Patent ID: 7741507

Claim:
An organic acid salt of N-[(2′-cyanophenyl-4-yl)methyl]-(L)-valine ester of formula (IV) wherein R 1 represents C 1 —C 4 alkyl selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, and 2-methylpropyl, or benzyl, and S represents organic acid selected from the group consisting of oxalic acid, acetic acid, formic acid, malic acid, maleic acid, malonic acid, succinic acid, fumaric acid, phthalic acid, terephthalic acid, citric acid, tartaric acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, trifluoroacetic acid, and ascorbic acid.