An improved process for making a compound B of the structure
wherein n, R
1
, R
2
, and R
3
are as defined in the specification. Compound B can be used to make tubulysin analogs that are, in turn, useful as anti-cancer agents, particularly when deployed in an antibody-drug conjugate.
一种改进的制备化合物B的方法,其中n,R1,R2和R3如规范中所定义。化合物B可用于制备图布林类似物,进而作为抗癌药物使用,特别是当其用于
抗体药物结合物中时。