Chiral liquid‐crystalline poly(ester/β‐sulfoxide)s by asymmetric oxidation of prochiral nematic poly(ester/β‐sulfide)s

A new class of prochiral liquid‐crystalline poly(ester/β‐sulfide)s 2 and 3 containing the SC6H4S group was prepared, which were then asymmetrically oxidized to chiral liquidcrystalline poly(ester/β‐sulfoxide)s 4 and 5 comprising the {article}{empty}{document}--- S^ * ( O )--- C₆ H₄ --- S^ * ( O )---{document} group. A chiral 2‐sulfonyloxaziridine 6 was used as the asymmetric oxidant and the reaction is highly chemoselective with quantitative yield. A 13C NMR analysis of a model poly(ester/β‐sulfoxide) 8 is performed, which allows to evaluate the asymmetric induction and the enantiomeric excess for the asymmetric oxidation product. While the parent polymers 2 and 3 are nematic, the chiral modified polymers 4 and 5 are cholesteric.