1: 3-chloro-2-methyl-propene With magnesium in tetrahydrofuran T=0 - 20°C; Inert atmosphere; 2: 4-bromo-benzyl bromide in tetrahydrofuran T=0 - 20°C; Inert atmosphere;

boron trifluoride diethyl etherate in dichloromethane T=25°C; 2 h; Yield given. Yields of byproduct given;