Elucidation of the opening of the epoxidic ring of the 3β-acetoxy-14α,15α-epoxy-5α-cholest-8-en-7-one by methanol, using NMR techniques assisted by a conformational study through theoretical calculations

This paper demonstrates that the crystallization of 3β-acetoxy-14α,15α-epoxy-5α-cholest-8-en-7-one from methanol affords the 3β-acetoxy-9α-methoxy-15α-hydroxycholest-8(14)-en-7-one. The structure of this steroid, which shows an apparently anomalous UV absorption maximum, is determined by high field NMR experiments, supporting the coupling constant values assignments and the NOE contacts by a conformational study through theoretical calculations at the B3LYP/6-31G* level. The computational study also justifies the observed UV absorption of the steroid, thus demonstrating the usefulness of computer chemistry in providing support for the identification of unknown compounds.