A process for the preparation of a compound of formula (I) or a pharmaceutically acceptable salt thereof:
wherein R₁, R₂ and R₃ are as defined in formula (A); and in which any OH groups in R₁, R₂ and/or R₃ may be in the form of O-acyl, phosphate, cyclic acetal or cyclic carbonate derivatives thereof;
which process comprises the ring closure of a compound of formula (II):
wherein Ra is amino or a group or atom convertible thereto; Rb is amino or an amino derivative and R₁′, R₂′ and R₃′ are R₁, R₂ and R₃ respectively or R₁, R₂, and/or R₃ wherein OH group(s) is/are protected; and thereafter converting Ra when other than amino, to amino; R₁′ to R₁, R₂′ to R₂ and/or R₃′ to R₃ when necessary and/or optionally forming a pharmaceutically acceptable salt or derivative thereof as defined.
一种制备式(I)化合物或其药学上可接受的盐的方法:其中R₁,R₂和R₃如式(A)所定义;并且在其中R₁,R₂和/或R₃中的任何OH基团可以是其O-酰基,
磷酸酯,环状
缩醛或环状
碳酸酯衍
生物的形式;该方法包括闭环化合式(II)的步骤:其中Ra是
氨基或可转化为
氨基的基团或原子;Rb是
氨基或
氨基衍
生物,R₁',R₂'和R₃'分别是R₁,R₂和R₃或R₁,R₂和/或R₃,其中OH基团受到保护;然后在Ra不是
氨基的情况下将其转化为
氨基;必要时将R₁'转化为R₁,R₂'转化为R₂和/或R₃'转化为R₃,并/或形成药学上可接受的盐或其衍
生物。