1: 2-methyl-but-3-yn-2-ol With n-butyllithium in tetrahydrofuran; hexane T=-30°C; 1 h; 2: cyclopentanone in tetrahydrofuran; hexane T=-30 - 20°C;

in tetrahydrofuran T=20 - 23°C;

diethyl ether anschliessend Behandeln mit Cyclopentanon;