| 摘要 |
The present invention relates to a process for the preparation of compounds of formula (I)wherein R, Rand Rare each independently of the others hydrogen or C-Calkyl, by a) reacting compounds of formula (II)wherein R, Rand Rare as defined for formula (I) and X is bromine or chlorine, with a compound of formula (III)wherein Ris hydrogen or C-Calkyl, in the presence of a base and catalytic amounts of at least one palladium complex compound, to form compounds of formula (IV)wherein R, Rand Rand Rare as defined for formula (I), and b) converting those compounds, using a reducing agent, into compounds of formula (I). |
