5462 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 17
Brief Articles
otide inhibits osteoclastic bone resorption. J. Biol. Chem. 1997, 272,
8109–8112.
(5) Garnero, P.; Borel, O.; Byrjalsen, I.; Ferreras, M.; Drake, F. H.;
McQueney, M. S.; Foged, N. T.; Delmas, P. D.; Delaisse´, J-M. The
collagenolytic activity of cathepsin K is unique among mammalian
proteinases. J. Biol. Chem. 1998, 273, 32347–32352.
(6) Grabowska, U. B.; Chambers, T. J.; Shiroo, M. Recent developments
in cathepsin K inhibitor design. Curr. Opin. Drug DiscoVery DeV.
2005, 8, 619–630.
(7) Altmann, E.; Cowan-Jacob, S. W.; Missbach, M. Novel purine nitrile
derived inhibitors of the cysteine protease cathepsin K. J. Med. Chem.
2004, 47, 5833–5836.
2-[2-Cyano-7-(2,2-dimethyl-propyl)-7H-pyrrolo[2,3-d]pyrimidin-
6-ylmethyl]-1,3-dioxo-2,8-diaza-spiro[4.5]decane-8-carboxylic acid
tert-butyl ester (7-c). 1 (1.0 g, 3.25 mmol) and 7-b (0.82 g, 3.42
mmol) were dissolved in DMF (15 mL), and potassium carbonate
(0.58 g, 4.23 mmol) was added to the solution. The reaction mixture
was stirred at room temperature for 15 h and quenched with
saturated ammonium chloride and extracted with ethyl acetate. The
combined extracts were washed with water and brine and dried
over magnesium sulfate. Chromatography on silica gel (eluent;
n-hexane:ethyl acetate ) 2:1) gave 1.56 g of desired 7-c in 97%
yield. Rf ) 0.30 (n-hexane:ethyl acetate ) 1:1). 1H NMR (400
MHz, CDCl3) δ 9.07 (s, 1H), 6.62 (s, 1H), 4.91 (s, 2H), 4.25 (s,
2H), 3.88-3.85 (m, 2H), 2.93-2.89 (m, 2H), 1.68-1.67 (m, 4H),
1.40 (s, 9H), 0.99 (s, 9H).
(8) Teno, N.; Irie, O.; Miyake, T.; Gohda, K.; Horiuchi, M.; Tada, S.;
Nonomura, K.; Kometani, M.; Iwasaki, G.; Betschart, C. New
chemotypes for cathepsin K inhibitors. Bioorg. Med. Chem. Lett. 2008,
18, 2599–2603.
7-(2,2-Dimethyl-propyl)-6-(1,3-dioxo-2,8-diaza-spiro[4.5]dec-2-
ylmethyl)-7H-pyrrolo[2,3-d] pyrimidine-2-carbonitrile (7). To a
solution of 7-c (1.5 g, 3.1 mmol) in CH2Cl2 (20 mL), TFA (5 mL)
was added at 0 °C. The reaction mixture was stirred at room
temperature for 2 h. After removal of the solvent, saturated sodium
bicarbonate was added to the residue and the mixture was extracted
with CH2Cl2. The combined extracts were washed with water and
brine and dried over magnesium sulfate and concentrated under
vacuum to give desired product 7. Yield: 91%; Rf ) 0.15 (CH2Cl2:
MeOH ) 10:1). 1H NMR (400 MHz, CDCl3) δ 8.90 (s, 1H), 6.59
(s, 1H), 4.91 (s, 2H), 4.34 (s, 2H), 3.16-3.13 (m, 2H), 2.72-2.69
(m, 2H), 2.66 (s, 2H), 2.02-1.95 (m, 2H), 1.69 (brs, 1H), 1.48-1.45
(m, 2H), 1.03 (s, 9H). HRMS: 395.2190 [M + H]+ (calcd
395.2195).
(9) Altmann, E.; Aichholz, R.; Betschart, C.; Buhl, T.; Green, J.; Irie, O.;
Teno, N.; Lattmann, R.; Tintelnot.Blomley, M.; Missbach, M. 2-Cy-
ano-pyrimidines: a new chemotype for inhibitors of the cysteine
protease cathepsin K. J. Med. Chem. 2007, 50, 591–594.
(10) Teno, N.; Miyake, T.; Ehara, T.; Irie, O.; Sakaki, J.; Ohmori, O.; Gunji,
H.; Matsuura, N.; Masuya, K.; Hitomi, Y.; Nonomura, K.; Horiuchi,
M.; Gohda, K.; Iwasaki, A.; Umemura, I.; Tada, S.; Kometani, M.;
Iwasaki, G.; Cowan-Jacob, S. W.; Missbach, M.; Lattmann, R.;
Betschart, C. Novel scaffold for cathepsin K inhibitors. Bioorg. Med.
Chem. Lett. 2007, 17, 6096–6100.
(11) Betschart, C.; Hayakawa, K.; Irie, O.; Sakaki, J.; Iwasaki, G.; Lattmann,
R.; Missbach, M.; Teno, N. Pyrroloptrimidines as agents for the cystein
proteases. World Patent WO2003020721, 2003.
(12) Bleicher, K. H.; Wu¨thrich, Y.; DeBoni, M.; Kolczewski, S.; Hoffmann,
T.; Sleight, A. J. Parallel solution- and solid-phase synthesis of
spirohydantoin derivatives as neurokinin-1 receptor ligands. Bioorg.
Med. Chem. Lett. 2002, 12, 2519–2522.
Acknowledgment. We thank Junichi Yamanaka, Yoshihiro
Funahashi, Nami Suzuki, and Tomoko Ohkubo for excellent
technical assistance. We are grateful to Dr. Robert Hof and Dr.
Muneto Mogi for helpful critical reading of the manuscript.
(13) Elliott, J. M.; Broughton, H.; Cascieri, M. A.; Chicchi, G.; Huscroft,
I. T.; Kurtz, M.; MacLeod, A. M.; Sadowski, S.; Stevenson, G. I.
Serine derived NK1 antagonists 2: a pharmacophore model for
arylsulfonamide binding. Bioorg. Med. Chem. Lett. 1998, 8, 1851–
1856.
(14) Irie, O.; Iwasaki, G.; Masuya, K.; Miyake, T.; Teno, N. Preparation
of spiro-substituted pyrrolopyrimidines as inhibitors of cathepsin S
and/or cathepsin K. World Patent WO 2004076455, 2004.
(15) Kumar, S.; Dare, L.; Vasko-Moser, J. A.; James, I. E.; Blake, S. M.;
Rickard, D. J.; Hwang, S.-M.; Tomaszek, T.; Yamashita, D. S.;
Marquis, R. W.; Oh, H.; Jeong, J. U.; Veber, D. F.; Gowen, M.; Lark,
M. W.; Stroup, G. A highly potent inhibitor of cathepsin K (relacatib)
reduces biomarkers of bone resorption both in vitro and in an acute
model of elevated bone turnover in vivo in monkeys. Bone 2007, 40,
122–131.
Supporting Information Available: Experimental procedures
for the synthesis of compounds 2 and 5 and characterization (1H
NMR and HRMS) of compounds 3, 4, 6, 8, and 9. Description of
pharmacokinetics analysis, urinary CTx assay in rats and monkeys.
This material is available free of charge via the Internet at http://
pubs.acs.org.
References
(16) Stoch, S. A.; Wagner, J. A. Cathepsin K Inhibitors: A novel target
for osteoporosis therapy. Clin. Pharmacol. Ther. 2008, 83, 172–176.
(17) The dealkylated derivative 4 was found as the metabolite in the BM
sample treated with 3.
(18) Mundy, G.; Garrett, R.; Harris, S.; Chan, J.; Chen, D.; Rossini, G.;
Boyce, B.; Zhao, M.; Gutierrez, M. Stimulation of bone formation in
vitro and in rodents by statins. Science 1999, 286, 1946–1949.
(19) Edwards, C. J.; Hart, D. J.; Spector, T. D. Oral statins and increased
bone-mineral density in postmenopausal women. Lancet 2000, 355,
2218–2219.
(1) Turk, V.; Turk, B.; Guncar, G.; Turk, D.; Kos, J. Lysosomal cathepsins:
structure, role in antigen processing and presentation, and cancer. AdV.
Enzyme Regul. 2002, 42, 285–303.
(2) Saftig, P.; Hunziker, E.; Wehmeyer, O.; Jones, S.; Boyde, A.;
Rommerskirch, W.; Moritz, J. D.; Schu, P.; von Figura, K. Impaired
osteoclastic bone resorption leads to osteopetrosis in cathepsin-K-
deficient mice. Proc. Natl. Acad. Sci. U.S.A. 1998, 95, 13453–13458.
(3) Gelb, B. D.; Shi, G.-P.; Chapman, H. A.; Desnick, R. J. Pycnodys-
ostosis, a Lysosomal Disease Caused by Cathepsin K Deficiency.
Science 1996, 273, 1236–1238.
(4) Inui, T.; Ishibashi, O.; Inaoka, T.; Origane, Y.; Kumegawa, M.;
Kokubo, T.; Yamamura, T. Cathepsin K antisense oligodeoxynucle-
JM800626A