2H,5H-Pyrano[4,3-b]pyranyl Mupirocin Methyl Ester

2H,5H-Pyrano[4,3-b]pyranyl Mupirocin Methyl Ester is an intermediate in the synthesis of 2H,5H-Pyrano[4,3-b]pyranyl Mupirocin Sodium Impurity (P840550), which also a mupirocin (M794000) impurity. The rearrangement isomer of Mupirocin is prepared using an enzyme-catalyzed, selective deesterification.