| abstract |
A process for synthesizing a sitagliptin intermediate represented by formula I by asymmetric reduction, characterized in that it comprises the following steps: in the presence of hydrogen and a transition metal catalyst having a chiral phosphine ligand, a compound is subjected of formula II to an asymmetric reductive amination with ammonia or an ammonium salt in a suitable organic solvent with the condition of adding an acid additive to produce the intermediate of sitagliptin of formula I, with the following reaction formula: ** (See formula) ** where an R- or S- configuration of a stereocenter is represented by *; and where R1 and R2 are each independently selected from hydrogen, C1-C12 alkyl, linear or branched, C3-C12 cycloalkyl, C2-C12 alkenyl, C2-C12 alkynyl, and C7-C12 arylalkyl; and where the acidic additive is an organic acid selected from salicylic acid, tartaric acid, p-toluenesulfonic acid, or a combination of these compounds. |