Thiosugars. Part 9: Synthesis and biological evaluation of some 4′-thio-L-arabino nucleoside analogues

Article abstract of DOI:10.1016/S0960-894X(01)00124-X

1-O-Acetyl-2, 3, 5-tri-O-benzyl-4-thio-L-arabinofuranose (10) was transformed into the corresponding cytidine derivative 9 and the adenosine derivative 12. Both nucleosides, as well as the previously reported uridine and thymidine analogues 2 and 3, were tested for their in vitro antiviral activity.

Full text of DOI:10.1016/S0960-894X(01)00124-X

Bioorganic & Medicinal Chemistry Letters 11 (2001) 1049–1051
Thiosugars. Part 9: Synthesis and Biological Evaluation of Some
40-Thio-L-arabino Nucleoside Analoguesy
Jorn Wirsching,a Jurgen Voss,a,* Gunadi Adiwidjaja,b Jan Balzarinic and Erik De Clercqc
aInstitut fur Organische Chemie der Universitat Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
¨
¨
bMineralogisch-Petrographisches Institut der Universitat Hamburg, Grindelallee 48, 20146 Hamburg, Germany
¨
cRega Institute for Medical Research, Catholic University of Leuven, Minderbroederstraat 10, B-3000, Leuven, Belgium
Received 29 December 2000; revised 12 February 2001; accepted 21 February 2001
Abstract—1-O-Acetyl-2,3,5-tri-O-benzyl-4-thio-l-arabinofuranose (10) was transformed into the corresponding cytidine derivative
9 and the adenosine derivative 12. Both nucleosides, as well as the previously reported uridine and thymidine analogues 2 and 3,
were tested for their in vitro antiviral activity. # 2001 Elsevier Science Ltd. All rights reserved.
40-Thionucleosides with the natural d-configuration of
the sugar moiety have been compounds of interest for a
period of about 35 years.1 Several of the synthesised
nucleoside analogues exhibit antiviral and antitumour
activities.2 Since the synthesis of 3TC (1) and the dis-
covery of its remarkable anti-HIV activity3 40-thionu-
cleosides derived from l-pentofuranoses became
interesting targets of synthetic efforts.4,5 Satoh et al.6
have reported the synthesis of the 40-thio-l-arabino
nucleosides 3 and 9. Independently we have published
the preparation of 3 via a different route, as well as the
synthesis of the uridine derivative 2.7 In addition, we
have synthesised the 5-halo derivatives of 2 and 4–6,
which exhibited, however, neither antiviral activity nor
cytotoxicity.8 In continuation of our investigations in
the 40-thio-l-arabino series we report here the synthesis
of the cytidine 9 by a route different from that published
by Satoh et al. and the first preparation of a purine
nucleoside (12) of this series. The results of the antiviral
testing of these compounds and of 2 and 3 will be given
as well.
achieved by an alternative route according to a proce-
dure of Uenishi et al.5 To this end, an anomeric mixture
of the uridine 2 (a:b=2:1)7 was transformed into the
triazolo derivative 7 (49%, a:b=2:1), which after
ammonolysis gave the protected cytidine derivative 8
(70%, a:b=2:1). Treatment of 8 with boron tribromide
at ꢀ90 ꢁC,12 followed by neutralisation of the hydro-
bromic acid with silver carbonate7 and reversed phase
HPLC gave the deblocked cytidine 913 with a yield of
39%. The product was obtained as a mixture of the
anomers (a:b=5:1) (Scheme 1). In contrast to Satoh et
al.,6 we were not able to separate the anomers on an
ODS (octadecyl silane) column.14
Starting from d-xylose we prepared the required 1-O-
acetyl glycosyl donor 10 in six steps7 according to
Dyson, Coe and Walker.9 Coupling of 10 with silylated
cytosine10 in the presence of trimethylsilyl tri-
fluoromethanesulfonate (TMSOTf)11 failed. The pre-
paration of the cytidine derivative 9 was, however,
Reaction of 10 with adenine and TMSOTf, on the other
hand, yielded the benzyl protected adenosine derivative
11 as a 3:4 mixture of the anomers (a:b). Cleavage of the
protecting groups with boron tribromide and sub-
sequent HPLC13 led to the separated anomers of the
free adenosine 1215 with a total yield of 36% (Scheme
2). The ratio of the separated anomers was a:b=2:1.
The a-anomer was crystalline and its structure and
yPart 8: Wirsching, J.; Voss, J.; Adiwidjaja, G.; Balzarini, J.; De
Clercq, E. Nucleosides Nucleotides 2001, in press.
*Corresponding author. Tel.: +49-(0)40-428382803; fax: +49-(0)40-
428385592; e-mail: voss@chemie.uni.hamburg.de
0960-894X/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(01)00124-X

1050
J. Wirsching et al. / Bioorg. Med. Chem. Lett. 11 (2001) 1049–1051
Scheme 1.
Scheme 2.
configuration was confirmed by an X-ray diffraction
analysis, which revealed an envelope (E3) conforma-
tion16 of the thiofuranose ring (cf. Fig. 1).17
mum concentration of 48 mg/mL was found for a-2
against HSV-1 (KOS), for b-3 against HSV-1 (KOS and
TKꢀ VMW 1837) and for a-12 against Reovirus-1.
These test results for 3 and 9 correspond with those of
Satoh et al.6 None of the nucleosides was cytotoxic at
the highest concentration level applied (200–400 mM).
The a- and b-anomers of 2, 3 and 12 and the anomeric
mixture of 9 were tested for antiviral activity against
HIV-1, HIV-2, HCMV, VZV, HSV-1, HSV-2, Vaccinia
virus, Vesicular stomatitis virus, Coxsackie B4 virus,
Respiratory syncytial virus, Parainfluenza-3 virus, Reo-
virus-1, Sindbis virus and Punta Toro virus. The mini-
mum inhibitory concentration required to reduce the
virus-induced cytopathogenicity by 50% was higher
than 240 or 400 mg/mL in all but three cases. A mini-
Acknowledgements
The authors thank the Deutsche Forschungs-
gemeinschaft, the Fonds der Chemischen Industrie and
the European Commission for their financial support.
The authors also thank the Degussa-Huls AG for the
supply of silver carbonate. Prof. Dr. Chris Meier and
Dipl.-Chem. Andreas Lomp, University of Hamburg,
are gratefully acknowledged for helpful discussions and
for making the HPLC equipment available to us. We
also thank Mrs. Ann Absillis, Mrs. Anita Camps and
Mrs. Lies Vandenheurck for technical assistance.
References and Notes
1. (a) Reist, E. J.; Gueffroy, D. E.; Goodman, L. J. Am.
Chem. Soc. 1964, 86, 5658. (b) Reist, E. J.; Fisher, L. V.;
Figure 1. ORTEP view of the a-12 molecule.17

J. Wirsching et al. / Bioorg. Med. Chem. Lett. 11 (2001) 1049–1051
1051
Goodman, L. J. Org. Chem. 1968, 33, 189. (c) Walker, R. T.
40-Thio-20-deoxyribonucleosides, Their Chemistry and Biologi-
cal Properties—A Review in Anti-infectives: Recent Advances in
Chemistry and Structure–Activity Relationships, Royal Soc.
Chem., Special Publ. 1997, 198, 203–237.
14. Column used for semipreparative HPLC: LiChroCART
250-10 with Lichrosphere 100-10 RP 18 (10 mM) filling mate-
rial. HPLC was performed with MeCN/H2O as eluent; 9: 7:93;
12: 8:92.
15. a-12: [a]2D0 ꢀ47.3 (c 0.5, MeOH); mp 249 ꢁC (decomp.); IR
2. Graciet, J.-C. G.; Schinazi, R. F. Adv. Antiviral Drug Des.
1999, 3, 1.
(KBr) n 3393, 3276, 2927, 2887, 1708, 1616, 1572, 1481, 1425,
1303, 1253, 1217, 1186, 1109, 1037, 914, 814, 791, 650, 613,
1
546 cmꢀ1; H NMR(DMSO- d6) d 3.43 (1H, ddd, J5 a,4 =8.0,
0
0
3. (a) Beach, J. W.; Jeong, L. S.; Alves, A. J.; Pohl, D.; Kim,
H. O.; Chang, C.-N.; Doong, S.-L.; Schinazi, R. F.; Cheng,
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B. A.; Kemp, S. D.; Harrigan, P. R. Science 1995, 269, 696.
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Chem. Soc., Perkin Trans. 1 2000, 1327.
J5 a,5 b=10.9, J5 a,OH=6.0 Hz, H-50a), 3.66 (1H, ddd,
0
0
0
J4 ,3 =8.0, J4 ,5 b=5.5 Hz, H-40), 3.75 (1H, ddd, J3 ,2 =7.6,
0
0
0
0
0
0
J3 ,OH=5.2 Hz, H-30), 3.89 (1H, ddd, J5 b,OH=4.5 Hz, H-50b),
0
0
4.56 (1H, ddd, J2 ,1 =7.2, J2 ,OH=5.9 Hz, H-20), 4.93 (1H, dd,
50-OH), 5.60 (1H, d, 30-OH), 5.73 (1H, d, H-10), 5.78 (1H, d,
20-OH), 7.23 (2H, ws, NH2), 8.15 (1H, s, Hadenine), 8.40 (1H, s,
0
0
0
H
adenine) ppm; 13C NMR(DMSO- d6) d 50.97 (C-40), 58.71 (C-
10), 62.00 (C-50), 74.84 (C-30), 79.07 (C-20), 117.65 (Cadenine),
138.74 (CHadenine), 148.17 (Cadenine), 151.03 (CHadenine), 154.62
(Cadenine) ppm; FAB MS (mNBA) m/z 284 [M+H]; FAB
HRMS (mNBA) calcd 284.0817 (C10H14N5O3S); found
284.0802; b-12: [a]2D0 +12.8 (c 1.0, MeOH); mp 229–231 ꢁC
(decomp.); IR(KBr) n 3382, 3205, 2923, 2873, 1645, 1606,
1577, 1477, 1417, 1338, 1303, 1245, 1201, 1104, 1054, 910, 817,
5. Uenishi, J.; Takahashi, K.; Motoyama, M.; Akashi, H.;
Sasaki, T. Nucleosides Nucleotides 1994, 13, 1347.
6. Satoh, H.; Yoshimura, Y.; Sakata, S.; Miura, S.; Machida,
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1991, 216, 237.
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11. (a) Leydier, C.; Bellon, L.; Barascut, J.-L.; Deydier, J.;
Maury, G.; Pelicano, H.; El Alaoui, M. A.; Imbach, J.-L.
Nucleosides Nucleotides 1994, 13, 2035. (b) Branalt, J.;
Kvarnstrom, I.; Niklasson, G.; Svensson, S. C. T. J. Org.
Chem. 1994, 59, 1783.
12. (a) Bellon, L.; Barascut, J.-L.; Imbach, J.-L. Nucleosides
Nucleotides 1992, 11, 1467. (b) Secrist, J. A., III; Tiwari, K.
N.; Shortnacy-Fowler, A. T.; Messini, L.; Roirdan, J. M.;
Montgomery, J. A. J. Med. Chem. 1998, 41, 3865.
689, 647, 587 cmꢀ1 1H NMR(DMSO- d6) d 3.25 (1H, ddd,
;
J4 ,3 =6.2, J4 ,5 a=5.9, J4 ,5 b=4.4 Hz, H-40), 3.75 (1H, ddd,
0
0
0
0
0
0
J5 a,5 b=11.1, J5 a,OH=5.3 Hz, H-50a), 3.86 (1H, ddd,
0
0
0
J5 b,OH=4.7 Hz, H-50b), 4.10–4.16 (2H, m, H-20, 0 H-30), 5.19
0
(1H, dd, 50-OH), 5.50 (1H, d, JOH,3 =4.7 Hz, 3 -OH), 5.71
0
0 0
0 0 0
(1H, d, JOH,2 =3.5 Hz, 2 -OH), 6.06 (1H, d, J1 ,2 =5.2 Hz, H-1 ),
7.21 (2H, ws, NH2), 8.13 (1H, s, Hadenine), 8.36 (1H, s, Hadenine
)
ppm; 13C NMR(DMSO- d6) d 51.30 (C-40), 56.48 (C-10), 61.00
(C-50), 74.42 (C-30), 76.30 (C-20), 117.23 (Cadenine), 139.66
(CHadenine), 148.91 (Cadenine), 151.15 (CHadenine), 154.84 (Cadenine
)
ppm; FAB MS (mNBA) m/z 284 [M+H]; FAB HRMS
(mNBA) calcd 284.0805 (C10H14N5O3S); found 284.0802.
16. (a) Cremer, D.; Pople, J. A. J. Am. Chem. Soc. 1975, 97,
1354. (b) Koll, P.; John, H.-G.; Kopf, J. Liebigs Ann. Chem.
1982, 626.
17. Crystallographic details of a-12 have been deposited with
the Cambridge Crystallographic Data Centre and may be
obtained, on request, from the CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK. Tel. +44-1223-336408, fax +44-1223-
336033, e-mail: deposit@ccdc.cam.ac.uk. Deposition number:
CCDC 153055.
13. IR(KBr, anomeric mixture) n 3340, 3206, 2923, 2873,
1650, 1528, 1493, 1400, 1284, 1186, 1102, 1044, 833, 789, 588
cmꢀ1; FAB MS (mNBA, anomeric mixture) m/z 260 [M+H];
FAB HRMS (mNBA, anomeric mixture) calcd 260.0705
(C9H14N3O4S); found 260.0707.