy)olean-12-en-28-oate (P26)
To a solution of P21 (0.30 g, 0.48 mmol) and 6 (83.00 mg,
0.48 mmol) in CH2Cl2 (1.5 mL) and H2O (1.5 mL) were added
CuSO4$5H2O (23.70 mg, 0.095 mmol) and sodium ascorbate
(37.97 mg, 0.19 mmol). The resulting solution was stirred at room
temperature overnight. The reaction mixture was diluted with
water (5 mL) and extracted with CH2Cl2 (3 ꢂ 2 mL). The combined
organic layers were washed with water and brine, dried (Na2SO4),
filtered, and concentrated. Purification by flash column chroma-
tography (petroleum ether/AcOEt 3:1, v/v) afforded P26 (0.36 g,
94.5%). M.p. 75e76 ꢁC. IR (KBr, cmꢀ1): 2947, 1738, 1454, 1158. 1H
cmꢀ1): 2966, 1725, 1455, 1175. 1H NMR (CDCl3, 300 MHz):
d 0.67,
0.93, 0.95, 0.97, 0.99, 1.12, 1.14, 1.16, 1.19 (each 3H, s), 2.74 (4H, qua),
2.97 (1H, d, J ¼ 10.2 Hz), 3.40 (2H, s), 4.59e4.64 (1H, m), 5.03 (1H,
dd, J ¼ 12.5, 17.6 Hz), 5.09 (1H, dd, J ¼ 12.5, 17.6 Hz), 5.35 (1H, t,
J ¼ 3.5 Hz), 7.34e7.42 (5H, m). 13C NMR (CDCl3, 75 MHz)
d 177.4;
171.3; 143.7; 136.4; 128.3; 127.9; 127.8; 122.4; 80.9; 65.8; 55.2;
54.1; 47.7; 47.5; 46.7; 45.8; 41.6; 41.4; 39.3; 38.1; 37.6; 36.8; 33.8;
33.0; 32.6; 32.3; 30.6; 28.0; 27.6; 25.8; 23.6; 23.3; 23.0; 18.2; 16.9;
16.8; 15.3; 12.4. ESIMS m/z: [M þ H]þ calcd for C43H66NO4: 660.5;
found: 660.5.
NMR (CDCl3, 300 MHz) d 0.60, 0.73, 0.83, 0.89, 0.90, 0.92, 1.12 (each
3H, s), 2.90 (1H, d, J ¼ 10.2 Hz), 3.64 (2H, s), 4.54e4.60 (1H, m), 5.02
(1H, d, J ¼ 12.6 Hz), 5.08 (1H, d, J ¼ 12.6 Hz), 5.12 (2H, s), 5.27 (2H, s),
5.27 (1H, br s), 7.25e7.30 (4H, m), 7.34 (5H, s), 7.67 (1H, s). 13C NMR
4.4.4. Benzyl 3b-(4-nitrobenzoyloxy)olean-12-en-28-oate (P23)
To a mixture of oleanolic acid benzyl ester 2 (0.48 g, 0.88 mmol),
NaHCO3 (0.30 g, 3.5 mmol) and DMAP (11.00 mg, 0.09 mmol) in
(CDCl3, 75 MHz) d 177.3; 171.4; 165.7; 143.7; 143.2; 136.4; 133.6;