反应详情

Advantageously, compared to this preparation which comprises six steps in all, the preferred process for the purposes of the invention, which is faster and more economical, enables (S)-(-)-2-amino-2-(3,4-dichlorobenzyl)-1-propanol to be prepared in four synthesis steps from 3,4-dichlorophenylacetone. Essentially, the process consists in reacting the ketone by the Bucherer-Berg reaction with potassium cyanide and ammonium carbonate to obtain (+/-)-5-(3,4-dichlorobenzyl)-5-methylhydantoin, which is subjected in an alkaline aqueous-acetone medium to a stereospecific salification with (R)-(+)-α-methylbenzylamine so as to obtain the addition salt thereof with the (S)-(-) enantiomer of the hydantoin, which, being insoluble, is filtered off, and from which (S)-(-)-5-(3,4-dichlorobenzyl)-5-methylhydantoin is obtained in a state of optical purity greater than 98% by treatment in an acid solution.

1. customto obtain the addition salt
2. filtrationis filtered off