Varenicline Impurity 3 synthesis

Yield:-

Reaction Conditions:

with water;sodium hydroxide in methanol at 40 - 45; for 1 h;

Steps:

3.II

Step-II: Preparation of 6-Methyl-5, 8,14-triazatetracyclo[l 0.3.1.0²'ⁿ.0⁴'⁹]hexadeca- 2(1 l),3,5,7,9-pentaene (Methylvarenicline)l-(6-Methyl-5,8,14-triazatetracyclo[10.3.1.0²'ⁿ.0⁴'⁹]hexadeca-2(l l),3,5,7,9-pentaene)-2,2,2- trifluoro-ethanone (5 g, obtained in step-I) was slurried in methanol (50 ml), followed by treatment with sodium hydroxide (1.28 g) in water (25 ml). The mixture was heated at 40- 45°C for 1 hour and then concentrated under vacuum at below 45 °C, followed by treatment with water (50 ml) and adjusting the pH to 10 with glacial acetic acid at 25-30°C. The resulting mass was extracted with dichloro methane (2 x 50 ml), the organic layer was washed with water (50 ml) and then dried over anhydrous sodium sulfate. Dichloro methane was distilled out under vacuum, followed by crystallization in diisopropyl ether. The brownish color solid obtained was dried at 50-55°C to give 2.5 g of 6-methyl-5,8,14- triazatetracyclo[10.3.1.0²'ⁿ.0⁴'⁹]hexadeca-2(l l),3,5,7,9-pentaene (Purity by HPLC: 98.77%).

References:

WO2011/110954,2011,A1 Location in patent:Page/Page column 22-23