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S. Venkateswarlu et al. / Bioorg. Med. Chem. 13 (2005) 6374–6380
7.49 (2H, d, J = 15.6 Hz, H-1,7); 13C NMR (DMSO-d6)
d 183.0, 148.5, 146.0, 139.3, 127.6, 125.6, 122.7, 110.5,
109.6, 101.3, 56.4; LC–MS m/z (%): (ESI-positive mode)
525 [(M+H)+, 47], 527 [(M+2H)+, 79], 529 [(M+5H)+,
54]; Elemental analysis, Calcd for C21H18O6Br2: C,
47.15; H, 3.29. Found: C, 47.06; H, 3.32.
The combined ethyl acetate layer was dried over anhy-
drous sodium sulfate. The residue obtained after evapo-
ration of the solvent was chromatographed over silica
gel column using chloroform/methanol (95:5) as eluent,
followed by recrystallization from methanol to give 5l
(401 mg, 29%), mp 302–304 ꢁC (lit.9 mp 306–308 ꢁC
dec.); IR (KBr) mmax 3488, 3386, 1629, 1617, 1271,
4.2.11. 1,7-Bis(3-tert-butyl-4-hydroxyphenyl)-1,6-hept-
adiene-3,5-dione (5h). Yield 34%, mp 204–206 ꢁC; IR
1289, 1142, 1120, 955 cmꢀ1 1H NMR (DMSO-d6) d
;
6.06 (1H, s, H-4), 6.56 (2H, d, J = 15.6 Hz, H-2,6),
6.77 (2H, d, J = 8.3 Hz, H-50,500), 7.00 (2H, d,
J = 1.7 Hz, H-20,200), 7.06 (2H, dd, J = 8.3, 1.7 Hz, H-
60,600), 7.44 (2H, d, J = 15.6 Hz, H-1,7); 13C NMR
(DMSO-d6) d 183.1, 147.8, 145.1, 140.8, 127.7, 126.5,
121.9, 115.9, 114.5, 100.9; LC–MS m/z (%): (ESI-nega-
tive mode) 339 [(MꢀH)ꢀ, 100].
1
(KBr) mmax 3368, 2953, 1615, 1269, 1138, 968 cmꢀ1; H
NMR (DMSO-d6) d 1.40 (18H, s, 2· Ar–C(CH3)3),
5.84 (1H, s, H-4), 6.45 (2H, d, J = 15.8 Hz, H-2,6),
6.85 (2H, d, J = 7.9 Hz, H-50,500), 7.27 (2H, d,
J = 8.0 Hz, H-60,600), 7.41 (2H, s, H-20,200), 7.56 (2H, d,
J = 15.8 Hz, H-1,7), 9.41 (2H, br s, 2· Ar-OH); 13C
NMR (DMSO-d6) d 184.5, 159.0, 141.7, 137.3, 128.4,
128.1, 127.5, 121.7, 117.8, 101.4, 35.5, 29.7; EIMS m/z
(%): 420 (M+, 78), 402 (73), 324 (51), 216 (48), 217
(11), 203 (88), 176 (18), 163 (20), 161 (61), 147 (54), 57
(100), 42 (31); Elemental analysis, Calcd for C27H32O4:
C, 77.14; H, 7.62. Found: C, 77.23; H, 7.58.
4.3.2. 1-(3,4-Dihydroxyphenyl)-7-(3-methoxy-4-hydroxy-
phenyl)-1,6-heptadiene-3,5-dione (5m). Yield 22%, mp
164–166 ꢁC (lit.9 mp 165–167 ꢁC); IR (KBr) mmax 3484,
1620, 1267, 1132, 1140, 964 cmꢀ1; 1H NMR (DMSO-d6)
d 3.82 (3H, s, Ar-OCH3), 6.04 (1H, s, H-4), 6.53 (1H, d,
J = 16.0 Hz, H-2 or H-6), 6.74 (1H, d, J = 16.0 Hz, H-2
or H-6), 6.76 (1H, d, J = 8.7 Hz, H-50), 6.80 (1H, d,
J = 8.3 Hz, H-500), 7.07 (1H, dd, J = 8.7, 1.8 Hz, H-60),
7.00 (1H, d, J = 1.8 Hz, H-20), 7.12 (1H, d, J = 1.8 Hz,
H-200), 7.29 (1H, dd, J = 8.3, 1.8 Hz, H-600), 7.44 (1H, d,
J = 16.0 Hz, H-1 or H-7), 7.51 (1H, d, J = 16.0 Hz, H-1
or H-7); 13C NMR (DMSO-d6) d 183.2, 183.0, 148.6,
147.9, 147.7, 145.1, 140.8, 140.7, 126.5, 122.8, 121.9,
121.0, 120.7, 115.9, 115.6, 114.6, 111.0, 101.0, 55.4; EIMS
m/z (%): 354 (M+, 16), 336 (20), 328 (54), 271 (71), 192
(53), 191 (30), 177 (100), 167 (47), 163 (49), 150 (40), 149
(24), 145 (84), 135 (48), 117 (42), 89 (57), 77 (43).
4.2.12.
1,7-Bis(3,5-di-tert-butyl-4-hydroxyphenyl)-1,6-
heptadiene-3,5-dione (5i). Yield 45%, mp 190–192 ꢁC
(lit.30 mp 190–192 ꢁC); IR (KBr) mmax 3627, 2959,
1
1623, 1207, 969, 757 cmꢀ1; H NMR (CDCl3) d 1.46
(36H, s, 4· Ar–C(CH3)3), 5.49 (2H, br s, 2· Ar-OH),
5.85 (1H, s, H-4), 6.48 (2H, d, J = 15.8 Hz, H-2,6),
7.39 (4H, s, H-20,200,60,600), 7.62 (2H, d, J = 15.8 Hz, H-
1,7); EIMS m/z (%): 532 (M+, 45), 436 (100), 259 (38),
219 (11), 57 (46).
4.2.13.
heptadiene-3,5-dione (5j). Yield 25%, mp 114–116 ꢁC;
IR (neat) mmax 1626, 1338, 1125, 964, 735 cmꢀ1 1H
1,7-Bis(3,4-dibenzyloxy-5-methoxyphenyl)-1,6-
;
4.3.3. 1,7-Bis(2,5-dihydroxyphenyl)-1,6-heptadiene-3,5-
dione (5n). Yield 9%, mp 202–204 ꢁC; IR (KBr) mmax
NMR (CDCl3) d 3.81 (6H, s, 2· Ar-OCH3), 5.01 (4H,
s, –OCH2Ar), 5.06 (4H, s, –OCH2Ar), 5.75 (1H, s, H-
4), 6.41 (2H, d, J = 15.8 Hz, H-2,6), 6.72 (2H, s, H-
60,600), 6.75 (2H, s, H-20,200), 7.2–7.4 (20H, m, Ar–H),
7.47 (2H, d, J = 15.8 Hz, H-1,7).
3398, 1623, 1354, 1197, 1144, 976 cmꢀ1 1H NMR
;
(DMSO-d6) d 6.12 (1H, s, H-4), 6.69–6.75 (4H, m, H-
30,300,40,400), 6.77 (2H, d, J = 16.0 Hz, H-2,6), 6.96 (2H,
d, J = 2.2 Hz, H-60,600), 7.81 (2H, d, J = 16.0 Hz, H-
1,7), 8.90 (2H, br s, 2· Ar-OH), 9.53 (2H, br s, 2· Ar-
OH); LC–MS m/z (%): (ESI-negative mode) 339
[(MꢀH)ꢀ, 100].
4.2.14.
1,7-Bis(3-carbomethoxy-4-hydroxyphenyl)-1,6-
heptadiene-3,5-dione (5k). Yield 9%, mp 210–212 ꢁC; IR
1
(KBr) mmax 3106, 1678, 1630, 1216, 971, 668 cmꢀ1; H
NMR (CDCl3) d 3.99 (6H, s, 2· –COOCH3), 5.80 (1H,
s, H-4), 6.50 (2H, d, J = 15.6 Hz, H-2,6), 7.01 (2H, d,
J = 8.6 Hz, H-50,500), 7.60–7.70 (2H, m, H-60,600), 7.60
(2H, d, J = 15.6 Hz, H-1,7), 8.03 (2H, d, J = 2.0 Hz, H-
20,200); EIMS m/z (%): 424 (M+, 48), 406 (22), 374 (16),
328 (23), 260 (13), 245 (7), 219 (21), 205 (77), 187 (42),
173 (100), 165 (38), 146 (22), 133 (20).
4.3.4. 1-(4-Hydroxyphenyl)-7-(3,4-dihydroxyphenyl)-1,6-
heptadiene-3,5-dione (5o). Yield 54%, mp 218–220 ꢁC; IR
(KBr) mmax 3338, 1627, 1302, 962 cmꢀ1 1H NMR
;
(DMSO-d6)
d 6.06 (1H, s, H-4), 6.59 (1H, d,
J = 15.9 Hz, H-2 or H-6), 6.69 (1H, d, J = 15.9 Hz, H-2
or H-6), 6.83 (1H, d, J = 8.2 Hz, H-500), 6.79 (2H, d,
J = 8.0 Hz, H-30,50), 7.03 (1H, s, H-200), 7.09 (1H, d,
J = 8.2 Hz, H-600), 7.45 (1H, d, J = 15.9 Hz, H-1 or H-
7), 7.47 (1H, d, J = 15.9 Hz, H-1 or H-7), 7.57 (2H, d,
J = 8.0 Hz, H-20,60), 9.17 (1H, br s, Ar-OH), 9.63 (1H,
br s, Ar-OH), 10.04 (1H, br s, Ar-OH); EIMS m/z (%):
324 (M+, 18), 306 (8), 299 (34), 298 (90), 242 (30), 241
(100), 163 (49), 161 (26), 162 (38), 147 (87), 110 (43), 119
(39), 91 (21), 44 (34); Elemental analysis, Calcd for
C19H16O5: C, 70.36; H, 4.97. Found: C, 69.98; H, 5.02.
4.3. General procedure for demethylation
4.3.1. 1,7-Bis(3,4-dihydroxyphenyl)-1,6-heptadiene-3,5-
dione (5l). To an ice cold solution of 1 (1.5 g, 4.0 mmol)
in dichloroethane (75 mL) was added aluminum chlo-
ride (2.1 g, 15.8 mmol), followed by the dropwise addi-
tion of pyridine (4.8 mL, 59.4 mmol) for 15 min and
the reaction mixture was heated under reflux for 36 h.
After cooling the reaction mixture to 10 ꢁC, cold dil.
HCl (20%) was added to decompose aluminum chloride
complex and extracted with ethyl acetate (5· 30 mL).
4.3.5. 1,7-Bis(3,4-dihydroxy-5-methoxyphenyl)-1,6-hept-
adiene-3,5-dione (5p). Yield: 24%, mp 230–232 ꢁC; IR
(KBr) mmax 3484, 1621, 1384, 1289, 1135, 1091,