Modified coumarins. 3. Psoralen and allopsoralen analogs

Article abstract of DOI:10.1023/A:1014402906251

1,2,3,4-Tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-ones and 8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-ones, analogs of psoralen and allopsoralen, were synthesized from 1-hydroxy- and 3-hydroxy-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-ones.

Full text of DOI:10.1023/A:1014402906251

Chemistry of Natural Compounds, Vol. 37, No. 5, 2001
MODIFIED COUMARINS.
3. PSORALEN AND ALLOPSORALEN ANALOGS
Ya. L. Garazd,1 M. M. Garazd,1
S. V. Shilin,2 and V. P. Khilya2
UDC 547.814.5
c
1,2,3,4-Tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-ones and 8,9,10,11-tetrahydro-7H-benzo[ ]furo[2,3-
f]chromen-7-ones, analogs of psoralen and allopsoralen, were synthesized from 1-hydroxy- and 3-hydroxy-
c
7,8,9,10-tetrahydro-6H-benzo[ ]chromen-6-ones.
Key words: coumarins, furocoumarins, psoralen, allopsoralen, 7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one.
Furocoumarins are an important class of natural compounds and are mainly derivatives of the linear furocoumarin
psoralen (7H-furo[3,2- ]chromen-7-one) or its angular isomer angelicin (2H-furo[2,3- ]chromen-2-one). Derivatives of the
g
h
angular furocoumarin allopsoralen (7H-furo[2,3- ]chromen-7-one) are rarer in nature. Allopsoralen was isolated from seeds
f
of
[1] and the aerial parts of
[2].
Psoralea plicata
Psoralea corylifolia
Natural furocoumarins and their synthetic analogs exhibit a variety of pharmacologic properties. In particular, they
increase the sensitivity of the organism to sunlight, i.e., they possess photosensitizing activity. Furocoumarins are used to treat
vitiligo (leucodermia), alopecia areata, and other skin diseases [3]. 8-Substituted furocoumarins are used as antitumor agents
because they inhibit pathological tissue growth [4]. Derivatives of psoralen and angelicin typically have spasmolytic and
coronary vasodilating properties. They have a papaverine-like mechanism of action on smooth muscle of internal organs and
cardiovascular tissues [5].
Compounds based on the 7,8,9,10-tetrahydro-6H-benzo[ ]chromen-6-one skeleton are known to act as insecticides [6,
c
7], antireserpine agents, CNS depressants, anticonvulsants, analgetics, antipyretics, and anti-inflammatory agents [8, 9].
Thus, the goal of our research is to modify the structure of 7,8,9,10-tetrahydro-6H-benzo[ ]chromen-6-one by fusing
c
a furan ring to it. The starting 3-hydroxy- (1), 3-hydroxy-4-methyl- (2), and 1-hydroxy-3-methyl-7,8,9,10-tetrahydro-6H-
benzo[ ]chromen-6-one (3) were prepared by Pechmann condensation of 2-carbethoxycyclohexanone with resorcinol, 2-
c
methylresorcinol, and orcinol, respectively, in the presence of conc. H SO at 0oC [10].
2
4
The furan ring was fused to the 7,8,9,10-tetrahydro-6H-benzo[ ]chromen-6-one system using the method of MacLeod
c
that is based on cyclization in alkaline medium of 7-(2-oxopropoxy)coumarin derivatives [11].
The Williamson reaction of 1-3 with α-halogenketones forms the corresponding substituted oxoethers 4-39. The
reactions included α-bromoacetone (4, 5, and 28), 3-chloro-2-butanone (6, 7, and 29), α-bromopropiophenone (8, 9, and 30),
α-bromoacetophenone (10, 11, and 31), α-chloro-4-fluoroacetophenone (12, 13, and 32), α-bromo-4-chloroacetophenone (14,
15, and 33), 4-bromophenacylbromide (16, 17, and 34), 4-methylphenacylbromide (18, 19, and 35), 4-methoxyphenacylbromide
(20, 21, and 36), 3-methoxyphenacylbromide (22, 23, and 37), α-bromo-3,4-methylenedioxyacetophenone (24, 25, and 38), and
2-chlorocyclohexanone (26, 27, and 39).
The resulting ketones cyclized readily on heating in 1 N NaOH to the corresponding 1,2,3,4-tetrahydro-5H-benzo
[c]furo[3,2-g]chromen-5-ones 24-37 (psoralen-type furocoumarins) and 8,9,10,11-tetrahydro-7H-benzo[c]furo [2,3-f]
chromen-7-ones 38-43 (allopsoralen-type furocoumarins).
1) Institute of Bioorganic Chemistry and Petroleum Chemistry, National Academy of Sciences of Ukraine, 02094, Kiev,
ul. Murmanskaya, 1; 2) Taras Shevchenko Kiev National University, 01033, Kiev, ul. Vladimirskaya, 64. Translated from
Khimiya Prirodnykh Soedinenii, No. 5, pp. 349-358, September-October, 2001. Original article submitted August 27, 2001.
0009-3130/01/3705-0409$25.00 ©2001 Plenum Publishing Corporation
409

R
R
R
6
8
O
O
7
O
O
5
O
O
O
O
O
9
Me
4
10
11
Me
R
1
3
1
2
42 - 45
40, 41
46 - 57
R
1
1N NaOH
1N NaOH
O
1N NaOH
R
R
O
O
O
Me
O
O
O
O
R
O
O
O
O
R
1
Me
6- 9
R
1
10 - 21
4, 5
O
R CO(Me)CHHal,
1
Hal
K CO
2
3
MeCOCH Br,
2
, K CO
2
3
R
1
K CO
2
3
R
O
HO
O
O
Cl
O
, K CO
Br
2
3
MeO
1, 2
O
, K CO
2
3
Br
O
O
, K CO
2
R
3
R
R
O
O
O
O
O
O
O
O
O
O
O
MeO
O
O
O
26, 27
22, 23
24, 25
1N NaOH
1N NaOH
1N NaOH
R
R
R
6
8
O
O
7
O
O
5
O
O
O
O
O
9
4
3
10
O
O
MeO
13
1
11
12
2
58, 59
60, 61
62, 63
1: R = H; 2: R = Me; 4: R = H; 5: R = Me; 6: R = H, R = Me; 7: R = R = Me; 8: R = H, R = Ph; 9: R = Me, R = Ph;
1
1
1
1
10: R = R = H; 11: R = Me, R = H; 12: R = H, R = F; 13: R = Me, R = F; 14: R = H, R = Cl; 15: R = Me, R = Cl;
1
1
1
1
1
1
16: R = H, R = Br; 17: R = Me, R = Br; 18: R = H, R = Me; 19: R = R = Me; 20: R = H, R = OMe;
1
1
1
1
1
21: R = Me, R = OMe; 22: R = H; 23: R = H; 24: R = H; 25: R = Me; 26: R = H; 27: R= Me; 40: R = H; 41: R = Me;
1
42: R = H, R = Me; 43: R = R =Me; 44: R = H, R = Ph; 45: R = Me, R = Ph; 46: R = R = H; 47: R = Me, R = H;
1
1
1
1
1
1
48: R = H, R = F; 49: R = Me, R = F; 50: R = H, R = Cl; 51: R = Me, R = Cl; 52: R = H, R = Br; 53: R = Me, R = Br;
1
1
1
1
1
1
54: R = H, R = Me; 55: R = R = Me; 56: R = H, R = OMe; 57: R = Me, R = OMe; 58: R = H; 59: R = Me; 60: R = H;
1
1
1
1
61: R = Me; 62: R= H; 63: R = Me
Many routes to furocoumarins are known. In particular, psoralen and its isomers are prepared by the Späth method
[11] and those based on Dickman condensation[12], Perkin reaction [13], and Claisen rearrangement [14]. The above methods
410

involve several steps, give low yields, and have limited capability to modify the coumarin and furan moieties. A different
method for forming psoralen and its angular isomers is known. This is the MacLeod method based on cyclization in alkaline
medium of 7-(2-oxopropoxy)coumarin derivatives [15].
6
O
5
Me
O
O
Me
O
O
7
Me
O
4
R
1
3
R
1
Me
8
O
O
O1
9
11
Me
10
64
65, 66
67 - 72
1N NaOH
1N NaOH
O
1N NaOH
Me
O
O
29, 30
O
Me
O
O
Me
O
O
O
O
O
O
R
1
O
Me
Me
R
1
31 - 36
28
O
MeCO(Me)CHHal,
K CO
Hal
2
3
MeCOCH Br,
2
, K CO
2
3
R
1
K CO
2
3
Me
O
O
O
OH
MeO
Br
Cl
3
, K CO
2
3
, K CO
2
3
O
O
O
Br
, K CO
2
3
Me
O
O
Me
O
O
O
Me
O
O
O
O
O
O
MeO
O
O
37
39
O
38
1N NaOH
1N NaOH
1N NaOH
MeO
Me
O
O
6
5
7
Me
O
O
Me
O
O
8
O
O
9
4
10
O
O
O
1
3
13
11 12
73
74
75
R = Me;
1
R = Ph;
1
R = Ph;
1
R = H;
1
R = H;
1
R = F;
1
R = F;
1
R = Cl;
1
R = Cl;
1
R = Br;
1
R = Br;
1
R = Me;
1
R = Me;
1
R = OMe;
1
R = OMe
1
29:
30:
31:
67:
32:
68:
33:
69:
34:
70:
35:
71:
36:
72:
R = Me;
1
65:
66:
In our opinion, this method is most acceptable because the target furocoumarins can be modified without limitation
in high yields.
We confirmed the fusion of the furan ring to the 2,3-position of 7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (for
411

40-63) or the 1,2-position of this same system (for 64-75) using PMR spectroscopy. The aromatic protons in the PMR spectra
of 40-63 are simply split due to the lack of coupling to H-2 of the 7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one. As a result,
aromatic H-11 of the furocoumarin appears as a singlet. The situation is analogous for 64-75, where H-5 of the furocoumarin
gives a singlet owing to a lack of coupling with H-2 of the starting coumarin. Furthermore, a 1H singlet is observed at 7.8-8.5
ppm for 40, 41, and 46-61, which are unsubstituted in the 9-position, and for 64 and 67-74, which are unsubstituted in the 2-
position. This is also a characteristic feature of furocoumarin ring formation.
Thus, we prepared new synthetic analogs of psoralen and allopsoralen based on 1-hydroxy- and 3-hydroxy-7,8,9,10-
tetrahydro-6H-benzo[c]chromen-6-ones.
EXPERIMENTAL
The course of the reactions and the purity of the products were monitored by TLC on Silufol UV-254 plates in
CHCl —CH OH (9:1 and 95:5). PMR spectra were measured on a Varian VXR-300 instrument in DMSO-d and
3
3
6
deuteroacetone relative to TMS (internal standard). Elemental analyses of all compounds corresponded with those calculated.
Hydroxycoumarins 1, 2, and 3 were prepared by the literature method [10].
3-(2-Oxopropoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (4). A hot solution of 1 (2.16 g, 10 mmole) in
absolute acetone (50 mL) was treated with freshly calcined potash (2.76 g, 20 mmole), vigorously stirred and heated (50-56oC),
and treated with α-bromoacetone (1.5 g, 11 mmole). The reaction mixture was held for 1 h with heating and vigorous stirring
(the completion of the reaction was determined by TLC) and transferred into H SO solution (1 N, 200 mL) The resulting
2
4
precipitate was filtered off and crystallized from propan-2-ol (70%). Yield 74%, mp 131oC, C16H16O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.82 (4H, m, CH -8 and CH -9), 2.25 (3H, s, CH CO), 2.46
2
2
3
(2H, m, CH -10), 2.77 (2H, m, CH -7), 4.89 (2H, s, COCH O), 6.84 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 6.98 (1H, d, J = 2, H-4),
2
2
2
7.61 (1H, d, J = 8, H-1).
4-Methyl-3-(2-oxopropoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (5) was prepared analogously to 4 from
2 (2.30 g, 10 mmole) and α-bromoacetone (1.5 g, 11 mmole). Yield 79%, mp 157oC (70% propan-2-ol), C17H18O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.81 (4H, m, CH -8 and CH -9), 2.25 (3H, s, CH CO), 2.32
2
2
3
(3H, s, CH -4), 2.47 (2H, m, CH -10), 2.76 (2H, m, CH -7), 4.86 (2H, s, COCH O), 6.87 (1H, d, J = 8, H-2), 7.48 (1H, d,
3
2
2
2
J = 8, H-1).
3-(1-Methyl-2-oxopropoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (6) was prepared analogously to 4 from
1 (2.16 g, 10 mmole) and 3-chloro-2-butanone (1.11 mL, 11 mmole). The reaction mixture was heated for 3 h. Yield 65%,
mp 87oC (60% propan-2-ol), C17H18O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.53 (3H, d, α-CH ), 1.82 (4H, m, CH -8 and CH -9), 2.21
3
2
2
(3H, s, CH CO), 2.44 (2H, m, CH -10), 2.79 (2H, m, CH -7), 4.98 (1H, q, COCHO), 6.82 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 6.96
3
2
2
(1H, d, J = 2, H-4), 7.64 (1H, d, J = 8, H-1).
4-Methyl-3-(1-methyl-2-oxopropoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (7) was prepared analogously
to 4 from 2 (2.30 g, 10 mmole) and 3-chloro-2-butanone (1.11 mL, 11 mmole). The reaction mixture was heated for 3 h. Yield
76%, mp 93oC (60% propan-2-ol), C18H20O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.55 (3H, d, α-CH ), 1.81 (4H, m, CH -8 and CH -9), 2.21
3
2
2
(3H, s, CH CO), 2.32 (3H, s, CH -4), 2.45 (2H, m, CH -10), 2.76 (2H, m, CH -7), 4.95 (1H, q, COCHO), 6.79 (1H, d, J = 8,
3
3
2
2
H-2), 7.46 (1H, d, J = 8, H-1).
3-(1-Methyl-2-oxo-2-phenylethoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (8) was prepared analogously
to 4 from 1 (2.16 g, 10 mmole) and 2-bromopropiophenone (1.64 mL, 11 mmole). The reaction mixture was heated for 2 h.
Yield 86%, mp 121oC (propan-2-ol), C22H20O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.67 (3H, d, α-CH ), 1.78 (4H, m, CH -8 and CH -9), 2.43
3
2
2
(2H, m, CH -10), 2.76 (2H, m, CH -7), 6.00 (1H, q, COCHO), 6.81 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 6.94 (1H, d, J = 2, H-4),
2
2
7.62 (1H, d, J = 8, H-1), 7.64 (3H, m, H-3 , H-4 , H-5 PhCO), 8.14 (2H, m, H-2 , H-6 PhCO).
4-Methyl-3-(1-methyl-2-oxo-2-phenylethoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (9) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and 2-bromopropiophenone (1.64 mL, 11 mmole). The reaction mixture was heated
for 2 h. Yield 88%, mp 155oC (propan-2-ol), C23H22O4.
412

PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.71 (3H, d, α-CH ), 1.78 (4H, m, CH -8 and CH -9), 2.30
3
2
2
(3H, s, CH -4), 2.45 (2H, m, CH -10), 2.71 (2H, m, CH -7), 5.96 (1H, q, COCHO), 6.82 (1H, d, J = 8, H-2), 7.41 (1H, d,
3
2
2
J = 8, H-1), 7.60 (3H, m, H-3 , H-4 , H-5 PhCO), 8.12 (2H, m, H-2 , H-6 PhCO).
3-(2-Oxo-2-phenylethoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (10) was prepared analogously to 4 from
1 (2.16 g, 10 mmole) and α-bromoacetophenone (2.19 g, 11 mmole). The reaction mixture was heated for 1 h. Yield 95%,
mp 169oC (propan-2-ol), C21H18O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.41 (2H, m, CH -10), 2.75 (2H,
6
2
2
2
m, CH -7), 5.68 (2H, s, COCH O), 6.88 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.02 (1H, d, J = 2, H-4), 7.59 (1H, d, J = 8, H-1), 7.65
2
2
(3H, m, H-3 , H-4 , H-5 PhCO), 8.04 (2H, m, H-2 , H-6 PhCO).
4-Methyl-3-(2-oxo-2-phenylethoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (11) was prepared analogously
to 4 from 2 (2.30 g, 10 mmole) and 3. α-bromoacetophenone (2.19 g, 11 mmole). The reaction mixture was heated for 1 h.
Yield 96%, mp 199oC (propan-2-ol), C22H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -4), 2.41 (2H,
6
2
2
3
m, CH -10), 2.74 (2H, m, CH -7), 5.71 (2H, s, COCH O), 6.98 (1H, d, J = 8, H-2), 7.45 (1H, d, J = 8, H-1), 7.55-7.70 (3H, m,
2
2
2
H-3 , H-4 , H-5 PhCO), 8.01 (2H, m, H-2 , H-6 PhCO).
3[2-(4-Fluorophenyl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (12) was prepared analogously
to 4 from 1 (2.16 g, 10 mmole) and α-chloro-4-fluoroacetophenone (1.90 g, 11 mmole). The reaction mixture was heated for
1 h. Yield 91%, mp 147oC (propan-2-ol), C21H17FO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.40 (2H, m, CH -10), 2.76 (2H,
6
2
2
2
m, CH -7), 5.70 (2H, s, COCH O), 7.02 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.05 (1H, d, J = 2, H-4), 7.42 (2H, m, H-3 , H-5
2
2
ArCO), 7.60 (1H, d, J = 8, H-1), 8.13 (2H, m, H-2 , H-6 ArCO).
3-[2-(4-Fluorophenyl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (13) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and α-chloro-4-fluoroacetophenone (1.90 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 94%, mp 197oC (propan-2-ol), C22H19FO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -4), 2.41 (2H,
6
2
2
3
m, CH -10), 2.75 (2H, m, CH -7), 5.72 (2H, s, COCH O), 7.00 (1H, d, J = 8, H-2), 7.42 (1H, d, J = 8, H-1), 7.47 (2H, m, H-3 ,
2
2
2
H-5 ArCO), 8.11 (2H, m, H-2 , H-6 ArCO).
3-[2-(4-Chlorophenyl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (14) was prepared analogously
to 4 from 1 (2.16 g, 10 mmole) and α-bromo-4-chloroacetophenone (2.57 g, 11 mmole). The reaction mixture was heated for
1 h. Yield 88%, mp 178oC (propan-2-ol), C21H17ClO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.39 (2H, m, CH -10), 2.75 (2H,
6
2
2
2
m, CH -7), 5.67 (2H, s, COCH O), 6.98 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.05 (1H, d, J = 2, H-4), 7.62 (1H, d, J = 8, H-1), 7.64
2
2
(2H, d, J = 8, H-3 , H-5 ArCO), 8.05 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(4-Chlorophenyl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (15) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and α-bromo-4-chloroacetophenone (2.57 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 90%, mp 182oC (propan-2-ol), C22H19ClO4.
PMR spectrum (300 MHz, DMSO-d , , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.27 (3H, s, CH -4), 2.41 (2H,
6
2
2
3
m, CH -10), 2.74 (2H, m, CH -7), 5.68 (2H, s, COCH O), 6.99 (1H, d, J = 8, H-2), 7.44 (1H, d, J = 8, H-1), 7.65 (2H, d,
2
2
2
J = 8, H-3 , H-5 ArCO), 8.01 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(4-Bromophenyl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (16) was prepared analogously
to 4 from 1 (2.16 g, 10 mmole) and 4-bromophenacylbromide (3.06 g, 11 mmole). The reaction mixture was heated for 1 h.
Yield 91%, mp 194oC (propan-2-ol), C21H17BrO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.40 (2H, m, CH -10), 2.76 (2H,
6
2
2
2
m, CH -7), 5.69 (2H, s, COCH O), 6.98 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.05 (1H, d, J = 2, H-4), 7.60 (1H, d, J = 8, H-1), 7.82
2
2
(2H, d, J = 8, H-3 , H-5 ArCO), 7.95 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(4-Bromophenyl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (17) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and 4-bromophenacylbromide (3.06 g, 11 mmole). The reaction mixture was heated
for 1 h. Yield 93%, mp 207oC (propan-2-ol), C22H19BrO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.27 (3H, s, CH -4), 2.41 (2H,
6
2
2
3
m, CH -10), 2.75 (2H, m, CH -7), 5.69 (2H, s, COCH O), 6.99 (1H, d, J = 8, H-2), 7.45 (1H, d, J = 8, H-1), 7.80 (2H, d,
2
2
2
413

J = 8, H-3 , H-5 ArCO), 7.94 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(4-Methylphenyl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (18) was prepared analogously
to 4 from 1 (2.16 g, 10 mmole) and 4-methylphenacylbromide (2.34 g, 11 mmole). The reaction mixture was heated for 1 h.
Yield 81%, mp 169oC (propan-2-ol), C22H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -8 and CH -9), 2.40 (3H, s, CH -4 ArCO), 2.41
6
2
2
3
(2H, m, CH -10), 2.75 (2H, m, CH -7), 5.66 (2H, s, COCH O), 6.98 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.02 (1H, d, J = 2, H-4),
2
2
2
7.40 (2H, d, J = 8, H-3 , H-5 ArCO), 7.59 (1H, d, J = 8, H-1), 7.93 (2H, d, J = 8, H-2 H-6 ArCO).
3-[2-(4-Methylphenyl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (19) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and 4-methylphenacylbromide (2.34 g, 11 mmole). The reaction mixture was heated
for 1 h. Yield 82%, mp 197oC (propan-2-ol), C23H22O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -4), 2.40 (3H,
6
2
2
3
s, CH -4 ArCO), 2.41 (2H, m, CH -10), 2.74 (2H, m, CH -7), 5.68 (2H, s, COCH O), 6.96 (1H, d, J = 8, H-2), 7.39 (2H, d,
3
2
2
2
J = 8, H-3 , H-5 ArCO), 7.45 (1H, d, J = 8, H-1), 7.91 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(4-Methoxyphenyl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (20) was prepared
analogously to 4 from 1 (2.16 g, 10 mmole) and 4-methoxyphenacylbromide (2.52 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 90%, mp 168oC (propan-2-ol), C22H20O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -8 and CH -9), 2.39 (2H, m, CH -10), 2.74 (2H,
6
2
2
2
m, CH -7), 3.87 (3H, s, CH O-4 ArCO), 5.64 (2H, s, COCH O), 6.97 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.01 (1H, d, J = 2, H-4),
2
3
2
7.11 (2H, d, J = 8, H-3 , H-5 ArCO), 7.58 (1H, d, J = 8, H-1), 8.01 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(4-Methoxyphenyl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (21) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and 4-methoxyphenacylbromide (2.52 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 89%, mp 200oC (propan-2-ol), C23H22O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -4), 2.41 (2H,
6
2
2
3
m, CH -10), 2.75 (2H, m, CH -7), 3.86 (3H, s, CH O-4 ArCO), 5.66 (2H, s, COCH O), 6.96 (1H, d, J = 8, H-2), 7.11 (2H, d,
2
2
3
2
J = 8, H-3 , H-5 ArCO), 7.46 (1H, d, J = 8, H-1), 7.99 (2H, d, J = 8, H-2 , H-6 ArCO).
3-[2-(3-Methoxyphenyl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (22) was prepared
analogously to 4 from 1 (2.16 g, 10 mmole) and 3-methoxyphenacylbromide (2.52 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 92%, mp 161oC (propan-2-ol), C22H20O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.40 (2H, m, CH -10), 2.76 (2H,
6
2
2
2
m, CH -7), 3.85 (3H, s, CH O-3 ArCO), 5.69 (2H, s, COCH O), 7.00 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.03 (1H, d, J = 2, H-4),
2
3
2
7.28 (1H, dd, J5',6' = 2, J5',4' = 2, H-5 ArCO), 7.48 (1H, d, J = 8, H-1), 7.52 (1H, m, H-4 ArCO), 7.62 (2H, m, H-2 , H-6
ArCO).
3-[2-(3-Methoxyphenyl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (23) was prepared
analogously to 4 from 2 (2.30 g, 10 mmole) and 3-methoxyphenacylbromide (2.52 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 95%, mp 167oC (propan-2-ol), C23H22O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.73 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -4), 2.40 (2H,
6
2
2
3
m, CH -10), 2.75 (2H, m, CH -7), 3.84 (3H, s, CH O-3 ArCO), 5.74 (2H, s, COCH O), 6.96 (1H, d, J = 8, H-2), 7.29 (1H, dd,
2
2
3
2
J5',6' = 2, J5',4' = 2, H-5 ArCO), 7.46 (1H, d, J = 8, H-1), 7.50 (1H, m, H-4 ArCO), 7.60 (2H, m, H-2 , H-6 ArCO).
3-[2-(1,3-Benzodioxol-5-yl)-2-oxoethoxy]-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (24) was prepared
analogously to 4 from 1 (2.16 g, 10 mmole) and -bromo-3,4-methylenedioxyacetophenone (2.67 g, 11 mmole). The reaction
mixture was heated for 1 h. Yield 88%, mp 174oC (propan-2-ol), C22H18O6.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -8 and CH -9), 2.39 (2H, m, CH -10), 2.74 (2H,
6
2
2
2
m, CH -7), 5.64 (2H, s, COCH O), 6.13 (2H, s, OCH O), 6.97 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 7.01 (1H, d, J = 2, H-4), 7.08
2
2
2
(1H, d, J = 8.5, H-7 ArCO), 7.48 (1H, d, J = 2.0, H-4 ArCO), 7.58 (1H, d, J = 8, H-1), 7.69 (1H, dd, J6,4 = 2.0, J6,7 = 8.5, H-6
ArCO).
3-[2-(1,3-Benzodioxol-5-yl)-2-oxoethoxy]-4-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (25) was
prepared analogously to 4 from 2 (2.30 g, 10 mmole) and -bromo-3,4-methylenedioxyacetophenone (2.67 g, 11 mmole). The
reaction mixture was heated for 1 h. Yield 91%, mp 208oC (propan-2-ol), C23H20O6.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -4), 2.41 (2H,
6
2
2
3
m, CH -10), 2.75 (2H, m, CH -7), 5.64 (2H, s, COCH O), 6.16 (2H, s, OCH O), 6.94 (1H, d, J = 8, H-2), 7.09 (1H, d, J = 8.5,
2
2
2
2
414

H-7 ArCO), 7.47 (1H, d, J = 8, H-1), 7.51 (1H, d, J = 2.0, H-4 ArCO), 7.67 (1H, dd, J6,4 = 2.0, J6,7 = 8.5, H-6 ArCO).
3-(2-Oxocyclohexyloxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (26). A solution of 1 (3.24 g, 15 mmole)
in dry DMF (50 mL) was treated with freshly calcined potash (6.2 g, 45 mmole) and 2-chlorocyclohexanone (3.43 mL,
30 mmole). The reaction mixture was vigorously stirred and heated (75-80oC) for 24 h and treated with H SO solution
2
4
(1 N, 200 mL). The resulting precipitate was filtered off and crystallized from propan-2-ol. Yield 62%, mp 163oC (propan-
2-ol), C19H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.70-2.80 [16H, m, CH -7, CH -8, CH -9, CH -10 and (CH )
6
2
2
2
2
2 4
of cyclohexanone], 5.18 (1H, m, α-CH), 6.82 (1H, dd, J2,4 = 2, J2,1 = 8, H-2), 6.89 (1H, d, J = 2, H-4), 7.55 (1H, d, J = 8, H-1).
4-Methyl-3-(2-oxocyclohexyloxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (27) was prepared analogously
to 26 from 2 (3.45 g, 15 mmole) and 2-chlorocyclohexanone (3.43 mL, 30 mmole). Yield 68%, mp 184oC (propan-2-ol),
C20H22O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.70-2.80 [16H, m, CH -7, CH -8, CH -9, CH -10 and (CH )
6
2
2
2
2
2 4
of cyclohexanone], 2.22 (3H, s, CH -4), 5.15 (1H, m, α-CH), 6.85 (1H, d, J = 8, H-2), 7.40 (1H, d, J = 8, H-1).
3
3-Methyl-1-(2-oxopropoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (28) was prepared analogously to 4
from 3 (2.30 g, 10 mmole) and α-bromoacetone (1.5 g, 11 mmole). Yield 78%, mp 176oC (70% propan-2-ol), C17H18O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.75 (4H, m, CH -8 and CH -9), 2.25 (3H, s, CH CO), 2.35
2
2
3
(3H, s, CH -3), 2.47 (2H, m, CH -10), 3.21 (2H, m, CH -7), 4.93 (2H, s, COCH O), 6.65 (1H, d, J = 2, H-2), 6.71 (1H, d,
3
2
2
2
J = 2, H-4).
3-Methyl-1-(1-methyl-2-oxopropoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (29) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and 3-chloro-2-butanone (1.11 mL, 11 mmole). The reaction mixture was heated
for 3 h. Yield 71%, mp 159oC (60% propan-2-ol), C18H20O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.58 (3H, d, -CH ), 1.76 (4H, m, CH -8 and CH -9), 2.22
3
2
2
(3H, s, CH CO), 2.33 (3H, s, CH -3), 2.46 (2H, m, CH -10), 3.23 (2H, m, CH -7), 5.06 (1H, q, COCHO), 6.54 (1H, d, J = 2,
3
3
2
2
H-2), 6.72 (1H, d, J = 2, H-4).
3-Methyl-1-(1-methyl-2-oxo-2-phenylethoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (30) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and 2-bromopropiophenone (1.64 mL, 11 mmole). The reaction mixture was heated
for 2 h. Yield 85%, mp 157oC (propan-2-ol), C23H22O4.
PMR spectrum (300 MHz, deuteroacetone, δ, ppm, J/Hz): 1.71 (3H, d, -CH ), 1.78 (4H, m, CH -8 and CH -9), 2.26
3
2
2
(3H, s, CH -3), 2.48 (2H, m, CH -10), 3.21 (2H, m, CH -7), 6.16 (1H, q, COCHO), 6.64 (1H, d, J = 2, H-2), 6.70 (1H, d,
3
2
2
J = 2, H-4), 7.62 (3H, m, H-3 , H-4 , H-5 PhCO), 8.10 (2H, m, H-2 , H-6 PhCO).
3-Methyl-1-(2-oxo-2-phenylethoxy)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (31) was prepared analogously
to 4 from 3 (2.30 g, 10 mmole) and α-bromoacetophenone (2.19 g, 11 mmole). The reaction mixture was heated for 1 h. Yield
88%, mp 161oC (propan-2-ol), C22H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.28 (3H, s, CH -3), 2.42 (2H,
6
2
2
3
m, CH -10), 3.19 (2H, m, CH -7), 5.69 (2H, s, COCH O), 6.77 (1H, d, J = 2, H-2), 6.87 (1H, d, J = 2, H-4), 7.58 (2H, m, H-3',
2
2
2
H-5 PhCO), 7.71 (1H, m, H-4 PhCO), 8.05 (2H, m, H-2 , H-6 PhCO).
1-[2-(4-Fluorophenyl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (32) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and α-chloro-4-fluoroacetophenone (1.90 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 94%, mp 197oC (propan-2-ol), C22H19FO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.33 (3H, s, CH -3), 2.42 (2H,
6
2
2
3
m, CH -10), 3.19 (2H, m, CH -7), 5.69 (2H, s, COCH O), 6.79 (1H, d, J = 2, H-2), 6.88 (1H, d, J = 2, H-4), 7.42 (2H, m, H-3 ,
2
2
2
H-5 ArCO), 8.14 (2H, m, H-2 , H-6 ArCO).
1-[2-(4-Chlorophenyl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (33) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and α-bromo-4-chloroacetophenone (2.57 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 93%, mp 185oC (propan-2-ol), C22H19ClO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.33 (3H, s, CH -3), 2.41 (2H,
6
2
2
3
m, CH -10), 3.16 (2H, m, CH -7), 5.67 (2H, s, COCH O), 6.78 (1H, d, J = 2, H-2), 6.86 (1H, d, J = 8, H-4), 7.65 (2H, d,
2
2
2
J = 8, H-3 , H-5 ArCO), 8.05 (2H, d, J = 8, H-2 , H-6 ArCO).
1-[2-(4-Bromophenyl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (34) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and 4-bromophenacylbromide (3.06 g, 11 mmole). The reaction mixture was heated
415

for 1 h. Yield 91%, mp 203oC (propan-2-ol), C22H19BrO4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.33 (3H, s, CH -3), 2.42 (2H,
6
2
2
3
m, CH -10), 3.19 (2H, m, CH -7), 5.69 (2H, s, COCH O), 6.80 (1H, d, J = 2, H-2), 6.87 (1H, d, J = 2, H-4), 7.82 (2H, d,
2
2
2
J = 8, H-3 , H-5 ArCO), 7.97 (2H, d, J = 8, H-2 , H-6 ArCO).
1-[2-(4-Methylphenyl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (35) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and 4-methylphenacylbromide (2.34 g, 11 mmole). The reaction mixture was heated
for 1 h. Yield 88%, mp 167oC (propan-2-ol), C23H22O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.30 (3H, s, CH -3), 2.40 (3H,
6
2
2
3
s, CH -4 ArCO), 2.41 (2H, m, CH -10), 3.16 (2H, m, CH -7), 5.59 (2H, s, COCH O), 6.73 (1H, d, J = 2, H-2), 6.83 (1H, d,
3
2
2
2
J = 2, H-4), 7.39 (2H, d, J = 8, H-3 , H-5 ArCO), 7.92 (2H, d, J = 8, H-2 , H-6 ArCO).
1-[2-(4-Methoxyphenyl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (36) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and 4-methoxyphenacylbromide (2.52 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 93%, mp 183oC (propan-2-ol), C23H22O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.32 (3H, s, CH -3), 2.43 (2H,
6
2
2
3
m, CH -10), 3.19 (2H, m, CH -7), 3.87 (3H, s, CH O-4 ArCO), 5.62 (2H, s, COCH O), 6.77 (1H, d, J = 2, H-2), 6.86 (1H, d,
2
2
3
2
J = 2, H-4), 7.11 (2H, d, J = 8, H-3 , H-5 ArCO), 8.01 (2H, d, J = 8, H-2 , H-6 ArCO).
1-[2-(3-Methoxyphenyl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (37) was prepared
analogously to 4 from 3 (2.30 g, 10 mmole) and 3-methoxyphenacylbromide (2.52 g, 11 mmole). The reaction mixture was
heated for 1 h. Yield 92%, mp 169oC (propan-2-ol), C23H22O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.68 (4H, m, CH -8 and CH -9), 2.32 (3H, s, CH -3), 2.42 (2H,
6
2
2
3
m, CH -10), 3.19 (2H, m, CH -7), 3.85 (3H, s, CH O-3 ArCO), 5.67 (2H, s, COCH O), 6.77 (1H, d, J = 2, H-2), 6.86 (1H, d,
2
2
3
2
J = 2, H-4), 7.28 (1H, dd, J5',6' = 2, J5',4' = 2, H-5 ArCO), 7.50 (1H, m, H-4 ArCO), 7.62 (2H, m, H-2 , H-6 ArCO).
1-[2-(1,3-Benzodioxol-5-yl)-2-oxoethoxy]-3-methyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (38) was
prepared analogously to 4 from 3 (2.30 g, 10 mmole) and α-bromo-3,4-methylenedioxyacetophenone (2.67 g, 11 mmole). The
reaction mixture was heated for 1 h. Yield 85%, mp 178oC (propan-2-ol), C23H20O6.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.69 (4H, m, CH -8 and CH -9), 2.30 (3H, s, CH -4), 2.42 (2H,
6
2
2
3
m, CH -10), 3.18 (2H, m, CH -7), 5.64 (2H, s, COCH O), 6.16 (2H, s, OCH O), 6.73 (1H, d, J = 2, H-2), 6.84 (1H, d, J = 2,
2
2
2
2
H-4), 7.09 (1H, d, J = 8.5, H-7 ArCO), 7.51 (1H, d, J = 2.0, H-4 ArCO), 7.67 (1H, dd, J6,4 = 2.0, J6,7 = 8.5, H-6 ArCO).
3-Methyl-1-(2-oxocyclohexyl)-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one (39) was prepared analogously to
26 from 3 (3.45 g, 15 mmole) and 2-chlorocyclohexanone (3.43 mL, 30 mmole). Yield 53%, mp 149oC (propan-2-ol),
C20H22O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.70-2.50 [14H, m, CH -8, CH -9, CH -10, and (CH ) of
6
2
2
2
2 4
cyclohexanone], 2.30 (3H, s, CH -3), 3.10 (2H, m, CH -7), 5.24 (1H, m, α-CH), 6.63 (1H, d, J = 2, H-2), 6.74 (1H, d, J = 2,
3
2
H-4).
1,2,3,4-Tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-ones (40-63) and 8,9,10,11-tetrahydro-7H-benzo[c]furo
[2,3-f]chromen-7-ones (64-75). A solution or suspension of ketone 4-39 (6 mmole) in propan-2-ol (50 mL) was diluted with
NaOH solution (1 N, 50 mL). The reaction mixture was heated for 3-4 h until the starting ketone completely dissolved (course
of reaction monitored by TLC) and transferred into H SO solution (1 N, 300 mL). The resulting precipitate was filtered off
2
4
and crystallized from propan-2-ol.
10-Methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (40). Yield 81%, mp 198oC, C16H14O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.78 (4H, m, CH -2 and CH -3), 2.25 (3H, s, CH -10), 2.43 (2H,
6
2
2
3
m, CH -1), 2.71 (2H, m, CH -4), 7.58 (1H, s, H-11), 7.84 (1H, s, H-9), 7.86 (1H, s, H-7).
2
2
7,10-Dimethyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (41). Yield 84%, mp 199oC, C17H16O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.78 (4H, m, CH -2 and CH -3), 2.24 (3H, s, CH -10), 2.45 (3H,
6
2
2
3
s, CH -7), 2.43 (2H, m, CH -1), 2.86 (2H, m, CH -4), 7.66 (1H, s, H-11), 7.78 (1H, s, H-9).
3
2
2
9,10-Dimethyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (42). Yield 87%, mp 214oC, C17H16O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.76 (4H, m, CH -2 and CH -3), 2.16 (3H, s, CH -10), 2.38 (3H,
6
2
2
3
s, CH -9), 2.49 (2H, m, CH -1), 2.86 (2H, m, CH -4), 7.40 (1H, s, H-11), 7.67 (1H, s, H-7).
3
2
2
7,9,10-Trimethyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (43). Yield 83%, mp 195oC,C18H18O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -2 and CH -3), 2.15 (3H, s, CH -10), 2.39 (3H,
6
2
2
3
416

s, CH -9), 2.42 (3H, s, CH -7), 2.49 (2H, m, CH -1), 2.84 (2H, m, CH -4), 7.51 (1H, s, H-11).
3
3
2
2
9-Methyl-10-phenyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (44). Yield 89%, mp 176oC,
C22H18O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -2 and CH -3), 2.43 (2H, m, CH -1), 2.54 (3H,
6
2
2
2
s, CH -9), 2.83 (2H, m, CH -4), 7.42-7.60 (5H, m, Ph-10), 7.62 (1H, s, H-11), 7.71 (1H, s, H-7).
3
2
7,9-Dimethyl-10-phenyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (45). Yield 91%, mp 249oC,
C23H20O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -2 and CH -3), 2.43 (2H, m, CH -1), 2.47 (3H,
6
2
2
2
s, CH -7), 2.54 (3H, s, CH -9), 2.77 (2H, m, CH -4), 7.43-7.53 (5H, m, Ph-10), 7.55 (1H, s, H-11).
3
3
2
10-Phenyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (46). Yield 88%, mp 192oC, C21H16O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -2 and CH -3), 2.44 (2H, m, CH -1), 2.93 (2H,
6
2
2
2
m, CH -4), 7.43 (1H, m, H-4 Ph-10), 7.54 (2H, m, H-3 and H-5 Ph-10), 7.73 (1H, s, H-11), 7.79 (2H, m, H-2 and H-6 Ph-
2
10), 8.05 (1H, s, H-7), 8.44 (1H, s, H-9).
7-Methyl-10-phenyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (47). Yield 89%, mp 200oC,
C22H18O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -2 and CH -3), 2.45 (2H, m, CH -1), 2.50 (3H,
6
2
2
2
s, CH -7), 2.89 (2H, m, CH -4), 7.42 (1H, m, H-4 Ph-10), 7.53 (2H, m, H-3 and H-5 Ph-10), 7.76 (2H, m, H-2 and H-6
3
2
Ph-10), 7.87 (1H, s, H-11), 8.41 (1H, s, H-9).
10-(4-Fluorophenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (48). Yield 89%, mp 199oC,
C21H15FO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.78 (4H, m, CH -2 and CH -3), 2.45 (2H, m, CH -1), 2.93 (2H,
6
2
2
2
m, CH -4), 7.37 (2H, m, H-3 and H-5 Ar-10), 7.72 (1H, s, H-11), 7.83 (2H, m, H-2 and H-6 Ar-10), 8.03 (1H, s, H-7), 8.42
2
(1H, s, H-9).
10-(4-Fluorophenyl)-7-methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (49). Yield 86%,
mp 201oC, C22H17FO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.72 (4H, m, CH -2 and CH -3), 2.40 (2H, m, CH -1), 2.42 (3H,
6
2
2
2
s, CH -7), 2.80 (2H, m, CH -4), 7.34 (2H, m, H-3 and H-5 Ar-10), 7.73 (1H, s, H-11), 7.77 (2H, m, H-2 and H-6 Ar-10),
3
2
8.39 (1H, s, H-9).
10-(4-Chlorophenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (50). Yield 88%, mp 234oC,
C21H15ClO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -2 and CH -3), 2.44 (2H, m, CH -1), 2.91 (2H,
6
2
2
2
m, CH -4), 7.57 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.71 (1H, s, H-11), 7.81 (2H, d, J = 8, H-2 and H-6 Ar-10), 8.01 (1H,
2
s, H-7), 8.47 (1H, s, H-9).
10-(4-Chlorophenyl)-7-methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (51). Yield 91%,
mp 205oC, C22H17ClO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.76 (4H, m, CH -2 and CH -3), 2.42 (2H, m, CH -1), 2.44 (3H,
6
2
2
2
s, CH -7), 2.82 (2H, m, CH -4), 7.53 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.72 (2H, d, J = 8, H-2 and H-6 Ar-10), 7.76 (1H,
3
2
s, H-11), 8.42 (1H, s, H-9).
10-(4-Bromophenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (52). Yield 90%, mp 248oC,
C21H15BrO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -2 and CH -3), 2.45 (2H, m, CH -1), 2.91 (2H,
6
2
2
2
m, CH -4), 7.68 (1H, s, H-11), 7.70 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.76 (2H, d, J = 8, H-2 and H-6 Ar-10), 8.01 (1H,
2
s, H-7), 8.44 (1H, s, H-9).
10-(4-Bromophenyl)-7-methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (53). Yield 88%,
mp 191oC, C22H17BrO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -2 and CH -3), 2.45 (2H, m, CH -1), 2.49 (3H,
6
2
2
2
s, CH -7), 2.89 (2H, m, CH -4), 7.68 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.74 (2H, d, J = 8, H-2 and H-6 Ar-10), 7.86 (1H,
3
2
s, H-11), 8.48 (1H, s, H-9).
10-(4-Methylphenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (54). Yield 82%, mp 193oC,
C22H18O3.
417

PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.78 (4H, m, CH -2 and CH -3), 2.38 (3H, s, CH -4 Ar-10), 2.43
6
2
2
3
(2H, m, CH -1), 2.89 (2H, m, CH -4), 7.35 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.63 (2H, d, J = 8, H-2 and H-6 Ar-10), 7.68
2
2
(1H, s, H-11), 7.99 (1H, s, H-7), 8.36 (1H, s, H-9).
7-Methyl-10-(4-methylphenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (55). Yield 88%,
mp 202oC, C23H20O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.74 (4H, m, CH -2 and CH -3), 2.38 (3H, s, CH -4 Ar-10), 2.43
6
2
2
3
(2H, m, CH -1), 2.46 (3H, s, CH -7), 2.84 (2H, m, CH -4), 7.34 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.62 (2H, d, J = 8, H-2
2
3
2
and H-6 Ar-10), 7.80 (1H, s, H-11), 8.37 (1H, s, H-9).
10-(4-Methoxyphenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (56). Yield 81%, mp 201oC,
C22H18O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -2 and CH -3), 2.43 (2H, m, CH -1), 2.90 (2H,
6
2
2
2
m, CH -4), 3.83 (3H, s, CH O-4 Ar-10), 7.08 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.68 (1H, s, H-11), 7.75 (2H, d, J = 8, H-2
2
3
and H-6 Ar-10), 7.98 (1H, s, H-7), 8.33 (1H, s, H-9).
10-(4-Methoxyphenyl)-7-methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (57). Yield 86%,
mp 203oC, C23H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -2 and CH -3), 2.41 (2H, m, CH -1), 2.44 (3H,
6
2
2
2
s, CH -7), 2.82 (2H, m, CH -4), 3.83 (3H, s, CH O-4 Ar-10), 7.07 (2H, d, J = 8, H-3 and H-5 Ar-10), 7.66 (2H, d, J = 8, H-2
3
2
3
and H-6 Ar-10), 7.76 (1H, s, H-11), 8.32 (1H, s, H-9).
10-(3-Methoxyphenyl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (58). Yield 86%, mp 182oC,
C22H18O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -2 and CH -3), 2.44 (2H, m, CH -1), 2.90 (2H,
6
2
2
2
m, CH -4), 3.86 (3H, s, CH O-3 Ar-10), 7.00 (1H, dd, J5',6' = 2, J5',4' = 2, H-5 Ar-10), 7.27 (1H, m, H-4 Ar-10), 7.35 (1H, m,
2
3
H-6 Ar-10), 7.45 (1H, dd, J2',6' = 2, J2',4' = 2, H-2 Ar-10), 7.66 (1H, s, H-11), 8.00 (1H, s, H-7), 8.39 (1H, s, H-9).
10-(3-Methoxyphenyl)-7-methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (59). Yield 88%,
mp 224oC, C23H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.78 (4H, m, CH -2 and CH -3), 2.44 (2H, m, CH -1), 2.48 (3H,
6
2
2
2
s, CH -7), 2.88 (2H, m, CH -4), 3.85 (3H, s, CH O-3 Ar-10), 7.01 (1H, dd, J5',6' = 2, J5',4' = 2, H-5 Ar-10), 7.27 (1H, m, H-4
3
2
3
Ar-10), 7.36 (1H, m, H-6 Ar-10), 7.45 (1H, dd, J2',6' = 2, J2',4' = 2, H-2 Ar-10), 7.83 (1H, s, H-11), 8.43 (1H, s, H-9).
10-(1,3-Benzodioxol-5-yl)-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (60). Yield 80%, mp 189oC,
C22H16O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -2 and CH -3), 2.44 (2H, m, CH -1), 2.90 (2H,
6
2
2
2
m, CH -4), 6.09 (2H, s, OCH O Ar-10), 7.04 (1H, d, J = 8.5, H-7 Ar-10), 7.25 (1H, dd, J6,4 = 2.0, J6,7 = 8.5, H-6 Ar-10), 7.30
2
2
(1H, d, J = 2, H-4 Ar-10), 7.63 (1H, s, H-11), 7.96 (1H, s, H-7), 8.30 (1H, s, H-9).
10-(1,3-Benzodioxol-5-yl)-7-methyl-1,2,3,4-tetrahydro-5H-benzo[c]furo[3,2-g]chromen-5-one (61). Yield 89%,
mp 198oC, C23H18O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.76 (4H, m, CH -2 and CH -3), 2.42 (2H, m, CH -1), 2.44 (3H,
6
2
2
2
s, CH -7), 2.83 (2H, m, CH -4), 6.08 (2H, s, OCH O Ar-10), 7.03 (1H, d, J = 8.5, H-7 Ar-10), 7.21 (1H, dd, J6,4 = 2.0,
3
2
2
J6,7 = 8.5, H-6 Ar-10), 7.25 (1H, d, J = 2, H-4 Ar-10), 7.74 (1H, s, H-11), 8.26 (1H, s, H-9).
1,2,3,4,9,10,11,12-Octahydro-5H-benzo[c]benzo[4,5]furo[3,2-g]chromen-5-one (62). Yield 78%, mp 187oC,
C19H18O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75-1.90 (8H, m, CH -2, CH -3, CH -10, CH -11), 2.44 (2H,
6
2
2
2
2
m, CH -1), 2.62 (2H, m, CH -12), 2.73 (2H, m, CH -9), 2.86 (2H, m, CH -4), 7.48 (1H, s, H-11), 7.71 (1H, s, H-7).
2
2
2
2
7-Methyl-1,2,3,4,9,10,11,12-octahydro-2H-benzo[c]benzo[4,5]furo[3,2-g]chromen-5-one (63). Yield 86%,
mp 242oC, C20H20O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.80-1.90 (8H, m, CH -2, CH -3, CH -10, CH -11), 2.42 (2H,
6
2
2
2
2
m, CH -1), 2.44 (3H, s, CH -7), 2.60 (2H, m, CH -12), 2.74 (2H, m, CH -9), 2.83 (2H, m, CH -4), 7.52 (1H, s, H-11).
2
3
2
2
2
3,4-Dimethyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (64). Yield 79%, mp 176oC, C17H16O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.77 (4H, m, CH -9 and CH -10), 2.36 (3H, s, CH -4), 2.44 (2H,
6
2
2
3
m, CH -11), 2.64 (3H, s, CH -3), 3.13 (2H, m, CH -8), 6.97 (1H, s, H-5), 7.77 (1H, s, H-2).
2
3
2
2,3,4-Trimethyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (65). Yield 82%, mp 189oC, C18H18O3.
418

PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.75 (4H, m, CH -9 and CH -10), 2.27 (3H, s, CH -4), 2.36 (3H,
6
2
2
3
s, CH -3), 2.41 (2H, m, CH -11), 2.50 (3H, s, CH -2), 3.06 (2H, m, CH -8), 6.88 (1H, s, H-5).
3
2
3
2
2,4-Dimethyl-3-phenyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (66). Yield 79%, mp 154oC,
C23H20O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.76 (4H, m, CH -9 and CH -10), 2.06 (3H, s, CH -4), 2.32 (3H,
6
2
2
3
s, CH -2), 2.42 (2H, m, CH -11), 3.14 (2H, m, CH -8), 6.95 (1H, s, H-5), 7.38-7.52 (5H, m, Ph-3).
3
2
2
4-Methyl-3-phenyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (67). Yield 83%, mp 179oC,
C22H18O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.78 (4H, m, CH -9 and CH -10), 2.21 (3H, s, CH -4), 2.45 (2H,
6
2
2
3
m, CH -11), 3.18 (2H, m, CH -8), 7.07 (1H, s, H-5), 7.40-7.50 (5H, m, Ph-3), 8.12 (1H, s, H-2).
2
2
3-(4-Fluorophenyl)-4-methyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (68). Yield 84%,
mp 207oC, C22H17FO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.76 (4H, m, CH -9 and CH -10), 2.18 (3H, s, CH -4), 2.40 (2H,
6
2
2
3
m, CH -11), 3.09 (2H, m, CH -8), 6.98 (1H, s, H-5), 7.30 (2H, m, H-3 and H-5 Ar-3), 7.50 (2H, m, H-2 and H-6 Ar-3), 8.09
2
2
(1H, s, H-2).
3-(4-Chlorophenyl)-4-methyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (69). Yield 89%,
mp 224oC, C22H17ClO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -9 and CH -10), 2.23 (3H, s, CH -4), 2.47 (2H,
6
2
2
3
m, CH -11), 3.21 (2H, m, CH -8), 7.10 (1H, s, H-5), 7.50 (4H, m, Ar-3), 8.14 (1H, s, H-2).
2
2
3-(4-Bromophenyl)-4-methyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (70). Yield 82%,
mp 238oC, C22H17BrO3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.80 (4H, m, CH -9 and CH -10), 2.22 (3H, s, CH -4), 2.45 (2H,
6
2
2
3
m, CH -11), 3.18 (2H, m, CH -8), 7.08 (1H, s, H-5), 7.46 (2H, d, J = 8, H-3 and H-5 Ar-3), 7.66 (2H, d, J = 8, H-2 and H-6
2
2
Ar-3), 8.13 (1H, s, H-2).
4-Methyl-3-(4-methylphenyl)-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (71). Yield 81%,
mp 195oC, C23H20O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.76 (4H, m, CH -9 and CH -10), 2.18 (3H, s, CH -4), 2.38 (3H,
6
2
2
3
s, CH -4 Ar-3), 2.40 (2H, m, CH -11), 3.12 (2H, m, CH -8), 6.99 (1H, s, H-5), 7.25 (2H, d, J = 8, H-3 and H-5 Ar-3), 7.33
3
2
2
(2H, d, J = 8, H-2 and H-6 Ar-3), 8.04 (1H, s, H-2).
3-(4-Methoxyphenyl)-4-methyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (72). Yield 89%,
mp 200oC, C23H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.81 (4H, m, CH -9 and CH -10), 2.22 (3H, s, CH -4), 2.44 (2H,
6
2
2
3
m, CH -11), 3.17 (2H, m, CH -8), 3.82 (3H, s, CH O-4 Ar-3), 7.02 (2H, d, J = 8, H-3 and H-5 Ar-3), 7.05 (1H, s, H-5), 7.38
2
2
3
(2H, d, J = 8, H-2 and H-6 Ar-3), 8.06 (1H, s, H-2).
3-(3-Methoxyphenyl)-4-methyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (73). Yield 83%,
mp 210oC, C23H20O4.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.81 (4H, m, CH -9 and CH -10), 2.24 (3H, s, CH -4), 2.44 (2H,
6
2
2
3
m, CH -11), 3.19 (2H, m, CH -8), 3.81 (3H, s, CH O-3 Ar-3), 7.03 (1H, s, H-5), 7.05 (3H, m, H-4 , H-5 , H-6 Ar-3), 7.39
2
2
3
(1H, m, H-2 Ar-3), 8.08 (1H, s, H-2).
3-(1,3-Benzodioxol-5-yl)-4-methyl-8,9,10,11-tetrahydro-7H-benzo[c]furo[2,3-f]chromen-7-one (74). Yield 82%,
mp 181oC, C23H18O5.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.79 (4H, m, CH -9 and CH -10), 2.25 (3H, s, CH -4), 2.40 (2H,
6
2
2
3
m, CH -11), 3.15 (2H, m, CH -8), 6.05 (2H, s, OCH O Ar-10), 7.01 (1H, s, H-5), 7.05 (1H, d, J = 8.5, H-7 Ar-10), 7.18 (1H,
2
2
2
dd, J6,4 = 2.0, J6,7 = 8.5, H-6 Ar-10), 7.25 (1H, d, J = 2, H-4 Ar-10), 8.07 (1H, s, H-2).
8-Methyl-1,3,4,5,9,10,11,12-octahydro-2H-benzo[c]benzo[4,5]furo[2,3-f]chromen-5-one (75). Yield 65%,
mp 172oC, C20H20O3.
PMR spectrum (300 MHz, DMSO-d , δ, ppm, J/Hz): 1.70-1.90 (8H, m, CH -2, CH -3, CH -10, CH -11), 2.41 (2H,
6
2
2
2
2
m, CH -9), 2.57 (3H, s, CH -8), 2.78 (4H, m, CH -1, CH -12), 3.14 (2H, m, CH -4), 6.93 (1H, s, H-7).
2
3
2
2
2
419

REFERENCES
1.
2.
3.
4.
5.
Y. Kondo, A. Kato, Y. Kubota, and S. Nozoe, Heterocycles, 31, 187 (1990).
A. Hamed, I. Springuel, N. El-Amary, H. Mitome, and Y. Yamada, Phytochemistry, 1257 (1997).
M. D. Mashkovskii, Medicinal Preparations [in Russian], Gamta, Vilnius (1994), Vol. 2, p. 170.
I. S. Chekman and G. N. Lipkan, Plant Medicinal Preparations [in Russian], Kolos, Kiev (1993).
N. P. Maksyutina, N. F. Komisarenko, and A. F. Prokopenko, Plant Medicinal Preparations [in Russian],
Zdorov e, Kiev (1985).
6.
7.
U.S. Pat. No. 2860085; Chem. Abstr., 53, 9560d (1959).
U.S. Pat. No. 3294636; Chem. Abstr., 66, 85699v (1967).
8.
U.S. Pat. No. 3325489; Chem. Abstr., 68, 68886x (1968).
9.
U.S. Pat. No. 3325490; Chem. Abstr., 68, 95689x (1968).
10.
11.
12.
13.
14.
15.
P. N. Confalone and D. L. Confalone, Tetrahedron, No. 8, 1265 (1983).
E. C. Horning and D. B. Reisner, J. Am. Chem. Soc., 70, 3619 (1948).
J. K. MacLeod and M. Nakayama, Org. Mass Spectrom., 6, No. 3, 293 (1972).
R. M. Naik and V. M. Thakor, J. Org. Chem., 1696 (1957).
K. D. Kaufman, F. J. Gaiser, T. D. Leth, and L. R. Worden, J. Org. Chem., 117 (1961).
J. K. MacLeod, B. R. Worth, and R. J. Wells, Aust. J. Chem., 1533 (1978).
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