1: spiropentyl bromide With tert.-butyl lithium in diethyl ether; pentane T=-78°C; Metallation; 1 h; 2: in tetrahydrofuran T=-110 - -40°C; complex formation; 20 h; 3: tert-butyl-acetyloxydiphenylmethyleneaminoacetate in tetrahydrofuran T=-10°C; Substitution; 6.5 h;