Condensation of hydroxy naphthazarins with aromatic aldehydes

Article abstract of DOI:10.1007/s11172-008-0332-0

Hydroxy naphthazarins (2,5,8-trihydroxy-1,4-naphthoquinones) react with aromatic aldehydes containing no hydroxy groups at position 2 under mild acid catalysis to form 3,3'-(arylmethylene)bisnaphthazarins. On the example of o-vanillin, it was shown that t

Full text of DOI:10.1007/s11172-008-0332-0

Russian Chemical Bulletin, International Edition, Vol. 57, No. 11, pp. 2335—2339, November, 2008
2335
Condensation of hydroxy naphthazarins with aromatic aldehydes
D. N. Pelageev and V. Ph. Anufriev
Pacific Institute of Bioorganic Chemistry, FarꢀEastern Branch of the Russian Academy of Sciences
159 prosp. 100ꢀletiya Vladivostoka, 690022 Vladivostok, Russian Federation.
Fax: +7 (423) 231 4050. Eꢀmail: pelageev@piboc.dvo.ru
Hydroxy naphthazarins (2,5,8ꢀtrihydroxyꢀ1,4ꢀnaphthoquinones) react with aromatic
aldehydes containing no hydroxy groups at position 2 under mild acid catalysis to form
3,3´ꢀ(arylmethylene)bisnaphthazarins. On the example of oꢀvanillin, it was shown that the
reaction of 2ꢀhydroxybenzaldehydes with hydroxy naphthazarins under the same conditions
leads to 7,10ꢀdihydroxyꢀ12Hꢀbenzo[b]xantheneꢀ6,11ꢀdione derivatives.
Key words: naphthazarins, 5,8ꢀdihydroxyꢀ1,4ꢀnaphthoquinone; 4ꢀmethoxybenzaldehyde,
2ꢀhydroxyꢀ3ꢀmethoxybenzaldehyde, 2,3ꢀdimethoxybenzaldehyde; 3,3´ꢀ(phenylmethylene)ꢀ
bis(5,8ꢀdihydroxyꢀ1,4ꢀnaphthoquinone),
3,3´ꢀ(phenylmethylene)bisnaphthazarin;
7,10ꢀdihydroxyꢀ12Hꢀbenzo[b]xantheneꢀ6,11ꢀdione.
Earlier, we have shown that the reaction of hydroxyꢀ
lated naphthazarins (5,8ꢀdihydroxyꢀ1,4ꢀnaphthoquinoꢀ
nes) with saturated and unsaturated aliphatic aldehydes is
a convenient approach for the structure and properties
modification of these compounds.1,2 Development of this
approach allowed one to accomplish the first synthesis
of ploiariquinones A and B (metabolites of the higher
plant Ploiarium alternifolium3,4), ( )ꢀnaphthgeranine A
(one of the metabolites of a microorganism of the genus
Streptomyces), and ( )ꢀnaphterpin methyl ether,5,6 as well
as their analogs.7 In addition, these works aroused interest
to the study of prototropic tautomerism in 3ꢀalkenylꢀ
1: R = H (a), Me (b); 2: R1 = R2 = H, R3 = OMe (a), R1 = R2 = OMe, R3 = H (b), R1 = OH, R2 = OMe, R3 = H (c); 3: R = H (a), Me (b); 5: R = H, Me;
Ar = 4ꢀMeOC6H4, 2,3ꢀ(MeO)2C6H3, 2ꢀHOꢀ3ꢀMeOC6H3.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2290—2293, November, 2008.
1066ꢀ5285/08/5711ꢀ2335 © 2008 Springer Science+Business Media, Inc.

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Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008
Pelageev and Anufriev
Scheme 1
1,4,6,7: R = H (a); R = Me (b)
2ꢀhydroxynaphthazarins8 and 6ꢀ or 7ꢀhydroxypyranoꢀ
naphthazarins9 forming in these reactions. At the same
time, there is no enough information on the reactions of
hydroxy naphthazarins with aromatic aldehydes in the
literature,10—12 though this can serve as an alternative
approach to the known syntheses of biologically active
natural compounds of the benzopyranonaphthoquinonoid
series.13,14
We have studied the condensation reactions of naphthoꢀ
purpurin (1a) and 2ꢀhydroxyꢀ6,7ꢀdimethylnaphthazarin
(1b) with 4ꢀmethoxybenzaldehyde (2a), 2,3ꢀdimethoxyꢀ
benzaldehyde (2b), and 2ꢀhydroxyꢀ3ꢀmethoxybenzaldeꢀ
hyde (2c). It was found that the reaction of substrates 1a,b
with aldehyde 2a in the presence of catalytic amounts of
Et3N•HCl, alike as the reactions with aliphatic aldeꢀ
hydes,1 generally leads to symmetric bisnaphthazarins
3a,b, the structural analogs of pigments of sea urchins
Strongylocentrotus intermedius and S. droebachiensis.15
The reaction of compound 1a with aldehyde 2b gave two
products, the structures of which according to the spectral
data corresponded to benzylidenebisnaphthazarin 3c
and benzoxanthenedione 4a. In this case, anhydrobisꢀ
naphthazarins of the type 5, which are the structural anaꢀ
logs of pigments isolated from the same sources,15—17 have
not been found in the reaction mixtures. Apparently, more
drastic conditions are needed for their formation.16
The formation of compound 4a can be explained, by all
appearances, by ready hydrolysis of the methoxy group at
position 2 of aldehyde 2b, that leads to the formation of
the benzo[b]xanthenedione product.
The latter suggestion is completely confirmed by the
alternative synthesis of compound 4a on the example of
the reaction of substrate 1a with aldehyde 2c. Thus, the
condensation of hydroxynaphthazarins 1a,b with excess
of aldehyde 2c in 2ꢀmethoxyethanol in the presence of
catalytic amounts of Et3N•HCl (reflux, 3 h) gave benzoꢀ
xanthenediones 4a,b (Scheme 1) without contamination
with symmetric (arylmethylene)bisnaphthazarins 6a,b.
The more prolonged reflux of the reaction mixture (10 h)
led to further conversion of pyranonaphthazarins 4a,b to the
corresponding benzoxanthenylbenzaldehydes 7a,b.
The condensation of substrates 1a,b with aldehyde 2c
proceeds, apparently, through the corresponding bisnaphthꢀ
azarins 6a,b, the structural analogs of compounds 3a—c,
which are labile under acidic conditions (see Scheme 1).
In fact, the reaction of 1a,b with 2c in pyridine gave
bisnaphthazarins 6a,b. The latter were readily converted
to benzopyranonaphthazarins 4a,b in the presence of
Et3N•HCl. As in the case of aldehydes 2a,b, derivatives
of the type 5 were not found in the reaction mixtures.
A plausible mechanism for the formation of pyranoꢀ
naphthazarins 7a,b from 4a,b is given in Scheme 2.
Xanthilium ions 8a,b, arising from 4a,b under the reacꢀ
tion conditions, attack the molecules of aldehyde 2c at
position 5 with the highest electron density, that leads to
products 7a,b.

Synthesis of benzopyranonaphthazarins
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008 2337
Scheme 2
Experimental
1H NMR spectra were recorded on a Bruker Avance
DPXꢀ300 spectrometer (300 MHz) in CDCl3. Chemical shifts
were measured in the δ scale relatively to Me4Si. Mass spectra
(EI) were recorded on a LKBꢀ9000 instrument (ionization
potential 70 eV) with the direct inlet. Melting points of comꢀ
pounds were measured on a Boetius heating stage and were not
corrected.
Monitoring of the reaction course and purity of compounds
was performed by TLC using Merck Kieselgel 60Fꢀ254 plates.
In most cases, the hexane—acetone mixture (3 : 1) was used as
the eluent. The yields of products were not optimized.
Isolation of individual compounds from the mixtures of
products was performed by preparative thinꢀlayer chromatoꢀ
graphy (PTLC) using 20×20ꢀcm plates with unbonded layer of
silica gel 5—40 μm (H+ form).18 Synthesis of starting 2ꢀhydroxyꢀ
naphthazarin (1a)19 and 6,7ꢀdimethylꢀ2ꢀhydroxynaphthazarin
(1b)1 was carried out according to the known procedures.
Condensation of quinones 1a,b with aldehydes 2a,b. A solution
of quinone 1a,b (0.1 mmol), aldehyde 2a,b (0.5 mmol), and
Et3N•HCl (1.4 mg, 0.01 mmol) in 2ꢀmethoxyethanol (1.5 mL)
was refluxed for 2.5 h (for the reaction of 1a,b with 2a) or 5 h
(for the reaction of 1a with 2b). The reaction mixture was cooled,
diluted with water (3 mL), extracted with chloroform, the extract
was dried with Na2SO4 and concentrated in vacuo. Compounds
3a—c were isolated by PTLC (hexane—acetone, 3 : 1).
3,3´ꢀ[(4ꢀMethoxyphenyl)methylene]bis(2,5,8ꢀtrihydroxyꢀ
1,4ꢀnaphthoquinone) (3a). The yield was 56%, m.p. 268—270 °C,
Rf 0.38. Found (%): C, 63.28; H, 3.48. C28H18O11. Calcuꢀ
The structure and composition of compounds obtained
were established based on the elemental analysis data and
1H NMR and mass spectra. In the mass spectra of
arylmethylenebisnaphthazarins 3a—c and 6a,b, the most
intensive are peaks of ions with m/z equal to the masses
of the corresponding starting substrates 1a,b [M1a,b]+,
[M1a,b – 1]+ (100%) and compounds with the formal strucꢀ
tures of enones of the type 9 or their protonated forms,
which are formed by the cleavage of the product molꢀ
ecules at the C(3)—C(9) or C(3´)—C(9) bonds, that agrees
with the fragmentation of alkylmethylenebisnaphthazarins
observed by us earlier.1 In the mass spectra of compounds
4a,b and 7a,b, the peaks of the corresponding xanthilium
ions of the type 8a,b are the most stable.
1
lated (%): C, 63.39; H, 3.41. H NMR, δ: 3.79 (s, 3 H, OMe),
6.16 (s, 1 H, H(9)), 6.84 (dd, 2 H, H(3″), H(5″), J1 = 6.0 Hz,
J2 = 1.2 Hz), 7.18 (dd, 2 H, H(2″), H(6″), J1 = 6.0 Hz, J2 = 1.2 Hz),
7.20 (d, 2 H, H(6), H(6´), J = 9.3 Hz), 7.30 (d, 2 H, H(7),
H(7´), J = 9.3 Hz), 7.89 (br.s, 2 H, C(2)OH, C(2´)OH), 11.59
(s, 2 H, C(8)OH, C(8´)OH), 12.64 (s, 2 H, C(5)OH, C(5´)OH).
MS, m/z (Irel (%)): 324 (56), 206 (100).
3,3´ꢀ[(4ꢀMethoxyphenyl)methylene]bis(2,5,8ꢀtrihydroxyꢀ
6,7ꢀdimethylꢀ1,4ꢀnaphthoquinone) (3b). The yield was 58%,
m.p. 274—276 °C (decomp.), Rf 0.43. Found (%): C, 65.38;
H, 4.55. C32H26O11. Calculated (%): C, 65.52; H, 4.47. 1H NMR,
δ: 2.17 (s, 6 H, C(7)Me, C(7´)Me), 2.27 (s, 6 H, C(6)Me,
C(6´)Me), 3.78 (s, 3 H, OMe), 6.20 (s, 1 H, H(9)), 6.83 (dd,
2 H, H(3″), H(5″), J1 = 8.0 Hz, J2 = 1.2 Hz), 7.17 (dd, 2 H,
H(2″), H(6″), J1 = 8.0 Hz, J2 = 1.2 Hz), 7.75 (br.s, 2 H, C(2)OH,
C(2´)OH), 12.37 (s, 2 H, C(8)OH, C(8´)OH), 13.34 (s, 2 H,
C(5)OH, C(5´)OH). MS, m/z (Irel (%)): 352 (31), 234 (100).
3,3´ꢀ[(2,3ꢀDimethoxyphenyl)methylene]bis(2,5,8ꢀtrihydroxyꢀ
1,4ꢀnaphthoquinone) (3c). The yield was 54%, m.p. 257—270 °C,
Rf 0.33. Found (%): C, 62.05; H, 3.66. C29H20O12. Calculated
1
(%): C, 62.15; H, 3.60. H NMR, δ: 3.86 (s, 3 H, C(3″)OMe),
9: R = H, Me; Ar = 4ꢀMeOC H ,
6
4
3.89 (s, 3 H, C(2″)OMe), 6.37 (s, 1 H, H(9)), 6.78 (dd, 1 H,
H(4″), J1 = 7.7 Hz, J2 = 1.5 Hz), 6.88 (dd, 1 H, H(6″), J1 = 7.7 Hz,
J2 = 1.5 Hz), 6.99 (t, 1 H, H(5″), J = 7.7 Hz), 7.18 (d, 2 H,
H(7), H(7´), J = 9.5 Hz), 7.28 (d, 2 H, H(6), H(6´), J = 9.5 Hz),
7.69 (br.s, 2 H, C(2)OH, C(2´)OH), 11.49 (s, 2 H, C(8)OH,
C(8´)OH), 12.70 (s, 2 H, C(5)OH, C(5´)OH). MS, m/z
(Irel (%)): 354 (17), 206 (100).
Condensation of quinones 1a,b with aldehyde 2c. A solution
of quinone 1a,b (0.1 mmol), aldehyde 2c (76 mg, 0.5 mmol),
and Et3N•HCl (1.4 mg, 0.01 mmol) in 2ꢀmethoxyethanol
2,3ꢀ(MeO) C H , 2ꢀHOꢀ3ꢀMeOC H .
2
6
3
6 3
In conclusion, the reactions of hydroxy naphthazarins
with aromatic aldehydes in general lead to (arylmethylene)ꢀ
bisnaphthazarins. The reaction of the indicated substrates
with aromatic aldehydes bearing hydroxy group in orthoꢀ
position opens a fairy simple way to the synthesis of
benzopyranonaphthazarins and further, xanthones, comꢀ
pounds with potential biological activity.

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Pelageev and Anufriev
(1.5 mL) was refluxed for 3 h. The reaction mixture was cooled
and a precipitate of product 4b, formed on the reaction of 1b
with 2c, was filtered off, washed with water (1 mL), and dried.
After the reflux of the reaction mixture of 1a with 2c was stopped,
water (5 mL) was added to it, and this was extracted with
chloroform, the extract was dried with Na2SO4 and concentrated
in vacuo. Compound 4a was isolated by PTLC (hexane—acetone,
3 : 1).
C(4´)OH), 13.09 (s, 1 H, C(7)OH), 13.28 (s, 1 H, C(10)OH).
MS, m/z (Irel (%)): 502 [M]+ (30), 351 (100).
Condensation of quinones 1a,b with aldehyde 2c in pyridine.
A solution of quinone 1a,b (0.1 mmol), aldehyde 2c (76 mg,
0.5 mmol) in pyridine (0.5 mL) was stirred for 30 min. The
reaction mixture was concentrated, the dry residue was dissolved
in CHCl3 (1 mL), and products 6a,b were isolated by PTLC
(hexane—acetone, 3 : 1).
7,10ꢀDihydroxyꢀ4ꢀmethoxyꢀ12ꢀ(3,5,8ꢀtrihydroxyꢀ1,4ꢀdioxoꢀ
1,4ꢀdihydroꢀ2ꢀnaphthyl)ꢀ12Hꢀbenzo[b]xantheneꢀ6,11ꢀdione (4a).
The yield was 63%, m.p. 252—255 °C (decomp.), Rf 0.31. Found
(%): C, 63.52; H, 3.40. C28H16O11. Calculated (%): C, 63.64;
H, 3.05. 1H NMR, δ: 3.98 (s, 3 H, OMe), 5.92 (s, 1 H, H(12)),
6.76 (dd, 1 H, H(1), J1 = 7.7 Hz, J2 = 1.2 Hz), 6.86 (dd, 1 H,
H(3), J1 = 7.7 Hz, J2 = 1.2 Hz), 7.05 (t, 1 H, H(2), J = 7.7 Hz),
7.17 (d, 1 H, H(7´), J = 9.3 Hz), 7.21 (d, 1 H, H(8), J = 9.3 Hz),
7.28 (d, 1 H, H(9), J = 9.3 Hz), 7.31 (d, 1 H, H(6´), J = 9.3 Hz),
7.62 (br.s, 1 H, C(3´)OH), 11.40 (s, 1 H, C(5´)OH), 12.33 (s, 1 H,
C(7)OH), 12.41 (s, 1 H, C(8´)OH), 12.75 (s, 1 H, C(10)OH).
MS, m/z (Irel (%)): 323 (100), 205 (51).
7,10ꢀDihydroxyꢀ8,9ꢀdimethylꢀ4ꢀmethoxyꢀ12ꢀ(3,5,8ꢀtrihydroxyꢀ
6,7ꢀdimethylꢀ1,4ꢀdioxoꢀ1,4ꢀdihydroꢀ2ꢀnaphthyl)ꢀ6,11ꢀdihydroꢀ
12Hꢀbenzo[b]xantheneꢀ6,11ꢀdione (4b). The yield was 64%,
m.p. 255—260 °C (decomp.), Rf 0.59. Found (%): C, 65.63;
H, 4.20. C32H24O11. Calculated (%): C, 65.75; H, 4.14. 1H NMR,
δ: 2.23 (s, 3 H, C(8)Me), 2.24 (s, 3 H, C(9)Me), 2.26 (s, 3 H,
C(6´)Me), 2.29 (s, 3 H, C(7´)Me), 3.97 (s, 3 H, OMe), 5.94
(d, 1 H, H(12), J = 0.7 Hz), 6.77 (ddd, 1 H, H(1), J1 = 8.0 Hz,
J2 = 1.5 Hz, J3 = 0.7 Hz), 6.84 (dd, 1 H, H(3), J1 = 8.0 Hz,
J2 = 1.5 Hz), 7.02 (t, 1 H, H(2), J = 8.0 Hz), 7.53 (br.s, 1 H,
C(3´)OH), 12.06 (s, 1 H, C(5´)OH), 13.12 (s, 1 H, C(8´)OH),
13.15 (s, 1 H, C(7)OH), 13.52 (s, 1 H, C(10)OH). MS, m/z
(Irel (%)): 351 (100), 233 (27).
3,3´ꢀ[(2ꢀHydroxyꢀ3ꢀmethoxyphenyl)methylene]bis(2,5,8ꢀ
trihydroxyꢀ1,4ꢀnaphthoquinone) (6a). The yield was 67%,
m.p. 228—232 °C, Rf 0.22. Found (%): C, 61.37; H, 3.47.
C28H18O12. Calculated (%): C, 61.54; H, 3.32. 1H NMR, δ: 3.88
(s, 3 H, OMe), 5.83 (br.s, 1 H, C(2″)OH), 6.36 (s, 1 H, H(9)),
6.73 (dd, 1 H, H(4″), J1 = 6.7 Hz, J2 = 3.0 Hz), 6.80 (dd,
1 H, H(6″), J1 = 6.7 Hz, J2 = 3.0 Hz), 6.81 (t, 1 H, H(5″),
J = 6.7 Hz), 7.18 (d, 2 H, H(7), H(7´), J = 9.5 Hz), 7.28 (d, 2 H,
H(6), H(6´), J = 9.5 Hz), 7.68 (br.s, 2 H, C(2)OH, C(2´)OH),
11.53 (s, 2 H, C(8)OH, C(8´)OH), 12.69 (s, 2 H, C(5)OH,
C(5´)OH). MS, m/z (Irel (%)): 341 (39), 205 (100).
3,3´ꢀ[(2ꢀHydroxyꢀ3ꢀmethoxyphenyl)methylene]bis(2,5,8ꢀ
trihydroxyꢀ6,7ꢀdimethylꢀ1,4ꢀnaphthoquinone) (6b). The yield was
54%, m.p. 240—243 °C, Rf 0.45. Found (%): C, 63.65; H, 4.47.
C32H26O12. Calculated (%): C, 63.78; H, 4.35. 1H NMR, δ: 2.17
(s, 6 H, C(7)Me, C(7´)Me), 2.25 (s, 6 H, C(6)Me, C(6´)Me),
3.86 (s, 3 H, OMe), 5.16 (br.s, 1 H, C(2″)OH), 6.39 (s, 1 H,
H(9)), 6.75 (dd, 1 H, H(4″), J1 = 6.7 Hz, J2 = 2.4 Hz), 6.79
(dd, 1 H, H(6″), J1 = 6.7 Hz, J2=2.4 Hz), 6.77 (t, 1 H, H(5″),
J = 6.5 Hz), 7.58 (br.s, 2 H, C(2)OH, C(2´)OH), 12.25 (s, 2 H,
C(5)OH, C(5´)OH), 13.43 (s, 2 H, C(8)OH, C(8´)OH). MS,
m/z (Irel (%)): 369 (41), 233 (100).
Conversion of bisnaphthazarins 6a,b to benzopyranonaphthꢀ
azarins 4a,b. A solution of bisnaphthazarins 6a,b (0.05 mmol),
Et3N•HCl (0.7 mg, 0.005 mmol) in 2ꢀmethoxyethanol (1 mL)
was refluxed for 0.5 h. After cooling, water (2 mL) was added,
and the mixture was extracted with chloroform, the extract was
dried with Na2SO4 and concentrated in vacuo. The products
were isolated by PTLC (hexane—acetone, 3 : 1), which proved
to be completely identical to compounds 4a and 4b (1H NMR
and mass spectra are given above).
Condensation of quinones 1a,b with aldehyde 2c. A mixture of
products 4a and 7a with Rf 0.31 in the ratio 1 : 1 (72%) or
compound 7b were isolated by PTLC (hexane—acetone, 3 : 1)
from the reaction mixtures obtained by the reaction of, respectively,
quinone 1a or 1b (0.1 mmol), aldehyde 2c (76 mg, 0.5 mmol)
and Et3N•HCl (1.4 mg, 0.01 mmol) in 2ꢀmethoxyethanol
(reflux, 10 h).
This work was partially financially supported by
the Russian Foundation for Basic Research (Project
No. 06ꢀ04ꢀ96974), the Russian Academy of Sciences
(Grant of the Presidium of RAS, the Molecular and Cell
Biology Program), and the FarꢀEastern and Siberian
Branches of the Russian Academy of Sciences (Interꢀ
disciplinary Integrational Project FEB and SB of RAS
No. 07ꢀIIꢀSOꢀ05ꢀ020).
12ꢀ(5ꢀFormylꢀ4ꢀhydroxyꢀ3ꢀmethoxyphenyl)ꢀ7,10ꢀdihydroxyꢀ
4ꢀmethoxyꢀ6,11ꢀdihydroꢀ12Hꢀbenzo[b]xantheneꢀ6,11ꢀdione (7a).
The yield was 34%, m.p. 220 °C (decomp.), Rf 0.31. Found (%):
C, 65.71; H, 3.94. C26H18O9. Calculated (%): C, 65.82; H, 3.82.
1H NMR, δ: 3.88 (s, 3 H, C(4)OMe), 4.00 (s, 3 H, C(3´)OMe),
5.36 (s, 1 H, H(12)), 6.73 (dd, 1 H, H(1), J1 = 8.0 Hz, J2 = 1.5 Hz),
6.90 (dd, 1 H, H(3), J1 = 8.0 Hz, J2 = 1.5 Hz), 7.02 (d, 1 H,
H(2´), J = 2.0 Hz), 7.10 (d, 1 H, H(6´), J = 2.0 Hz), 7.11 (t,
1 H, H(2), J = 8.0 Hz), 9.81 (s, 1 H, C(5´)CHO), 11.02 (s, 1 H,
C(4´)OH), 12.30 (s, 1 H, C(7)OH), 12.50 (s, 1 H, C(10)OH).
MS, m/z (Irel (%)): 474 [M]+ (41), 323 (100).
References
12ꢀ(5ꢀFormylꢀ4ꢀhydroxyꢀ3ꢀmethoxyphenyl)ꢀ7,10ꢀdihydroxyꢀ
8,9ꢀdimethylꢀ4ꢀmethoxyꢀ6,11ꢀdihydroꢀ12Hꢀbenzo[b]xantheneꢀ
6,11ꢀdione (7b). The yield was 42%, m.p. 212—216 °C, Rf 0.28.
Found (%): C, 66.72; H, 4.51. C28H22O9. Calculated (%):
1. V. F. Anufriev, A. Ya. Chizhova, V. A. Denisenko, V. L.
Novikov, Zh. Org. Khim., 1993, 29, 2008 [Russ. J. Org. Chem.,
1993, 29, 2008 (Engl. Transl.)].
1
C, 66.93; H, 4.41. H NMR, δ: 2.24 (s, 3 H, C(8)Me), 2.25 (s,
2. A. Ya. Chizhova, V. F. Anufriev, V. L. Novikov, Zh. Org.
Khim., 1995, 31, 237 [Russ. J. Org. Chem., 1995, 31, 237
(Engl. Transl.)].
3. A. Ya. Tchizhova, V. Ph. Anufriev, V. A. Denisenko, V. L.
Novikov, J. Nat. Prod., 1995, 11, 1772.
3 H, C(9)Me), 3.88 (s, 3 H, C(4)OMe), 4.00 (s, 3 H, C(3´)OMe),
5.40 (s, 1 H, H(12)), 6.74 (dd, 1 H, H(1), J1 = 8.0 Hz, J2 = 1.5 Hz),
6.89 (dd, 1 H, H(3), J1 = 8.0 Hz, J2 = 1.5 Hz), 7.02 (d, 1 H,
H(6´), J = 2.0 Hz), 7.09 (t, 1 H, H(2), J = 8.0 Hz), 7.12 (d, 1 H,
H(2´), J = 2.0 Hz), 9.80 (s, 1 H, C(5´)CHO), 11.00 (s, 1 H,

Synthesis of benzopyranonaphthazarins
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008 2339
4. G. L. Bennett, L. J. Harrison, M.ꢀSh. Lim, K.ꢀY. Sim,
E.ꢀCh. Tan, J. D. Connolly, Phytochem., 1991, 30, 3141.
5. A. Ya. Tchizhova, V. Ph. Anufriev, V. L. Novikov, in Recent
Discoveries in Natural Product Chemistry, Elite Publishers:
Karachi, 1995, 101.
6. K. Shinꢀya, S. Imai, K. Furihata, Y. Hayakawa, Y. Kato,
G. D. Vanduyne, J. Clardy, H. Seto, J. Antibiot., 1990, 43, 444.
7. A. Ya. Chizhova, V. F. Anufriev, Zh. Org. Khim., 2000, 36,
1038 [Russ. J. Org. Chem., 2000, 36, 1007 (Engl. Transl.)].
8. A. Ya. Yakubovskaya, N. D. Pokhilo, V. P. Glazunov, V. F.
Anufriev, G. B. Elyakov, Izv. Akad. Nauk, Ser. Khim., 2004,
2519 [Russ. Chem. Bull., Int. Ed., 2004, 53, 2626].
9. G. I. Sopelnyak, A. Ya. Yakubovskaya, N. D. Pokhilo, V. P
Glazunov, V. Ph. Anufriev, 3rd EuroAsian Heterocyclic Meetꢀ
ing Heterocycles in Organic and Combinatorial Chemistry»,
Novosibirsk, 2004, p. 204.
13. R. H. Thomson, Naturally Occurring Quinones; 3rd., Chapman
& Hall; London, 1987, 732 p.
14. R. H. Thomson, Naturally Occurring Quinones; 4th ed.,
Chapman & Hall; London, 1997, 746 p.
15. R. H. Thomson, Naturally Occurring Quinones; 2nd ed., Acad.
Press, London, 1971, p. 734.
16. J. W. Mathieson, R. H. Thomson, J. Chem. Soc., 1971, 153.
17. E. A. Kol´tsova, V. A. Denisenko, O. B. Maksimov, Khim.
Prirod. Soedin., 1978, 4, 438 [Chem. Nat. Comp., 1978, 4
(Engl. Transl.)].
18. G. V. Malinovskaya, A. Ya. Chizhova, V. F. Anufriev, Izv.
Akad. Nauk, Ser. Khim., 1999, 1019 [Russ. Chem. Bull., Int.
Ed., 1999, 48, 1010].
19. N. Donaldson, Chemistry and Technology of Compounds
of the Naphthalene Series, Moscow, Goskhimizdat, 1963,
p. 444.
10. S. Patai, The Chemistry of Quinonoid Compounds, New York,
1974, 1274 p.
11. S. Patai, Z. Rappaport, The Chemistry of Quinonoid Comꢀ
pounds, New York, 1988, 1199 p.
12. H. Ulrich, R. Richter, Die paraꢀChinone der Benzolꢀ und
NaphthalinꢀReihe, in I. Houben, T. Weyl, Methoden der
Organischen Chemie, Georg Thieme Verlag: Stuttgart, 1977,
Bd. 7/3a, 832 p.
Received May 23, 2008;
in revised form July 29, 2008