488
L. Borkova et al. / European Journal of Medicinal Chemistry 96 (2015) 482e490
purity wasn't sufficient yet, the sample was chromatographed on
preparative HPLC in hexane/EtOAc 9:1 to give difluoroallobetulin
4.2.12. 3b
-O-30,30-dimethylhemisuccinyl-2,2-
difluorodihydrobetulinic acid (18)
14 (850 mg; 57%); mp. 297e300 ꢁC (MeCN), [
a]
þ46 (c 0.39) (lit
Difluorodihydrobetulinic acid (11) (760 mg; 1.5 mmol) and
dimethylsuccinic anhydride (650 mg; 5.1 mmol) reacted according
to the general procedure to give ester 18 (264 mg; 28%); mp
D
[17]. mp. 299e301 ꢁC, [
1H NMR was identical to the spectrum in lit [17].
a
]
D
þ48).
203e205 ꢁC (2,2,4-trimethylpentane); [
a]
ꢀ22.9 (c 0.35). IR
D
4.2.9. 3
b
-O-hemiglutaryl-2,2-difluorodihydrobetulinic acid (15)
(DRIFT): 1682 (C]O), 1706 (C]O), 1742 (C]O), 2400e3400
Difluorodihydrobetulinic acid (11) (500 mg; 1.01 mmol) and
(COOH) cmꢀ1 1H NMR (300 MHz; CDCl3):
.
d
¼ 0.76 (d, 3H,
glutaric anhydride (580 mg; 5.08 mmol) reacted according to the
J ¼ 9.0 Hz), 0.86 (d, 3H, J ¼ 6.0 Hz), 0.89 (s, 3H), 0.92 (s, 3H), 0.94 (d,
3H, J ¼ 9.0 Hz), 0.95 (s, 3H), 1.01 (s, 3H),1.33 (s, 6H, 2ꢂ CH3),1.88 (m,
1H), 2.10e2.50 (m, 5H, H-1a, H-1b, H-13, H-16, H-19), 2.65 (d, 1H,
J ¼ 16.0 Hz, 1ꢂ H-hemiester), 3.80 (d, 1H, J ¼ 16.0 Hz, 1ꢂ H-
general procedure to give ester 15 (445 mg; 72%); mp 219e220 ꢁ
C
(2,2,4-trimethylpentane). IR (DRIFT): 1694 (C]O), 1729 (C]O),
2500e3300 (COOH) cmꢀ1. 1H NMR (500 MHz; CDCl3):
d
¼ 0.75 (d,
3H, J ¼ 6.9 Hz), 0.86 (d, 3H, J ¼ 6.9 Hz), 0.90 (s, 3H), 0.92 (s, 3H), 0.93
(s, 3H), 0.95 (s, 3H), 1.02 (s, 3H), 1.68 (bd, 1H, J ¼ 13.2 Hz), 1.73e1.83
(m, 1H), 1.87 (dd, 1H, J ¼ 12.6 Hz, 7.5 Hz), 1.95e2.06 (m, 2H,
HOOCCH2CH2CH2COO), 2.13e2.35 (m, 4H, HOOCCH2CH2CH2COO),
2.40e2.60 (m, 4H, H-1b, H-13, H-16, H-19), 4.86 (dd,1H, J ¼ 22.9 Hz,
hemiester), 4.86 (bd, 1H, J ¼ 22.0, Hz, H e 3
a
). 13C NMR (75.45 MHz;
¼ 14.6, 14.8, 15.8, 16.3, 16.6, 18.2, 21.3, 22.9, 23.1, 25.3, 25.7,
CDCl3):
d
26.8, 28.8, 29.8, 30.2, 32.2, 34.2, 37.6, 38.2, 38.5, 39.6, 40.5, 41.0,
42.9, 44.3, 44.3, 44.3, 48.8, 50.0, 50.7, 55.0, 56.8, 77.2, 171.2, 180.6,
180.6. 19F NMR
d
¼ ꢀ103.59 (dm, J ¼ 251.9 Hz), ꢀ88.70 (d,
5.7 Hz, H - 3
a
).13C NMR (125.77 MHz; CDCl3)
d
¼ 14.5,14.6,15.6,15.6,
J ¼ 244.7 Hz). MS (ESIꢀ): m/z (%) ¼ 621 (75, [M ꢀ H]ꢀ). MS (ESIþ): m/
z (%) ¼ 645 (100, [M þ Na]þ). Anal. Calcd for C36H56F2O6: C, 69.44;
H, 9.06; F, 6.09; O, 15.41. Found: C, 69.42; H, 9.06; F, 6.10; O, 15.41.
16.2, 16.5, 18.0, 19.9, 21.1, 22.7, 23.0, 26.6, 28.8, 29.5, 29.7, 30.1, 32.0,
32.9, 33.2, 34.0, 37.3, 38.1, 38.4 (d, J ¼ 9.6 Hz), 39.4 (d, J ¼ 4.8 Hz),
40.8, 42.7, 44.2, 46.4 (t, J ¼ 19.2 Hz), 48.7, 50.5, 54.8, 56.8,172.3,179.0,
183.0. 19F NMR
d
¼ ꢀ105.59 (dm, J ¼ 251.7 Hz), ꢀ90.04 (d,
4.2.13. 2,2-Difluoro-19
hemiglutarate (19)
b,28-epoxy-18a-oleanane-3b-yl
J ¼ 251.9 Hz). MS (ESIþ): m/z (%) ¼ 631 (100, [M þ Na]þ). MS (ESIꢀ):
m/z (%) ¼ 607 (100, [M ꢀ H]ꢀ). Anal. Calcd for C36H54F2O6: C, 69.05;
H, 8.94; F 6.24; O, 15.77. Found: C, 69.11; H, 8.95; F 6.12; O, 15.70.
Hemiglutarate 19 was prepared by the general procedure from
14 (200 mg; 0.40 mmol). Crude product was chromatographed on
silica gel (40 g) in gradient from 40% EtOAc in hexane to 100% EtOAc
to give 19 (110 mg; 44%); mp. 230.0 ꢁC (lyophylized from t-BuOH);
4.2.10. 3b-O-hemisuccinyl-2,2-difluorodihydrobetulinic acid (16)
Difluorodihydrobetulinic acid (11) (500 mg; 1.0 mmol) and
succinic anhydride (500 mg; 5.0 mmol) reacted according to the
general procedure to give ester 16 (344 mg; 57%); mp 256e257 ꢁC
[
a
]
þ41.5 (c 0.24). IR (DRIFT): 1710 (C]O), 1744 (C]O), 2866
D
(COOH), 2946 (COOH) cmꢀ1. 1H NMR (400 MHz; CDCl3):
d
¼ 0.80 (s,
3H), 0.90 (s, 3H), 0.92 (s, 3H), 0.93 (d, 3H, J ¼ 0.9 Hz), 0.93 (s, 3H),
(2,2,4-trimethylpentane); [
O), 1761 (C]O), 2350e3300 (COOH) cmꢀ1
CDCl3)
a
]
D ꢀ10.0 (c 0.40). IR (DRIFT): 1706 (C]
1.00 (s, 3H), 1.04 (s, 3H), 1.97e2.10 (m, 2H, HOOCCH2CH2CH2COO),
.
1H NMR (300 MHz;
2.31 (td, 1H,
HOOCCH2CH2CH2COO), 3.46 (d, 1H, J ¼ 7.8 Hz, H-28a), 3.54 (s, 1H,
H-19
), 3.78 (d, 1H, J ¼ 7.6 Hz, H-28b), 4.87 (dd, 1H, J ¼ 23.3, 5.8, H-
). 13C NMR (125 MHz; CDCl3):
J
¼
13.7, 4.9 Hz, H-1a), 2.40e2.60 (m, 4H,
d
¼ 0.76 (d, 3H, J ¼ 6.0 Hz), 0.86 (d, 3H, J ¼ 6.0 Hz), 0.90 (d,
3H, J ¼ 6.0 Hz), 0.94 (s, 3H) 0.95 (s, 3H) 0.96 (s, 3H), 1.02 (s, 3H), 1.79
(m, 1H), 1.88 (m, 1H), 2.10e2.45 (m, 4H, H-1b, H-13, H-16, H-19),
2.78 (m, 4H, SJ ¼ 51 Hz, 2ꢂ CH2), 4.89 (dd, 1H, J ¼ 12.9 Hz, 5.2 Hz, H
a
3
a
d
¼ 13.42, 15.67, 15.94 (d, J ¼ 6 Hz),
16.48 (d, J ¼ 3 Hz), 17.95, 19.96, 21.28, 24.51, 26.17, 26.22, 26.29,
28.75, 28.75, 32.60, 32.66, 33.16, 33.56, 33.99, 36.23, 36.68, 38.43 (d,
J ¼ 9 Hz), 39.37 (d, J ¼ 6 Hz), 40.77, 40.88, 41.44, 46.66 (t, J ¼ 19 Hz),
46.74, 51.42, 55.04, 71.16, 77.20, 87.92, 121.54 (J ¼ 248, 240 Hz),
e 3
a
). 13C NMR (75.45 MHz; CDCl3)
d
¼ 14.5, 14.7, 15.6 (d), 16.0, 16.4,
18.0, 21.3, 22.8, 23.0, 26.8, 28.8, 29.75, 29.8, 32.2, 34.1, 37.5, 38.1,
38.4 (d), 39.6 (d), 40.9, 42.8, 44.3, 44.3, 44.3, 46.5 (t), 48.7, 50.0, 50.7,
54.9, 56.7, 77.2, 171.7, 178.4, 183.2. 19F NMR
d
¼ ꢀ105.54 (dm,
172.41,177.69. 19F NMR:
d
¼ ꢀ90.06 (d, 2 F, J ¼ 244.7 Hz). MS (EI): m/
J ¼ 251.9 Hz), ꢀ90.01 (d, J ¼ 251.9 Hz). MS (ESIꢀ): m/z (%) ¼ 593
(100, [MꢀH]-). MS (ESIþ): m/z (%) ¼ 617 (75, [M þ Na]þ). Anal. Calcd
for C34H52F2O6: C, 68.69; H, 8.80; F, 6.37; O, 16.14. Found: C, 68.66;
H, 8.81; F, 6.39; O, 16.14.
z (%) ¼ 591 (MþꢀH,100), 544 (5), 425 (13), 361 (13), 32 (13), 265 (8).
Anal. Calcd for C35H54F2O5: C 70.91; H 9.18; F 6.41. Found: C 70.89; H
9.17; F 6.44.
4.2.14. 2,2-Difluoro-19
hemisuccinate (20)
b,28-epoxy-18a-oleanane-3b-yl
4.2.11. 3b
-O-30,30-dimethylhemiglutaryl-2,2-
difluorodihydrobetulinic acid (17)
Hemisuccinate 20 was prepared by the general procedure from
14 (200 mg; 0.40 mmol). Crude product was chromatographed on
silica gel (40 g) in gradient from 40% EtOAc in hexane to 100% EtOAc
Difluorodihydrobetulinic acid (11) (500 mg; 1.0 mmol) and 3,3-
dimethylglutaric anhydride (700 mg; 4.9 mmol) reacted according
to the general procedure to given ester 17 (516 mg; 80%); mp
to give 20 (100 mg; 41%); mp. 109.3 ꢁC (acetonitrile); [
a]
D þ48,1 (c
0.26). IR (DRIFT): 1731 (C]O), 1751 (C]O), 2736 (COOH), 2851
(COOH), 2957 (COOH), 3407 (OeH) cmꢀ1 1H NMR (400 MHz;
CDCl3):
¼ 0.80 (s, 3H), 0.89 (s, 3H), 0.92 (s, 3H), 0.93 (s, 3H), 0.94
(d, 3H, J ¼ 0.9 Hz), 1.00 (s, 3H), 1.04 (s, 3H), 2.32 (td, 1H, J ¼ 13.8,
4.8 Hz, H-1 ), 2.67e2.81 (m, 4H, HOOCCH2CH2COO), 3.46 (d, 1H,
J ¼ 7.8 Hz, H-28a), 3.54 (s, 1H, H-19 ), 3.78 (d, 1H, J ¼ 7.5 Hz, H-28b),
4.88 (dd, 1H, J ¼ 23.1, 5.7 Hz, H-3
). 13C NMR (125 MHz; CDCl3):
¼ 13.42, 15.67, 15.93 (d, J ¼ 6 Hz), 16.41 (d, J ¼ 3 Hz), 17.93, 21.30,
204e205 ꢁC (2,2,4-trimethylpentan);
[a
]
ꢀ14.3 (c 0.35). IR
D
(DRIFT): 1702 (C]O), 1736 (C]O), 2500e3300 (COOH) cmꢀ1
.
1H
.
NMR (300 MHz; CDCl3): 0.76 (d, 3H, J ¼ 6.0 Hz), 0.86 (d, 3H,
J ¼ 6.0 Hz), 0.89 (s, 3H), 0.92 (d, 3H, J ¼ 3.0 Hz), 0.94 (s, 3H), 0.97 (s,
3H), 1.03 (s, 3H), 1.10 (s, 3H), 1.18 (s, 3H), 1.88 (m, 1H), 2.10e2.50 (m,
7H, H-1a, H-1b, H-13, H-16, H-19, 2ꢂ H-hemiester), 2.83 (d, 1H,
J ¼ 16.3 Hz, 1ꢂ H-hemiester), 3.80 (d, 1H, J ¼ 16.3 Hz, 1ꢂ H-
d
a
a
a
hemiester), 4.86 (dd, 1H, J ¼ 22.9.0, 6.2 Hz, H - 3
(75.45 MHz; CDCl3):
a
). 13C NMR
d
d
¼ 14.1, 14.4, 15.7 (d), 16.5 (d), 18.1, 21.1, 22.8,
24.51, 26.18, 26.22, 26.29, 28.57, 28.76, 28.80, 28.90, 32.66, 33.56,
34.00, 36.23, 36.68, 38.42 (d, J ¼ 9 Hz), 39.44 (d, J ¼ 6 Hz), 40.77,
40.88, 41.44, 46.68 (t, J ¼ 19 Hz), 46.75, 51.41, 55.09, 71.17, 77.65 (t,
J ¼ 19 Hz), 87.93, 121.47 (dd, J ¼ 242, 250 Hz), 171.64, 177.00. 19F
NMR spectrum: ꢀ90.60 (dd, J ¼ 248, 4.8 Hz), ꢀ106.32 (dddd,
J ¼ 249.2, 34.7, 22.9, 14.1). MS (EI): m/z (%) ¼ 577 (Mþ ꢀ H, 90), 478
(56), 458 (61), 407 (93), 342 (22), 323 (19), 297 (7), 269 (10), 236
23.0, 25.4, 26.3, 28.4, 28.5, 29.6, 30.1, 32.2, 33.7, 37.2, 38.1, 38.4 (d),
39.5 (d), 40.6, 42.5, 43.2, 44.3, 44.5, 48.9, 49.9, 53.1, 54.5, 56.9, 171.4,
178.3, 183.1. 19F NMR
d
¼ ꢀ102.52 (dm, J ¼ 244.7 Hz), ꢀ88.54 (d,
J ¼ 251.9 Hz). MS (ESIꢀ): m/z (%) ¼ 635 (45, [M ꢀ H]ꢀ). MS (ESIþ): m/
z (%) ¼ 659 (80, [M þ Na]þ). Anal. Calcd for C37H58F2O6: C, 69.79; H,
9.17; F, 5.96; O, 15.08. Found: C, 69.78; H, 9.18; F, 5.97; O, 15.07.