The reaction of 3,5-difluorophenylacetic acid (I) with oxalyl chloride and DMF in dichloromethane gives the corresponding acyl chloride (II), which is condensed with L-alanine (III) by means of aqueous NaOH, yielding N-(3,5-difluorophenylacetyl)-L-alanine (IV). Finally, this compound is condensed with L-phenylglycine tert-butyl ester (V) by means of 2-ethoxy-1,2-dihydroquinoline-1-carboxylic acid ethyl ester (EEDQ) and NMM in THF.