Electrochemical oxidation of chiral 5-substituted 2-oxazolidinones: A key building block for dichiral beta-amino alcohols

The 4-methoxylation of some chiral 5-substituted 2-oxazolidinones can be performed successfully by direct electrochemical oxidation at 50 mA/cm(2) in methanol at graphite electrodes using an undivided or quasi-divided cell and sodium tetrafluoroborate or sodium benzene sulfonate as supporting electrolytes. The yields and selectivities are depending on the pH of the solution and the concentration of the substrate. Thus, (4RS,5S)-chloromethyl-4-methoxy-2-oxazolidinone (7) could be obtained in 76% yield from (5S)-chloromethyl-2-oxazolidinone (3). Through nucleophilic methoxy-group exchange these heterocycles are key intermediates for enantiomerically pure trans-4,5-difunctionalized-2-oxazolidinones in both enantiomeric forms, which are very interesting targets due to their various pharmacological effects and as precursors for beta-amino alcohols and protease inhibitors. Copyright (C) 1996 Elsevier Science Ltd.