Lovastatin EP Impurity D (Lovastatin Dimer)

(3R,5R)-(2R,4R)-2-(2-((1S,2S,6R,8S,8aR)-2,6-dimethyl-8-(((S)-2-methylbutanoyl)oxy)-1,2,6,7,8,8a-hexahydronaphthalen-1-yl)ethyl)-6-oxotetrahydro-2H-pyran-4-yl7-((1S,2S,6R,8S,8aR)-2,6-dimethyl-8-(((S)-2-methylbutanoyl)oxy)-1,2,6,7,8,8a-hexahydronaphthalen-1-yl)-3,5-dihydroxyheptanoate