Separation of stereoisomeric n, n-dialkylamino-2-alkyl-3-hydroxy-3-phenylalkanes

The invention concerns a method for the isolation of a stereoisomer from a mixture comprising the two stereoisomers of the general formulae (I-A) and (I-A') and/or the two stereoisomers of the general formulae (I-B) and (I-B') in which R1, R2 and R3, identical or different, are selected from the group consisting of -H, -F, -Cl, -C1-C6-alkyl, -S-C1-C6-alkyl, -OH, -O-C1-C6-alkyl, -O-C1-C6-alkylenephenyl, -OCO-C1-C6-alkyl, -OCON(C1-C6-alkyl)2 and -O-SiR8R9R10 (in which R8, R9 and R10, identical or different, are -C1-C6-alkyl or -phenyl); R4 is -H or -C1-C6-alkyl; R5 is -C1-C6-alkyl; and R6 and R7, identical or different, are -H or -C1-C6-alkyl; or their salts with organic or inorganic acids; comprising the step (a) manipulating the mixture ratio of the stereoisomers in the mixture so that at least one of the stereoisomers is present in an enantiomeric excess.