Synthesis of novel functionally substituted esters of m-carborane-1,7- dicarboxylic acid

Article abstract of DOI:10.1007/s11176-005-0274-2

m-Carborane-1,7-dicarbonyl dichloride was reacted with functionally substituted alcohols and phenols to obtain previously unknown esters, peroxy-containing inclusive. 2005 Pleiades Publishing, Inc.

Full text of DOI:10.1007/s11176-005-0274-2

Russian Journal of General Chemistry, Vol. 75, No. 4, 2005, pp. 575 579. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005,
pp. 614 618.
Original Russian Text Copyright
2005 by Dikusar, Zvereva, Kozlov, Potkin, Yuvchenko, Kovganko.
Synthesis of Novel Functionally Substituted Esters
of m-Carborane-1,7-dicarboxylic Acid
,
E. A. Dikusar,* ** T. D. Zvereva,* N. G. Kozlov,* V. I. Potkin,*
A. P. Yuvchenko,** and N. V. Kovganko***
*Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
**Institute of New Material Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
***Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received October 17, 2003
Abstract m-Carborane-1,7-dicarbonyl dichloride was reacted with functionally substituted alcohols and
phenols to obtain previously unknown esters, peroxy-containing inclusive.
One of the perspective lines of the search for
agents for diagnostics and treatment of cancer is syn-
thesis of functionally substituted carborane derivatives
[1 7]. In the present work we describe the synthesis
of novel functionally substituted m-carborane-1,7-di-
carboxylic acid esters IIIa IIIw. As starting com-
pounds we used fuctionally substituted alcohols and
phenols Ia Iw, including terpene Ib, Ic, and Il I,
steroid It Iw, vegetable Io Iq, peroxy-containing Ih
Ik, and acetylenic Id If and Ih Ik [8 11]. Esters
IIIa IIIw were obtained by refluxing m-carborane-
1,7-dicarbonyl dichloride (II) with compounds Ia Iw
in absolute benzene in the presence of pyridine. The
yields of the target products were 71 90%.
The structure of esters IIIa IIIw was confirmed
1
by their elemental analyses, H NMR, IR, and UV
spectra. The yields and physicochemical character-
istics of compounds IIIa IIIw are listed in Table 1,
1
the H NMR spectra, in Table 2, and IR and UV
spectra, in Table 3. The purity of the esters, as judged
1
from the H NMR spectra, was 98 1%.
C6H6
2ROH + m-1,7-ClC(O)CB10H10CC(O)Cl
m-1,7-CB10H10C[C(O)(OR]2,
Py
Ia Iw
II
IIIa IIIw
I, III, R = Me(CH2)16 (a), Me2C=CH(CH2)2CHMe(CH2)2 (b), Me2C=CH(CH2)2CMe=CHCH2 (c), HC C(CH2)2 (d),
HC C(CH2)3 (e), HC CCMe2 (f), MeC(O)CH2 (g), EtMe2COOCMe2C CCH(CH2)2Me (h), Me3COOCMe2C CCH
(CH2)6Me (i), EtMe2COOCMe2C CCH(CH2)6Me (j), p-PrMe2COOCMe2C CCH(CH2)6Me (k),
Me
Me
Me
Me
Me
(m),
Me
(l),
Me
(n),
Me
Me
CHO
CHO
COOMe
(s),
(o),
OMe MeO
(p),
EtO
(q),
(r),
N
H2C=CHCH2
1070-3632/05/7504-0575 2005 Pleiades Publishing, Inc.

576
DIKUSAR et al.
Me
Me
Me
Me
O
Me
Me
Me
Me
Me
Me
O
Me
Me
(v),
(u),
(t),
Me
Me
Me
H
Me
Me
N
Me
O
(w).
Me
Table 1. Properties of esters IIIa IIIw
Found, %
H
Calculated, %
M
mp,
C
d240
n2D0
Formula
C
B
C
H
B
IIIa
IIIb
IIIc
IIId
IIIe
IIIf
IIIg
IIIh
IIIi
79
83
80
88
90
75
77
80
85
81
80
76
78
75
84
88
87
83
83
76
71
80
75
31 32
38 39
64.51 11.48 15.09 C38H80B10O4
64.36 11.37 15.25 698.3 709.2
56.66 9.51 21.25 497.2 508.8
57.11 8.79 21.42 494.6 504.7
42.85 5.99 32.14 322.7 336.4
46.14 6.64 29.66 349.0 364.5
46.14 6.64 29.66 351.5 364.5
34.88 5.85 31.39 328.1 344.4
56.44 8.88 15.88 661.4 680.9
59.65 9.48 14.13 747.8 765.1
60.57 9.66 13.63 778.5 793.2
61.43 9.82 13.17 804.9 821.2
56.66 9.51 21.25 495.8 508.8
57.11 8.79 21.42 492.5 504.7
57.11 8.79 21.42 495.0 504.7
54.95 6.15 20.61 507.3 524.6
47.99 4.83 21.60 490.4 500.5
49.99 5.34 20.45 509.7 528.6
47.99 4.83 21.60 491.2 500.5
0.9952 1.5020 57.01 10.03 21.10 C24H48B10O4
1.0431 1.5150 57.42 9.02 21.13 C24H44B10O4
1.0330 1.5220 43.04 6.12 31.87 C12H20B10O4
1.0602 1.5200 46.36 6.81 29.30 C14H24B10O4
46.29 6.72 29.49 C14H24B10O4
1.2800 1.5205 35.07 6.04 31.04 C10H20B10O6
1.0242 1.4865 56.69 9.03 15.65 C32H60B10O8
0.9895 1.4795 59.83 9.67 13.92 C38H72B10O8
0.9978 1.4840 60.74 9.81 13.44 C40H76B10O8
1.0255 1.4825 61.76 10.04 12.89 C42H80B10O8
1.0113 1.5060 56.80 9.64 21.04 C24H48B10O4
57.32 8.94 21.30 C24H44B10O4
IIIj
IIIk
IIIl
IIIm
IIIn
IIIo
IIIp
IIIq
IIIr
IIIsa
IIIt
132 133
104 105
67 68
33 34
75 76
103 104
222 223
233 234
223 224
275 276
315(dec.)
57.35 8.89 21.33 C24H44B10O4
55.12 6.31 20.37 C24H32B10O6
48.23 5.05 21.38 C20H24B10O8
50.19 5.46 20.33 C22H28B10O8
48.11 5.00 21.41 C20H24B10O8
54.43 4.66 22.09 C22H22B10N2O4 54.31 4.56 22.22 470.1 486.5
72.04 10.63 10.95 C58H100B10O4
72.77 10.74 10.30 C62H108B10O4
68.19 9.21 10.22 C58H92B10O8
71.85 10.40 11.15 931.8 969.5
72.61 10.61 10.54 993.5 1025.6
67.93 9.04 10.54 989.7 1025.5
IIIu
IIIv
IIIwb
68.21 9.40 10.35 C58H94B10N2O6 68.06 9.26 10.56 987.1 1023.5
a
b
Found N, %: 5.61. Calculated N, %: 5.76.
Found N, %: 2.58. Calculated N, %: 2.74.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

SYNTHESIS OF NOVEL FUNCTIONALLY SUBSTITUTED ESTERS
Table 2. 1H NMR spectra of esters IIIa IIIw
577
, ppm
3
IIIa
IIIb
IIIc
IIId
1.00 6.00 m (10H, B10H10), 0.89 t (6H, 2Me, J 6.0 Hz), 1.10 1.85 m [60H, 2(CH2)15], 4.14 t (4H, 2CH2O,
3J 6.0 Hz)
1.00 6.00 m (10H, B10H10), 0.91 d (6H, 2C3Me, J 5.7 Hz), 1.00 2.20 m (14H, 2C3H, 2C2H2, 2C4H2, and
3
2C5H2), 1.61 s and 1.69 s (2H, 2C7Me2), 4.18 t (4H, 2C1H2, 3J 6.5 Hz), 4.85 5.20 m (2H, 2C6H)
1.00 6.00 m (10H, B10H10), 1.61 s (6H, 2C3Me), 1.69 s (2H, 2C7Me2), 0.80 2.15 m (8H, 2C4H2, and 2C5H2),
4.63 d (4H, 2C1H2, 3J 6.8 Hz), 4.85 5.35 m (4H, 2C2H and 2C6H)
4
3
4
1.00 6.00 m (10H, B10H10), 2.00 t (2H, 2C CH, J 2.6 Hz), 2.54 t.d [4H, J(CH2) 6.8, 2CH2C C, J(C CH)
2.6 Hz], 4.23 t (4H, 2CH2O, 3J 6.8 Hz)
IIIe
IIIf
IIIg
IIIh
1.00 6.00 m (10H, B10H10), 1.70 2.40 m [10H, 2C CH, and 2(CH2)2C C], 4.25 t (4H, 2CH2O, 3J 6.3 Hz)
1.50 6.00 m (10H, B10H10), 1.67 s (12H, 2Me2C), 2.58 s (2H, 2C CH)
1.00 6.00 m (10H, B10H10), 2.15 s (6H, 2Me), 4.69 s (4H, 2CH2)
1.00 6.00 m (10H, B10H10), 0.75 1.05 m (12H, 4Me), 1.20 s (12H, 2Me2COO), 1.45 s (12H, 2Me2C), 1.30
2.00 m [12H, 2CH2 and 2(CH2)2], 5.30 t (2H, 2CHO, 3J 7.3 Hz)
IIIi
1.00 6.00 m (10H, B10H10), 0.75 1.00 m (6H, 2Me), 1.22 s (18H, 2Me3COO), 1.15 1.90 m [24H, 2(CH2)6],
1.45 s (12H, 2Me2C), 5.25 t (2H, 2CHO, 3J 7.1 Hz)
IIIj
IIIk
IIIl
1.00 6.00 m (10H, B10H10), 0.75 1.05 m (12H, 4Me), 1.10 1.90 m [28H, 2CH2, and 2(CH2)6], 1.20 s (12H,
2Me2COO), 1.45 s (12H, 2Me2C), 5.27 t (2H, 2CHO, 3J 7.2 Hz)
1.00 6.00 m (10H, B10H10), 0.75 1.05 m (12H, 4Me), 1.15 1.95 m [32H, 2(CH2)2, and 2(CH2)6], 1.21 s (12H,
2Me2COO), 1.45 s (12H, 2Me2C), 5.30 t (2H, 2CHO, 3J 7.2 Hz)
3
3
1.00 6.00 m (10H, B10H10), 0.74 d (6H, 2C1Me, J 6.7 Hz), 0.91 d (12H, 2C8Me2, J 6.7 Hz), 0.85 2.05 m
(18H, 2C1H, 2C2H2, 2C4H, 2C5H2, 2C6H2 and 2C8H), 4.45 4.80 m (2H, 2C3H)
IIIm
IIIn
IIIo
1.00 6.8 0 m (10H, B10H10), 0.85 s (6H, 2Me10), 0.92 s (12H, 2Me8, and 2Me9), 0.95 2.50 m (14H, 2C3H2,
2C4H, 2C5H2 and 2C6H2), 4.75 4.95 m (2H, 2C2Hexo
)
1.00 6.20 m (10H, B10H10), 0.85 s (12H, 2Me9, and 2Me10), 0.98 s (6H, 2Me8), 0.75 2.20 m (14H, 2C3H2,
2C4H, 2C5H2 and 2C6H2), 4.50 4.75 m (2H, 2C2Hendo
)
1.00 6.00 m (10H, B10H10), 3.36 d (4H, 2CH2O, 3J 6.7 Hz), 3.79 s (6H, 2Me), 4.92 5.25 m (4H, 2=CH2), 5.67
6.23 m (2H, 2=CH), 6.55 6.97 m (6H, 2C6H3)
IIIp
IIIq
1.00 6.00 m (10H, B10H10), 3.90 s (6H, 2Me), 7.12 7.55 m (6H, 2C6H3), 9.93 s (2H, 2CHO)
1.00 6.00 m (10H, B10H10), 1.43 t (6H, 2Me, J 7.4 Hz), 4.11 q (4H, 2CH2, J 7.4 Hz), 7.10 7.50 m (6H,
2C6H3), 9.92 s (2H, 2CHO)
3
3
IIIr
IIIs
IIIt
1.00 6.00 m (10H, B10H10), 3.90 s (6H, 2Me), 6.90 8.10 m (8H, 2C6H4)
1.00 6.00 m (10H, B10H10), 7.20 8.90 m (12H, 2C9H6N)
1.00 6.00 m (10H, B10H10), 0.69 s (6H, 2Me18), 0.80 1.00 m (18H, 2Me21, 2Me26, and 2Me27), 1.03 s (6H,
2Me19), 0.80 2.45 m (56H, CH2 and CH), 4.35 4.75 m (2H, 2C3H), 5.27 5.47 m (2H, 2C6H)
1.00 6.00 m (10H, B10H10), 0.69 s (6H, 2Me18), 1.02 s (6H, 2Me19), 0.65 2.45 m (82H, 8Me, CH2, and CH),
4.30 4.85 m (2H, 2C3H), 5.35 5.50 m (2H, 2C6H)
IIIu
IIIv
IIIw
1.00 6.00 m (10H, B10H10), 0.80 s (6H, 2Me18), 1.05 s (6H, 2Me19), 0.70 2.45 m (60H, 4Me, CH2, and CH),
3.20 4.75 m (8H, 2C3H, 2C16H and 2CH2O), 5.35 5.50 m (2H, 2C6H)
1.00 6.00 m (10H, B10H10), 0.82 s (6H, 2Me18), 1.04 s (6H, 2Me19), 0.80 1.15 m (12H, 2Me), 1.15 3.00 m
(52H, CH2, and CH), 3.20 4.80 m (4H, 2C3H and 2C16H), 5.20 5.50 m (2H, 2C6H)
3
1
EXPERIMENTAL
ment for 1 10 M solutions in 1-butanol. The H
NMR spectra were run on a Tesla-567A spectrometer
(100 MHz) in CDCl3 against internal TMC. The
molecular weights were measured by cryoscopy in
benzene. The starting m-carborane-1,7-dicarbonyl
dichloride (II) was prepared by the procedure in [1],
The IR spectra were obtained on a Protege-460
Fourier spectrometer in KBr pellets (IIIa, IIIf, IIIm
IIIw) or in thin films (IIIb IIIe, IIIg IIIl). The UV
spectra were measured on a Specord UV-Vis instru-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

578
DIKUSAR et al.
Table 3. IR and UV spectra of esters IIIa IIIw
1
IR spectrum, , cm
UV spectrum, max, nm ( )
IIIa
IIIb
IIIc
IIId
IIIe
IIIf
IIIg
IIIh
IIIi
2955, 2918, 2850 (CHAlk); 2621, 2598, 2586 (BH); 1743 (C=O); 1471 (CH2); 1263 201 (100), 211 (150),
(C O); 740, 719 (BH) 220 (100)
3030 (=CH); 2964, 2927, 2915, 2873, 2855 (CHAlk); 2619 (BH); 1749 (C=O); 204 (8000)
1670 (C=C); 1458 (CH2); 1260 (C O); 760, 737 (BH)
3055, 3025 (=CH); 2966, 2927, 2875, 2856 (CHAlk); 2618 (BH); 1747 (C=O); 206 (16000)
1660, 1643 (C=C); 1452 (CH2); 1256 (C O); 760, 737 (BH)
3304 ( CH); 2970, 2915, 2900, 2850 (CHAlk); 2619 (BH); 2130 (C C); 1748 201 (100), 208 (500), 220
(C=O); 1459 (CH2); 1260 (C O); 764, 736 (BH); 649 ( CH)
3304 ( CH); 2965, 2935, 2900, 2850 (CHAlk); 2619 (BH); 2120 (C C); 1748 201 (100), 208 (500), 221
(C=O); 1460, 1434 (CH2); 1259 (C O); 765, 735 (BH); 642 ( CH) (400)
(400)
3288, 3270 ( CH); 3010, 2992, 2945, 2925 (CHAlk); 2950, 2625, 2606, 2595, 2580 202 (100), 208 (500), 220
(BH); 2125 (C C); 1752 (C=O); 1285, 1267, 1122 (C O); 740 (BH); 625 ( CH) (400)
2997, 2941 (CHAlk); 2621 (BH); 1759, 1736 (C=O); 1421 (CH2); 1276, 1259, 210 (500), 220 (100), 255
1181, 1139, 1034 (C O); 754, 735 (BH)
2968, 2937, 2877 (CHAlk); 2619 (BH); 1752 (C=O); 1463 (CH2); 1243, 1160, 203 (100), 208 (500), 220
1118, 1012, 928 (C O); 870 (O O); 760, 740 (BH) (400)
2980, 2957, 2930, 2859 (CHAlk); 2618 (BH); 1751 (C=O); 1466 (CH2); 1250, 203 (100), 207 (500), 221
1161, 1120, 1011, 946 (C O); 870 (O O); 760, 740 (BH) (400)
2980, 2960, 2930, 2858 (CHAlk); 2619 (BH); 1752 (C=O); 1463 (CH2); 1250, 202 (100), 208 (500), 220
1159, 1120, 1010, 946 (C O); 859 (O O); 760, 736 (BH) (400)
2983, 2958, 2931, 2872, 2859 (CHAlk); 2618 (BH); 1752 (C=O); 1465 (CH2); 203 (100), 208 (500), 220
1250, 1159, 1120, 1010, 958 (C O); 875 (O O); 765, 740 (BH) (400)
2958, 2927, 2871 (CHAlk); 2618 (BH); 1743 (C=O); 1456 (CH2); 1257, 1013, 957 201 (100), 211 (150), 220
(C O); 756, 736 (BH) (100)
2980, 2956, 2884, 2865 (CHAlk); 2622, 2598, 2570 (BH); 1740 (C=O); 1474, 1454 201 (100), 211 (150), 220
(CH2); 1262, 1016, 974 (C O); 754, 736 (BH) (100)
3002, 2981, 2956, 2877 (CHAlk); 2619 (BH); 1743 (C=O); 1477, 1456 (CH2); 201 (100), 210 (150), 221
1262, 1047, 1013, 964 (C O); 760, 740 (BH) (100)
(200)
IIIj
IIIk
IIIl
IIIm
IIIn
IIIo
3079 (=CH and CHAr); 2997, 2977, 2939, 2916, 2850, 2835 (CHAlk); 2670, 2619, 207 (28000), 218 (16000),
2600, 2579 (BH); 1766 (C=O); 1640 (C=C); 1606, 1513, 1465 (Ar); 1450, 1424 272 (6000), 281 (5000)
(CH2); 1270, 1250, 1240, 1195, 1184, 1149, 1123, 1035, 1000 (C O); 913, 845,
825, 793 (CHAr); 753, 735 (BH)
IIIp
IIIq
3120, 3075, 3015 (CHAr); 2970, 2941, 2855, 2835 (CHAlk); 2740 (CHCHO); 2618 207 (17000), 210 (16000),
(BH); 1771, 1702 (C=O); 1605, 1503, 1465, 1423, 1390 (Ar); 1279, 1237, 1194, 222 (15000), 260 (13000),
1144, 1119, 1029, 1002 (C O); 850, 831, 797, 778, 732 (CHAr); 760, 740 (BH) 310 (6000)
315, 3070, 3045, 3015 (CHAr); 2981, 2940, 2895, 2880, 2870, 2850, 2835, 2810 206 (18000), 210 (16000),
(CHAlk); 2745 (CHCHO); 2655, 2624, 2615, 2600 (BH); 1769, 1698 (C=O); 1601, 222 (15000), 258 (14000),
1503, 1437, 1391 (Ar); 1470 (CH2); 1278, 1259, 1238, 1189, 1150, 1118, 1031, 311 (6000)
1005 (C O); 860, 830, 790, 743 (CHAr); 755, 740 (BH)
IIIr
IIIs
IIIt
3082, 3024, 2993 (CHAr); 2948, 2900, 2839 (CHAlk); 2673, 2645, 2620, 2608, 205 (30000), 226 (20000),
2597, 2575 (BH); 1766, 1728 (C=O); 1609, 1485, 1450, 1432 (Ar); 1273, 1249, 275 (4000)
1239, 1203, 1188, 1083, 1006 (C O); 810, 742, 689 (CHAr and BH)
3070, 3054, 3020 (CHAr); 2660, 2623, 2575 (BH); 1762 (C=O); 1596, 1572, 1499, 205 (30000), 228 (35000),
1470, 1427, 1389, 1367 (Ar); 1247, 1226, 1166, 1124, 1073, 1051, 1025, 1001 230 (35000), 280 (5000),
(C O); 832, 810, 801, 777 (CHAr); 761, 735 (BH)
313 (4000)
3040 (=CH); 2940, 2910, 2867, 2855, 2822 (CHAlk); 2636, 2621, 2607 (BH); 1741 204 (8000)
(C=O); 1670 (C=C); 1468, 1442 (CH2);1271, 1252, 1008, 994 (C O); 764, 735 (BH)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

SYNTHESIS OF NOVEL FUNCTIONALLY SUBSTITUTED ESTERS
579
Table 3. (Contd.)
1
IR spectrum, , cm
UV spectrum, max, nm ( )
IIIu
IIIv
IIIw
3035 (=CH); 2960, 2936, 2900, 2867, 2851 (CHAlk); 2616 (BH); 1743 (C=O); 204 (8000)
1664 (C=C); 1466 (CH2); 1270, 1256, 1133, 1055, 1022, 1008, 958 (C O); 765,
738 (BH)
3040 (=CH); 2970, 2950, 2928, 2906, 2872, 2850 (CHAlk); 2666, 2617, 2575, 204 (8000)
2569 (BH); 1742 (C=O); 1670 (C=C); 1465, 1454 (CH2); 1271, 1257, 1170, 1128,
1096, 1053, 1007, 982 (C O); 768, 733 (BH)
3030 (=CH); 2947, 2905, 2871, 2850 (CHAlk); 2610, 2563 (BH); 1739 (C=O); 204 (8000)
1670 (C=C); 1459 (CH2); 1267, 1255, 1136, 1013, 983 (C O); 754, 737 (BH)
and the synthesis of compounds Ih Ik has been
described in [10].
2. Locher, G.L., Am. J. Roentgenol. Radium Ther., 1936,
vol. 36, no. 1, p. 1.
Functionally substituted m-carborane-1,7-di-
carboxylatic acid esters IIIa IIIw (general proce-
dure). Compounds Ia Iw (10 mmol) were dissolved
in 130 ml of absolute benzene. From the resulting
solution, about 30 ml of the solvent was azeotropical-
ly distilled to remove traces of water adsorbed by
starting compounds Ia Iw. After cooling, 1.4 g of
chloride II and 1.2 of absolute pyridine were added
in one portion. The mixture was refluxed for 8 h and
cooled. The pyridine hydrochloride that precipitated
was filtered off, the filtrate was washed with water
(3 50 ml) and 5% aqueous sodium bicarbonate (3
50 ml), and dried with CaCl2. The drier was filtered
off, and the solvent was removed. Compounds IIIa,
IIIf, and IIIm IIIw were purified by low-temperature
crystallization from 96% ethanol and compounds
IIIb IIIe and IIIg IIIl, by column chromatography
on alumina (Brockmann activity grade II, neutral,
100 160 m), eluent hexane.
3. Hawthorne, M.F., Mol. Med. Today, 1998, no. 4,
p. 174.
4. Hawthorne, M.F., Varadarajan, A., Knobler, C.B.,
and Chakrabarti, S., J. Am. Chem. Soc., 1990,
vol. 112, no. 22, p. 5365.
5. Goudgaon, N.M., El-Kattan, G.F., and Schinazi, R.F.,
Nucleosides Nucleotides, 1994, vol. 13, nos. 1 3,
p. 849.
6. Dikusar, E.A., Yuvchenko, A.P., Zvereva, T.D.,
Makhnach, T.D., and Filanchuk, L.P., Zh. Obshch.
Khim., 1996, vol. 66, no. 11, p. 1813.
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ko, V.L., Moiseichuk, K.L., Yuvchenko, A.P., and
Ol’khovik, V.K., Vesci Nat. Akad. Navuk Belarusi,
Ser. Khim. Navuk, 2002, no. 4, p. 54.
8. Pentegova, V.A., Dubovenko, Zh.V., Raldugin, V.A.,
and Shmidt, E.N., Terpenoidy khvoinykh rastenii
(Terpenoids of Conifers), Novosibirsk: Nauka, 1987.
ACKNOWLEDGMENTS
The work was financially supported by the Bela-
russian Foundation for Basic Research (project
no. X03-079), INTAS (grant no. 99-00806), and
Interbioscreen Co. (Moscow).
9. Fieser, L. F. and Fieser, M., Steroids, New York:
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