| 摘要 |
Process for the preparation of compounds of the formula I <IMAGE> in which R<1> is C3, C4-alkyl and R<2> is (C1-C2)alkyl, by reacting a compound of the formula II <IMAGE> with the compounds of the formulae III and IV <IMAGE> in which R<1> and R<2> have the abovementioned meanings, characterised in that a mixture of the starting materials II-IV is passed continuously along an acid catalyst. |
