A process for producing proline derivatives of formula (1) below or acid adduct salts thereof, including: the step of reacting N-protected pyrrolidinones of formula (2) below with reducing agents to thereby obtain N-protected pyrrolidinols of formula (3) below (step A); the step of reacting the N-protected pyrrolidinols obtained in the step A with cyanating agents to thereby obtain N-protected cyanopyrrolidines of formula (4) below (step B); the step of reacting the N-protected cyanopyrrolidines obtained in the step B with alcohols and bases to thereby obtain imidates of formula (5) below and treating the imidates with acids to thereby obtain N-protected prolines of formula (6) below (step C); and the step of treating the N-protected prolines obtained in the step C with acids (step D). In formulas (1)-(6) below, any two out of R
1
, R
2
, R
3
, R
4
, R
5
and R
6
are bonded with each other to thereby form an optionally substituted C
1
-C
4
polymethylene; and R
7
is an optionally substituted C
1
-C
10
linear alkyl, etc.
                            以下是生产公式(1)的脯
氨酸衍
生物或其酸加合物的过程,包括:将公式(2)的N-保护
吡咯烷酮与还原剂反应以获得公式(3)的N-保护
吡咯烷醇(步骤A);将步骤A中获得的N-保护
吡咯烷醇与
氰化剂反应以获得公式(4)的N-保护
氰基
吡咯烷(步骤B);将步骤B中获得的N-保护
氰基
吡咯烷与醇和碱反应以获得公式(5)的
咪唑酯,并用酸处理
咪唑酯以获得公式(6)的N-保护脯
氨酸(步骤C);将步骤C中获得的N-保护脯
氨酸用酸处理(步骤D)。在下面的公式(1)-(6)中,R1,R2,R3,R4,R5和R6中的任意两个可以彼此结合以形成可选的取代C1-C4聚亚甲基;而R7是可选的取代C1-C10线性烷基等。