Processes and intermediates for the preparation of piperazine derivatives

摘要

Compounds having the formulaR5O-A-NR4-R2(V)where R2 is a heteroaryl group linked to the remainder of the molecule via a carbon atom adjacent a nitrogen atom and R4 and R5 are both hydrogen atoms or together represent -SO- or -SO2- and A is C2-C4 alkylene optionally substituted by one or more lower alkyl groups are novel intermediates in the preparation of pharmaceutically useful piperazine derivatives as end compounds. The compounds having formula V where R4 and R5 are hydrogen may be prepared by a rearrangement of a compound having the formula (VI).R2O-A-NH2(VI)