title: Synthesis of hydroxymethyl branched [3.2.0]bicyclic nucleosides using a regioselective oxetane ring-formation.
abstract: Two [3.2.0]bicyclic nucleosides, 35 and 34, with one and two hydroxymethyl substituents, respectively, have been efficiently synthesized. A protected (3'-C-vinyl-beta-D-allofuranosyl)thymine derivative 28 was easily prepared from diacetone-D-glucose and the thymine moiety was protected with a BOM-group. After the introduction of a leaving group in the 2'-position, the subsequent nucleoside 31 was used as the substrate for a stereoselective dihydroxylation and a regioselective oxetane ring-formation to give after deprotection the bicyclic nucleoside 34. The surprisingly efficient formation of an oxetane was first discovered by serendipity on a corresponding methylfuranoside derivative. The allo-configured bicyclic nucleoside 34 was easily shortened to a ribo-configured analogue 35 by a diol-cleaving reaction and subsequent reduction. Both 34 and 35 are conformationally restricted in the important intermediate 04'-endo conformation.
authors.affiliation: Nucleic Acid Center, Department of Chemistry, University of Southern Denmark, 5230 Odense M, Denmark.
authors.forename: Nanna K
authors.initials: NK
authors.lastname: Christensen
authors.forename: Ann Katrine L
authors.initials: AK
authors.lastname: Andersen
authors.forename: Trine R
authors.initials: TR
authors.lastname: Schultz
authors.forename: Poul
authors.initials: P
authors.lastname: Nielsen
mesh_terms: D004988:Ethers, Cyclic / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry / Q000379:methods; D009705:Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D004988:Ethers, Cyclic; D009705:Nucleosides; C005287:oxetane