Structural elucidation of an unknown Simvastatin by-product in industrial synthesis starting from Lovastatin

Unknown by-product in Simvastatin synthesis from Lovastatin was found. The elucidation of this molecular structure by means of 1H and 13C NMR spectroscopy, HPLC/MS, MS/MS and FT-IR was shown. The mentioned by-product, originated during Merck Sharp and Dhome synthesis scheme was isolated in the second-last step replacing butylamine with benzylamine. The spectroscopic results agreed with a molecular formula C32H43NO3. The proposed structure of this compound, characterised by the presence of a conjugated dienic system in the heptanoic acid amide residue, was α,β,γ,δ unsaturated Simvastatin N-benzylamide.