*3.5. ECD Calculation*

Firstly, ECD calculations of compounds **1**–**3** and **14**–**15** were performed by the Gaussian 09 program and Spartan'14. Next, the conformations with a Boltzmann population (>5%) were selected for optimization and calculation in methanol at B3LYP/6-31+G (d, p). Finally, the ECD spectra were generated by the program SpecDis 1.6 (University of Würzburg, Würzburg, Germany) and drawn by OriginPro 8.0 (OriginLab, Ltd., Northampton, MA, USA) from dipole-length rotational strengths by applying Gaussian band shapes with sigma = 0.30 eV [29,30].
