Dr. Reddy's Laboratories, Incorporated

Glenmark Pharmaceuticals Limited

Sunil Kumar Singh

Shekhar Bhaskar Bhirud

Sachin Srivastava

Jangalgar Tirupathy Reddy

Gurram Ranga Madhaven

Velagala V R M K Reddy

Potlapally Rejender Kumar

The present invention provides a process for the preparation of linagliptin, a compound of Formula I, the process comprising deprotecting a compound of Formula II wherein Rand Rtogether 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 Rsubstituents selected from the group consisting of halogen, alkyl, nitro and amino; or Ris H and Ris selected from the group consisting of trialkylsilyl, 2-trialkylsilylethoxycarbamates, acetyl, trihaloacetyl, 9-fluorenylmethoxycarbonyl, trityl, alkylsulfonyl, arylsulfonyl, diphenylphosphine and sulfonylethoxycarbonyl. 

Process for the preparation of dipeptidylpeptidase inhibitors

Provided is a process for the preparation of linagliptin of Formula I, comprising deprotecting a compound of Formula II wherein Rand Rtogether 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 Rsubstituents selected from the group consisting of halogen, alkyi, nitro and amino; or Ris H and Ris selected from the group consisting of trialkylsilyl, 2-trialkylsilylethoxycarbamates, acetyl, trihaloacetyl, 9-fluorenylmethoxycarbonyl, trityl, alkylsulfonyl, arylsulfonyl, diphenylphosphine and sulfonylethoxycarbonyl. 

The invention provides a process for preparing R-(+)-2-(4-hydroxyphenoxy)-2-methyl-butyric acid methyl ester of the formula (I): Various embodiments and variants are provided. The invention also provides a process for preparing S-(&#x2212;)-2-(4-hydroxyphenoxy)-2-methyl-butyric acid methyl ester of the formula (II) Various embodiments and variants are provided.

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Hyderabad Telangana, India

Sunil Kumar Singh