Pseudomonic acid was dissolved in isobutyl acetate (130 ml). Calcium oxide (0.29 g) was suspended in water (32 ml) and added to the solution of pseudomonic acid. The mixture was stirred for 2 hours, and the phases were separated. The volume of the aqueous phase was reduced to 15 ml by vacuum distillation. The mixture was cooled to 5° C. After stirring for 2 hours, the crystalline product was filtered and washed with cooled water (5 ml). The product was dried in an air circulated oven at RT. Mupirocin calcium dihydrate (3.3 g, 62%) was obtained.
