The chemoenzymatic synthesis of clofarabine and related 2′-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases

• DOI: 10.3762/bjoc.10.173
• Publication Date: 2014-07-22T07:42:52Z
• Authors: Ilja V Fateev; Konstantin V Antonov; Irina D Konstanti...; Tatyana I Muravyova; Frank Seela; Roman S Esipov; Anatoly I Miroshn...; Igor A Mikhailopulo
• Keywords: Thymine; Hypoxanthine; Biocatalysis

Two approaches to the synthesis of 2-chloro-9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine ( 1 , clofarabine) were studied. The first approach consists in chemical 2-deoxy-2-fluoro-α-D-arabinofuranose-1-phosphate 12a 2F Ara-1P) via three step conversion 1,3,5-tri- O -benzoyl-2-deoxy-2-fluoro-α-D-arabinofuranose 9 ) into phosphate without isolation intermediary products. Condensation with 2-chloroadenine catalyzed by recombinant E. coli purine nucleoside phosphorylase (PNP) resulted formation clofarabine 67% yield. reaction was also studied a number bases (2-aminoadenine and hypoxanthine), their analogues (5-aza-7-deazaguanine 8-aza-7-deazahypoxanthine) thymine. results compared those similar α-D-arabinofuranose-1-phosphate 13a Ara-1P). Differences reactivity various substrates analyzed ab initio calculations terms electronic structure (natural purines vs analogues) stereochemical features Ara-1P compounds determine substrate recognition phosphorylases. second starts cascade one-pot enzymatic transformation 2-deoxy-2-fluoro-D-arabinose followed its condensation thereby affording ca. 48% yield 24 h. following enzymes catalyze sequential : ribokinase (2-deoxy-2-fluoro-D-arabinofuranose-5-phosphate), phosphopentomutase (PPN; no 1,6-diphosphates D-hexoses as co-factors required) ), finally PNP. activities D-arabinose, D-ribose D-xylose syntheses relevant nucleosides 2-deoxy-2-fluoro-D-arabinose. As expected, exhibited best activity [90% 2-chloroadenosine 8 30 min], D-arabinose reached an equilibrium at concentration 1:1 starting base formed 2-chloro-9-(β-D-arabinofuranosyl)adenine 6 45 min, 2-chloro-9-(β-D-xylofuranosyl)adenine 7 proceeded very slowly attaining 8% 48