The space group of the obtained single crystal is C2221 (No. 20), which belongs to the Sohncke group. We randomly chose four single crystals and determined their enantiomeric excesses to be >99% ee (Figure ). These results indicate that during the crystallization of 2a it undergoes a spontaneous resolution to afford a conglomerate, which is informative for the development of a practical procedure that yields enantiopure 2a.