Synthesis of 3-substituted (azido, acylthio, chloro or fluoro)-2,3-dideoxy-D-erythro-pentoses and 3-methyl-3-substituted-2,3-dideoxy-D-erythro-pentoses

Abstract The enantioselective synthesis of 3-substituted and 3-methyl-3-substituted 2,3-dideoxy-D- erythro -pentoses from (3 R ,4 R )-1,1-diethoxy-3,4-epoxypentane-5-ol, (3 R ,4 R) -1,1-diethoxy-3,4-epoxy-3-methylpentane-5-ol and (2 R ,3 R )-2,3-epoxy-5-hexen-1-ol is reported. The key step is cleavage of the oxirane ring by Ti(O- i -Pr) 3 X class reagents followed by selective cyclization of the acyclic acetals to the furanosides. Fluorination with the complex of titanium (IV) iso -propoxide - titanium (IV) fluoride provides an enantioselective synthesis of 3-fluoro-2,3-dideoxy-D- erythro -pentose and 3-fluoro-3-methyl-2,3-dideoxy-D- erythro -pentose.