Use of 2-oxazolidinones as latent aziridine equivalents. III. Preparation of N-substituted piperazines

A number of N-aryl and N-alkyl substituted piperazines 1 were prepared from variously substituted 2-oxazolidinone derivatives 3. The method involved treatment of 3 with HBr in glacial acetic acid followed by heating the resulting ring-opened salts 5 in alcoholic solvent. The piperazines 1a-1q were isolated by crystallization in yields ranging from 23-91%.