Reaction of adenine nucleosides, tosylated in the carbohydrate moiety, with lithium triethylborohydride

Abstract

The reaction of lithium triethylborohydride with the 2′,3′-di-O-p-tolyl-sulphonyl derivatives of 9-/bg-D-ribofuranosyladenine, 9-β-D-arabinofuranosyl-adenine, 9-β-D-xylofuranosyladenine and 9-β-D-lyxofuranosyladenine was studied. The reaction of 2′,3′-di-O-p-tolysulphonyladenosine with LiEt 3BH gave 9-(3-deoxy-β-D- threo -pentofuranosyl)adenine. This rearrangement reaction was used for the synthesis of 9-(3,5-dideoxy-β-D- threo -pentofuranosyl)adenine in one step from 2′,3′,5′-tri-O-p-tolylsulphonyladenosine in 58% yield. The p-tolylsulphonyl group in the 2′-“up” configuration of unprotected adenine nucleosides was preferentially attacked by LiEt 3BH giving SO-bond scission. This was shown by the formation of 9-(3-deoxy-β-D- threo -pentofuranosyl)adenine from 2′,3′,-dir-O-p-tolylsulphonyl-9-β-D-arabinofuranosyladenine and by the formation of 9-β-D-lyxofuranosyladenine from 2′-O-p-tolylsulphonyl-9-β-D-lyxofuranoslydenine with LiEt 3BH. 9-β-D-Lyxofuranosyldenine was synthesized from 3′,5′-di-O-benzoyl-9-β-D-xylofuranosyladenosine in 88% yield using a triflate displacement reaction.