CORE Metadata, citation and similar papers at core.ac.uk Provided by Archive Ouverte en Sciences de l'Information et de la Communication Synthesis of 2’,3’-Dideoxynucleoside Phosphoesters Using H-Phosphonate Chemistry on Soluble Polymer Support Céline Crauste, Christian Perigaud, Suzanne Peyrottes To cite this version: Céline Crauste, Christian Perigaud, Suzanne Peyrottes. Synthesis of 2’,3’-Dideoxynucleoside Phospho- esters Using H-Phosphonate Chemistry on Soluble Polymer Support. Journal of Organic Chemistry, American Chemical Society, 2011, 76 (3), pp.997-1000. 10.1021/jo1022958. hal-02309881 HAL Id: hal-02309881 https://hal.archives-ouvertes.fr/hal-02309881 Submitted on 9 Oct 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. pubs.acs.org/joc 0 0 Synthesis of 2 ,3 -Dideoxynucleoside Phosphoesters SCHEME 1. Attempts toward ddC and 3TC Monophosphory- V Using H-Phosphonate Chemistry on lation Using P Reagent on a Soluble Support Soluble Polymer Support Celine Crauste, Christian Perigaud, and Suzanne Peyrottes* UMR 5247 CNRS-UM1-UM2, IBMM, Nucleosides & Phosphorylated Effectors Team, University Montpellier 2, cc1705, place E. Bataillon, 34095 Montpellier, France [email protected] Received November 18, 2010 We report herein the extension of this methodology for acid-sensitive analogues such as 20,30-dideoxynucleosides. 0 0 5 Indeed, 1-(2 ,3 -dideoxy-β-D-ribofuranosyl)-cytosine (ddC) 0 0 0 and 1-(2 ,3 -dideoxy-3 -thia-β-L-ribofuranosyl)-cytosine (3TC)6 are commonly used as antiviral nucleoside analo- gues,1 and easy access to their corresponding phosphory- Phosphorylation of ddC and 3TC was efficiently per- lated forms is greatly needed. In a preliminary set of experi- formed on soluble poly(ethylene glycol) support. The ments, previously described conditions3 (PV reagent) were corresponding 50-monophosphate derivatives were ob- 0 applied to PEG-ddC (1a) and PEG-3TC (1b) (Scheme 1). tained by oxidation of the support bound 5 -H-phospho- Briefly, the anchoring of both nucleosides onto the succiny- nate intermediates. Then, di- and triphosphorylations late PEG support7 was carried out using DCC/HOBt as were carried out using a carbonyldiimidazole activation coupling agents,8 and then monophosphorylation was per- step followed by nucleophilic substitution with suitable formed in triethylphosphate at 35-40 °C (due to the low phosphate salts. Trivalent phosphorus chemistry ap- solubility of PEG-supported substrates 1a and 1b at 0 °C), peared as a good alternative for monophosphate synth- and in presence of 30 equiv of POCl3. Unfortunately, as a esis of acid-sensitive 20,30-dideoxynucleosides. result of acidic reaction conditions, cleavage of the glycosidic bond was observed for both derivatives, and the use of lower amounts of POCl3 led to decreased phosphorylation ratio 1 A wide variety of nucleoside analogues, mostly active as (estimated by H NMR analysis). 9 their 50-triphosphate forms, are currently used as antiviral To avoid this side reaction, proton sponge or activated 10 agents.1 Despite the importance of such phosphorylated molecular sieves were added to the reaction mixture. In the analogues as biological tools, to date no protocol for making case of ddC, the presence of activated molecular sieves nucleoside 50-triphosphates is universally satisfactory. In- allowed the formation of PEG-ddCMP (2a) and only 10% deed, the success of the phosphorylation depends consider- glycosidic cleavage was observed (Scheme 1). However, these ably on the nature of the substrate, and several fastidious conditions were not appropriate for the 3TC derivative. We purification steps cannot be avoided.2 hypothesized that the sulfur atom participates to the stabi- To reach reaction completion and to significantly simplify lization of the carbocation species generated during the purification procedures, we recently developed an effi- cleavage of the glycosidic bond, thus increasing chemical cient solution-phase process based on the use of a soluble instability of PEG-3TC (1b). Consequently, a new synthetic III poly(ethylene glycol) (PEG) support, for the synthesis of pathway involving P chemistry was explored to perform 50-mono, di-, and triphosphates of cytidine derivatives.3 0 Thus, the support-bound nucleoside 5 -monophosphates of (4) Hoard, D. E.; Ott, D. G. J. Am. Chem. Soc. 1965, 87, 1785. araC, dC, and C were obtained using phosphorus oxychlor- (5) Mitsuya, H.; Broder, S. Proc. Natl. Acad. Sci. U.S.A. 1986, 83, V 1911. ide (POCl3)asP phosphorylating reagent, and such inter- (6) Soudeyns, H.; Yao, X. J.; Gao, Q.; Belleau, B.; Kraus, J. L.; Nghe, mediates allowed the synthesis of the corresponding di- and N. B.; Spira, B.; Wainberg, M. A. Antimicrob. Agents Chemother. 1991, 35, triphosphate derivatives following the Hoard phosphoryla- 1386. tion method.4 (7) Denapoli, L.; Messere, A.; Montesarchio, D.; Piccialli, G.; Santacroce, C.; Bonora, G. M. Nucleosides Nucleotides 1993, 12,21. (8) Guo, Z. W.; Gallo, J. M. J. Org. Chem. 1999, 64, 8319. (1) De Clercq, E. Rev. Med. Virol. 2009, 19, 287. (9) Kovacs, T.; Otvos, L. Tetrahedron Lett. 1988, 29, 4525. (2) Burgess, K.; Cook, D. Chem. Rev. 2000, 100, 2047. (10) Matulic-Adamic, J.; Beigelman, L. Patent WO/1993/023416, US, (3) Crauste, C.; Perigaud, C.; Peyrottes, S. J. Org. Chem. 2009, 74, 9165. 1993. DOI: 10.1021/jo1022958 J. Org. Chem. XXXX, XXX, 000–000 A r XXXX American Chemical Society JOCNote Crauste et al. SCHEME 2. Monophosphorylation of ddC Using PIII Reagent and Oxidation with tert-Butyl Hydroperoxide on Soluble Support FIGURE 1. 1H NMR spectra of PEG-3TC (A), PEG-3TC 50-HP (B), PEG-3TCMP (C), and 3TCMP (D). 0 0 0 the 5 -monophosphorylation of acid sensitive 2 ,3 -dideox- tert-butyl hydroperoxide (t-BuOOH) or I2/H2O/Pyridine ynucleosides on soluble support. mixture. The use of an excess of BSA (40 equiv) at 50 °C Phosphate monoesters have frequently been synthesized and the addition of triethylamine were essential for an from H-phosphonate diester or phosphite triester intermedi- efficient conversion of the H-phosphonate derivative into ates, after subsequent oxidation and removal of the phos- the corresponding silyl phosphite intermediate. t-BuOOH phate protecting group.11 However, we aimed at developing was also used in large excess (100 equiv) to overcome the a rapid and efficient synthetic pathway including the lowest formation of the less reactive t-BuOOTMS in the presence of number of steps possible. Thereby, we envisaged the direct remaining BSA. Thus, PEG-ddCMP (2a) was finally ob- oxidation of 50-H-phosphonate monoester nucleosides to tained albeit contaminated with 16% (estimated by integra- their corresponding 50-monophosphates. This reaction has tion of nucleobase signals in 1H NMR analysis) of starting been less often reported in view of the lower reactivity of material (PEG-ddC 50-HP, 3a). H-phosphonate monoesters toward oxidation, compared to Applied to PEG-3TC-50HP (3b), this last protocol led to H-phosphonate diesters or phosphite triesters. The H-phos- the formation of secondary products (probably associated phonate monoester has to be temporarily convert to its with sulfur oxidation), and a low conversion into the highly reactive phosphite form using silylated protecting 50-monophosphate (2b) was observed. Even so, oxidation groups.12-14 After mild oxidation by elemental iodine,15,16 tert- with peroxide had already been reported for a 3TC butyl hydroperoxide,17 or (camphorsulfonyl)oxazirine,18 a derivative20 without mention of side reaction. In view of one-pot deprotection step is performed in basic conditions to the particular reactivity of 3TC, the use of an iodine solution release the monophosphate function. Thus, phosphitylation in a mixture of pyridine and water (ratio 98/2, v/v)15,16 was carried out on PEG support using a large excess of resulted in complete disappearance of the starting 50-H- diphenylphosphite19 in pyridine in order to achieve reaction phosphonate (3b, Figure 1C). However, 31P NMR analysis completion (Scheme 2). revealed the presence of a dinucleoside (P,P0) pyrophosphate A quantitative conversion was estimated by comparing 1H entity (10) in addition to the desired 50-monophosphate NMR integration of both signals of the H6 from the nucleo- compound (2b) (scheme 3, A). base and of the characteristic signal of the H-phosphonate The structure of this byproduct was proposed on the basis proton (Figure 1, panels A and B). PEG-ddC 50-HP (3a) and of the presence of an extra phosphate signal at -11 ppm, PEG-3TC 50-HP (3b) were isolated in 98% and 88% yields, characteristic of 50,50-pyrophosphate dinucleosides and respectively, after extraction and precipitation in cold diethyl further spectral analysis after cleavage of the compound ether. Among the reagents already described to perform the from the support (see Supporting Information). This com- phosphite oxidation,15-18 we first tested easily available pound (10) may result from a nucleophilic attack of the silylating and oxidizing reagents such as trimethylsilyl chlor- monophosphate species (2a,b) on the activated pyridinium ide (TMSCl), N,O-bis(trimethylsilyl) acetamide (BSA), and intermediate (4) generated in situ during the oxidation. Thus, we hypothesized that by increasing the amount of water in the reaction mixture, the hydrolysis of the pyridinium inter- (11) Stawinski, J. In Handbook of Organophosphorus Chemistry; Engel, mediate would be favored compared to the nucleophilic R., Ed.; Marcel Dekker, Inc.: New York, 1992; p 377. 0 (12) Hata, T.; Sekine, M. Tetrahedron Lett. 1974, 3943. attack of the 5 -monophosphate (2a,b) already formed (13) Sekine, M.; Yamagata, H.; Hata, T.