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Polymorphs

  • US 9,815,837 B2
  • Filed: 10/05/2016
  • Issued: 11/14/2017
  • Est. Priority Date: 05/04/2006
  • Status: Active Grant
First Claim
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1. A method of preparing polymorph C of the compound 1-[(4-methyl-quinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-(3-(R)-amino-piperidin-1-yl)-xanthine, the method comprising:

  • (a) refluxing a solution of 1-[(4-methyl-quinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-(3-(R)-amino-piperidin-1-yl)-xanthine in methanol to provide a hot methanolic solution,(b) cooling the hot methanolic solution to a temperature of 40-60°

    C. to provide a cooled methanolic solution,(c) adding tert-butylmethylether to the cooled methanolic solution to form a suspension,(d) cooling the suspension first to a temperature of 15-25°

    C. and then to a temperature of 0-5°

    C. to provide crystals,(e) suction filtering the crystals, and(f) drying the crystals obtained in step (e) in vacuo at a temperature of 70°

    C. to provide Polymorph C,wherein Polymorph C loses water at a temperature of 30-100°

    C. and exhibits further thermal effects at a temperature of about 150°

    C. and about 175°

    C. in a differential scanning calorimetry (DSC) analysis.

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