Trifluoroacetic acid → (1R,3R)-3-aminocyclopentane-1-carbonitrile 2,2,2-trifluoroacetate

In a round-bottomed flask, ((1R,3R)-3-cyano-cyclopentyl)-carbamic acid tert-butyl ester (crude from Step 2) was dissolved in dichloromethane (2.5 ml). The solution was cooled to 0° C. and trifluoroacetic acid (1.1 ml, 14.3 mmol) was slowly added. After the addition was complete, the ice bath was removed and the reaction mixture was stirred at room temperature for 2 h then concentrated to give (1R,3R)-3-amino-cyclopentanecarbonitrile trifluoroacetate as a light brown oil which was used without further purification.