1: anhydrous 1-octyne With methylmagnesium bromide in tetrahydrofuran T=0 - 60°C; 4 h; Inert atmosphere; 2: With anhydrous iron chloride; lithium bromide in tetrahydrofuran T=0°C; 0.5 h; Inert atmosphere; 3: isopropenyl bromide in tetrahydrofuran T=0 - 60°C; 24 h; Inert atmosphere;