It was deduced empirically that

It was deduced empirically that the helix direction of the COOC torsion might relate to the sign of the peroxide Cotton effect. Huang reported ab initio calculation of the peroxide bond using MRDCI method and DZP basis set, but only the fragment CH3OOCH3 instead of full molecule was studied [19]. Since the peroxide bridge might interact with other chromophores to give a complex ECD profile, a systematic investigation of this Iberiotoxin mg correlation in various natural peroxides using TDDFT methodology is underway.
Conclusion In conclusion, ECD bands of 1 and 2 have been interpreted theoretically using modern quantum-chemical calculation via TDDFT methodology. The peroxide group can produce two significant rotatory strengths in the far-UV range due to the lowest-energy electronic transitions of HOMO→LUMO/LUMO+1 for 1, and HOMO−2/HOMO−1/HOMO→LUMO for 2. Interaction might occur between the lone pair electrons of the peroxide bridge and lactone. This work also showed larva the absolute configuration assignments of 1 and 2 could be unambiguously achieved by comparison of experimental and theoretical data.
Acknowledgments All quantum computations were carried out using Gaussian 09 package, on an IBM cluster machine located at the High Performance Computing Center of Peking Union Medical College. This study was supported by the Fundamental Research Funds for the Central Institutes of China (No. 2012ZD03).