1: 1-bromospiro[5.5]undec-1-ene With tert.-butyl lithium in tetrahydrofuran; hexane T=-80°C; Inert atmosphere; 2: methyl vinyl ketone in tetrahydrofuran; hexane T=-80 - 20°C; Inert atmosphere; 3: With water in tetrahydrofuran; hexane T=20°C;