VERFAHREN ZUR HERSTELLUNG OPTISCH AKTIVER 1,3- IMIDAZOLIDIN-4-ONE

2.1. The said compounds are to be prepared as economically and cleanly as possible. Depending on the costs of the starting compounds, an optimisation should be possible with respect to the necessary process steps, the yield and/or the purity. Complicated process steps such as extractions and problematical solvents such as dichloromethane should particularly be dispensed with. 2.2. The 1,3-imidazolidin-4-ones of the general formula are obtained pure in their preparation, in particular by precipitation, it being possible to employ an optically active acid to 0.5 - 0.8 eq for resolving the racemate. The undesired enantiomer can be racemised in an inert solvent, and the cyclisation to the imidazolidinone can even be carried out by means of the optically active acid, after which the resolution of the racemates takes place directly. 2.3. The 1,3-imidazolidin-4-ones are useful starting materials for the preparation of branched or unbranched, proteinogenic or non-proteinogenic alpha -aminoacids by means of diastereoselective alkylation and subsequent ring cleavage.