Fig. 5: Computational studies and mechanistic consideration.

a Calculated rotational barriers for 3aa, 5aa, and 7aa. b X-ray crystal structures of 3ba, 3ld, and 7da. c Calculated and experimental ECD spectra of 3aa, 5aa, and 7aa. d Transition state structures for synthesizing 3aa, 5aa, and 7aa. (All H atoms are omitted for clarity).