Preparation of specifically-labelled buspirone -14C and buspirone - 15N2

Buspirone 1 is a novel, clinically effective anxiolytic agent which is devoid of the sedative, anticonvulsant or muscle relaxant properties normally associated with the benzodiazepines. Buspirone labelled with both radioactive (14C) and stable (15N) isotopes was required in order to investigate the metabolism of the compound. The synthesis of both labelled compounds beginning with either urea - 14C or urea - 15N2 is described.