An improved synthesis of benzyl 3,5-di-O-benzyl-2-deoxy-1,4-dithio-D-erythro-pentofuranoside, an intermediate in the synthesis of 4'-thionucleosides

Article abstract of DOI:10.1016/0008-6215(92)84165-O

Treatment of methyl 3,5-di-O-benzyl-2-deoxy-α,β-D-erythro-pentofuranoside with α-toluenethiol and conc. hydrochloric acid gave 3,5-di-O-benzyl-2-deoxy-D-erythro-pentose dibenzyl dithioacetal (21).Mesylation of 21 and ring closure gave benzyl 3,5-di-O-benzyl-2-deoxy-1,4-dithio-α,β-L-threo-pentofuranoside.Inversion of configuration at C-4 of 21 was achieved by the Mitsunobu reaction, to produce 4-O-benzoyl-3,5-di-O-benzyl-2-deoxy-L-threo-pentose dibenzyl dithioacetal.Successive debenzoylation, mesylation, and ring closure then gave the title compound.Several new dithioacetal derivatives of 2-deoxy-D-erythro-pentose were prepared in exploratory routes to the described thio sugar or as intermediates.