| 摘要 |
The compounds of formula I' are prepared by cyclisation of the compounds of formula V in the presence of a basic agent. R<1> to R<4> represent H or a hydrocarbon radical, R<5> represents an alcohol residue and Y and Z each represent H or a halogen. R<1> and R<2> or R<1> and R<3> can be joined to form a ring with the C atoms to which they are fixed. The compounds of formula V are obtained by reaction of a 1-halo-3-alken-2-ol of formula II in which X represents a halogen with an orthocarboxylic ester of formula III. This process leads to the products of formula I' by a more economical route than the prior processes. <IMAGE> |
