| 摘要 |
A process for the production of a compound of formula (I), which comprises a) reacting a compound of formula (II), wherein Rand Rare both independently C-Calkyl, with methylhydrazine in the presence of water and a water-immiscible organic solvent being inert in saponification reactions, to form a compound of formula (III) wherein Ris as defined for formula (II) and b) saponifying that compoundleading to the formation of the compound of formula (I) by b1) adding a base to form the anion of the compound of formula (I) and then adding an; acid to form the compound of formula (I); or b2) adding an acid to form the compound of formula (I).
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