** (0.00 mM), *rac*-**0a** (0.00 mM), **0b**·(*R*,*R*)-**0a** (0.00 mM), **0b**·(*S*,*S*)-**0a** (0.00 mM), **0b**·(*R*,*R*)-**0a** (0.00 mM), **0b**·(*S*,*S*)-**0a** (0.00 mM) and a mixture of **0b** (0.00 mM) and two equivalents of *rac*-**0a** (0.0 mM) and *rac*-**0a** (0.0 mM) in CDCl~0~ at 00 °C. Full-scale spectra are shown in [Supplementary Fig. 00](#S0){ref-type="supplementary-material"}. (**b**) CD (upper) and absorption (bottom) spectra (0.00 mM) of **0b**