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B. C. Maiti et al. / Tetrahedron 61 (2005) 6568–6574
ether (20 ml) and the mixture was kept for four days at
20 8C. Evaporation of the solvent and crystallisation of
the residue from light petroleum/chloroform gave a
mixture of 4-methoxy-1,5-naphthylene diacetate 6 (80%)
and 5-methoxy-l,4-naphthylene diacetate 8 (20%) (92 mg,
0.34 mmol, 88%) as needles, mp 107–112 8C (Found: MC,
274.0840. Calcd for C15H14O5: M, 274.0841); m/z 274
(26%, M), 232 (20, MKCH2CO) and 190 (100, 232-
CH2CO); nmax/cmK1 1757 (aryl acetate C]O); lmax/nm
298 (log 3 3.88), 312 (3.78) and 326.5 (3.64); dH 2.40 and
2.47 (each 3H, s, CH3CO2Ar), 3.98 (3H, s, CH3OAr) and
6.75–7.85 (5H, m, ArH).
and -80), 8.30 (1H, s, H-3), 8.49 (1H, s, H-30), 8.78 (1H, s,
OH at C-50) and 13.45 (1H, s, OH at C-8).
(c) The slowest-moving0 blue product crystallised from
chloroform to give 5,5 -dihydroxy-4,40-dimethoxy-2,20-
binaphthyl-1,10-quinone 19 (11 mg, 0.029 mmol, 37%) as
deep blue needles, mp 259–260 8C (decomp.) (Found: MC,
376.09433, C22H16O6 requires M, 376.0946); m/z 378 (45%,
MC2H), 376 (100, M), 361 (67, MKMe), 346 (20, 361-
Me) and 345 (40, MKMeO); nmax/cmK1 3340 (ArOH),
1605 (quinone C]O) and 1588 (aromatic C]C); lmax/nm
(CHCl3) 286 (log 3 4.18), 316infl (3.98) and 668 (4.28); dH
4.13 (6H, s, MeO at C-4 and -40), ca. 7.11 (2H, m, H-6 and
-60), ca. 7.36 (2H, m, H-7 and0 -70), ca. 7.76 (2H, m, H-8
and -80), 8.40 (2H, s, H-3 and -3 ) and 8.83 (2H, s, OH at C-5
and -50). This was identical with an authentic specimen
prepared from 4-methoxy-1,5-naphthylene diacetate by the
same procedure.
3.4.4. Oxidative coupling of 1-methoxynaphthylene-4,5-
diol 10 with 4-methoxy-naphthylene-1,5-diol 17. A
mixture of 4-methoxy-1,5-naphthylene diacetate 6 (27 mg,
0.10 mmol, containing 20% of 5-methoxy-1,4-naphthylene
diacetate 8) and 1-methoxy-4,5-naphthylene diacetate8
(10 diacetate) (22 mg, 0.085 mmol) was hydrolysed and
oxidatively coupled as above. Preparative TLC afforded
three blue products.
The mother-liquor from the above crystallisations, on being
subjected to TLC using chloroform, gave a solid which
afforded 5-methoxy-1,4-naphthoquinone 9 (2.5 mg) as
12
yellow needles, mp 184–185 8C (lit.,
186 8C) (Found:
(a). The fastest-moving compound crystallised from chloro-
form to give 8,80-dihydroxy-4,40-dimethoxy-2,20-
binaphthyl-1,10-quinone 12 as deep blue needles (10 mg,
0.027 mmol, 33%), mpO350 8C (lit.,6 (350 8C) (Found:
MC, 376.0947. C, 69.9; H, 4.0%. C22H16O6 requires: M
376.0947. C, 70.2; H, 4.3%); m/z 376 (50%, M), 361 (32,
MKMe), 346 (22, 361-Me), 345 (100, MKMeO) and 92
(30, C6H4O); nmax/cmK1 1578 (quinone C]O); lmax/nm
(CHCl3) 285 (log 3 4.40), 326infl (4.02), 507 (3.57), 664infl
(4.32) and 703 (4.40). This was identical with an authentic
specimen prepared from 1-methoxy-4,5-naphthylene
diacetate by the same procedure.
MC, 188.0476. C11H8O3 requires M, 188.0473); nmax/cmK1
1673 and 1666 (quinone C]O) and 1624 (aromatic C]C);
lmax/nm 245 (log 3 4.20), 328 (3.05) and 394 (3.58); dH 4.00
(3H, s, MeO at C-5), 6.67 (2H, s, H-2 and -3), ca. 7.32 (1H,
m, H-6) and ca. 7.49 (2H, m, H-7 and -8). This was identical
with an authentic specimen.12
3.4.5. Oxidative demethylation of the bisnaphthalene
indigos 12, 19 and 23. (a) The oxidation product obtained
from the symmetrical quinone 12 c0rystallised from l0ight
petroleum to give 8,80-dihydroxy-2,2 -binaphthyl-1,4:1 ,40-
diquinone 15 as red-brown needles (72%), mp 270–273 8C
(decomp.) (Found: MC, 346.0476. C, 69.1; H, 2.8%.
C20H10O6 requires M 346.0477. C, 69.4; H, 2.9%); m/z
346 (100%, M), 329 (17, MKOH), 290 (4, MK2CO), 289
(8, MKCO–CHO), 262 (5, 290-CO), 234 (3, 262-CO), 120
(10, C7H4O2)- and 92 (21, C6H4O); nmax/cmK1 1670, 1650
Reductive acetylation of the quinone 12 gave the corre-
sponding leucotetra-acetate 14 which crystallised from
ethanol in needles, mp 251.5–253.5 8C (Found: MC, 546.
C, 66.2; H, 5.0%. C30H26O10 requires M 546. C, 65.9; H,
4.8%); m/z 546 (0.5%, M), 504 (10), 462 (13), 420 (1.5) and
378 (25) (each MKnCH2CO), 444 (13, 462-H2O), 402 (100,
420-H2O), 387 (2, 402-Me), 360 (45, 378-H2O), 346 (11,
and 1635 (quinone C]O) and 1608 (aromatic C]C); lmax
/
nm 256infl (log 3 4.18), 274 (4.19),0434 (3.83) and 560infl
(3.24); dH 7.06 (2H, s, H-3 and -3 ), 7.33 (2H, dd, JZ5,
5 Hz, H-6 and -60), 7.70 (4H, dd, JZ1, 5 Hz, H-5, -50, -7 and
-70) and 11.73 (2H, s, OH at C-8 and -80).
402-2CO), 345 (11, 360-Me) and 331 (5, 346-Me); nmax
/
cmK1 1770 and 1758 (aryl acetate C]O) and 1598
(aromatic C]C); lmax/nm 242 (log 3 4.72), 257infl (4.38),
262infl (4.32), 307 (4.03), 317 (4.02) and 330 (3.95); dH
2.00 (6H, s, CH3CO2Ar at C-1 and -10), 2.35 (6H, s,
CH3CO2Ar at C-8 and -80), 3.98 (6H, s, CH3O at C-4 and
-40), 6.75 (2H, s, H-3 and -30), 7.18 (2H, dd, JZ1.5, 8 Hz,
H-7 and -70), 7.52 (2H, dd, JZ8, 8 0Hz, H-6 and -60) and 8.28
(2H, dd, JZ1.5, 8 Hz, H-5 and -5 ).
(b) The oxidation product from the unsymmetrical quinone
23 crystallised from light 0petroleum to give 50,8-dihydroxy-
2,20-binaphthyl-1,4:10,4 -diquinone 25 as red-brown
needles (70%), mp 247–250 8C (decomp.) (Found: MC,
346.0476. C20H10O6 requires M 346.0477); m/z 348 (10%,
MC2H), 346 (100, M), 329 (13, MKOH), 290 (6, MK
2CO), 289 (10, MKCO–CHO), 262 (7, 290-CO), 120 (8,
C7H4O2) and 92 (16, C6H4O); nmax/cmK1 1670 and 1638
(quinone C]O) and 1600 (aromatic C]C); lmax/nm
240infl (log 3 4.30), 266infl (4.27) and 434 (3.83); dH 7.02
and 7.05 (each 1H, s, H-3 and -30), ca. 7.32 (2H, m, H-60 and
-7), ca. 7.69 (4H, m, H-5, -6, -70 and -80), 11.74 (1H, s, OH at
C-8) and 11.84 (1H, s, OH at C-50).
(b) The next blue product crystallised from light petroleum
/chloroform to yield 50,8-dihydroxy-4,40-dimethoxy-2,20-
binaphthyl-1,10-quinone 23 (5 mg, 0.013 mmol, 17%) as
deep blue needles, mp 244–245 8C (decomp.) (Found: MC,
376.0946. C22H16O6 requires M, 376.0946); m/z 378 (19%,
MC2H), 376 (84, M). 361 (45, MKMe), 345 (100, MK
MeO); nmax/cmK1 3400 (hydrogen-bonded ArOH), 1595
and 1580 (quinone C]O); lmax/nm (CHCl3) 283 (log 3
4.36), 320infl (4.14), 514infl (3.69), 638infl (4.32) and 684
(4.41); dH 4.02 (3H, s, MeO at C-4), 4.15 (3H, s, hydrogen-
bonded MeO at C-40), 6.98–7.78 (6H, m, H-5, -6., -60, -7, -70
(c) The oxidation product from the symmetrical quinone 19
crystallised from light petroleum to give 5,50-dihydroxy-
2,20-binaphthyl-1,4:10,40-diquinone 21 as yellow plates