| 摘要 |
What is described is a process for preparing compounds of the general formula (I) in which R1, R2 and R3 independently of one another represent hydrogen, an alkyl group or an aryl group, wherein compounds of the general formula (II) in which R1 and R2 have the meaning given for formula (I), are reacted with an alkylating agent of the general formula (III) R3X  (III), in which X represents a halogen atom and R3 has the meaning given for formula (I), if appropriate in a solvent. |
