A process for the preparation of the compounds of the formula (I), or salts thereof, wherein R represents a hydrogen atom or difluoromethanesulfonyl, characterized in that compounds of the formula (II), or salts thereof, wherein R has the same definition as aforementioned, and n represents 0 or 1, are reacted in the presence of hydrogen peroxide and acetic acid.
                            一种制备式(I)化合物或其盐的方法,其中R代表氢原子或二
氟甲磺酰基,其特征在于在
过氧化氢和
乙酸的存在下,式(II)化合物或其盐被反应,其中R具有与上述相同的定义,n代表0或1。