Inhibition of telomerase by BIBR 1532 and related analogues

Article abstract of DOI:10.1016/S0960-894X(03)00101-X

BIBR 1532 has been reported to be a potent, small molecule inhibitor of human telomerase, suggesting it as a lead for the development of anti-telomerase therapy. We confirm the ability of BIBR 1532 to inhibit telomerase and report the discovery of an equa

Full text of DOI:10.1016/S0960-894X(03)00101-X

BMCL 6516 Disk used
No. pages 4, DTD=4.3.1
Version 7.51e
ARTICLE IN PRESS
Bioorganic & Medicinal Chemistry Letters & (&&&&) &–&
Inhibition of Telomerase by BIBR 1532 and Related Analogues
D. K. Barma, Anissa Elayadi, J. R. Falck and David R. Corey*
Departments of Pharmacology and Biochemistry, University of Texas Southwestern Medical Center at Dallas,
5323Harry Hines Blvd., Dallas, TX 75390-9041, USA
Received 4 December 2002; accepted 9 January 2003
Abstract—BIBR 1532 has been reported to be a potent, small molecule inhibitor of human telomerase, suggesting it as a lead for
the development of anti-telomerase therapy. We confirm the ability of BIBR 1532 to inhibit telomerase and report the discovery of
an equally potent analogue. Importantly, IC50 values in cell extract are considerably higher than those previously reported using
assays for purified enzyme, indicating that substantial improvement may be necessary.
# 2003 Elsevier Science Ltd. All rights reserved.
Linear chromosomes are capped by telomeres contain-
ing variable numbers of nucleotide repeats, TTAGGG/
AATCCC in humans.1 Telomeres protect the gene
encoding regions of chromosomes and are essential for
maintaining the stability of the genome. Telomeres
cannot be fully replicated by standard DNA poly-
merases and, in the absence of any mechanism for
maintaining telomere length, telomeres will erode
50–100 bases per population doubling.2
dominant negative hTERT,10,11 oligonucleotides,12ꢀ14
or small molecules.16ꢀ19 To date, the most potent
inhibitors have been phosphoramidate or 20-methox-
yethyl oligonucleotides complementary to the telomer-
ase RNA template.12,13 While oligonucleotides are
generating increasing excitement as potential drugs,15
the advantages of small molecules continue to attract
interest to their development as telomerase inhibitors.
To date, several small molecule inhibitors of telomerase
function have been developed,16ꢀ20 many of which act
to stabilize G-quadruplex structure.
In humans, a solution to the problem of maintaining
telomere length is provided by telomerase, a ribonu-
cleoprotein with one RNA (hTR) and one protein
component (hTERT).3ꢀ6 Telomerase has attracted great
attention as a target for chemotherapy because telo-
merase activity is expressed in most tumor types but not
in adjacent normal tissue.7,8 This correlation has led to
two related hypotheses: (1) reactivation of telomerase is
necessary for maintaining viable telomeres during the
rapid cell proliferation that characterizes cancer and (2)
inhibition of telomerase may cause the telomeres of
cancer cells to erode to a critical length and reduce the
rate of tumor cell proliferation.
One recently described small molecule, BIBR 1532, has
been reported to be a promising telomerase inhibitor. It
causes telomeres to shorten and reduces tumor cell pro-
liferation.18 Here, we describe the synthesis of BIBR
1532 and derivatives, and their ability to inhibit human
telomerase.
Inhibitor Syntheses
Our strategy for the preparation of the inhibitors 1 is
outlined in Figure 1 and utilized the high-yield addition
of methyl anthranilate (3) to the acid chloride derived
via standard procedures from 2 followed by aryl ester
saponification. The key intermediate, 2, was obtained
by a novel Cr(II)-mediated condensation between com-
mercial carbonyl 4 and either methyl 2,2-dichloro- or
2,2,2-trichloroacetates (5). The latter reaction21 is nota-
ble for its excellent yields and unprecedented Z-stereo-
selectivity with trihaloacetates.22,23
The hypothesis that telomerase is a novel target for
cancer chemotherapy is supported by numerous obser-
vations of reduced cell growth upon telomerase inhibi-
tion by antisense RNA,4 ribozymes,9 expression of a
*Corresponding author. Tel.: +1-214-648-5096; fax: +1-214-648-
5095; e-mail: david.corey@utsouthwestern.edu
0960-894X/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0960-894X(03)00101-X

BMCL 6516 Disk used
No. pages 4, DTD=4.3.1
Version 7.51e
ARTICLE IN PRESS
D. K. Barma et al. / Bioorg. Med. Chem. Lett. & (&&&&) &–&
2
Figure 1. Retrosynthetic analysis.
Inhibition of Telomerase by BIBR 1532 and Derivatives
We assayed inhibition of telomerase using the telomeric
repeat amplification protocol (TRAP).24 TRAP is a
sensitive assay that uses polymerase chain reaction
(PCR) to amplify telomerase activity and we worked
within the linear range of the assay. TRAP uses an
internal amplification standard to insure that addition
of inhibitor is not interfering with the amplification
step. HeLa cells, derived from human cervical carci-
noma, were lysed to obtain nuclear extract and the
extract was used as a source for telomerase activity.
Using TRAP, we found that BIBR 1532 inhibited telo-
merase with an IC50 value of 5 mM. The cis isomer of
BIBR 1532 (221-32) was also an inhibitor, with an IC50
value of 5 mM (Figs. 2 and 3). None of the other com-
pounds tested inhibited telomerase at concentrations as
high as 50 mM. The IC50 value of BIBR 1532 is sub-
stantially above the IC50 value, ꢁ100 nM, reported by
Damm and coworkers.19,20
One source of the different values is that our assays were
conducted in a crude cell extract, while the previous
work employed purified telomerase. The crude extract
may contain interfering cellular components that reduce
the potency of inhibitor, possibly by binding to it or
modifying it. Alternatively, the crude extracts may con-
tain a factor that interacts with telomerase and limits
the ability of BIBR 1532 to be an inhibitor. Other
workers have directly compared the IC50 values for
BIBR 1532 in cell extract and with purified enzymes and
report similar differences in inhibitory potency (Harley
and Chin, personal communication).
Figure 2. Compounds synthesized in these studies and the IC50 values
that characterize their inhibition of telomerase. ND, inhibition not
detected at concentrations as high as 50 mM.
Conclusion
We have used a novel synthetic method to synthesize
the anti-telomerase agent BIBR 1532 and related com-
pounds. We find that both BIBR 1532 and the one
active derivative (221-32) have IC50 values of 5 mM,
substantially above the IC50 values for BIBR 1532
reported in the literature.19 Our results emphasize the
importance of considering the purity of enzyme when
evaluating IC50 values and comparing values between
laboratories, and suggest that the synthesis of deriva-
tives of BIBR 1532 that are potent enough to use in
clinical trials may be more challenging than had been
anticipated.
Figure 3. Inhibition of telomerase by BIBR 1532 monitored by
TRAP. (ꢀ) Buffer only. (+) Cell extract only, no inhibitor added.
Concentrations of BIBR 1532 ranged from 0.001 to 50 mM. Experi-
ments were performed in duplicate. The lowest band is the internal
amplification standard.
that it is difficult to identify highly potent small mol-
ecule lead compounds. Potent inhibition can be
achieved by use of oligonucleotides.12ꢀ14 Combined,
these results suggest that in the near term oligonucleo-
tides, not small molecules, may be better suited for use
in clinical trials of anti-telomerase therapy.
Our data impact our working model for telomerase
recognition of inhibitors by reinforcing the conclusion

BMCL 6516 Disk used
No. pages 4, DTD=4.3.1
Version 7.51e
ARTICLE IN PRESS
D. K. Barma et al. / Bioorg. Med. Chem. Lett. & (&&&&) &–&
3
Assay for Telomerase Activity
19. Damm, K.; Hemmann, U.; Garin-Chesa, P.; Hauel, N.;
Kaufffman, I.; Priepke, H.; Niestroj, C.; Daiber, C.; Enenkel,
B.; Guilliard, B.; Lauritsch, I.; Muller, E.; Pascolo, E.; Sauter,
G.; Pantic, M.; Martens, U. M.; Wenz, C.; Lingner, J.; Kraut,
N.; Rettig, W. J.; Schnapp, A. EMBO J. 2001, 20, 6958.
20. Pascolo, E.; Wenz, C.; Lingner, J.; Hauel, N.; Priepke, H.;
Kauffmann, I.; Garin-Chesa, P.; Rettig, W. J.; Damm, K.;
Schnapp, A. J. Biol. Chem. 2002, 277, 15566.
Telomerase activity was determined with the telomere
repeat-amplification protocol (TRAP) and analyzed as
described using whole cell lysate.24
Acknowledgements
21. The scope and limitations of this methodology will be
reported elsewhere.
Supported financially by the Robert A. Welch Founda-
tion (I-1244 and GL625910) and grants from the
National Institutes of Health GM31278, CA 85363 and
CA70907. We thank Becky McKinney for skilled assis-
tance with telomerase assay.
22. For condensations using other metals see: Ishino, Y.;
Mihara, M.; Nishihama, S.; Nishiguchi, I. Bull. Chem. Soc.
Jpn. 1998, 71, 2669.
23. Shihara, T.; Kuroboshi, M. Chem. Lett. 1987, 1145.
24. Holt, S. E.; Norton, J. C.; Wright, W. E.; Shay, J. W.
Meth. Cell. Sci. 1996, 18, 237.
25. Gurtler, C.; Buchwald, S. L. Chemistry-A European Jour-
nal 1999, 5, 3107.
26. Summers, J. B., Jr. U.S. (1986), US 4608390 A 19860826
CAN 106:18160 AN 1987:18160.
References and Notes
1. Moyzis, R. K.; Buckingham, J. M.; Cram, L. S.; Dani, M.;
Deaven, L. L.; Jones, M. D.; Meyne, J.; Ratliff, R. L.; Wu, J.-
R. Proc. Natl. Acad. Sci. U.S.A. 1988, 85, 6622.
2. Harley, C. B.; Futcher, A. B.; Greider, C. W. Nature 1990,
345, 458.
3. Feng, J.; Funk, W. D.; Wang, S.-S.; Weinrich, S. S.; Avi-
lion, A. A.; Chiu, C.-P.; Adams, R. R.; Chang, E.; Allsopp,
R. C.; Yu, J.; Le, S.; West, M. D.; Harley, C. B.; Andrews,
W. H.; Greider, C. W.; Villeponteau, B. Science 1995, 269,
1236.
4. Nakamura, T. M.; Morin, G. B.; Chapman, K. B.; Wein-
rich, S. L.; Andrews, W. H.; Lingner, J.; Harley, C. B.; Cech,
T. R. Science 1997, 277, 955.
5. Harrington, L.; Zhou, W.; McPhail, T.; Oulton, R.; Yeung,
D. S.; Mar, V.; Bass, M. B.; Robinson, M. O. Genes Dev.
1997, 11, 3109.
General procedure: preparation of (Z)-ꢀ-chloro-ꢀ,ꢁ-unsat-
urated esters and ꢀ,ꢁ-unsaturated esters
A solution of aldehyde or ketone (1 equiv) and methyl 2,2,2-
trichloroacetate or 2,2-dichloroacetate (1.2 equiv) in dry THF
(1 mL/mmol RCHO) was added to a stirring, room tempera-
ture suspension of commercial anhydrous CrCl2 (5 equiv) in
THF (10 mL/100 mg CrCl2) under an argon atmosphere.
Methyl 2,2,2-trichloroacetate reactions were continued at rt
for 0.5
h whereas methyl 2,2-dichloroacetate reactions
required 12 h at rt (or 2 h at 60 ꢂC). The reddish, heterogenous
reaction mixture was quenched with ice water and extracted
thrice with Et2O. The combined ethereal extracts were washed
with brine, dried, and evaporated in vacuo. Chromatographic
purification of the residue on SiO2 afforded (Z)-a-chloro-a,b-
unsaturated ester or a,b-unsaturated ester, respectively, in 98–
100% yield.
6. Meyerson, M.; Counter, C. M.; Ng Eaton, E.; Ellisen,
L. W.; Steiner, P.; Caddle, S. D.; Ziaugra, L.; Beijersbergen,
R. L.; Davidoff, M. J.; Liu, Q.; Bacchetti, S.; Haber, D. A.;
Weinberg, R. A. Cell 1997, 785.
7. Kim, N. W.; Piatyszek, M. A.; Prowse, K. R.; Harley, C. B.;
West, M. D.; Ho, P. L. C.; Coviello, G. M.; Wright, W. E.;
Weinrich, S. L.; Shay, J. W. Science 1994, 266, 2011.
8. Counter, C. M.; Hirte, H. W.; Bachetti, S.; Harley, C. B.
Proc. Natl. Acad. Sci. U.S.A. 1994, 91, 2900.
General procedure: ester hydrolysis
LiOH (1 M aq solution, 4 equiv) was added to a room tem-
perature solution of the above methyl ester in THF/H2O (5:1,
10 mL/100 mg ester). After 12 h, the reaction mixture was
acidified to pH 4 using 1 M aq oxalic acid solution, extracted
thrice with EtOAc, and the combined organic extracts were
evaporated in vacuo. Chromatographic purification of the
residue on SiO2 gave the corresponding carboxylic acid in 90–
98% yield.
9. Ludwig, A.; Saretzki, G.; Holm, P. S.; Tiemann, F.; Lor-
enz, M.; Emrich, T.; Harley, C. B.; von Zglinicki, T. Cancer
Res. 2001, 61, 3053.
10. Hahn, W. C.; Counter, C. M.; Lundberg, A. S.; Bei-
jersbergen, R. L.; Brooks, M. W.; Weinberg, R. A. Nature
1999, 400, 464.
11. Zhang, X.; Mar, V.; Zhou, W.; Harrington, L.; Robinson,
M. O. Genes Dev. 1999, 13, 2388.
12. Herbert, B.-S.; Pongracz, K.; Shay, J. W.; Gryaznov, S. M.
Oncogene 2002, 21, 638.
13. Elayadi, A. N.; Demieville, A.; Wancewicz, E. V.; Monia,
B. P.; Corey, D. R. Nucl. Acids. Res. 2001, 29, 1683.
14. Herbert, B.-S.; Pitts, A. E.; Baker, S. I.; Hamilton, S. E.;
Wright, W. E.; Shay, J. W.; Corey, D. R. Proc. Natl. Acad.
Sci. U.S.A. 1999, 96, 14726.
15. Braasch, D. A.; Corey, D. R. Biochemistry 2002, 41, 4503.
16. Read, M.; Harrison, R. J.; Romagnoli, B.; Tanious, F. A.;
Gowan, S. H.; Reszka, A. P.; Wilson, W. D.; Kelland, L. R.;
Neidle, S. Proc. Natl. Acad. Sci. U.S.A. 2001, 98, 4844.
17. Riou, J. F.; Guitat, L.; Mailliet, P.; Laoui, A.; Renou, E.;
Petitegenet, O.; Megnin-Chanet, F.; Helene, C.; Mergny, J. L.
Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 2672.
General procedure: amidation
A solution of carboxylic acid (1 equiv) in SOCl2 (5 mL/100 mg
acid) containing 1–2 drops (catalytic) of DMF was heated
under reflux for 2 h. After cooling, all volatiles were removed
under reduce pressure and the crude acid chloride was dis-
solved in ether (5 mL/100 mg acid) under an argon atmos-
phere. To this was added methyl anthranilate (1.1 equiv)
followed by pyridine (1.3 equiv). After stirring at room tem-
perature for 5 h, the reaction mixture was poured into 1 N HCl
(5 mL/100 mg acid), extracted thrice with Et2O, and the com-
bined ethereal extracts were evaporated in vacuo. Chromato-
graphic purification of the residue on SiO2 furnished the
corresponding methyl anthrailamide in 91–95% yield.
Methyl (E)- and (Z)-3-(naphthalen-2-yl)-but-2-enoates. Methyl
2,2-dichloroacetate and 20-acetonaphthone were condensed in
accordance with the general procedure to give methyl
3-(naphthalen-2-yl)-but-2-enoate as
a chromatographically
separable (SiO2: 15% EtOAc/hexanes) trans/cis-mixture
(70:30) whose spectral data were identical with the literature
values.25
3-(Naphthalen-2-yl)-but-2(E)-enoic acid. All the spectral data
were consistent with the literature values.26
N-(2-Carbomethoxyphenyl)-3-(naphthalen-2-yl)-but-2(E)-enam-
18. Parkinson, G. N.; Lee, M. P. H.; Neidle, S. Nature 2002,
417, 876.
1
ide. H NMR (CDCl3, 300 MHz) d 2.76 (d, 3H, J=1.2 Hz),

BMCL 6516 Disk used
No. pages 4, DTD=4.3.1
Version 7.51e
ARTICLE IN PRESS
D. K. Barma et al. / Bioorg. Med. Chem. Lett. & (&&&&) &–&
4
3.93 (s, 3H), 6.39 (d, 1H, J=1.5 Hz), 7.04–7.12 (m, 1H), 7.45–
7.66 (m, 4H), 7.80–7.89 (m, 3H), 7.97 (d, 1H, J=1.81 Hz),
8.04 (dd, 1H, J=1.5, 8.1 Hz), 8.88 (dd, 1H, J=0.9, 8.4 Hz);
13C NMR (CDCl3, 75 MHz) d 18.12, 52.53, 114.94, 120.50,
121.35, 122.52, 124.28, 125.99, 126.65, 126.65, 126.76, 127.78,
128.32, 128.67, 131.08, 133.35, 133.59, 134.86, 139.92, 142,22,
153.43, 165.62, 169.06. MS: m/z 345 (M+).
N-(2-Carboxyphenyl)-3-(naphthalen-2-yl)-but-2(E)-enamide
(BIBR 1532). 1H NMR (CDCl3, 300 MHz) d 2.75 (d, 3H,
J=1.2 Hz), 6.43 (s, 1H), 7.17 (t, 1H, J=8.4 Hz), 7.40–7.80 (m,
4H), 7.81–7.84 (m, 3H), 8.15–8.20 (m, 2H), 8.88 (dd, 1H,
J=0.90, 8.40 Hz); 13C NMR (CDCl3, 75 MHz): d 19.16,
109.68, 120.97, 123.68, 127.13, 127.20, 127.78, 127.89, 128.89,
129.07, 129.73, 133.16, 134.38, 135.30, 137.99, 140.99, 151.89,
162.22, 165.25. MS: m/z 331 (M+).
20.54, 39.84, 52.63, 116.13, 120.72, 123.37, 125.28, 126.95,
127.27, 128.88, 131.12, 134.68, 140.86, 143.23, 143.32, 163.63,
168.47. MS: m/z 343 (M+), 345 (M++2).
N-(2-Carboxyphenyl)-2-chloro-4-(phenyl)-pent-2(Z)-enamide
(224-33). 1H NMR (CDCl3, 300MHz) d 2.70 (d, 3H, J=1.2 Hz),
4.00–4.20 (m, 1H), 7.10–7.36 (m, 6H), 7.40 (d, 1H, J=8.7 Hz),
7.47–7.60 (m, 1H), 8.02 (dd, 1H, J=1.5, 7.8 Hz), 8.76 (dd, 1H,
J=0.9, 8.4 Hz); 13C NMR (CDCl3, 75 MHz) d 20.63, 40.01,
115.23, 120.92, 123.72, 125.11, 127.05, 127.29, 128.95, 132.19,
135.87, 141.37, 143.16, 143.91, 160.85, 173.09. MS: m/z 329 (M+).
N-(2-Carboxyphenyl)-3-(naphthalen-2-yl)-butenamide (257-30).
N-(2-Carboxyphenyl)-2-chloro-3-(naphthalen-2-yl)-but-2(Z)-
enamide was stirred with 10% Pd/C in MeOH under a
hydrogen atmosphere (1 atm) for 3 h. The reaction mixture
was filtered and all volatiles remove in vacuo to give the title
1
N-(2-Carbomethoxyphenyl)-3-(naphthalen-2-yl)-but-2(Z)-enam-
1
compound in 98% yield. H NMR (CDCl3, 300 MHz) d 1.45
ide. H NMR (CDCl3, 300 MHz) d 2.76 (d, 3H, J=0.9 Hz),
(d, 3H, J=6.9 Hz), 2.72 (dd, 1H, J=7.8, 14.4 Hz), 2.85 (dd,
2H, J=6.9, 14.4 Hz), 3.54–3.70 (m, 1H), 7.04 (t, 1H, J=7.2
Hz), 7.30–7.42 (m, 3H), 7.45–7.81 (m, 1H), 7.62–7.80 (m, 4H),
8.05 (d, 1H, J=8.10 Hz), 8.75 (d, 1H, J=8.2 Hz), 11.04 (s,
1H); 13C NMR (CDCl3, 75 MHz) d 21.78, 37.30, 47.61, 114.68,
120.88, 123.13, 125.16, 125.57, 125.61, 126.14, 127.71, 127.81,
128.44, 131.88, 132.50, 133.73, 135.57, 141.69, 143.07, 171.76,
172.27. MS: m/z 333 (M+).
Methyl 2-chloro-3-(3-methoxy-4-benzyloxyphenyl)-prop-2(Z)-
enoate. Methyl 2,2,2-trichloroacetate and 3-methoxy-4-benzy-
loxybenzaldehyde were condensed in accordance with the
general procedure. 1H NMR (CDCl3, 400 MHz) d 3.89 (s,
3H,–CO2CH3), 3.93 (s, 3H, –OCH3), 5.21 (s, 2H), 6.91 (d, 1H,
J=8.4 Hz), 7.28–7.40 (m, 4H), 7.43 (d, 2H, J=7.2 Hz), 7.57
(s, 1H), 7.84(s, 1H); 13C NMR (CDCl3, 75 MHz) d 53.46,
56.19, 70.92, 113.16, 113.73, 119.47, 125.42, 126.23, 127.37,
128.23, 128.84, 136.64, 137.15, 149.33, 150.23, 164.35. MS: m/z
332 (M+), 334 (M++2).
3.93 (s, 3H), 6.39 (d, 1H, J=1.2 Hz), 7.09 (t, 1H, J=8.1 Hz),
7.40–7.68 (m, 4H), 7.80–8.05 (m, 5H), 8.70 (d, 1H, J=8.40
Hz), 11.26 (s, 1H). MS: m/z 345 (M+).
N-(2-Carboxyphenyl)-3-(naphthalen-2-yl)-but-2(E)-enamide (221-
1
32). H NMR (CDCl3, 300 MHz) d 2.70 (d, 3H, J=1.2 Hz),
6.44 (d, 1H, J=1.50 Hz), 7.08–7.15 (m, 1H), 7.40–7.61 (m,
3H), 7.72 (dd, 1H, J=1.8, 8.7 Hz), 7.82–8.00 (m, 3H), 8.10–
8.17 (m, 2H), 8.85 (dd, 1H, J=0.9, 8.1 Hz), 11.45 (s, 1H). MS:
m/z 331 (M+).
Methyl 2-chloro-3-(naphthalen-2-yl)-but-2(Z)-enoate. Methyl
2,2,2-trichloroacetate and 20-acetonaphthone were condensed
1
in accordance with the general procedure. H NMR (CDCl3,
300 MHz) d 2.37 (s, 3H,–CH3), 3.46 (s, 3H, –CO2Me), 7.25–
7.30 (m, 1H), 7.42–7.52 (m, 2H), 7.62 (s, 1H), 7.76–7.84 (m,
3H). MS: m/z 260 (M+), 262 (M++2).
N-(2-Carbomethoxyphenyl)-2-chloro-3-(naphthalen-2-yl)-but-2
1
(Z)-enamide. H NMR (CDCl3, 300 MHz) d 2.43 (s, 3H), 3.65
(s, 3H), 6.94–7.02 (m, 1H), 7.20–7.45 (m, 4H), 7.67–7.85 (m,
5H), 8.54 (d, 1H, J=8.4 Hz), 11.27 (s, 1H); 13C NMR (CDCl3,
75 MHz) d 23.69, 52.27, 115.56, 120.67, 123.12, 124.23, 125.69,
126.41, 126.45, 126.62, 127.80, 128.06, 128.32, 130.81, 132.94,
133.29, 134.55, 137.80, 140.71, 142.46, 162.82, 168.07. MS: m/z
379 (M+), 381 (M++2).
N - (2 - Carbomethoxyphenyl) - 2 - chloro - 3 - (3 - methoxy - 4-
benzyloxyphenyl)-prop-2(Z)-enamide (245-32). 1H NMR
(CDCl3, 300 MHz) d 3.93 (s, 3H), 3.97 (s, 3H), 5.22 (s, 2H), 6.92
(d, 1H, J=8.4 Hz), 7.09–7.20 (m, 1H), 7.30–7.50 (m, 6H), 7.52–
7.64 (m, 2H), 8.03 (s, 1H), 8.08 (dd, 1H, J=1.5, 7.8 Hz), 8.83 (d,
1H, J=8.4 Hz). 13C NMR (CDCl3, 75 MHz) d 52.73, 56.19,
70.97, 113.28, 113.69, 116.26, 120.85, 121.83, 123.41, 125.12,
126.64, 127.40, 128.23, 128.26, 131.23, 134.75, 134.79, 136.78,
141.13, 149.33, 149.91, 161.73. MS: m/z 451 (M+), 453 (M++2).
N-(2-Carboxyphenyl)-2-chloro-3-(3-methoxy-4-benzyloxyphenyl)-
prop-2(Z)-enamide (258-30). 1H NMR (CDCl3, 300 MHz) d
3.84 (s, 3H), 5.18 (s, 2H) 7.05–7.72 (m, 10H), 8.00–8.10 (m, 2H),
8.71 (d, 1H, J=8.7 Hz). MS: m/z 437 (M+).
N-(2-Carboxyphenyl)-3-(3-methoxy-4-hydroxyphenyl)-propana-
mide. N-(2-Carboxyphenyl)-2-chloro-3-(3-methoxy-4-benzy-
loxyphenyl)-prop-2(Z)-enamide was stirred with 10% Pd/C in
MeOH under a hydrogen atmosphere (1 atm) for 3 h. The
reaction mixture was filtered and all volatiles remove in vacuo
to give the title compound in 98% yield. 1H NMR (CDCl3,
300 MHz) d 2.68 (t, 2H, J=8.1 Hz), 2.93 (t, 2H, J=7.5 Hz),
3.78 (s, 3H), 6.71 (d, 2H, J=1.2 Hz), 6.90 (s, 1H), 7.09 (t, 1H,
J=8.1 Hz), 7.53 (t, 1H, J=8.1 Hz), 8.10 (dd, 1H, J=1.5, 7.8
Hz), 8.73 (dd, 1H, J=1.5, 7.8 Hz), 11.60 (s, 1H). MS: m/z 315
(M+).
N-(2-Carboxyphenyl)-2-chloro-3-(naphthalen-2-yl)-but-2(Z)-
1
enamide (225-32). H NMR (CDCl3, 300 MHz) d 2.45 (s, 3H),
7.09 (t, 1H, J=6.9 Hz), 7.32–7.45 (m, 3H), 7.52 (t, 1H, J=9.0
Hz), 7.70–7.80 (m, 4H), 8.01 (dd, 1H, J=1.2, 7.80 Hz), 8.60
(d, 1H, J=8.7 Hz), 11.05 (s, 1H). MS: m/z 365 (M+).
Methyl 2-chloro-4-phenyl-pent-2(Z)-enoate. Methyl 2,2,2-tri-
chloroacetate and 2-phenylpropionaldehyde were condensed
1
in accordance with the general procedure. H NMR (CDCl3,
300 MHz) d 1.44 (d, 3H, J=6.6 Hz, CH3), 3.81 (s, 3H,
CO2CH3), 4.35–4.15 (m, 1H), 7.60 (d, 1H, J=9.6 Hz), 7.20–
7.36 (m, 5H); 13C NMR (CDCl3, 75 MHz) d 20.10, 39.75,
53.29, 123.24, 127.13, 127.26, 128.98, 142.92, 146.15, 163.28.
MS: m/z 224 (M+), 226 (M++2).
N-(2-Carbomethoxyphenyl)-2-chloro-4-(phenyl)-pent-2(Z)-
1
enamide. H NMR (CDCl3, 300 MHz) d 1.47 (d, 3H, J=7.2
Hz), 3.93 (s, 3H), 4.05–4.17 (m, 1H), 7.06–7.14 (m, 1H), 7.20–
7.40 (m, 6H), 7.51–7.60 (m, 1H), 8.03 (dd, 1H, J=1.5, 7.8 Hz),
8.75 (dd, 1H, J=0.9, 8.4 Hz); 13C NMR (CDCl3, 75 MHz) d