Patent ID: 6936444

Claim:
A process for preparing L-2-amino-4-(hydroxymethylphosphinyl)butyric acid (L-phosphinothricin, L-PPT) of the formula (I), its derivatives which are selected from the group of carboxylic esters and carboxamides and phosphinic esters and/or its respective salts from 4-(hydroxymethylphosphinyl)-2-oxobutyric acid (HMPB, PPO) of the formula (II) its derivatives which are selected from the group of carboxylic esters and carboxamides and phosphinic esters and/or its respective salts as acceptor by enzymatic transamination in the presence of aspartate as donor, where the transamination takes place in the presence of one or more acceptor-specific aspartate transaminase(s) (Asp-TA) which transaminase(s) catalyze the direct transfer of the a-amino group from aspartate to 4(hydroxymethylphosphinyl)-2-oxybutyric acid (HMPB, PPO) or its derivatives to give oxaloacetate and the compound of the formula (I), its derivatives and/or salts.