Y. Zhong et al.
Carbohydrate Research 503 (2021) 108311
Fig. 4. Effects of compound 6 on the cell cycle distribution of A431 cells.
mL) was reflux for 1 h till the mixture was completely dissolved. Then
the solution was cooled to r.t., and a solution of AcCl in toluene (10% v/
v, 0.3 mL) was added dropwise. The resulting solution was stirred for 8
h, concentrated and purified through a silica gel column chromatog-
raphy (10:1, petroleum ether-EtOAc) to afford 19 (100 mg, 32% for
three steps) as a white foam. The mixture of compound 19 (200 mg,
0.25 mmol) and 10% Pd–C (20 mg) in EtOAc (20 mL) was stirred under
H2 for 4 h. Pd–C was removed through filtration, and the filtrate was
concentrated and purified by a silica gel column chromatography (2:1,
petroleum ether-acetone) to afford 4 (110 mg, 70.7%) as a white foam.
(3.5:1, petroleum ether-acetone) to afford 5 (220 mg) as a white foam.
[α]25 D = +54.2 (c 1.03, CHCl3); Rf = 0.4 (2:1, petroleum ether-
acetone); Mp 251.2–254.2 ◦C; 1H NMR (CDCl3, 600 MHz): 5.28 (t, 1H,
J = 3.6 Hz, H-12), 5.24 (t, 1H, J = 1.8 Hz, H-4′), 4.95 (dd, 1H, J = 10.2,
3.6 Hz, H-3′), 4.33 (d, 1H, J = 7.2 Hz, H-1′), 3.98 (dd, 1H, J = 13.2, 1.8
Hz, H-5′-1), 3.87 (dd, 1H, J = 10.2, 7.8 Hz, H-2′), 3.62 (d, 1H, J = 12.6
Hz, H-5′-2), 3.18 (dd, 1H, J = 12.0, 4.8 Hz, H-3), 2.82 (dd, 1H, J = 13.8,
4.2 Hz, H-18), 2.12 (s, 3H, CH3CO), 2.07 (s, 3H, CH3CO), 1.12, 1.01,
0.93, 0.92, 0.90, 0.83, 0.74 (s, 7 × 3H, Me); 13C NMR (CDCl3, 150 MHz):
183.7, 170.4, 143.6, 122.6, 105.6, 90.1, 72.2, 70.0, 68.3, 64.2, 55.5,
46.5, 41.5, 40.9, 39.3, 39.0, 36.8, 33.1, 30.6, 29.7, 28.3, 26.0, 23.6,
22.7, 20.9, 20.8, 17.1, 16.6, 15.3, 14.1. ESI-MS (m/z): 695.7 [ (M + Na)+
], 711.7 [ (M + K)+ ].
[α]25 D = +61.0 (c 1.05, CHCl3); Rf = 0.4 (1:1, petroleum ether-
1
◦
acetone); Mp 270.5–274.0 C; H NMR (CDCl3, 600 MHz): 5.21 (br s,
1H, H-12), 4.81 (dd, 1H, J = 9.6 Hz, 3, H-3′), 4.25 (d, 1H, J = 7.2 Hz, H-
1′), 3.96 (br s, 1H, H-4′), 3.79 (dd, 1H, J = 12.6, 2.4 Hz, H-5′-1), 3.51
(dd, 1H, J = 9.6, 7.2 Hz, H-2′), 3.11 (dd, 1H, J = 12, 4.8 Hz, H-3), 2.75
(dd, 1H, J = 13.8, 3 Hz, H-18), 2.10 (s, 3H, CH3CO), 1.05, 0.93, 0.86,
0.85, 0.83, 0.74, 0.67 (s, 7 × 3H, Me); 13C NMR (CDCl3, 150 MHz):
183.2, 170.7, 143.6, 122.6, 105.6, 104.9, 90.1, 89.8, 74.6, 70.2, 67.2,
65.9, 65.6, 55.5, 47.6, 46.5, 45.9, 41.2, 40.9, 39.3, 39.1, 38.4, 36.8,
33.8, 33.1, 30.7, 28.3, 27.7, 25.9, 23.6, 21.1, 18.1, 17.1, 16.6, 15.3. ESI-
MS (m/z): 629.2 [ (M ꢀ H)-].
5 Oleanolic acid 3-O-(2′,4′-di-O-acetyl)-
α-L-arabinopyranoside (6)
A solution of 16 (960 mg, 1.33 mmol), CH3C(OEt)3 (1.22 mL, 6.65
mmol) and TsOH (23 mg) in CH2Cl2 (50 mL) was stirred at rt for 5 h,
then the solvent was removed in vacuum. The mixture was then dis-
soloved in 50% aq HOAc (10 mL) and vigorous stirred overnight.
Coevaporation with toluene and purified by a silica gel column chro-
matography (3:1, petroleum ether-acetone) to afford 21 (810 mg,
79.7%) as a white foam. To a mixture of compounds 21 (690 mg, 0.90
mmol) and 10% Pd–C (69 mg) in EtOAc (50 mL) was stirred under H2 for
4 h. Pd–C was removed through filtration and the filtrate was concen-
trated and purified by a silica gel column chromatography (6:1, petro-
4 Oleanolic acid 3-O-(3′,4′-di-O-acetyl)-
α-L-arabinopyranoside (5)
To a solution of compound 18 (390 mg, 0.51 mmol) in pyridine (10
mL) stirred at rt was added acetic anhydride. The mixture was stirred for
12 h followed by addition of water (10 mL). The reaction mixture was
extracted with CH2Cl2 (15 mL) for three times. The organic layer was
separated and successively washed with water, diluted HCl, saturated
NaHCO3 and saturated NaCl, dried Na2SO4 and concentrated to afford
crude 20 Rf = 0.8 (2:1, petroleum ether-acetone). To a mixture of
compounds 20 and 10% Pd–C (43 mg) in EtOAc (20 mL) was stirred
under H2 for 4 h. Pd–C was removed through filtration and the filtrate
was concentrated and purified by a silica gel column chromatography
leum ether-acetone) to afford 6 (420 mg, 69.0%) as a white foam. [α]25
D = +78.2 (c 1.10, CHCl3); Rf = 0.3 (3:1, petroleum ether-acetone); Mp
176.5–181.6 ◦C; 1H NMR (CDCl3, 600 MHz): 5.27 (s, 1H, H-12), 5.03 (d,
1H, J = 6 Hz, H-4′), 5.00 (t, 1H, J = 8.4 Hz, H-2′), 4.56 (d, 1H, J = 8.4
Hz, H-1′), 4.05–3.88 (m, 2H, J = 12.6, 2.4 Hz, H-3′, H-5′-1), 3.57 (br d,
1H, J = 13.2 Hz, H-5′-2), 3.11 (dd, 1H, J = 11.4, 4.2 Hz, H-3), 2.82 (br d,
1H, J = 10.2 Hz, H-18), 2.14 (s, 3H, CH3CO), 2.13 (s, 3H,CH3CO), 1.26,
1.12, 0.97, 0.92, 0.90, 0.78, 0.74 (s, 7 × 3H, Me); 13C NMR (CDCl3, 150
6