Expanding the BT 2 T 4 Chiral Platform: Synthesis, Enantioseparation, and Absolute Configuration of the Hydroxymethylated Derivative BT
Tiziana Benincori, Sara Ghirardi, Camilla Loro, Clarissa Pupillo, Roberto CirilliABSTRACT
A novel π‐conjugated chiral system, BT 2 T 4 –(CH 2 OH) 2 , derived from the atropisomeric scaffold 2,2′‐bis[2‐(5,2′‐bithienyl)]‐3,3′‐bithianaphthene ( BT 2 T 4 ), was synthesized to provide terminal hydroxymethyl groups for further functionalization. Baseline enantioseparation was achieved by high‐performance liquid chromatography using the immobilized polysaccharide‐derived Chiralpak IB chiral stationary phase under medium‐polarity mobile‐phase conditions, which ensured adequate analyte solubility while maintaining excellent chiral recognition. The optimized protocol allowed the isolation of the individual enantiomers in high enantiomeric purity (ee > 99%). The absolute configuration of the separated enantiomers was assigned through a direct correlation between on‐line CD detection and CD spectra, providing a reliable stereochemical readout. Under specific synthetic conditions, additional minor species were detected; however, their formation was found to depend on reaction and handling parameters, such as the solvent, and can be minimized by conducting both the synthesis and storage in dichloromethane. Overall, BT 2 T 4 –(CH 2 OH) 2 represents a chiral π‐conjugated platform that offers potential applications in enantioselective recognition and in the development of chiroptical and sensing materials.