Simvastatin Dihydro Diol Impurity 

Chemical Name: [1S-[1α,3α,4β,6α,7β,8β(2S*,4S*),8aβ]]-Butanoic Acid 2,2-Dimethyl-1,2,3,4,6,7,8,8a- octahydro-4,6-dihydroxy-3,7-dimethyl-8-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl) ethyl]-1-naphthalenyl ester ;

Synonym: (3S,5S)-Dihydroxy Simvastatin