7-Functionalized 7-deazapurine beta-D and beta-L-ribonucleosides related to tubercidin and 7-deazainosine: glycosylation of pyrrolo[2,3-d] pyrimidines with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D or beta-L-ribofuranose

Abstract

Several 7-functionalized 7-deazapurine ribonucleosides were prepared. Glycosylation of 7-halogenated 6-chloro-7-deazapurines with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose or 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-L-ribofuranose gave the protected beta-D-nucleosides 8c-e (53-62%) and the beta-L-nucleosides 9b-e (57-72%), which were transformed to 7-halogenated 7-deazapurine ribonucleosides related to tubercidin and 7-deazainosine. 7-Alkynyl derivatives (1f,g) and (2f,g) were obtained from the 7-iodo nucleosides 1e and 2e employing the palladium-catalyzed Sonogashira cross-coupling reaction. Within the series of 7-deazaadenosine ( tubercidin) analogues and 7-deazainosine derivatives physical data such as pK(a) values, chromatographic mobilities, C-13 NMR chemical shifts were determined and correlated to each other. (C) 2007 Elsevier Ltd. All rights reserved.