D. G. Barrett et al. / Bioorg. Med. Chem. Lett. 15 (2005) 3039–3043
3043
6. Anonymous (2004). AAE-581, Pharmaprojects, Novem-
ber 12, 2004.
7. Anonymous (2004) 462795, Pharmaprojects, November 5,
2004.
8. Deaton, D. N.; Hassell, A. M.; McFadyen, R. B.; Miller,
A. B.; Miller, L. R.; Shewchuk, L. M.; Tavares, F. X.;
Willard, D. H., Jr.; Wright, L. L. Bioorg. Med. Chem.
Lett. 2005, 15, 1815.
on the carbonyl carbon electrophile; whereas the sp
hybridized cyanamide carbon accommodates less opti-
mal trajectories of assault. This azacyanamide contains
no P3 group, thus no interaction is realized with the S3
subsite. Additional binding energy is obviously obtained
via incorporation of a P3 substituent as in cyanamides
6a and r.
9. Falgueyret, J.-P.; Oballa, R. M.; Okamoto, O.; Wesolow-
ski, G.; Aubin, Y.; Rydzewski, R. M.; Prasit, P.;
Riendeau, D.; Rodan, S. B.; Percival, M. D. J. Med.
Chem. 2001, 44, 94.
10. Catalano, J. G.; Deaton, D. N.; Furfine, E. S.; Hassell, A.
M.; McFadyen, R. B.; Miller, A. B.; Miller, L. R.;
Shewchuk, L. M.; Willard, D. H., Jr.; Wright, L. L.
Bioorg. Med. Chem. Lett. 2004, 14, 275.
11. Boros, E. E.; Deaton, D. N.; Hassell, A. M.; McFadyen,
R. B.; Miller, A. B.; Miller, L. R.; Paulick, M. G.;
Shewchuk, L. M.; Thompson, J. B.; Willard, D. H., Jr.;
Wright, L. L. Bioorg. Med. Chem. Lett. 2004, 14,
3425.
In summary, very potent acyclic cyanamides such as 6a
were designed and synthesized, starting from the proline
derived cyanamide 3. Verifying the design hypothesis, an
X-ray crystal structure of a cathepsin K/azacyanamide
complex confirmed that these inhibitors form a key
hydrogen bond with 161Asn of the protein. Furthermore,
a representative cyanamide inhibitor 6r is capable of
attenuating bone resorption in a rat calvarial assay.
These promising results warrant additional efforts to im-
prove the metabolic stability and other drug properties
of these novel inhibitors.
12. Iwatsubo, T.; Hirota, N.; Ooie, T.; Suzuki, H.; Shimada,
N.; Chiba, K.; Ishizaki, T.; Green, C. E.; Tyson, C. A.;
Sugiyama, Y. Pharmacol. Ther. 1997, 73, 147.
13. Hahn, T. J.; Westbrook, S. L.; Halstead, L. R. Endocri-
nology 1984, 114, 1864.
Acknowledgments
The authors would like to thank James G. Conway for
statistical analyses.
14. Conaway, H. H.; Grigorie, D.; Lerner, U. H. J. Endocri-
nol. 1997, 155, 513.
15. (t-BuO(C@O))2NN(Me)CN was synthesized in a similar
manner to Scheme 1. Methyl hydrazine was treated with
cyanogen bromide and the resulting product was then
reacted with di-tert-butyl dicarbonate and triethylamine
to provide (t-BuO(C@O))2NN(Me)CN. Co-crystalliza-
tion of (t-BuO(C@O))2NN(Me)CN with cathepsin K at
acidic pH caused the loss of one tert-butyloxycarbonyl
References and notes
1. Einhorn, T. A. In Osteoporosis; Marcus, R., Feldman, D.,
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2. Rossouw, J. E.; Anderson, G. L.; Prentice, R. L.; LaCroix,
A. Z.; Kooperberg, C.; Stefanick, M. L.; Jackson, R. D.;
Beresford, S. A. A.; Howard, B. V.; Johnson, K. C.;
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3. Deaton, D. N.; Kumar, S. Prog. Med. Chem. 2004, 42, 245.
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5. Stroup, G. B.; Lark, M. W.; Veber, D. F.; Bhattacharyya,
A.; Blake, S.; Dare, L. C.; Erhard, K. F.; Hoffman, S. J.;
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protecting group, resulting in
a
inhibitor/enzyme
co-crystal containing t-BuO(C@O)NHN(Me)CN with
cathepsin K. The parent (t-BuO(C@O))2NN(Me)CN
inhibited cathepsin K with an Ki = 20 nM. In hindsight,
it is probably hydrolyzed under the acidic conditions of
the enzyme assay (pH = 5.5) to produce small quantities
of t-BuO(C@O)NHN(Me)CN. Therefore, the inhibitory
activity of t-BuO(C@O)NHN(Me)CN is likely below
20 nM. Since this X-ray crystal structure was solved
several months after resources were shifted to higher
priority targets, t-BuO(C@O)NHN(Me)CN was never
prepared and tested.