T. Kan et al. / Bioorg. Med. Chem. Lett. 14 (2004) 1983–1985
1985
The results of the inhibitory activity of 6a–o are also
given in Table 1. As expected, the benzyl 6a and the
benzhydryl amide 6c possessed similar activity to
the original DAPT (1). Among the derivatives 6a–o, the
benzophenonemethyl (p-benzoylbenzyl) amide deriva-
tive 6o10 showed the highest activity (30 times more
potent than 1). This result suggested that the C-terminal
benzophenone group would play a key role in the
activity. Furthermore, 6o could be used as a probe for
elucidation of g-secretase, since benzophenones have
been used extensively as photocross-linking agents.11
Recently, photoaffinity labeling has become a powerful
tool for identification of substrate binding sites of
membrane proteins. Utilizing the probe 6o to collect
detailed structure information for the g-secretase ulti-
mately would allow the discovery of novel drugs.
tase inhibition activity will be reported elsewhere. For the
detailed assay procedures, see: J. Biol. Chem. 2003, 278,
18664.
5. Methyl ester derivatives of 1 were prepared in a similar
manner with those described in Scheme 1. The benzyl
ester was synthesized by transesterification (Ti(O-i-Pr)4,
BnOH) of the methyl ester. These analogues were shown
to be less active than 1.
6. Spectroscopic data for 6a: white solid; [a]2D4 +75.6ꢀ
(c=0.03, CH3OH); IR (film) 3282, 1633, 1596, 1539, 1497,
1456, 1387, 1357, 1230, 1118, 996, 855, 728, 697, 728
cmÀ1 1H NMR (DMSO-d6, 400 MHz) d 8.75 (t, 1H,
;
J=5.9 Hz), 8.48 (d, 1H, J=7.8 Hz), 8.39 (d, 1H, J=7.6
Hz), 7.39 (d, 2H, J=6.6 Hz), 7.35–7.19 (m, 6H), 7.12 (d,
2H, J=7.1 Hz), 7.11–7.05 (m, 1H), 6.97 (d, 2H, J=6.6
Hz), 5.44 (d, 1H, J=7.8 Hz), 4.44–4.40 (m, 1H), 4.26 (d,
2H, J=5.9 Hz), 3.50 (s, 2H), 1.21 (d, 3H, J=10.0 Hz);
13C NMR (DMSO-d6, 100 MHz) d 171.8, 169.7, 168.9,
162.1 (dd, J=244.4, 13.2 Hz), 140.7 (t, J=10.3 Hz),
139.0, 138.5, 128.2, 128.2, 127.6, 127.4, 127.1, 18.5, 112.2
(dd, J=6.1 Hz), 101.9 (t, J=25.3), 56.3, 48.1, 42.0, 41.3,
18.0; HRMS (FAB) calcd for C26H25F2N3O3 (M+H)+
466.1942, found 466.1959.
Further application of this protocol for the synthesis of
various DAPT (1) derivatives and the photoaffinity
labeling experiment with derivatives of 6o are currently
under investigation in our laboratories.12
7. (a) Hidai, Y.; Kan, T.; Fukuyama, T. Tetrahedron Lett.
1999, 41, 4711. (b) Hidai, Y.; Kan, T.; Fukuyama, T.
Chem. Pharm. Bull. 2000, 48, 1570. (c) Kan, T.; Kobayashi,
H.; Fukuyama, T. Synlett 2002, 1338.
Acknowledgements
8. Since the diastereomers in the amide derivatives 6a–o was
1
This work was partially supported by the 21st Century
COE Program.
not observed in the H NMR spectra, the epimerization
did not occur during the condensation.
9. Since the benzophenonemethyl (p-benzoylbenzyl) amine
was not commercially available, it was prepared from
benzoyl chloride in the following three-step sequence:
(a) AlCl3, toluene; (b) NBS, (PhCO2)2, CCl4, 60 ꢀC, 53%
(2 steps); (c) liq. NH3, THF–MeOH, À33 ꢀC, 83%.
References and notes
1. For a recent review on b-amyloid in Alzheimer’s disease,
see; Birmingham, K.; Frantz, S. Nature Med. 2002, 8, 199.
2. For a recent review on secretases, see: Wolfe, M. S.
Nature. Rev. Drug. Discov. 2002, 1, 859 and references
therein.
3. Dovey, H. F.; John, V.; Anderson, J. P.; Chen, L. Z.;
deSaintAndrieu, P.; Fang, L. Y.; Freedman, S. B.; Fol-
mer, B.; Goldbach, E.; Holsztynska, E. J.; Hu, K. L.;
Johnson-Wood, K. L.; Kennedy, S. L.; Kholodenko, D.;
Knops, J. E.; Latimer, L. H.; Lee, M.; Liao, Z.; Lieber-
burg, I. M.; Motter, R. N.; Mutter, L. C.; Nietz, J.;
Quinn, K. P.; Sacchi, K. L.; Seubert, P. A.; Shopp, G. M.;
Thorsett, E. D.; Tung, J. S.; Wu, J.; Yang, S.; Yin, C. T.;
Schenk, D. B.; May, P. C.; Altstiel, L. D.; Bender, M. H.;
Boggs, L. N.; Britton, T. C.; Clemens, J. S.; Czilli, D. L.;
Dieckman-MacGinty, D. K.; Droste, J. J.; Fuson, K. S.;
Gitter, B. D.; Hyslop, P. A.; Johnstone, E. M.; Li, W. Y.;
Little, S. P.; Mabry, T. E.; Miller, F. D.; Audia, J. E. J.
Neurochem. 2001, 76, 173.
4. Takahashi, Y.; Hayashi, I.; Tominari, Y.; Rikimaru, K.;
Morohashi, Y.; Kan, T.; Natsugari, H.; Fukuyama, T.;
Tomita, T.; Iwatsubo, T. Inhibitory potencies of DAPT
derivatives on g-secretase activity were analyzed by cell-
based assays. Cultured cells overexpressing b-APP were
cultured at confluency in DMEM containing 10 mM
butyric acid to drive protein expression in the presence of
various concentrations of compounds for 16–18 h. Cul-
tured media were collected and subjected to BNT77/BA27
or BNT77/BC05 ELISAs. The detailed data for g-secre-
10. Spectroscopic data for 6o: white crystalline (mp=191 ꢀC),
[a]2D1 +25.5ꢀ (c=0.32, CH3OH), IR (film) 3285, 3068,
1647, 1597, 1499, 1469, 1318, 1280, 1243, 1116, 1007, 983,
1
939, 836, 701; H NMR (DMSO-d6, 400 MHz) d 8.87 (t,
1H, J=5.8 Hz), 8.51 (d, 1H, J=7.6 Hz), 8.39 (d, 1H,
J=7.3 Hz), 7.68 (d, 2H, J=7.1 Hz), 7.67–7.49 (m, 1H),
7.66 (d, 2H, J=7.6 Hz), 7.62 (d, 2H, J=8.0 Hz), 7.40 (d,
2H, J=7.1 Hz), 7.34–7.28 (m, 5H), 7.06 (t, 1H, J=9.3
Hz), 6.97 (d, 2H, J=6.6 Hz), 5.46 (d, 1H, J=7.6 Hz),
4.46–4.41 (m, 1H), 4.37 (d, 2H, J=5.8 Hz), 3.50 (s, 2H),
1.23 (d, 3H, J=7.1 Hz); 13C NMR (DMSO-d6, 100 MHz)
d 195.4, 171.9, 169.9, 168.9, 162.1 (dd, J=243.9, 14.4 Hz),
144.2, 140.6 (t, J=9.9 Hz), 138.3, 137.1, 135.5, 132.6,
129.7, 129.5, 128.6, 128.3, 127.7, 127.1, 126.9, 112.2 (dd,
J=17.7, 6.6 Hz), 101.8 (t, J=25.7 Hz), 56.4, 48.1, 41.8,
41.3, 18.0; HRMS (FAB) calcd for C33H29F2N3O4
569.2126, found 569.2109.
11. Dorman, G.; Prestwich, G. D. Biochemistry 1994, 33,
5661.
12. Kan, T.; Tominari, Y.; Morohashi, Y.; Natsugari, H.;
Tomita, T.; Iwatsubo, T.; Fukuyama, T. Chem. Commun.
2003, 2244.