Sodium mycophenolate

The title compound, sodium 6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-ox oisobenzofuran-5-yl)-4-methylhex-4-enoate, Na+. C17H19O6-, is the sodium sa lt of the natural immunosupppressant compound mycophenolic acid. It consist s of a phthalide moiety carrying four different substituents on the aromati c ring. The anion has no intramolecular hydrogen bonds, but a very strong i ntermolecular hydrogen bond links the phenolic hydroxy group to the carboxy l group of a neighbouring anion found in the same layer. Within a distance of 2.71 Angstrom, the Na+ ion is surrounded by five O atoms from four diffe rent anions, forming a distorted square pyramid. This Na-O network forms an infinite two-dimensional system running parallel to the bc plane.