1: With n-butyllithium; zirconocene dichloride in tetrahydrofuran T=20°C; retro-Brook rearrangement; 2: With hydrogenchloride; water Hydrolysis;

Multistep reaction;

Multistep reaction;

1: 1-Phenyl-2-aza-3-trimethylsilyloxy-1,3-butadiene; 2C5H5(1-)*Cl2Zr(2+) With n-butyllithium in tetrahydrofuran; hexane T=-78 - 20°C; Metallation; retro-Brook rearrangement; 2: With n-butyllithium in tetrahydrofuran; hexane T=-78°C; Metallation; 1 h; 3: benzaldehyde in tetrahydrofuran; hexane T=-78 - 20°C; Petersen reaction; 3 h;