Synthesis of triazenopyrazole derivatives as potential inhibitors of HIV-1

Article abstract of DOI:10.1007/pl00010295

Ethoxymethylenemalononitrile and bis(methylthio)methylenemalononitrile were condensed with hydrazine hydrate to yield 5-aminopyrazole-4-carbonitrile (3a) and 5-amino-3-methylthiopyrazole-4-carbonitrile (3b), respectively. These compounds were treated with nitrous acid and coupled with different secondary amines to yield the triazenopyrazoles 4a-j. 5-(3,3-Diethyl-1-triazeno)pyrazole-4-carbonitrile (4c) was transferred into its two regioisomeric 2-deoxyribose nucleosides 5a,b which were subsequently hydrolyzed with H₂O₂/OH^- to give the corresponding carboxamides 6a,b. All synthesized compounds were tested for biological activity against HIV-1 and herpes simplex virus, but only 4c showed moderate activity against HIV-1 with ED₅₀ = 32μM.

Full text of DOI:10.1007/pl00010295

Monatshefte fuÈr Chemie 130, 1167±1173 (1999)
Synthesis of Triazenopyrazole Derivatives
as Potential Inhibitors of HIV-1
Janus S. Larsen1, Magdy A. Zahran1, Erik B. Pedersen1;Ã, and Claus Nielsen2
1
Department of Chemistry, Odense University, DK-5230 Odense M, Denmark
2
Retrovirus Laboratory, Department of Virology, Statens Seruminstitut, DK-2300 Copenhagen,
Denmark
Summary. Ethoxymethylenemalononitrile and bis(methylthio)methylenemalononitrile were con-
densed with hydrazine hydrate to yield 5-aminopyrazole-4-carbonitrile (3a) and 5-amino-3-
methylthiopyrazole-4-carbonitrile (3b), respectively. These compounds were treated with nitrous
acid and coupled with different secondary amines to yield the triazenopyrazoles 4a±j. 5-(3,3-
Diethyl-1-triazeno)pyrazole-4-carbonitrile (4c) was transferred into its two regioisomeric 2-
deoxyribose nucleosides 5a,b which were subsequently hydrolyzed with H2O2/OHꢀ to give the
corresponding carboxamides 6a,b. All synthesized compounds were tested for biological activity
against HIV-1 and herpes simplex virus, but only 4c showed moderate activity against HIV-1 with
ED50 ˆ 32mM.
Keywords. Triazenopyrazoles; Nucleosides, convergent synthesis of; Nucleosides, 1-(5-triazeno)-
pyrazole; Nucleosides, 2-(5-triazeno)pyrazole; Human immunode®ciency virus; Herpes simplex virus.
Synthese von Triazenopyrazolderivaten als potentielle Inhibitoren von HIV-1
Zusammenfassung. Ethoxymethylenmalonitril und Bis(methlthio)methylenmalonitril wurden mit
Hydrazinhydrat zu 5-Aminopyrazol-4-carbonitril (3a) und 5-Amino-3-methyltiopyrazol-4-carboni-
È
È
tril (3b) umgesetzt. Behandlung mit salpetriger Saure und Kupplung mit verschiedenen sekundaren
Aminen ergab die Triazenopyrazole 4a±j. 5-(3,3-Diethyl-1-triazeno)pyrazol-4-carbonitril (4c) wurde
in seine beiden regioisomeren 2-Deoxyribonucleoside 5a,b uÈbergefuÈhrt, welche anschlieûend mit
H2O2/OHꢀ zu den entsprechenden Carboxamiden 6a,b hydrolysiert wurden. Alle hergestellten
È
È
Verbindungen wurden auf ihre biologische Aktivitat gegenuber HIV-1 und Herpes simplex getestet.
È
Nur 4c zeigte geringfuÈgige Aktivitat gegenuber HIV-1 (ED50 ˆ 32mM).
È
Introduction
In recent years, the interest in ®nding anti-HIV drugs has been exploding, and the
®eld is still rapidly growing. Among the most active compounds today are the non-
nucleoside reverse transcriptase inhibitors NNRTIs, MKC-442 [1], and HEPT [2],
but the nucleoside analogues AZT [3], ddC [4], and ddI [5] are also very potent
inhibitors of HIV-1. Triazenopyrazoles are new in HIV research but have been
Ã
Corresponding author

1168
J. S. Larsen et al.
widely tested in the ®eld of cancer research where these compounds showed
activity against L1210 leukemia in mice with low cytotoxicity [6]. In this paper we
present the synthesis and biological activity of several triazenopyrazoles and some
nucleoside analogues thereof. The background for this work came from an obser-
vation during random screening that 5-(3,3-diethyl-1-triazeno)pyrazole-4-carboni-
trile showed a moderate effect on a HIV-1 infected cell strain. It was therefore decided
to synthesize analogues of this compound. Furthermore, 5-(3,3-diethyl-1-triazeno)-
pyrazole-4-carbonitrile was also chosen for testing of the corresponding nucleoside.
Results and Discussion
Ethoxymethylenemalononitrile (1) and hydrazinehydrate 85% were re¯uxed in
methanol to give 5-aminopyrazole-4-carbonitrile (3a) [7] in 26% yield after
recrystallization from water. Compound 3a was then treated with HCl and NaNO2
at 0ꢁC to give the corresponding diazonium ion. After subsequent addition of a
secondary amine dissolved in aqueous K2CO3, the products 4a±e were obtained in
23±46% yield after extraction with chloroform.
Bis(methylthio)methylenemalononitrile (2) and hydrazinehydrate 85% were
treated in the same manner to give 5-amino-3-methylthiopyrazole-4-carbonitrile
(3b) [8] in 73% yield after recrystallization from methanol. Compound 3b was then
reacted with HCl and NaNO2 at 0ꢁC to give the intermediate diazonium ion which
was not isolated but submitted directly to an excess of amine dissolved in aqueous
K2CO3 to give 4f±j in 42±70% yield. In the 13C NMR spectra of all pyrazoles and
triazenopyrazoles, a line broadening of C-3, C-4, and C-5 in the pyrazole ring is
observed, indicating a tautomeric equilibrium between N1-H and N2-H.
5-(3,3-Diethyl-1-triazeno)pyrazole-4-carbonitrile (4c) was glycosylated with 1-
chloro-2-deoxy-3,5-di-O-p-tolyl-ꢀ-D-erythro-pentofuranose [9] using the sodium
salt procedure [10] in which the sodium salt is generated in situ by treatment with
sodium hydride in acetonitrile at room temperature. Deoxyribosylation of 4c had
occurred at both nitrogens of the pyrazole ring and produced a 1:1 mixture of the
desired nucleoside products according to 1H NMR. The mixture was not separated
but treated with methanolic sodium methoxide at room temperature to give a
mixture of the unprotected 20-deoxy-ꢁ-D-ribofuranosides 5a and 5b which were
separated using silica gel column chromatography. This gave 5a in 23% and 5b in
27% overall yield starting from 4c. Assignment of the regioisomeric glycosylation
and the anomeric con®guration was performed by NOE and 2D NMR experiments.
In an NOE experiment on 5a, irradiation of H-20ꢀ induced 6.6% NOE on H-10 and
1.4% NOE on H-30, whereas irradiation of H-20ꢁ induced 2.4% NOE on H-10 and
3.4% NOE on H-30, thus con®rming ꢁ-con®guration. As expected, the 1-glyco-
cylpyrazole 5a did not show an NOE effect at H-3 upon irradiation of H-20ꢁ. The
assignments also agree with the shift differences of H-3 and H-10 when compared
with those previously reported for the corresponding riboside derivatives [11].
The nucleosides 5a,b were subjected to alkaline hydrolysis in the presence of
hydrogen peroxide according to the procedure reported by Noller et al. [12] to afford
the corresponding 1-(2-deoxy-ꢁ-D-erythro-pentofuranosyl)-5-(3,3-diethyl-1-triazeno)-
pyrazole-4-carboxamide (6a) and 2-(2-deoxy-ꢁ-D-erythro-pentofyranosyl)-5-(3,3-
diethyl-1-triazeno)pyrazole-4-carboxamide (6b) in almost quantitative yields.

Potential Inhibitors of HIV-1
1169

1170
J. S. Larsen et al.
Compounds 4a±j, 5a, 5b, 6a, and 6b were tested for their activity aganist HIV-
1 cells. Only 4c showed moderate activity against HIV-1 with ED50 ˆ 32 mM which
is the effective dose achieving 50% inhibition of HIV-1 antigen production in MT-4
cultures. The cytotoxic dose CD50 is >200 mM for 4c. For all other compounds,
only the lipophilic derivatives 4d,i±j showed cytotoxicity against MT-4 cells at
100 mM but without showing activity against HIV-1 at subtoxic concentrations.
Upon testing against herpes simplex (strain McIntyre, African green monkey
kidney cell line Vero), no activity was found.
Experimental
NMR spectra were recorded at 250 MHz for 1H and 63 MHz for 13C on a Bruker AC-250 FT
spectrometer; ꢂ values are given in ppm relative to TMS as internal standard. EI mass spectra were
recorded on a Varian MAT 311A spectometer. The silica gel (0.004±0.063 mm) used for column
chromatography was purchased from Merck. Analytical TLC was performed on Merck precoated 60
F254 plates.
5-Aminopyrazole-4-carbonitrile (3a) [7]
Ethoxymethylenemalononitril (1; 20 g, 167 mmol) and hydrazine hydrate 85% (8.2 g, 167 mmol) was
re¯uxed in 100 cm3 of EtOH for 3 h. The solvent was removed in vacuo, and the solid compound was
recrystallized from H2O to give 3a as a yellow solid.
Yield: 4.7 g (26%); m.p.: 167±169ꢁC (Ref.: [7]; 172ꢁC); 1H NMR (DMSO-d6): ꢂ ˆ 6.03 (br s, 2H,
NH2), 7.72 (br s, 1H, CH), 12.09 (br s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 73.64 (C-4), 115.19
(CN), 138.77 (C-3), 154.41 (C-5) ppm.
5-Amino-3-methylthiopyrazole-4-carbonitrile (2) [8]
Bis(methylthio)methylenemalononitril (2; 17 g, 0.1 mol) and hydrazine hydrate 85% (6 g, 0.12 mol)
were re¯uxed in 200 cm3 of MeOH for 3 h. The solvent was removed in vacuo, and the yellow solid
was recrystallized from MeOH to give 3b as colourless crystals.
Yield: 11.31 g (73%); m.p.: 147ꢁC (Ref. [8]: 152ꢁC); 1H NMR (DMSO-d6): ꢂ ˆ 2.44 (s, 3H,
S-CH3), 6.43 (s, 2H, NH2), 11.95 (s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 13.72 (S-CH3), 72.18
(C-4), 114.64 (CN), 147.70 (C-3), 154.1 (C-5) ppm.
General procedure for the preparation of 4a±j
To a mixture of 5-aminopyrazole-4-carbonitrile (3a; 1.0 g, 9.35 mmol) or 5-amino-3-methylthiopyr-
azole-4-carbonitrile (3b; 1.86 g, 12 mmol) in 3 cm3 conc. HCl and 3 cm3 H2O cooled to 0ꢁC, a
solution of NaNO2 (1.05 g, 15.2 mmol) in 10 cm3 H2O was added. After stirring for additional
30 min, a mixture of the approriate amine (12 mmol) and K2CO3 (2.5 g, 18.1 mmol) in 25 cm3 of H2O
was added. The reaction mixture was stirred at room temperature until TLC showed that all
diazonium salt had disappeared. The reaction mixture was extracted with 3Â75 cm3 CHCl3. The
combined organic phases were washed with 3Â30 cm3 H2O, dried over Na2SO4, and evaporated in
vacuo to give the crude product which was washed with Et2O/petroleum ether (65±70ꢁC) (1:1, v/v)
to give 4a±j in 23±70% yield.
5-(3,3-Dimethyl-1-triazeno)pyrazole-4-carbonitrile (4a)
1
Yield: 603 mg (39%); light yellow solid; m.p.: 152±154ꢁC; H NMR (DMSO-d6): ꢂ ˆ 3.20 (s, 3H,
NCH3), 3.54 (s, 3H, N-CH3), 7.87 (br s, 1H, CH), 8.37 (br s, 1H, CH), 13.38 (br s, 1H, NH) ppm; 13
C

Potential Inhibitors of HIV-1
1171
NMR (DMSO-d6): ꢂ ˆ 36.20 (N-CH3), 43.30 (N-CH3), 79.45 (C-4), 115.07 (CN), 136.59 (C-3),
‡
142.60 (C-5) ppm; MS: m/z ˆ 164 (M ).
5-(3-Ethyl-3-methyl-1-triazeno)pyrazole-4-carbonitrile (4b)
Yield: 716 mg (43%); orange solid; m.p.: 112±116ꢁC; 1H NMR (DMSO-d6): ꢂ ˆ 1.31 (t, 3H,
J ˆ 7.0 Hz, CH3), 3.21 (s, 3H, N-CH3), 3.84 (q, 2H, J ˆ 7.0 Hz, CH2), 7.92 (br s, 1H, CH), 8.41 (br s,
1H, CH), 13.40 (br s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 13.19 (CH3), 34.45 (N-CH3), 50.96
‡
(CH2), 80.01 (C-4), 115.11 (CN), 136.5 (C-3), 142.71 (C-5) ppm; MS: m/z ˆ 178 (M ).
5-(3,3-Diethyl-1-triazeno)pyrazole-4-carbonitrile (4c)
Yield: 825 mg (46%); 1H NMR (CDCl3): ꢂ ˆ 1.25 (t, 3H, J ˆ 7.5 Hz, CH3), 1.39 (t, 3H, J ˆ 7.5 Hz,
CH3), 3.81 (q, 4H, J ˆ 7.5 Hz, 2  NCH2), 7.78 (s, 1H, H-3), 11.70 (br s, 1H, NH) ppm; 13C NMR
(CDCl3): ꢂ ˆ 10.55 (CH3), 13.75 (CH3), 42.10 (NCH2), 49.84 (NCH2), 80.43 (C-4), 114.64 (CN),
140.21 (C-3), 157.63 (C-5) ppm.
5-(3,3-Dipropyl-1-triazeno)pyrazole-4-carbonitrile (4d)
Yield: 730 mg (36%); yellow solid; m.p.: 104±106ꢁC; 1H NMR (DMSO-d6): ꢂ ˆ 0.90 (t, 6H,
J ˆ 7.4 Hz, 2  CH3), 1.65 (q, 2H, J ˆ 7.3 Hz, CH2), 1.76 (q, 2H, J ˆ 7.1 Hz, CH2), 3.70 (m, 4H,
2ÂN-CH2), 13.39 (br s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 10.95 (CH3), 11.39 (CH3), 18.29
(CH2), 21.25 (CH2), 48.66 (N-CH2), 56.37 (N-CH2), 79.19 (C-4), 115.17 (CN), 136.50 (C-3), 142.10
‡
(C-5) ppm; MS: m/z ˆ 220 (M ); C10H16N6; calcd.: C 54.53, H 7.32, N 38.15; found: C 54.57, H
7.50, N 37.85.
5-(3-Methyl-3-phenyl-1-triazeno)pyrazole-4-carbonitrile (4e)
1
Yield: 485 mg (23%); red solid; m.p.: 158±162ꢁC; H NMR (DMSO-d6): ꢂ ˆ 3.69 (s, 2H, N-CH3),
7.23 (t, 1H, J ˆ 7.2 Hz, Harom), 7.46 (t, 2H, J ˆ 7.6 Hz, Harom), 7.68 (d, 2H, J ˆ 8.2 Hz, Harom) ppm;
13C NMR (DMSO-d6): ꢂ ˆ 32.82 (N-CH3), 79.59 (C-4), 115.28 (CN), 117.25, 124.60, 129.22
‡
(Carom), 138.48 (C-3), 143.72 (C-5), 159.00 (Carom) ppm; MS: m/z ˆ 226 (M ).
3-Methylthio-5-(3,3-dimethyl-1-triazeno)pyrazole-4-carbonitrile (4f)
Yield: 1.44 g (57%); yellow solid; m.p.: 152±154ꢁC; 1H NMR (DMSO-d6): ꢂ ˆ 2.54 (s, 3H, S-CH3),
3.23 (s, 3H, N-CH3), 3.57 (s, 3H, N-CH3), 13.48 (br s,1H, NH) ppm; 13C NMR (DMSO-d6):
ꢂ ˆ 14.19 (S-CH3), 36.35 (N-CH3), 43.56 (N-CH3), 78.48 (C-4), 114.31 (CN), 148.78 (C-3), 156.79
‡
(C-5) ppm; MS: m/z ˆ 210 (M ).
3-Methylthio-5-(3-ethyl-3-methyl-1-triazeno)pyrazole-4-carbonitrile (4g)
Yield: 1.80 g (67%); yellow powder; m.p.: 107±109ꢁC; 1H NMR (DMSO-d6): ꢂ ˆ 1.31 (t, 3H,
J ˆ 7.0 Hz, CH3), 2.54 (s, 3H, S-CH3), 3.23 (s, 3H, N-CH3), 3.87 (q, 2H, J ˆ 7.0 Hz, CH2), 13.52 (br
s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 9.44 (CH3), 13.11 (S-CH3), 34.96 (N-CH3), 51.33
‡
(CH2), 77.76 (C-4), 114.37 (CN), 149.44 (C-3), 156.47 (C-5) ppm; MS: m/z ˆ 224 (M ); C8H12N6S;
calcd.: C 42.84, H 5.39, N 37.47; found: C 43.05, H 5.02, N 37.44.
3-Methylthio-5-(3,3-diethyl-1-triazeno)pyrazole-4-carbonitrile (4h)
Yield: 1.20 g (42%); brown crystals; m.p.: 99±100ꢁC; 1H NMR (DMSO-d6): ꢂ ˆ 1.19 (t, 3H,
J ˆ 7.0 Hz, CH3), 1.34 (t, 3H, J ˆ 7.0 Hz, CH3), 2.54 (s, 3H, S-CH3), 3.82 (t, 4H, J ˆ 7.0 Hz, 2

1172
J. S. Larsen et al.
ÂNCH2), 13.51 (s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 10.27 (CH3), 13.49 (CH3), 13.90
(S-CH3), 42.31 (CH2), 49.65 (CH2), 77.70 (C-4), 114.44 (CN), 149.48 (C-3), 156.69 (C-5) ppm; MS:
‡
m/z ˆ 238 (M ); C9H14N6S; calcd.: C 45.36, H 5.92, N 35.26, S 13.45; found: C 45.32, H 6.04, N
35.44, S 13.43.
3-Methylthio-5-(3,3-dipropyl-1-triazeno)pyrazole-4-carbonitrile (4i)
1
Yield: 1.90 g (61%); light yellow crystals; m.p.: 108±110ꢁC; H NMR (DMSO-d6): ꢂ ˆ 0.90 (t, 6H,
J ˆ 7.0 Hz, 2  CH3), 1.66 (q, 2H, J ˆ 7.0 Hz, CH2), 1.78 (q, 2H, J ˆ 7.0 Hz, CH2), 2.52 (s, 3H,
S-CH3), 3.73 (m, 4H, 2 ÂNCH2), 13.49 (s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 10.88 (CH3),
11.34 (CH3), 13.89 (S-CH3), 18.20 (CH2), 21.11 (CH2), 49.17 (N-CH2), 56.80 (N-CH2), 77.63 (C-4),
‡
114.36 (CN), 149.50 (C-3), 156.57 (C-5) ppm; MS: m/z ˆ 266 (M ); C11H18N6S; calcd.: C 49.60, H
6.81, N 31.55, S 12.04; found: C 49.56, H 6.93, N 31.66, S 11.77.
3-Methylthio-5-(3-methyl-3-phenyl-1-triazeno)pyrazole-4-carbonitrile (4j)
Yield: 2.30 g (70%); orange crystals; m.p.: 168±169ꢁC; 1H NMR (DMSO-d6): ꢂ ˆ 2.61 (s, 3H,
S-CH3), 3.70 (s, 3 H, N-CH3), 7.26 (t, 1H, J ˆ 7.0 Hz, Harom), 7.47 (t, 2H, J ˆ 7.0 Hz, Harom), 7.67 (d,
2H, J ˆ 7.0 Hz, Harom), 13.93 (br s, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ˆ 14.67 (S-CH3), 33.18
(N-CH3), 79.50 (C-4), 114.36 (CN), 117.52, 125.05, 129.16, 143.38 (Carom), 147.94 (C-3), 157.43
‡
(C-5) ppm; MS: m/z ˆ 272 (M ); C12H12N6S; calcd.: C 52.06, H 4.55, N 30.36, S 11.58; found: C
52.23, H 4.52, N 30.79, S 11.44.
1-(2-Deoxy-ꢁ-D-erythro-pentofuranosyl)-5-(3,3-diethyl-1-triazeno)pyrazole-4-carbonitrile (5a) and
2-(2-deoxy-ꢁ-D-erythro-pentofuranosyl)-5-(3,3-diethyl-1-triazeno)pyrazole-4-carbonitrile (5b)
To a stirred solution of 4c (4.65 g, 24.3 mmol) in MeCN (150 cm3), NaH (990 mg, 55±65% dispersed
in mineral oil) was added under nitrogen at room temperature. After 4 h, 2-deoxy-3,5-di-O-p-tolyl-ꢀ-
D-erythro-pentofuranosyl chloride (9.45 g, 24.3 mmol) was added in one portion, and stirring was
continued for 2 h. The mixture was ®ltered through celite and evaporated to dryness. The residue was
puri®ed on a silica gel column using 10±40% Et2O in petroleum ether (65±70ꢁC) to afford a 1:1
mixture of the protected nucleosides as an hygroscopic pale yellow foam in 65% yield. To a solution
of the protected nucleosides (8.60 g, 15.80 mmol) in dry MeOH (100 cm3), NaOMe (2.16 g,
40 mmol) in 10 cm3 dry MeOH was added, and the mixture was stirred at room temperature for
‡
30 min. The reaction mixture was then neutralized with Dowex-50 resin and ®ltered. The ®ltrate
was evaporated to dryness. The residual semisolid was chromatographed on a silica gel column using
1±2% MeOH in CHCl3 to give 5a in 27% and 5b in 23% yield, respectively.
1-(2-Deoxy-ꢁ-D-erythro-pentofuranosyl)-5-(3,3-diethyl-1-triazeno)pyrazole-4-carbonitrile (5a)
1
Yield: 1.10 g (23%); faint yellow oil; H NMR (CDCl3): ꢂ ˆ 1.25 (t, 3H, J ˆ 7.5 Hz, CH3), 1.41 (t,
3H, J ˆ 7.5 Hz, CH3), 2.42 (m, 1H, H-20ꢀ), 2.79 (m, 1H, H-20ꢁ), 3.76 (m, 2H, H-50), 3.85 (m, 4H,
2  NCH2), 4.13 (m, 1H, H-40), 4.25 (br s, 1H, OH-50), 4.74 (m, 1H, H-30), 6.66 (t, 1H, J ˆ 7.5 Hz, H-
13
10), 7.70 (s, 1H, H-3) ppm; C NMR (CDCl3): ꢂ ˆ 10.43 (CH3), 13.54 (CH3), 40.44 (C-20), 42.78
(NCH2), 50.28 (NCH2), 63.14 (C-50), 72.04 (C-30), 77.41 (C-4), 85.11 (C-40), 88.57 (C-10), 114.89
‡
‡
(CN), 142.65 (C-3), 154.59 (C-5) ppm; FAB MS (3-nitrobenzylalcohol): m/z ˆ 309 (M H ).
2-(2-Deoxy-ꢁ-D-erythro-pentofuranosyl)-5-(3,3-diethyl-1-triazeno)pyrazole-4-carbonitrile (5b)
Yield: 1.32 g (27%); foam; 1H NMR (CDCl3): ꢂ ˆ 1.21 (t, 3H, J ˆ 7.5 Hz, CH3), 1.37 (t, 3H,
J ˆ 7.5 Hz, CH3), 2.42 (m, 1H, H-20ꢀ), 2.77 (m, 1H, H-20ꢁ), 3.64 (m, 2H, H-50), 3.80 (m, 4H, 2 Â

Potential Inhibitors of HIV-1
1173
NCH2), 4.08 (m, 1H, H-30), 4.17 (br s, 1H, OH-50), 4.63 (m, 1H, H-30), 6.04 (t, 1H, J ˆ 6.0 Hz, H-10),
13
8.05 (s, 1H, H-3) ppm; C NMR (CDCl3): ꢂ ˆ 10.48 (CH3), 13.59 (CH3), 40.49 (C-20), 41.55
(NCH2), 49.29 (NCH2), 62.36 (C-50), 71.16 (C-30), 81.64 (C-4), 88.15 (C-40), 90.10 (C-10), 114.14
‡
(CN), 135.76 (C-3), 161.78 (C-5) ppm; FAB MS (3-nitrobenzylalchohol): m/z ˆ 309 (M H).
5-(3,3-Diethyl-1-triazeno)pyrazole-4-carboxamide nucleosides 6a and 6b; general procedure
To a solution of 5a or 5b (1.0 g, 3.24 mmol) and NaOH (0.38 g, 9.72 mmol) in EtOH (95%, 30 cm3)
H2O2 (35%, 4 cm3) was added. The mixture was stirred at 40±50ꢁC for 3 days and then ®ltered. The
®ltrate was evaporated in vacuo, and the residue was puri®ed on a silica gel using 0±3% MeOH in
CHCl3 to yield 0.92 g (87%) as an oil.
1-(2-Deoxy-ꢁ-D-erythro-pentofuranosyl)-5-(3,3-diethyl-1-triazeno)pyrazole-4-carboxamide (6a)
1H NMR (CDCl3): ꢂ ˆ 1.24 (t, 3H, J ˆ 7.5 Hz, CH3), 1.36 (t, 3H, J ˆ 7.5 Hz, CH3), 2.39 (m, 1H, H-
20ꢁ), 2.80 (m, 1H, H-20ꢀ), 3.80 (m, 6H, 2 Â NCH2, 2ÂH-50), 4.11 (m, 1H, H-40), 4.78 (m, 1H, H-30),
6.00 (m, 1H, NH), 6.56 (t, 1H, J ˆ 6.2 Hz, H-10), 7.60 (br s, 1H, NH), 7.97 (s, 1H, H-3) ppm; 13C
NMR (CDCl3): ꢂ ˆ 10.37 (CH3), 14.11 (CH3), 41.66 (C-20), 42.45 (NCH2), 50.02 (NCH2), 63.30 (C-
50), 72.30 (C-30), 87.03 (C-40), 89.11 (C-10), 106.84 (C-4), 142.27 (C-3), 147.09 (C-5), 164.89
‡
(C=O) ppm; FAB MS (3-nitrobenzylalcohol): m/z ˆ 327 (M‡H ).
2-(2-Deoxy-ꢁ-D-erythro-pentofyranosyl)-5-(3,3-diethyl-1-triazeno)pyrazole-4-carboxamide (6b)
1H NMR (CDCl3): ꢂ ˆ 1.21 (m, 3H, CH3), 1.33 (m, 3H, CH3), 2.45 (m, 1H, H-20), 2.74 (m, 1H, H-20),
3.79 (m, 6H, 2 Â NCH2, H-50), 4.13 (m, 1H, H-40), 4.69 (m, 1H, H-30), 5.24 (br s, 2H, OH-30,OH-50),
6.11 (m, 1H, H-10), 6.55, 7.83 (2Âs, 1H, NH2), 8.23 (s, 1H, H-3) ppm; 13C NMR (CDCl3): ꢂ ˆ 10.18
(CH3), 13.92 (CH3), 41.58 (C-20, NCH2), 49.81 (NCH2), 62.89 (C-50), 71.77 (C-30), 88.95 (C-40),
90.54 (C-10), 109.09 (C-4), 133.04 (C-3), 155.99 (C-5), 165.52 (C=O) ppm; FAB MS (3-nitrobenzyl-
‡
alcohol): m/z ˆ 327 (M‡H ).
References
[1] Baba M, Shigeta S, Yuasa S, Takashima H, Sehiya K, Ubasawa M, Tanaka H, Miyasaka T,
Walker RT, De Clercq E (1994) Antimicrob Agents Chemother 38: 688
[2] Baba M, Tanaka H, De Clercq E, Pauwels R, Balzarini J, Schols D, Nakashima H, Perno C-F,
Walker RT, Miyasaka T (1989) Biochem Biophys Res Commun 165: 1375
[3] Mitsuya H, Weinhold KJ, Furman PA, St. Clair MH, Nusinoff-Lehrmann S, Gallo RC, Bolognesi
D, Barry DW, Broder S (1985) Proc Natl Acad USA 82: 7096
[4] Mitsuya H, Broder S (1986) Proc Natl Acad USA 83: 1911
[5] Yarchoan R, Mitsuya H, Thomas RV, Pluda JM, Hartman NR, Perno CF, Marczyk KS, Allain JP,
Johns DG, Broder S (1989) Science 245: 412
[6] Hatheway GJ, Hansch C, Kim KH, Milstein SR, Schmidt CL, Smith RN, Quinn FR (1978) J Med
Chem 21: 563
[7] Hitchings HG, Falco EA (1956) US 2,759,949; (1957) CA 11391g
[8] Yoshinori T, Yasumasa H, Mayumii H, Akira H (1990) J Heterocyclic Chem 27: 775
[9] Hoffer M (1960) Chem Ber 93: 2777
[10] Kazimierczuk Z, Cottam HB, Revankar GR, Robins RK (1984) J Am Chem Soc 106: 6379
[11] Earl AR, Panzica RP, Townsend LB (1972) J Chem Soc Perkin Trans I, 2672
[12] Noller CR (1970) Org Synth Coll Vol 55: 586
Received November 27, 1998. Accepted (revised) March 4, 1999