toluene-4-sulfonic acid in methanol T=20°C;

1: (S)-5-triphenylmethoxymethyl-1,3-oxazolidin-2-one; alpha-bromoacetonitrile With potassium tert-butylate in tetrahydrofuran T=20°C; 1 h; 2: C25H22N2O3 With water; trifluoroacetic acid in dichloromethane T=20°C; 2 h;