| abstract |
The present invention relates to a 2,5-disubstituted 2-amino-10b-hydroxy-3,6-dioxo-octahydro-8H-oxazolo [3,2-a] pyrrolo [2,1c] pyrazine hydrous of formula (I). for the preparation of the compounds of formula (II), the 2,5-disubstituted 2-isocyanato-10b-hydroxy of formula (II), wherein R1 and RJ are independently C1-C6 alkyl and X is halogen; -3,6-Dioxo-8H-octahydro-8H-oxazolo [3,2-a] pyrrolo [2,1c] pyrazine, wherein R1 and R2 are hydrolyzed as the corresponding acid in an acid medium containing the hydrogen halide of the desired hydrohalide. In this way, free of side reactions, high purity is obtained for the synthesis of the parent araloid alkaloids. -1- |