1: diethyl malonate With sodium methylate in methanol 1 h; Heating / reflux; 2: 1-(bromomethyl)cyclopentane in methanol 3 h; 3: With hydrogenchloride; sodium hydroxide; water more than 3 stages;

1: With sodium hydroxide in methanol; water 1 h; Heating / reflux; 2: With hydrogenchloride in water pH=1;