n-butyllithium; Mukayama reagent; diisopropylamine in tetrahydrofuran; hexane T=-78°C; 0.5 h;

1: oxazolidin-2-one With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 0.25 h; Inert atmosphere; 2: butyryl chloride in tetrahydrofuran; hexane T=-78 - 20°C; 2.5 h; Inert atmosphere;

sodium acetate