Provided is a process for the preparation of linagliptin of Formula I, comprising deprotecting a compound of Formula II wherein R1 and R2 together with the nitrogen to which they are attached form a phthalimido group, wherein the aromatic ring of the phthalimido group is substituted with one or more R3 substituents selected from the group consisting of halogen, alkyi, nitro and amino; or R1 is H and R2 is selected from the group consisting of trialkylsilyl, 2-trialkylsilylethoxycarbamates, acetyl, trihaloacetyl, 9-fluorenylmethoxycarbonyl, trityl, alkylsulfonyl, arylsulfonyl, diphenylphosphine and sulfonylethoxycarbonyl.
提供的是制备化合物I的linagliptin的过程,包括去保护化合物II的步骤,其中R1和R2与它们连接的氮形成一个邻二苯
酰亚胺基团,其中邻二苯
酰亚胺基团的芳香环被一个或多个R3取代基替换,所述取代基选择自卤素,烷基,硝基和
氨基的群体中的一个或多个;或者R1为H,R2选择自三烷基
硅基,2-三烷基
硅基乙氧基羰基,乙酰基,三卤代乙酰基,9-
芴甲氧羰基,三苯甲基,烷基磺酰基,芳基磺酰基,
二苯基膦和磺基乙氧羰基的群体中的一个。