(EN) The present invention relates to synthesis of [3-amino acid derivatives and its salts of formula by a novel process. The process comprises the reduction of a protected or unprotected prochiral (3-amino acrylic acid or derivative there of, by using borane containing reducing agents at atmospheric pressure. The resulting racemic [3- amino compound is resolved to a pure stereoisomer of formula (I), specifically to (2R)-4- oxo-4-[3-(trifluoromethyl)-5,6-dihydro[ 1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]- l -(2,4,5- trifluorophenyl)butan-2-amine. In an embodiment the invention disclosed polymorphic forms, phosphate": salt and also a Dibenzoyl-L-tartaric acid salt.