Potassium Carbonate → Linagliptin

Participants

Reaction Conditions

Reaction Steps

1-[(4-Methyl-quinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-bromoxanthine (20 gm) and methyl isobutyl ketone (MIBK 200 mL) were charged into a 1000 mL round bottomed flask equipped with a mechanical stirrer. Potassium carbonate (18.3 gm) and (R)-piperidine-3-amine dihydrochloride (11.5 gm) were added to the reaction mixture at 30° C. The reaction mixture was heated to 95° C. and maintained at that temperature for 8 hours. The reaction mixture was cooled to 30° C. and filtered and washed with MIBK (40 mL). The filtrate was charged into another flask and added 10% aqueous acetic acid solution and stirred for one hour at room temperature. The aqueous layer was separated and washed with 60 mL of dichloromethane. The aqueous layer was charged into another flask and 200 mL of dichloromethane and 100 mL of aqueous sodium hydroxide solution was added drop-wise at 30° C. The mixture was stirred for one hour at 30° C. and the organic layer was separated and the aqueous layer was extracted with 100 ml of dichloromethane. Combined the organic layers and evaporated under vacuum at below 45° C. Isopropyl alcohol (100 mL) was added to the residue and stirred for 3 hours at room temperature. Filtered the compound and washed with isopropyl alcohol (20 mL) and dried the compound at below 60° C. under vacuum to give 17.6 gm of Linagliptin. PXRD pattern: FIG. 2, Purity: 99.0%

Provenance & Evidence