1: Hex-5-en-2-one N,N-dimethylhydrazone With n-butyllithium in tetrahydrofuran 0.5 h; 2: 4-bromo-but-1-ene in tetrahydrofuran T=-78°C; 0.5 h; 3: With hydrogenchloride in dichloromethane; water T=20°C; 10 h;

1.1: LDA / tetrahydrofuran / 20 h / 0 °C 1.2: 87 percent / tetrahydrofuran / 1 h / -78 °C 2.1: 84 percent / sodium metaperiodate; water; phosphate buffer / methanol / 25 °C / pH 7 3.1: formic acid; perchloric acid / 80 °C 3.2: 80 percent / Na2CO3; water / ethyl acetate View Scheme