Abstract: A process for preparing a compound of formula (IV): ##STR1## comprising a) contacting an oxazoline compound of formula (I): ##STR2## wherein Z is as defined hereinbefore, with a reagent capable of causing an equilibrium between oxazoline compound (I) and an oxazoline compound of formula (II) described herein, and the reagent drives the equilibrium toward oxazoline compound (II) by preferential precipitation of oxazoline compound (II);b) contacting compound (II) with a fluorinating agent to give a fluorinated oxazoline compound of formula (III) described herein; andc) hydrolyzing the compound of formula (III) to formula (IV). In an alternative embodiment, the process is directed toward a process for preparing oxazoline (II) in a single step.

Abstract: The present invention comprises a process for the asymmetric synthesis of florfenicol, thiamphenicol or chloramphenicol, from a derivative of trans-cinnamic acid, comprising the steps:(a) converting the acid to an acid chloride using a chlorinating agent, and reducing the acid chloride to a trans allylic alcohol with a reducing agent;(b) asymmetrically epoxidizing the allylic alcohol of step (a), by reacting with t-butylhydroperoxide in the presence of a chiral epoxidation catalyst prepared from titanium (IV) isopropoxide and L-diisopropyltartaric acid, to form a chiral epoxide;(c) regioselectively opening the epoxide of step (b) by sequentially treating with sodium hydride, zinc chloride and dichloroacetonitrile to form an oxazoline;(d) stereoselective inversion/isomerization of the oxazoline of step (c) by sequentially treating with: (i) a lower alkylsulfonyl chloride and a tertiary amine base; (ii) sulfuric acid and water; (iii) an alkali metal hydroxide; to form an oxazoline;(e) optionally treating the ox