METHOD FOR PRODUCING MINERAL ACID SALT OF CIS-4-AMINO-2- CYCLOPENTENECARBOXYLIC ACID

PROBLEM TO BE SOLVED: To establish a method for economically and safely producing a mineral acid salt of cis-4-amino-2-cyclopentenecarboxylic acid in high yield without isolating 2-azabicyclo[2.2.1]hept-5-en-3-one obtained from cyclopentadiene and a sulfonyl cyanide. SOLUTION: This method for producing the mineral acid salt of the cis-4- amino-2-cyclopentenecarboxylic acid is characterized by reacting the substituted sulfonyl cyanide represented by the general formula (1) R-SO2 CN (1) (wherein, R denotes an alkyl group, phenyl group which may have a substituent group or benzyl group which may have a substituent group) with the cyclopentadiene in a ketonic solvent and adding the resultant reactional mixture to an aqueous solution of the mineral acid.