| abstract |
A process for producing proline derivatives of the formula (1) or acid adduct salts thereof, comprising the step of reacting N-protected pyrrolidinones of the formula (2) with reducing agents to thereby obtain N-protected pyrrolidinols of the formula (3) (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 the formula (4) (step B); the step of reacting the N-protected cyanopyrrolidines obtained in the step B with alcohols and bases to thereby obtain imidates of the formula (5) and treating the imidates with acids to thereby obtain N-protected prolines of the formula (6) (step C); and the step of treating the N-protected prolines obtained in the step C with acids (step D). (1)-(6) In the formulae, any two out of R1, R2, R3, R4, R5 and R6 are bonded with each other to thereby form an optionally substituted C1-C4 polymethylene; and R7 is an optionally substituted C1-C10 linear alkyl, etc. |