8
36 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Ó 2003 The Chemical Society of Japan
1
give 3. The ꢀ-elimination of HI, yielding 4, followed by the
conjugate addition of a hydroxy group (3 ! 4 ! 5), or a
replacement of the ꢀ-iodine by an aryloxy group (3 ! 5), gave 5.
The ꢀ-elimination of HI gave flavones.
7-Hydroxyflavone (2f). H NMR (CDCl
3
) ꢁ 6.91 (s, 1H), 6.95
(dd, J ¼ 1:8, 9.0 Hz, 1H), 7.02 (d, J ¼ 1:8 Hz, 1H), 7.57–7.59 (m,
3H), 7.91 (d, J ¼ 9:0 Hz, 1H), 8.05–8.08 (m, 2H), 10.8 (s, 1H);
1
3
C NMR (CDCl ) ꢁ 102.6, 106.6, 115.1, 116.2, 126.2, 126.5, 129.1,
3
1
1
31.3, 131.5, 157.5, 161.2, 162.8, 176.4; IR (nujol) 2800, 1620, 1310,
ꢂ1
ꢁ
ꢁ
16
270, 1170, 850, 780 cm ; mp 240–243 C (lit. 240 C).
Experimental
General Procedure for the Preparation of Flavones (2).
solution of 1.0 mmol of 1 and 1.2 mmol of I in triethylene glycol (2
mL) was stirred at150 C for 4 hours. After themixture was cooled to
room temperature, it was poured into water, and extracted with ethyl
A
References
2
ꢁ
1
2
T. S. Wheeler, Org. Synth., Coll. Vol. IV, 478 (1963).
F. Bois, C. Beney, A. Mariotte, and A. Boumendjel, Synlett,
acetate. The organic layer was washed with a Na
2
S
2
O
3
solution, and
dried over anhydrous MgSO . After evaporation of the solvent, the
1999, 1480.
4
3
697.
4
S. Saxena, J. K. Makrandi, and S. K. Grover, Synthesis, 1985,
product was purified by column chromatography on silica gel to give
flavone (2).
D. Nagarathnam and M. Cushman, J. Org. Chem., 56, 4884
1
Flavone (2a). H NMR (CDCl
3
) ꢁ 6.82 (s, 1H), 7.36–7.44 (m,
H), 7.51–7.58 (m, 4H), 7.64–7.73 (m, 1H), 7.90–7.93 (m, 2H), 8.23
(1991).
5
1
(
1
M. S. Khanna, O. V. Singh, C. P. Grag, and R. P. Kapoor, J.
1
3
d, J ¼ 7:5 Hz, 1H); C NMR (CDCl ) ꢁ 107.6, 118.1, 124.0, 125.2,
25.9, 126.3, 129.0, 131.6, 131.8, 133.8, 156.3, 163.4, 178.4; IR
3
Chem. Soc., Perkin Trans. 1, 1992, 2565.
C. G. Shankar, B. V. Mallarah, and G. Srimnnarayama,
Synthesis, 1983, 310.
6
ꢂ1
(
9
nujol) 1660, 1320, 1240, 1140, 1060, 920, 860, 790, 770 cm ; mp
ꢁ
ꢁ
1
5–98 C (lit. 97–98 C).
0
7
(1939).
8
D. Chakravarti and J. Dutta, J. Indian Chem. Soc., 16, 639
1
4
3
-Methylflavone (2b). H NMR (CDCl ) ꢁ 2.37 (s, 3H), 6.74 (s,
1
H), 7.24 (d, J ¼ 8:0 Hz, 2H), 7.36 (dd, J ¼ 7:5, 7.6Hz, 1H), 7.49 (d,
W. Fatima, J. Iqbal, H. Ismail, K. Ishratullah, W. A. Shaida,
J ¼ 8:3 Hz, 1H), 7.64 (ddd, J ¼ 0:8, 7.6, 8.3 Hz, 1H), 7.74 (d, J ¼
and Kehaman, Chem. Ind. (London), 1979, 315.
W. Futima, J. Iqbal, V. Manchanda, W. A. Shaida, and W.
13
8
2
1
7
:0 Hz, 2H), 8.18 (dd, J ¼ 0:8, 7.5 Hz, 1H); C NMR (CDCl
3
) ꢁ
1.5, 106.7, 118.0, 123.8, 125.1, 125.5, 125.9, 126.1, 129.7, 133.6,
9
Rohaman, J. Chem. Res. (S), 1984, 29; J. Chem. Res. (M), 1984,
2656.
10 A. G. Doshi, P. A. Soni, and B. J. Ghiya, Indian J. Chem.,
Sect. B, 25, 259 (1986).
42.2, 156.1, 163.5, 178.4; IR (nujol) 1160, 1040, 960, 910, 820, 780,
5
ꢂ1
ꢁ
ꢁ
60, 730 cm ; mp 109–111 C (lit. 110–112 C).
0
0
1
3
,4 -Dimethoxyflavone (2c). H NMR (CDCl
3
) ꢁ 3.95 (s, 3H),
3
.97 (s, 3H), 6.73 (s, 1H), 6.96 (d, J ¼ 8:1 Hz, 1H), 7.36 (d, J ¼ 1:8
11 R. P. Kapoor, O. V. Singh, and C. P. Garg, J. Indian Chem.
Soc., 68, 367 (1991).
12 A. Kasahara, T. Izumi, and M. Ooshima, Bull. Chem. Soc.
Jpn., 47, 2526 (1974).
13 A. C. Jain, R. C. Gupta, and R. Khazanch, Tetrahedron, 35,
413 (1979).
14 J. H. van der Westhuizen, D. Ferreira, and D. G. Roux, J.
Chem. Soc., Perkin Trans. 1, 1980, 2856.
15 K. Imafuku, M. Honda, and J. F. W. McOmie, Synthesis,
1987, 199.
16 J. H. Looker and M. J. Holm, J. Org. Chem., 24, 567 (1959).
17 T. Patonay, J. A. S. Cavaleiro, A. Levai, and A. M. S. Silva,
Heterocycl. Commun., 3, 223 (1997).
Hz, 1H), 7.40 (dd, J ¼ 7:2, 7.5 Hz, 1H), 7.52 (dd, J ¼ 1:8, 8.1 Hz,
1
8
1
1
1
H), 7.53 (d, J ¼ 7:5 Hz, 1H), 7.67 (ddd, J ¼ 1:5, 7.2, 7.8 Hz, 1H),
1
3
.20 (dd, J ¼ 1:5, 7.8 Hz, 1H); C NMR (CDCl
3
) ꢁ 56.1, 106.4,
08.8, 111.2, 118.0, 111.2, 118.0, 120.0, 123.9, 124.2, 125.6, 133.6,
49.3, 152.1, 156.1, 163.3, 178.3; IR (nujol) 1670, 1610, 1280, 1160,
ꢂ1
ꢁ
ꢁ
15
040, 890 cm ; mp 153–154 C (lit. 154–155 C).
1
0
4 -Chloroflavone (2d). H NMR (CDCl
.58 (m, 4H), 7.61–7.70 (m, 1H), 7.77–7.88 (m, 2H), 8.12–8.22 (m,
H); C NMR (CDCl ) ꢁ 107.6, 117.8, 123.9, 125.3, 125.7, 127.5,
3
) ꢁ 6.73 (s, 1H), 7.32–
7
1
1
1
1
3
3
29.3, 130.2, 133.9,137.8, 156.1, 162.8, 178.2;IR(nujol)1630, 1450,
ꢂ1
ꢁ
ꢁ
5
365, 1080, 820, 750 cm ; mp 186–188 C (lit. 188–189 C).
0
1
4
-Hydroxyflavone (2e). H NMR (CDCl
3
) ꢁ 6.69 (s, 1H), 6.97
(
d, J ¼ 8:7 Hz, 2H), 7.39–7.44 (m, 1H), 7.57–7.62 (m, 1H), 7.69–
18 T. Kumazawa, T. Minatogawa, S. Matsuba, S. Sato, and J-i.
Onodera, Carbohydr. Res., 329, 507 (2000).
19 A. M. S. Silva, D. C. G. A. Pint, and J. A. S. Cavaleiro,
Tetrahedron Lett., 35, 5899 (1994).
7
1
1
1
2
.74 (m, 1H), 7.83 (d, J ¼ 8:7 Hz, 2H), 8.14–8.16 (m, 1H), 9.83 (s,
13
H); C NMR (CDCl
3
) ꢁ 103.1, 114.2, 116.3, 119.9, 121.7, 123.1,
23.2, 126.4, 131.9,153.9, 159.3, 161.5, 175.3;IR(nujol)1640, 1580,
ꢂ1
ꢁ
310, 1270, 1190, 1050, 850, 790, 770 cm ; mp 270–271 C (lit.
ꢁ
20 A. H. Blatt, Org. Synth., Coll. Vol. I, 78 (1956).
4
70–271 C).