2 one and the like in the step iii reaction it is necessary to react the bicyclo 3 1 0 hexan 2 one derivative having the formula iii with a cyanating reagent in an alkaline condition the typical cyanating reagents include hydrogen cyanide acetone cyanohydrin and metal cyanides such as potassium cyanide sodium cyanide copper cyanide mercury cyanide aluminum cyanide etc it is necessary to carry out the reaction under basic condition when an alkali metal cyanide is used the basic condition can be attained by the addition of the alkali metal cyanide accordingly it is unnecessary to add the other alkaline compound when hydrogen cyanide is used the basic condition can be attained by adding a base such as sodium hydroxide potassium hydroxide sodium carbonate potassium carbonate triethylamine pyridine etc it is preferable to carry out the reaction in an inert solvent such as alcohols ethers and dimethylformamide n methylpyrrolidone acetonitrile dimethyl sulfoxide hexamethylphosphoric triamide etc the reaction can be smoothly performed at the room temperature without using a special heating means or a cooling means it is considered that the reaction mechanism using a metal cyanide is as follows str6 as shown in the reaction formula a partial ring cleavage of the bicyclo ring of the compound iii is carried out by the attack of cn anions of the.