D-ARBINOSE-BASED SYNTHESIS OF HOMO-C-d4T AND HOMO-C-THYMIDINE

2,3,5-Tri-O-benzyl-D-arabinofuranosyl halides (chloride, bromide) were reacted with AllMgBr; MeMgBr, and VinMgBr to furnish anomeric mixtures of the C-glycosyl products. The factors that influenced the beta/alpha ratio are discussed. The alpha,beta-C-vinyl derivative was transformed into 1-deoxy-1-C-hydroxymethyl-beta- and -alpha-D-arabinofuranoses (2,5-anhydro-D-glucitol and -mannitol, ;respectively), separable after isopropylidenation step. 2,5-Anhydro-1,3-O-isopropylidene-D-glucitol was converted into 2,5-anhydro-6-O-triphenylmethyl-D-erythro-hex-3,4-enitol and 2,5-anhydro-4,6-di-O-benzoyl-3-deoxy-D-ribo-hexitol, which were coupled. with N-3-benzoylthymine under the Mitsunobu conditions to furnish two analogs of nucleosides with a -CH2- insert between sugar moieties and thymine. [GRAPHICS] .