Abstract: The present invention discloses an improved process for preparing an important intermediate of linagliptin. In particular, disclosed are a process for preparing a compound V which is an important intermediate of linagliptin and has the structure V, and an industrial process of preparing linagliptin having excellent chemical and optical purities, which is an inhibitor of dipeptidyl peptidase-4 (DPP-IV), from the compound V. The process employs a phase-transfer catalyst, is high in yield, easy and simple to handle, environmentally friendly, suitable for industrial mass production, and can be implemented by a “one-pot process”.

Abstract: The present invention discloses an improved process for preparing an important intermediate of linagliptin. In particular, disclosed are a process for preparing a compound V which is an important intermediate of linagliptin and has the structure V, and an industrial process of preparing linagliptin having excellent chemical and optical purities, which is an inhibitor of dipeptidyl peptidase-4 (DPP-IV), from the compound V. The process employs a phase-transfer catalyst, is high in yield, easy and simple to handle, environmentally friendly, suitable for industrial mass production, and can be implemented by a “one-pot process”.

Abstract: The chiral compound S-5-substituted-N-2?-(thienyl-2-yl-)ethyl-tetralin-2-amine or its chiral acid salts and preparation method thereof are disclosed, and the method for preparing Rotigotine by using the chiral compound is also disclosed. Racemic 5-substituted-N-2?-(thien-2-yl-)ethyl-tetralin-2-amine (compound 1) is resolved by using a conventional chiral acid to obtain an optically pure chiral acid salt of S-5-substituted-N-2?-(thien-2-yl-)ethyl-tetralin-2-amine, which is then dissociated to obtain S-5-substituted-N-2?-(thien-2-yl-)ethyl-tetralin-2-amine (compound 2). The compound 2 or chiral acid salt thereof is alkylated and deprotected to produce rotigotine (compound 5).

Abstract: The chiral compound S-5-substituted-N-2?-(thienyl-2-yl-)ethyl-tetralin-2-amine or its chiral acid salts and preparation method thereof are disclosed, and the method for preparing Rotigotine by using the chiral compound is also disclosed. Racemic 5-substituted-N-2?-(thien-2-yl-)ethyl-tetralin-2-amine (compound 1) is resolved by using a conventional chiral acid to obtain an optically pure chiral acid salt of S-5-substituted-N-2?-(thien-2-yl-)ethyl-tetralin-2-amine, which is then dissociated to obtain S-5-substituted-N-2?-(thien-2-yl-)ethyl-tetralin-2-amine (compound 2). The compound 2 or chiral acid salt thereof is alkylated and deprotected to produce rotigotine (compound 5).