4.2. General procedure for the synthesis of amino oxazolines
In a 100 mL two-necked flask, anhydrous zinc chloride
(10 mol %) was prepared by melting under high vacuum. After
cooling to room temperature under nitrogen, dry chlorobenzene
(10 mL), isatoic anhydride or N-alkyl isatoic anhydride (1 equiv)
and L-amino alcohol (1.2 equiv) were charged to this flask under
nitrogen. The mixture was then refluxed for 24 h. The solvent
was then removed under reduced pressure and the oily residue
was dissolved in dichloromethane (25–30 mL). The solution was
washed three times with water (3 20 mL) and the aqueous phase
was extracted again with dichloromethane (2 20 mL). The com-
bined organic phase was dried over anhydrous sodium sulfate
and the solvent was removed in vacuo. The resulting oil was puri-
fied by column chromatography on neutral alumina using light
petroleum ether as the eluent to afford a pure product.