Synthesis and anticancer effect of B-ring trifluoromethylated flavonoids

Article abstract of DOI:10.1016/S0960-894X(03)00752-2

A series of B-ring trifluoromethylated flavonoids derivatives were prepared and tested in vitro against human gastric adenocarcinoma cell line (SGC-7901). Among these derivatives, 5,7-dipropoxy-2-(4′ -trifluoromethylphenyl)-chromen-4-one 5c had the strongest activity against SGC-7901 cell.

Full text of DOI:10.1016/S0960-894X(03)00752-2

Bioorganic & Medicinal Chemistry Letters 13 (2003) 3423–3427
Synthesis and Anticancer Effect of B-Ring Trifluoromethylated
Flavonoids
Xing Zheng,a Jian-Guo Cao,b Wei-Dong Menga and Feng-Ling Qinga,c,*
aCollege of Chemistry and Chemical Engineering, Donghua University, 1882 West Yanan Lu, Shanghai 200051, China
bCancer Research Institute, Nanhua University, Hengyang, Hunan 421001, China
cKey Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, China
Received 21 May 2003; revised 16 July 2003; accepted 18 July 2003
Abstract—A series of B-ring trifluoromethylated flavonoids derivatives were prepared and tested in vitro against human gastric
adenocarcinoma cell line (SGC-7901). Among these derivatives, 5,7-dipropoxy-2-(40-trifluoromethylphenyl)-chromen-4-one 5c had
the strongest activity against SGC-7901 cell.
# 2003Elsevier Ltd. All rights reserved.
Introduction
often changes their physiological, physical and chemical
properties dramatically, without the introduction of
extra steric demand. Many efforts were made to intro-
duce the trifluoromethyl group into different types of
organic molecules in order to improve their stability and
lipophilicity.8 To our best knowledge, the introduction
of fluorine moiety into the aryl part of the flavonoids
molecule can enhance their biological activities includ-
ing anti-bacterial activity, anti-fungal activity and anti-
viral activity.9 Very recently, newly fluorinated 3,4-
dihydroxychalcones have been reported to have inter-
esting biological activities, including anti-peroxidation
activity and in vitro anti-tumor activities.10 However,
there were few literature references reported on the
synthesis of trifluoromethylated flavonoids. Earlier
studies11 of A-ring trifluoromethylated flavonoids (7-
Stomach cancer is the type most commonly seen in
China.1 In recent years, there has been a growing inter-
est in the search for anti-stomach cancer substances
with high efficacy, low toxicity and minimum side
effects. One approach is to search for it from plant ori-
gin. Flavonoids are a broad class of polyphenolic sec-
ondary metabolites abundant in plants and in a variety
of common foods such as apples, onions, tea and red
wine. Apart from their important biological roles in
nitrogen fixation and chemical defense, flavonoids pos-
sess a broad range of pharmacological properties
including anti-oxidant, anti-cancer, anti-viral and anti-
inflammatory properties.2 In anti-cancer area, flavo-
noids can inhibit the metabolism of the carcinogen
benzo[a]pyrene by hamster embryo cells in tissue cul-
ture3 and markedly augment the cytotoxicity of TNF
(tumor necrosis factor-a).4 Flavonoids are also found to
have tyrosinase inhibitory activity,5 moderate aroma-
tase inhibitory activity6 and inhibition of estradiol-
induced DNA synthesis.7 However, most of the anti-
cancer activities were low. It is known that fluorine is
the most electronegative element and the van der Waals
radius of fluorine is close to that of hydrogen, the
introduction of the CF3 group into organic molecules
methyl-8-trifluoromethyl-chrysin
1
and 6,8-ditri-
fluoromethyl-7-acetoxychrysin 2, Fig. 1) in our labora-
tory, showed some activities against SGC-7901 tumor
cell. As the presence of a hydrophobic substituent on the
*Corresponding author. Tel.: +86-21-6416-3300; fax: +86-21-6416-
6128; e-mail: flq@pub.sioc.ac.cn
Figure 1.
0960-894X/$ - see front matter # 2003Elsevier Ltd. All rights reserved.
doi:10.1016/S0960-894X(03)00752-2

3424
X. Zheng et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3423–3427
Scheme 1.
Scheme 2.
B-ring of flavonoids considerably enhanced biological
activities,12 we were interested in the introduction of
trifluoromethyl group into the B-ring of flavonoids.
Herein, we describe the synthesis of B-ring tri-
fluoromethylated flavonoids derivatives and their anti-
cancer activities against human gastric adenocarcinoma
cell line (SGC-7901).
with a,a,a-trifluoro-p-tolualdehyde in the presence of
excess NaOH in H2O/EtOH and followed by acidifica-
tion with aqueous HCl gave the expected compound 4.
The alkylation of 4 was carried out with alkyl halides in
the presence of K2CO3 in acetone to afford compounds
5a–g. When CH3I, CH3CH2Br and CH3CH2CH2Br
were used as alkylating agents, it was interesting that
the alkylation of 4 gave expected compounds 5a–c as
well as unexpected compounds 6a–c. The ratio of 5a–c:
6a–c was changed from 1:1 (in the case of CH3I) to 2:1
(in the case of CH3CH2Br and CH3CH2CH2Br). Treat-
ment of 5a–c with CH3I, CH3CH2Br and
CH3CH2CH2Br in the presence of K2CO3 in acetone
resulted in no reaction and 5a–c was recovered. These
Chemistry
Condensation of phloroglucinol with chloroacetonitrile
catalyzed by ZnCl2 and followed by hydrolysis with
HCl gas provided ketone 3 (Scheme 1).13 Treatment of 3

X. Zheng et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3423–3427
3425
that introduction of an alkyl group at the 3-position of
the C-ring resulted in a significant decrease in anti-SGC-
7901 tumor cell activity. (3) Comparing 5e–g with 4, we
found that alkylated compounds had less activities than
compound 4, meanwhile among them, compounds with
longer alkyl chain showed better activity. (4) When the
hydroxy group of flavonoids was transformed into pro-
poxy or allyloxy group, the resulted compounds 5c, 9c,
9d and 12c were more active for inhibition of SGC-7901
cell than parent compounds 4, 8 and 11, respectively.
However, the anti-tumor activity of the ethylated com-
pounds 5b, 9b, and 12b decreased dramatically. (5)
Comparing 9a–e with 8, the results showed that, apart
from 9b, the alkylated compounds were more active
than 8, the activity was enhanced with longer alkyl
chain. (6) Comparing 12a–e with 11, we disclosed that
6-alkoxy (except allyloxy compound 12c) substituted
products 12a, 12b, 12d and 12e had less activity than
compound 11. However, it may increase activity when
the alkyl chain was prolonged. (7) It was known that
flavonoid containing a g-pyrone ring was necessary for
their anti-bacterial property.9 However, for the flavo-
noids that we obtained with trifluoromethyl group
bound on B-ring, apart from that 9a had stronger
activities against SGC-7901 tumor cell than 12a, com-
pounds 8, 9b, 9d had less activities than 11, 12b and 12c,
respectively.
Table 1. In vitro cytotoxicity against the SGC-7901 cell line
Compd
IC50 (mM)
Compd
IC50 (mM)
1
2
5.90
8.60
8
9a
17.75
8.28
28.52
5.61
5.26
4.16
4.31
21.19
15.60
3.05
4
6.62
4.37
44.02
2.70
5.00
30.83
18.06
9.02
10.08
72.46
8.64
9b
9c
9d
9e
5a
5b
5c
5d
5e
5f
5g
6a
6b
6c
11
12a
12b
12c
12d
12e
14.72
5.35
results indicated 6a–c was not formed from 5a–c. The
mechanism for the formation of 5a–c was under
investigation.
The same procedure as described above can smoothly
convert resorcinol to B-ring trifluoromethylated flavo-
noids 9a–e via intermediates 7 and 8 (Scheme 2). We
also prepared trifluomethylated aurones from resorcinol
(Scheme 2). Treatment of 7 with sodium methoxide in
MeOH gave benzofuranone 10.14 Condensation of 10
with a,a,a-trifluoro-p-tolualdehyde in the presence of
excess NaOH in H2O/EtOH afforded the expected aur-
one 11. The alkylation of 11 with alkyl halides in the
presence of K2CO3 in acetone produced 12a–e.
In conclusion, we have designed and synthesized a series
of trifluoromethylated flavonoids.16 The preliminary
biological activity screening tests indicated that 5,7-
Dipropoxy-2-(40-trifluoromethyl phenyl)-chromen-4-one
5c was the most active compound against SGC-7901
tumor cell.
Biological Activity
All the above compounds were tested for their in vitro
anticancer activity against SGC-7901 cell by MTT-
Based Assay. The assays were performed in 96-well
plates essentially as described by Mosmann.15 The IC50
concentration represents the concentration which results
in a 50% decrease in cell growth after 6 days incubation.
The given values are mean values of three experiments.
Acknowledgements
We thank the National Natural Science Foundation of
China and the Ministry of Education of China for
financial support.
References and Notes
Results and Discussion
The pharmacological activity against the SGC-7901 cell
is summarized in Table 1. It appeared that these closely
related molecules displayed a remarkable difference in
cytotoxicity. As shown in Table 1, we disclosed that 5a,
5c, 5d, 9c, 9d, 9e, 11, 12c and 12e showed stronger
cytotoxicity towards SGC-7901 cell than 1, and 4, 5a,
5c, 5d, 9a, 9c, 9d, 9e, 11, 12c and 12e showed stronger
cytotoxicity towards SGC-7901 cell than 2. 5,7-Dipro-
1. King, R. J. B., Cancer Biology. 2nd ed.; Pearson Education,
2000.
2. (a) Flavonoids in Health and Disease, Rice-Evans, C. A.;
Packer, L. Eds. Marcel Dekker: New York, NY, 1997. (b)
Bertrand, A.; Olivier, D. Helv. Chim. Acta 1999, 82, 2201.
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J. M. Tetrahedron 2000, 56, 7613.
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1987, 26B, 493.
10. Nakamura, C.; Kawasaki, N.; Miyataka, H.; Jayachan-
poxy-2-(40-trifluoromethylphenyl)-chromen-4-one
5c
was identified as the most potent inhibitor of SGC-7901
tumor cell. Although general structure–activity rela-
tionship of those compounds was not elucidated from
these data, the following points were noteworthy: (1)
Compound 4 had stronger activity against SGC-7901
tumor cell than 8. This was probably due to the forma-
tion of intramolecular hydrogen bond of 5-hydroxyl
group in 4. (2) Compounds 5a, 5b and 5c had stronger
activities than 6a, 6b and 6c, respectively, suggesting

3426
X. Zheng et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3423–3427
dran, E.; Kim, I. H.; Kirk, K. L.; Taguchi, T.; Takeuchi, Y.;
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F. L. Bioorg. Med. Chem. Lett. 2003, 13, 881.
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Conseil, A.; Pietro, A. D. Bioorg. Med. Chem. Lett. 2001, 11,
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2001, 55, 967.
15. Mosman, T. J. Immunol. Methods 1983, 65, 55.
(2H, d, J=8.1 Hz), 7.953(2H, d, J=8.1 Hz). 19F NMR
(300 MHz) À76.214. HRMS calcd for C22H21F3O4: 406.14311;
Found: 406.13919. 6c MS (EI, 70 ev) m/z: 448; IR umax (cmÀ1
,
1
KBr): 1699 (C¼O); H NMR (300 MHz, CDCl3): 0.941–1.951
(15H, m), 2.637 (2H, m), 4.062 (2H, m), 4.381 (2H, m), 6.507
(1H, s), 6.720 (1H, s), 7.686 (2H, d, J=7.8 Hz), 7.971 (2H, d,
J=7.8 Hz). 19F NMR (300 MHz) À63.107. HRMS calcd for
C25H27F3O4: 448.18953; Found: 448.19087. 8 MS (EI, 70 ev)
1
m/z: 306; IR umax (cmÀ1, KBr): 1683(C ¼O), 3072 (OH); H
NMR (300 MHz, CD3COCD3): 6.818 (1H, s), 6.857 (1H, dd,
J=2.1, 8.4), 6.899 (1H, d, J=2.1 Hz), 7.692 (1H, d, J=8.4
Hz), 7.774 (2H, d, J=6.8 Hz), 8.220 (2H, d, J=6.8 Hz),
10.138 (1H, s). 19F NMR (300 MHz) À68.627. Anal. calcd for
C16H9F3O3: C, 62.75, H, 2.96; Found C, 62.90, H, 3.44. 9a MS
(EI, 70ev) m/z: 320; IR umax (cmÀ1, KBr): 1702 (C¼O); 1H
NMR (300 MHz, CDCl3): 3.972 (3H, s), 6.806 (1H, dd, J=2.1,
9.3Hz), 6.821 (1H, s), 7.709 (2H, d, J=8.4 Hz), 7.726 (1H, d,
J=2.1 Hz), 7.745 (1H, d, J=9.3Hz), 8.009 (2H, d, J=8.4
Hz). 19F NMR (300 MHz) À71.206. 9b MS (EI, 70 ev) m/z:
16. All the new compounds were characterized by detailed
spectroscopic analysis. 4 MS (EI, 70 ev) m/z: 322; IR umax
(cmÀ1, KBr): 1682 (C¼O), 3096, 3312 (OH); 1H NMR
(300 MHz, DMSO-d6): 6.100 (1H, d, J=1.5 Hz), 6.230 (1H,
d, J=1.5 Hz), 6.688 (1H, s), 7.801 (2H, d, J=8.1 Hz), 8.076
(2H, d, J=8.1 Hz), 11.006 (1H, s), 11.082 (1H, s). 19F NMR
(300 MHz) À70.95. Anal. calcd for C16H9F3O4: C, 59.64, H,
2.82; Found C, 59.44, H, 2.85. 5a MS (EI, 70 ev) m/z: 350; IR
umax (cmÀ1, KBr): 1705 (C¼O); 1H NMR (300 MHz, CDCl3):
3.952 (3H, s), 3.972 (3H, s), 6.156 (1H, d, J=1.8 Hz), 6.412
(1H, d, J=1.8 Hz), 6.755 (1H, s), 7.671 (2H, d, J=8.4 Hz),
7.958 (2H, d, J=8.4 Hz). 19F NMR (300 MHz) À62.686. 5b
MS (EI, 70 ev) m/z: 378; IR umax (cmÀ1, KBr): 1699 (C¼O);
1H NMR (300 MHz, CDCl3): 1.447–1.596 (6H, m), 4.162–
4.293(4H, m), 6.184 ( 1H, d, J=1.5 Hz), 6.412 (1H, d, J=1.5
Hz), 6.765 (1H, s), 7.717 (2H, d, J=8.1 Hz), 8.004 (2H, d,
J=8.1 Hz). 19F NMR (300 MHz) À76.240. 5c MS (EI, 70 ev)
m/z: 406; IR umax (cmÀ1, KBr): 1699 (C¼O); 1H NMR
(300 MHz, CDCl3): 1.066–1.114 (6H, m), 1.839–1.970 (4H, m),
4.014–4.111 (4H, m), 6.147 (1H, s), 6.373 (1H, s), 6.708 (1H,
s), 7.670 (2H, d, J=8.1 Hz), 7.958 (2H, d, J=8.1 Hz). 19F
NMR (300 MHz) À63.108. Anal. calcd for C22H21F3O4: C,
65.02, H, 5.21; Found C, 64.57, H, 5.19. 5d MS (EI, 70 ev) m/
z: 502; IR umax (cmÀ1, KBr): 1702 (C¼O); 1H NMR
(300 MHz, CDCl3): 5.137 (2H, s), 5.298 (2H, s), 6.277 (1H, d,
J=1.8), 6.480 (1H, d, J=1.8), 6.757 (1H, s), 7.333–7.507
(10H, m), 7.685 (2H, d, J=8.1 Hz), 7.968 (2H, d, J=8.1 Hz).
19F NMR (300 MHz) À62.768. Anal. calcd for C30H21F3O4:
C, 71.71, H, 4.21; Found C, 71.69, H, 4.17. 5e MS (EI, 70 ev)
m/z: 518; IR umax (cmÀ1, KBr): 1707 (C¼O); 1H NMR
(300 MHz, CDCl3): 0.683–1.896 (26H, m), 4.038–4.108 (4H,
m), 6.132 (1H, d, J=1.2 Hz), 6.363 (1H, d, J=1.2 Hz), 6.704
(1H, s), 7.661 (2H, d, J=8.4 Hz), 7.950 (2H, d, J=8.4). 19F
NMR (300 MHz) À62.709. HRMS calcd for C30H37F3O4:
518.26158; Found: 518.26439. 5f MS (EI, 70 ev) m/z: 546; IR
1
334; IR umax (cmÀ1, KBr): 1693(C ¼O); H NMR (300 MHz,
CDCl3): 1.492 (3H, t, J=6.9 Hz), 4.163(2H, q, J=6.9 Hz),
6.759 (1H, dd, J=2.1 Hz, 6.6), 6.780 (1H, s), 7.680 (2H, d,
J=8.4 Hz), 7.697 (1H, d, J=2.1 Hz), 7.705 (1H, d, J=6.6
Hz), 7.975 (2H, d, J=8.4 Hz). 19F NMR (300 MHz) À71.206.
Anal. calcd for C18H13F3O3: C, 64.67, H, 3.92; Found C,
65.23, H, 4.21. 9c MS (EI, 70 ev) m/z: 348; IR umax (cmÀ1
,
KBr): 1706 (C¼O); 1H NMR (300 MHz, CDCl3): 1.086 (3H, t,
J=7.5), 1.856–1.925 (2H, m), 4.059 (2H, t, J=6.6 Hz), 6.763
(1H, dd, J=2.4, 6.6 Hz), 6.781 (1H, d, J=6.6 Hz), 6.794 (1H,
s), 7.690 (2H, d, J=8.1 Hz), 7.704 (1H, d, J=2.4 Hz), 7.988
(2H, d, J=8.1 Hz). 19F NMR (300 MHz) À71.203. Anal. calcd
for C19H15F3O3: C, 65.52, H, 4.34; Found C, 65.32, H, 4.32.
9d MS (EI, 70 ev) m/z: 346; IR umax (cmÀ1, KBr): 1707 (C¼O);
1H NMR (300 MHz, CDCl3): 4.681–4.652 (2H, m), 5.505–
5.363 (2H, m), 6.028–6.120 (1H, m), 6.770 (1H, s), 6.786 (1H,
dd, J=2.1, 7.5 Hz), 6.798 (1H, d, J=7.5 Hz), 7.670 (2H, d,
J=7.8 Hz), 7.709 (1H, d, J=2.1 Hz), 7.960 (2H, d, J=7.8
Hz). 19F NMR (300 MHz) À67.021. Anal. calcd for
C19H13F3O3: C, 65.90, H, 3.70; Found C, 65.89, H, 3.89. 9e
MS (EI, 70 ev) m/z: 418; IR umax (cmÀ1, KBr): 1701 (C¼O);
1H NMR (300 MHz, CDCl3): 0.909 (3H, t, J=6.6 Hz), 1.313–
1.880 (12H, m), 4.088 (2H, t, J=6.6 Hz), 6.764 (1H, dd,
J=2.1, 6.6 Hz), 6.779 (1H, d, J=2.1 Hz), 6.789 (1H, s), 7.688
(2H, d, J=6.8 Hz), 7.712 (1H, d, J=6.6 Hz), 7.985 (2H, d,
J=6.8 Hz). 19F NMR (300 MHz) À68.437. Anal. calcd for
C24H25F3O3: C, 68.89, H, 6.02; Found C, 69.10, H, 6.13. 11
MS (EI, 70 ev) m/z: 306; IR umax (cmÀ1, KBr): 1778 (C¼O);
1H NMR (300 MHz, CD3COCD3): 6.781 (1H, s), 6.822 (1H,
dd, J=2.1, 7.8 Hz), 6.864 (1H, d, J=2.1 Hz), 7.656 (2H, d,
J=8.4 Hz), 7.821 (1H, d, J=7.8), 8.174 (2H, d, J=8.4 Hz),
10.118 (1H, s). 19F NMR (300 MHz) À70.772. Anal. calcd for
C16H9F3O3: C, 62.75, H, 2.96; Found C, 62.69, H, 2.97. 12a
MS (EI, 70 ev) m/z: 320; IR umax (cmÀ1, KBr): 1702 (C¼O);
1H NMR (300 MHz, CDCl3): 3.974 (3H, s), 6.798 (1H, s),
6.818 (1H, dd, J=2.1, 7.8 Hz), 7.710 (1H, d, J=2.1), 7.715
(2H, d, J=8.4), 7.747 (1H, d, J=7.8 Hz), 8.004 (2H, d, J=8.4
Hz). 19F NMR (300 MHz) À70.493. 12b MS (EI, 70 ev) m/z:
1
umax (cmÀ1, KBr): 1699 (C¼O); H NMR (300 MHz, CDCl3):
0.884–0.920 (6H, m), 1.501–1.274 (20H, m), 1.826–1.941 (4H,
m), 4.057–4.150 (4H, m), 6.151 (1H, d, J=1.2), 6.382 (1H, d,
J=1.2 Hz), 6.722 (1H, s), 7.682 (2H, d, J=8.4 Hz), 7.972 (2H,
d, J=8.4 Hz). 19F NMR (300 MHz) À76.194. HRMS calcd
for C32H41F3O4: 546.29234; Found: 546.29570. 5g MS (EI, 70
ev) m/z: 602; IR umax (cmÀ1, KBr): 1703(C ¼O); 1H NMR
(300 MHz, CDCl3): 0.884–0.920 (6H, m), 1.298–1.496 (28H,
m), 1.822–1.938 (4H, m), 4.053–4.145 (4H, m), 6.146 (1H, d,
J=1.2 Hz), 6.378 (1H, d, J=1.2), 6.717 (1H, s), 7.679 (2H, d,
J=8.1 Hz), 7.967 (2H, d, J=8.1 Hz). 19F NMR (300 MHz)
À76.194. HRMS calcd for C36H49F3O4: 602.35545; Found:
602.35829. 6a MS (EI, 70 ev) m/z: 364; IR umax (cmÀ1, KBr):
1696 (C¼O); 1H NMR (300 MHz, CDCl3): 2.079 (3H, s),
3.965 (3H, s), 4.185 (3H, s), 6.530 (1H, s), 6.730 (1H, s), 7.675
(2H, d, J=8.1 Hz), 7.947 (2H, d, J=8.1 Hz). 19F NMR
(300 MHz) À76.261. HRMS. calcd for C19H15F3O4:
364.08929; Found: 364.09225. 6b MS (EI, 70 ev) m/z: 406; IR
1
334; IR umax (cmÀ1, KBr): 1700 (C¼O); H NMR (300 MHz,
CDCl3): 1.499 (3H, t, J=6.9 Hz), 4.175 (2H, q, J=6.9 Hz),
6.760 (1H, dd, J=2.1, 7.8 Hz), 6.784 (1H, d, J=2.1 Hz), 6.799
(1H, s), 7.690 (2H, d, J=8.4 Hz), 7.715 (1H, d, J=7.8 Hz),
7.990 (2H, d, J=8.4 Hz). 19F NMR (300 MHz) À73.059. Anal.
calcd for C18H13F3O3: C, 64.67, H, 3.92; Found C, 65.45, H,
4.22. 12c MS (EI, 70 ev) m/z: 346; IR umax (cmÀ1, KBr): 1707
(C¼O); 1H NMR (300 MHz, CDCl3): 4.664–4.691 (2H, m),
5.369–5.515 (2H, m), 6.033–6.126 (1H, m), 6.787 (1H, s), 6.814
(1H, d, J=2.1), 7.671 (2H, d, J=7.8 Hz), 7.675 (1H, d, J=7.5
Hz), 7.719 (1H, dd, J=2.1, 7.5 Hz), 7.978 (2H, d, J=7.8 Hz).
19F NMR (300 MHz) À56.761. Anal. calcd for C19H13F3O3:
1
umax (cmÀ1, KBr): 1699 (C¼O); H NMR (300 MHz, CDCl3):
1.081 (3H, t, J=7.2), 1.433 (3H, t, J=6.9), 1.501 (3H, t,
J=6.9), 2.655 (2H, q, J=7.2 Hz), 4.163(2H, q, J=6.9 Hz),
4.456 (2H, q, J=6.9 Hz), 6.491 (1H, s), 6.703(1H, s), 7.665

X. Zheng et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3423–3427
3427
C, 65.89, H, 3.78; Found C, 65.76, H, 3.99. 12d MS (EI, 70 ev)
m/z: 396; IR umax (cmÀ1, KBr): 1699 (C¼O); 1H NMR
(300 MHz, CDCl3): 5.221 (2H, s), 6.815 (1H, s), 6.880 (1H, dd,
J=2.1,9.0), 7.425–7.470 (5H, m), 7.456 (1H, d, J=2.1 Hz),
7.703(2H, d, J=7.8), 7.747 (1H, d, J=9.0 Hz), 7.996 (2H, d,
J=7.8 Hz). 19F NMR (300 MHz) À74.146. Anal. calcd for
C23H15F3O3: C, 69.70, H, 3.81; Found C, 69.76, H, 3.91. 12e
MS (EI, 70 ev) m/z: 404; IR umax (cmÀ1, KBr): 1699 (C¼O);
1H NMR (300 MHz, CDCl3): 0.887 (3H, t, J=6.9 Hz),
0.925–1.873(10H, m), 4.079 (2H, t, J=6.9 Hz), 6.756 (1H, dd,
J=2.1, 9.0 Hz), 6.773(1H, d, J=2.1 Hz), 6.777 (1H, s), 7.677
(2H, d, J=7.8 Hz), 7.696 (1H, d, J=9.0 Hz), 7.972 (2H, d,
J=7.8 Hz). 19F NMR (300 MHz) À67.871. Anal. calcd for
C23H23F3O3: C, 68.31, H, 5.73; Found C, 68.92, H, 6.21.