Substituted 1,3-oxathiolanes, such as cis- and trans-2-ethoxycarbonyl-5-hydroxy-1,3-oxathiolane
and cis- and trans-2-ethoxycarbonyl-5-acetoxy-1,3-oxathiolane, are suitable as
intermediates for the production of substituted 1,3-oxathiolanes nucleoside analogs
having antiviral properties.