1630
Papia Dutta et al.
Lewis acid
(Cat.)
R
H
R
O
OH
R
H2O
+
RCHO
Solvent
H
O
OH
OH OH
(5)
(1)
R = Alkyl or aryl
(2)
(3)
(4)
Keto-enol tautomerism
Scheme 1. Synthesis of keto isomer (3), bisnaphthol (4) and dibenzoxanthene (5) derivatives.
2.2 Typical procedure for the preparation of aryl-bis
7.92 (d, J = 8.2Hz,2H), 7.81 (d, J = 7.3Hz,2H), 7.68
(2-hydroxy-1-naphthyl)methanes (4) and its keto isomers (d, J = 8.2Hz,2H), 7.24–7.42 (m,7H), 6.98 (m,2H);
(3)
13C NMR (CDCl3, 100 MHz): δ 152.2, 150.4, 146.5,
135, 130.3, 129.3, 128.6, 127.7, 123.9, 123.7, 122.2,
119.3, 118.1, 42.2; CHN analysis (%): C27H19O4N Cal.
C 76.95 , H 4.51 , N 3.32; Found C 77.10, H 4.55, N
3.36.
In a 50 mL round-bottomed flask, 2-naphthol(2 mmol)
and aldehyde(1 mmol) were added in presence of cata-
lysts CuSO4.5H2O (10 mol %) or BF3.OEt2 (28 mol %)
and acetic acid (2 drops). The entire mixture was then
treated thermally at different temperatures in organic
solvent (3 mL) or solvent-free condition for the spec-
ified reaction period. The progress of the reactions
was monitored by observing TLC at certain intervals
of time. After completion of the reaction, the mix-
ture was diluted with ethyl acetate (5 mL) and fil-
tered to remove the solid catalyst (CuSO4.5H2O) which
was not applicable for the BF3.OEt2 catalyzed reac-
tion. The organic extract was dried over anhydrous
Na2SO4 and distilled under reduced pressure to furnish
the crude product. Further purification by preparative
TLC yielded the pure product, which was analyzed by
different spectroscopic techniques.
2.3c
14-(4-Nitrophenyl)-14H-dibenzo[a.j]xanthene
(table 3, entry 4, (5d)): Light yellow; M.p. 303–
305◦C; FT-IR (KBr) cm−1: 3418, 2924, 2853, 2372,
2188, 1719, 1591, 1509, 1397, 1335, 1240, 1099, 952,
810, 741; 1H NMR (CDCl3, 400 MHz): δ 8.28 (d, J =
8.2Hz,2H), 7.99 (d, J = 8.2Hz,2H), 7.81–7.85 (m,4H),
7.65 (d, J = 8.3Hz,2H), 7.58 (t, J = 7.8Hz,2H), 7.50
(d, J = 9.2Hz,2H), 7.40–7.44(m,2H), 6.95(s,1H); 13C
NMR (CDCl3, 100 MHz): δ 152, 148.9, 146.4, 131.1,
129.7, 129.1, 129, 127.3, 124.7, 123.9, 122.1, 118.1,
116, 37.9; CHN analysis (%): C27H17O3N,Cal. C
80.39,H 4.21 ,N 3.47; Found C 80.43, H 4.24 , N 3.51.
2.3d 14-(4-Methylphenyl)-14H-dibenzo [a.j]xanthene
(table 3, entry-6, (5f)): Yellow solid; M.p. 227–228◦C;
FT-IR (KBr) cm−1: 3068, 2917, 1626, 1597, 1515,
1466, 1437, 1404, 1258, 1125, 1087, 967, 840, 815,
2.3 Selected spectral data of keto-enol intermediates
(3)–(4) and dibenzoxanthene derivatives (5)
2.3a Phenyl-bis-(2-hydroxy-1-naphthyl)methane
(table 3, entry 1, (4a)): White solid; M.p. 203–205◦C; 785, 745;1H NMR (CDCl3, 400 MHz): δ 7.69–7.78 (m,
FT-IR (KBr) cm−1: 3422, 2926, 2378, 1953, 1618, 3H), 7.36 (d, J = 7.8 Hz, 3H), 7.27 (t, J = 6.9Hz,
1505, 1436, 1358, 1257, 1210, 1146, 1031, 957, 813, 1H), 7.13–7.16 (m, 6H), 6.91 (t, J = 7.3 Hz, 1H), 6.77
749, 699; H NMR (CDCl3,400MHz): δ 7.91(d, J = (d, J = 7.8 Hz, 2H), 6.14(s, 1H), 2.3(s, 3H); 13C NMR
1
8.2Hz,2H), 7.8(d, J = 8.2 Hz,2H), 7.7(d, J = 9.1Hz, (CDCl3, 100 MHz): δ 156, 146.5, 138.4, 130, 129.9,
2H), 7.20–7.39 (m,9H), 7.01(d, J = 8.7 Hz,2H), 129.4, 129.1, 128.9, 127.9, 126.8, 122.8, 121.4, 199.9,
6.3(s,1H); 13C NMR (CDCl3, 100MHz): δ 152.9, 140.6, 116.5, 11.8, 62.7, 21.1;CHN analysis (%): C28H20O,
133.6, 130.1, 129.9, 129.7, 129, 128.4, 127.5, 123.6, Cal. C 90.32 , H 5.37; Found C 90.37, H 5.40.
122.6, 119.9, 118.6, 42.7; CHN analysis (%): C27H20O2
Cal. C 86.17, H 5.31; Found C 86.21, H 5.35.
2.3e 4-chlorophenyl-(2-hydroxy-1-naphthyl)(benzocyclohex-
3-en-2-one)methane (New) (table 3, entry 6, (3e)):
2.3b 4-Nitrophenyl-bis-(2-hydroxy-1-naphthyl)methane
Red solid; M.p. 243–245◦C; FT- IR (KBr) cm−1:
(table 3, entry 4, (4d)): Yellow solid; M.p. 145–147◦C; 3425, 2917, 3050, 2851, 1677, 1624, 1465, 1383,
FT-IR (KBr) cm−1: 3394, 2927, 2858, 2379, 2285, 1256, 1205, 1089, 1024, 939, 813, 747; H NMR
1
1603, 1511, 1342, 1257, 1209, 1147, 954, 811, 743; 1H (CDCl3,400MHz): δ 7.87 (d, 1H, J = 8.7Hz), 7.82
NMR (CDCl3, 400 MHz): δ 8.06 (d, J = 6.9Hz,2H), (d, 1H, J =8.3Hz), 7.44–7.15 (m, 13H), 6.91 (d, 1H,