Process for the alkylation of alkyl-or benzylcyanogen derivatives in the presence of trialkylamines or trialkylphosphines

A process for preparing a compound of formula I ##STR9## where R.sup.1 is 1. (C.sub.1 -C.sub.20)-alkyl,

• 2. (C.sub.1 -C.sub.20)-alkyl, which is mono-, di- or trisubstituted by
• 2.1. (C.sub.3 -C.sub.6)-cycloalkyl,
• 2.2. --OH,
• 2.3. (C.sub.1 -C.sub.6)-alkyl-C(O)--O--,
• 2.4. (C.sub.1 -C.sub.6)-alkyl-O--,
• 2.5. (C.sub.1 -C.sub.6)-alkyl-O--(C.sub.1 -C.sub.4)-alkyl-O--,
• 2.6. halogen,
• 2.7. --CF.sub.3,
• 2.8. --CN,
• 2.9. --NO.sub.2,
• 2.10. HO--C(O)--,
• 2.