| 摘要 |
<p>A process of preparing a piperazic acid derivative of formula (1) wherein R represents an amino, hydroxyl or thiol group or an organic group as defined below and each of A and B represents a hydrogen atom or a non-interfering substituent, A and B being separate or joined directly together, so that together with the nitrogen atoms shown they form a fused ring group, in the form of a free base or an acid addition salt, the said process comprising: (a) reacting a valeric acid derivative of formula (3) wherein R represents an amino, hydroxyl or thiol group protected to prevent self-cyclisation of the valeric acid derivative into a lactam, lactone or thiolactone respectively, or an organic group which is not cleavable from the rest of the molecule in this reaction step and L represents a leaving group which is displaceable in the cyclisation step defined below, with a strong base under enolisation conditions to produce an enolate; (b) hydrazinating the enolate with a diazo compound of formula (5) wherein A and B are as defined above; (c) cyclising the product of the hydrazination; (d) optionally cleaving the R group from the cyclised product; and (e) optionally replacing the A and B substituents by hydrogen atoms, said steps (d) and (e) being carried out in either order or simultaneously.</p> |
