Potassium Hydroxide → Potassium 4-[{[(4-fluorophenyl)methyl]imino}(hydroxy)methyl]-1-methyl-2-{2-[(5-methyl-1,3,4-oxadiazole-2-carbonyl)amino]propan-2-yl}-6-oxo-1,6-dihydropyrimidin-5-olate

A vial (20 ml) was charged with Raltegravir free hydroxy (200 mg) slurry in EtOH:H2O (1000:1, 0.2 ml) at room temperature. The slurry was heated to 50° C. A solution of 45% aqueous KOH (0.044 ml) was added at 50° C. to the mixture. The resulting mixture was stirred for 5.5 h at 50° C. To this mixture was added distilled H2O (1.5 ml) dropwise to produce a colorless solution. The solvent was then removed under reduced pressure to provide wet Raltegravir potassium crystalline Form VI. The product was dried in a vacuum oven at 40° C. for 3.5 hours to provide Raltegravir potassium crystalline Form VI.