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6.4. 3-Chloro-4-fluoro-2%-carboxyldiphenyl ether (6b)
6.8. 2-Phenyl-6-fluoro-7-(4-methyl-1-piperazinyl)-
4H-1-benzopyran-4-one (2c)
The above product (5.6 g, 0.02 mol) was refluxed
in 30 ml of a 1:1 mixture of acetic acid and 48%
hydrobromic acid for 1 h. The cooled solution was
poured into water and the separated solid collected
by filtration. The crude product (4.5 g) on crystalliz-
ing from cyclohexane gave 4.2 g (80%) of white solid
65% yield of yellow crystalline product m.p. 155–
158°C (ethanol). 1H NMR: l 2.4 (s, 3H), 2.7 (m,
4H), 3.35 (m, 4H), 6.75 (s, 1H, H-3), 6.95–7.95 (m,
7H, Ar). Anal. (C20H19FN2O2): C, H, N.
1
6.9. 2-Phenyl-6-fluoro-7-(4-hydroxyethyl-1-
piperazinyl)-4H-1-benzopyran-4-one (2d)
m.p. 113–114°C. H NMR: l 6.9–8.1 (m, 7H), 11.6
(s, 1H). Anal. (C13H8ClFO3): C, H.
72% yield of yellow crystalline product m.p. 220°C
(dec.) (ethanol). 1H NMR: l 2.62 (m, 2H), 2.7 (m,
4H), 3.3 (m, 4H), 3.7 (m, 2H), 6.74 (s, 1H, H-3),
6.94–7.95 (m, 7H, Ar). Anal. (C21H21FN2O3): C, H,
N.
6.5. 1-Chloro-2-fluoroxanthen-9-one (7) and
2-fluoro-3-chloroxanthen-9-one (8)
Compound 6b (2.66 g, 0.01 mol) in 50 g PPA was
stirred at 100–110°C for 1 h. On pouring the reaction
mixture into water the separated solid was isolated by
filtration. The collected solid was digested for 1 h in
5% NaHCO3 solution and then recovered by filtra-
tion. The crude product is a mixture in 1:2 ratio of
the two regioisomers 7 and 8 which were separated
by column chromatography using a 9:1 mixture of
petroleum ether and ethyl acetate: the first fraction
contains the 2-fluoro-3-chloroxanthen-9-one (8) 1.66 g
(67%) as white crystalline product m.p. 170–172°C
(ethanol). 1H NMR: l 7.3–7.82 (m, 4H), 8.02 (d,
J=8.51 Hz, 1H), 8.28 (d, J=7.77 Hz, 1H). Anal.
(C13H6ClFO2): C, H.
6.10. 2-Phenyl-6-fluoro-7-(4-o-methoxyphenyl-1-
piperazinyl)-4H-1-benzopyran-4-one (2e)
70% yield of yellow crystalline product m.p. 204–
1
206°C (ethyl acetate). H NMR: l 3.26 (m, 4H), 3.48
(m, 4H), 3.9 (s, 3H), 6.78 (s, 1H, H-3), 6.92–7.95 (m,
7H, Ar). Anal. (C26H23FN2O3): C, H, N.
6.11. 1-Piperidinyl-2-fluoroxanthen-9-one (3a)
85% yield of yellow solid m.p. 156–157°C
(ethanol). 1H NMR: l 1.76 (m, 6H), 3.22 (m, 4H),
6.84–8.32 (m, 6H, Ar). Anal. (C18H16FNO2): C, H,
N.
The second fraction consisted of the 1-chloro-2-
fluoroxanthen-9-one (7), 0.8 g (33%) as a white crys-
talline product m.p. 140–142°C (ethanol). H NMR:
l 7.3–7.56 (m, 4H), 7.7 (m, 1H), 8.24 (d, J=8.69
Hz, 1H). Anal. (C13H6ClFO2): C, H.
1
6.12. 1-Piperazinyl-2-fluoroxanthen-9-one (3b)
40% yield of yellow solid m.p. 145–146°C
(ethanol). 1H NMR: l 3.12 (m, 4H), 3.30 (m, 4H),
6.94–8.3 (m, 6H, Ar). Anal. (C17H15FN2O2): C, H, N.
6.6. 2-Phenyl-6-fluoro-7-piperidinyl-4H-1-
benzopyran-4-one (2a)
6.13. 1-(4-Methyl-1-piperazinyl)-2-fluoroxanthen-
9-one (3c)
A mixture of 0.5 g (0.0018 mol) of 9 and 3 ml
piperidine was stirred at 100°C overnight. On pouring
the reaction mixture into water the separated solid
was filtered, washed with water and dried. The crude
product on crystallizing from ethanol gave 0.4 g
50% yield of yellow solid m.p. 162–165°C
(ethanol). 1H NMR: l 2.4 (s, 3H, CH3), 2.68 (m,
4H), 3.38 (m, 4H), 6.96–8.36 (m, 6H, Ar). Anal.
(C18H17FN2O2): C, H, N.
1
(68%) of yellow crystalline solid m.p. 128–131°C. H
NMR: l 1.85 (m, 6H), 3.22 (m, 4H), 6.75 (s, 1H,
H-3), 6.94–7.95 (m, 7H, Ar). Anal. (C20H18FNO2): C,
H, N.
With the same procedure the following compounds
were prepared.
6.14. 1-(4-Hydroxyethyl-1-piperazinyl)-2-fluoroxanthen-
9-one (3d)
65% yield of yellow solid m.p. 118–120°C
(ethanol). 1H NMR: l 2.64 (m, 2H), 2.76 (m, 4H),
3.36 (m, 4H), 3.66 (m, 2H), 6.96–8.36 (m, 6H, Ar).
Anal. (C19H19FN2O3): C, H, N.
6.7. 2-Phenyl-6-fluoro-7-piperazinyl-4H-1-
benzopyran-4-one (2b)
60% yield of yellow crystalline product m.p. 158–
160°C (ethyl acetate). 1H NMR: l 3.1 (m, 4H), 3.2
(m, 4H), 6.75 (s, 1H, H-3), 6.9–8 (m, 7H, Ar). Anal.
(C19H17FN2O2): C, H, N.
6.15. 1-(4-o-Methoxyphenyl-1-piperazinyl)-2-
fluoroxanthen-9-one (3e)
65% yield of yellow solid m.p. 132–135°C (ethanol).