| 摘要 |
<p>BROMINATION PROCESS OF ERGOT ALKALOIDS The present invention provides a process for the production of a compound of formula I I wherein R1 is carboxyl, alkoxy(C1-5) carbonyl, amido, alkyl(C1-5)amido, di(alkyl(C1-5))amido or an amido radical of formula II II wherein Ra is alkyl(C1-4), Rb is alkyl(C1-4) or benzyl, and R2 is hydrogen or alkyl(C1-4), and either R3 is hydrogen and R4 is hydrogen or alkoxy(C1-4) or R3 and R4 together are a single bond, characterised in that a compound of formula III III wherein R1 to R4 are as defined above, is brominated with a bromine complex of 3-bromo-6-chloro-2-methyl-imidazo¢1,2-b!pyridazine.</p> |
