1: (4R,5S)-4-hydroxy-5-(hydroxymethyl)dihydrofuran-2(3H)-one With 2-methyl-but-2-ene; dimethylsulfide borane complex in tetrahydrofuran T=20°C; 20 h; 2: aniline in ethanol; water T=5°C; 3 h;

1: disiamylborane<(Sia2BH)2> / tetrahydrofuran / 22 h / Ambient temperature 2: ethanol; H2O / 5 °C / overnight View Scheme