J . M e d . Chem. 1986,29,2231-2235
223 1
Synthesis and Antitumor Activity of Certain 3-~-~-Ribofuranosyl-1,2,4-triazolo[ 3,4-f]-1,2,4-triazines Related to Formycin Prepared via Ring Closure of a 1,2,4-Triazine Precursor Kandasamy Ramasamy, Bheemarao G. Ugarkar,? Patricia A. McKernan, Roland K. Robins, and Ganapathi R. Revankar* Cancer Research Center, Department of Chemistry, Brigham Young University, Provo, U t a h 84602, and Nucleic Acid Research I n s t i t u t e , Costa Mesa, California 92626. Received J a n u a r y 3, 1986
Several 3-P-~-ribofuranosyl-l,2,4-triazolo[3,4-fl-1,2,4-triazines related to formycin were prepared and tested for their antitumor activity in cell culture. Dehydrative coupling of 3-amino-6-hydrazino-1,2,4-triazin-5(4ff)-one ( 5 ) with 3,4,6-tri-O-benzoyl-2,5-anhydro-~-allonic acid (6a)and further ring closure of the reaction product (7)provided 6-amino-3-(2,3,5-tri-O-benzoyl-~-~-r~bofuranosyl)-1,2,4-triazolo[3,4-~-1,2,4-triazin-8(7ff)-one (8). Condensation of 5 with 3,4,6-tri-O-benzoyl-2,5-anhydro-~-allonic acid chloride (6b),followed by ring annulation, also gave 8 in good yield. Debenzoylation of 8 furnished the guanosine analogue 6-am~no-3-~-~-r~bofuranosy~-1,2,4-tr~azo~o[3,4-~1,2,4-triazin-8(7H)-one (4b). Thiation of 8 with P&, followed by debenzoylation of the thiated product (lla),afforded 6-amino-3-~-~-ribofuranosyl-1,2,4-tr~azolo[3,4-~-1,2,4-tr~azin-8(7H)-thione (1 lb). Methylation of the soldium salt of 1 la gave the 8-methylthio derivative (lo),which on ammonolysis furnished 6,8-diamino-3-fl-~-ribofuranosyl1,2,4-triazolo[3,4-f)l,2,4-triazine(9). Diazotization of 10 with tert-butyl nitrite (TBN) and SbCl, in 1,2-dichloroethane gave the corresponding 6-chloro derivative (12a). Reaction of 10 with TBN in T H F in the absence of a halogen (12b). Amsource gave 8-(methylthio)-3-(2,3,5-tri-O-benzoyl-fl-~-ribofuranosyl)-l,2,4-triazolo[3,4-fl-l,2,4-triazine monolysis of 12b gave the azaformycin A analogue 8-amino-3-~-~-ribofuranosyl-1,2,4-triazolo[3,4-~-1,2,4-tr~az~ne (3), which on deamination afforded 3-~-D-ribofuranosyl-1,2,4-triazolo[3,4-fl-1,2,4-triazin-8(7~-one (4a). The azaformycin A analogue (3) showed pronounced inhibitory effects against L1210, WIL2, and CCRF-CEM cell lines with ID,, values ranging from 5.0 to 7.3 wM.
gH
Since the isolation1v2and structural elucidation3s4of the naturally occurring C-nucleoside antibiotics formycin A (7-amino-3-~-~-ribofuranosyl-l~-pyrazolo[4,3-d]pyrimidine (1)) and formycin B (3-/3-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(1H,6H)-one (2a))from Nocardia interforma, HO HO a number of reports have appeared in the literature describing their biological and physicochemical properties."21 HO OH HO OH Formycin A, a cytotoxic analogue of adenosine, is readily Formycin A 2a, R = H deaminated by the catabolic enzyme adenosine deaminase 1 h, R = NHz (ADA) to the less active inosine analogue formycin B (2ahn However, interest in the potential of formycin A as an antitumor agent has been rekindled by the observation that, in combination with an ADA inhibitor, compound 1 is superior to 9-p-D-arabinofuranosyladenine (am-A) in prolonging the life of mice infected with L1210 leukemia.23 Moderate antiviral activity with 1 has also been observed in cell c u l t ~ r e . ~Recently, ~ - ~ ~ it has been demonstrated in mammalian ~ e l l s and ~ ~ in s ~L ~e i s h m a n i ~that ~ ~ the ~~~ adenylosuccinate synthetase/lyase system provides a +a_, R = H pathway for the metabolic regeneration of formycin A from Q, R = NH, formycin B. synthesis and in vitro antitumor activity of 3,4a, and 4b. Important biological activity of aza/deaza analogues of It is of particular interest that unlike the natural N-nuguanine and its metabolites is anticipated31 from ever increasing knowledge of guanine nucleotide metabolism in microbial and mammalian system^.^^,^^ The guanosine (1) Hori, M.; Ito, E.; Takita, T.; Umezawa, H. J . Antibiot.,Ser. A analogue related to formycin B, 5-amino-3-P-~-ribo1964,17,96. furanosylpyrazolo[4,3-d]pyrimidin-7(1H, 6H)-one (2b),has (2) Koyama, G.; Umezawa, H. J. Antibiot., Ser. A 1965,18, 175. (3) Robins, R. K.; Townsend, L. B.; Cassidy, F. C.; Gerster, J. F.; recently been prepared.I7 In an effort to obtain metaLewis, A. F.; Miller, R. L. J. Heterocycl. Chem. 1966,3,110. bolically more stable C-nucleoside analogues, it was plan(4) Koyama, G.; Maeda, K.; Umezawa, H.; Iitake, Y. Tetrahedron ned to synthesize the aza congeners of formycin A, forLett. 1966,597. mycin B, and 2b (3, 4a, and 4b, respectively). Although (5) Suhadolnik, R. J. Nucleosides as Biological Probes; Wiley-Inthe synthesis of a carbon-linked acyclovir analogue, 6terscience: New York, 1979; pp 169-183. amino-3- [ (2-hydroxyethoxy)methyl]- 1,2,4-triazolo[3,4-fl(6) Long, R. A.; Lewis, A. F.; Robins, R. K.; Townsend, L. B. J . Chem. Soc. C 1971,2443. 1,2,4-triazin-8(7H)-one, has recently been described,34the (7) Robins, M. J.; McCarthy, 3. R., Jr.; Jones, R. A.; Mengel, R. total synthesis of ribonucleosides of the 1,2,4-triazoloCan. J. Chem. 1973,51,1313. [3,4-fl-1,2,4-triazinering system has not been realized. As ( 8 ) Jain, T. C.; Russell, A. F.; Moffatt, J. G. J . Org. Chem. 1973, part of an ongoing synthetic program directed toward the 38,3179. preparation of C - n u c l e o ~ i d e swe , ~ now ~ ~ ~report ~ ~ ~ ~the (9) Townsend, L. B.; Long, R. A,; McGraw, J. P.; Miles, D. W.; Robins, R. K.; Eyring, H. J. Org. Chem. 1974,39, 2023. Brigham Young University. *To whom correspondence should be addressed at the Nucleic Acid Research Institute.
(10) Robins, M. J.; Naik, S. R.; Lee, A. S. K. J. Org. Chem. 1974,
39, 1891. (11) Acton, E. M.; Fujiwara, A. N.; Goodman, L.; Henry, D. W.
Carbohydr. Res. 1974,33, 135.
0022-262318611829-2231$01.50/0 0 1986 American Chemical Society
2232 Journal of Medicinal Chemistry, 1986, Vol. 29, No. 11
cleosides of the heterocyclic analogues of purines containing a bridgehead nitrogen atom,36the azaformycin B analogues (4a and 4b) retain the Watson-Crick type hydrogen-bonding sites (N,H) of the aglycon moiety. Chemistry. The synthesis of the guanosine analogue 6-amino-3-~-~-ribofuranosyl-l,2,4-triazo~o[ 3,4-f]-1,2,4triazin-8(7H)-one (4b) was first approached by the ring annulation of the glycosyl derivative of an appropriately functionalized 172,4-triazine. We envisaged this approach as the straightforward and well-suited route to 4b. The synthesis of such a substituted 172,4-triazine,3-amino-6hydrazino-1,2,4-triazin-5(4H).one(51, was accomplished as r e p ~ r t e d . ~ ,Dehydrative coupling of 5 with 3,4,6-tri~-benzoyl-2,5-anhydro-~-allonic acid (6a)%in the presence
Ramasamy et al. Scheme I
(12) Zemlicka, J. J . Am. Chem. Sac. 1975, 97, 5896. (13) Huynh-Dinh, T.; Kolb, A.; Gouyette, C.; Igolen, J.; Tran-Dinh, S . J . Org. Chem. 1975, 40, 2825. (14) Chung, H. L.; Zemlicka, J. J. Heterocycl. Chem. 1977, 14, 135. (15) Makabe, 0.;Miyadera, A,; Kinoshita, M.; Umezawa, H.; Takeuchi, T. J . Antibiot. 1978, 31, 456. (16) Lewis, A. F.; Townsend, I,. B. J . Am. Chem. Soc. 1980. 202, 2817.
(17) Lewis, A. F.;Townsend, L. B. J . Am. Chem. Soc. 1982, 104, 10'73. (18) Acton, E. M.; Ryan, K. J. Nucleic Acids Res. Symp. Ser. 1981?
9, 243. (19) Acton, E. M.; Ryan, K. J. J . Org. Chem. 1984, 49, 528. (20) Ugarkar, B. G.; Robins, R. K.; Revankar, S . R. Nucleosides ,Vucleotides 1984, 3, 233. (21) Ugarkar, B. G.; Revankar, G. R.; Robins, R. K. J . Heterocycl. Chem. 1984, 21, 1865.
(22) Ishizuka, M.; Sawa, T.; Koyama, G.: Takeuchi. T.; Umezawa. H. J . Antibiot. 1968, 21, 1. (23) Hidaka, T.; Katayama, K.; Yamashita, K.; Yamashita, T.; Watanabe, K.; Shimasaki, M.; Ohno, M.; Takeuchi, T.; Umezawa, H. J . Antibiot. 1980, 33, 303. (24) Schneller, S. W.; Thompson, R. D.; Cory, J. G.; Olsson, R. A,; De Clercq. E.; Kim, I-K.; Chiang. P. K. J. Med. Chem. 1984, 27, 924. (25) Ishida, N.; Homma, M.; Kumagai, Y.; Schimizu, Y.; Matsumoto, S.; Isawa, A. J . Antibiot. 1967, 20A, 49. (26) Giziewicz, J.; De Clercq, E.; Luczak, M.; Shugar, D. Biochem. Pharmacol. 1975, 24, 1813. (27) Nelson, D. J.; La Fon, S. W.; Jones, T. E.; Spector, T.; Berens, R. I,.; Marr,
