| 摘要 |
This invention relates to a process for the preparation of derivatives having the formula: <IMAGE> in which R is hydrogen or the carboxy group, comprising reacting a compound of the formula <IMAGE> with nitrous acid, to give, respectively, the compounds of the formulae: <IMAGE> and then removing the nitroso group from the compounds of the formulae (V) and (VI), respectively, either by reaction with an acid, to give the derivatives of the formulae (I) and (II), respectively, in which R is hydrogen, or by reaction with an alkali metal hydroxide and subsequent neutralization, to give the derivatives of the formulae (I) and (II), respectively, in which R is the carboxy group. |
