The condensation of N-(tert-butoxycarbonyl)-L-tert-butyl-glycine N-succinimidyl ester (I) with L-prolinamide (II) by means of DIEA in dichloromethane gives the dipeptide amide (III), which is dehydrated by means of POCl3 and imidazole in pyridine to yield N-(tert-butoxycarbonyl)-L-tert-butylglycyl-L-prolinenitrile (IV). Finally, this compound is deprotected by means of trifluoroacetic acid to provide the target dipeptide nitrile.