Process for the enantioselective preparation of phenylisoserine derivatives

Process for the enantioselective preparation of phenylisoserine derivatives of formula (I) ##STR9## in which R is a phenyl or tert-butoxy radical and R.sub.1 is a protecting group for the alcohol group, comprising treating S(+)-phenylglycine with a reducing agent and an agent for introducing a benzoyl or t-butoxycarbonyl group to give an alcohol of formula V ##STR10## in which R is as defined above, which is oxidized and then reacted with a vinylmagnesium halide to give a product of the formula (VI) ##STR11## in which R is as defined above, the hydroxyl group of which is then protected by a group R.sub.1 to give a product of formula (VII) ##STR12## in which R and R.sub.1 are as defined above, which is oxidized to the product of formula (I).