Multimilligram scale production implementation of atropisomers of 2,2’-bis(2,2’-bithiophene-5-yl)-3,3’-bithianaphthene

2,20-Bis[2-(5,20-bithienyl)]-3,30-bithianaphthene (1) is the progenitor of a class
of C2 symmetric thiophene-based electroactive monomers that, when electrooxidized
in the enantiomerically pure form, produce inherently chiral films
endowed with outstanding electrochemical enantiorecognition properties. The
enantioselective high-performance liquid chromatography (HPLC) is the only
approach used so far to resolve the racemic form of 1 into enantiomers. In this
work, an improved HPLC method for multimilligram enantiomer production
is presented. Key factors controlling the enantioseparation, such as mobile
phase composition and column temperature, were identified using a
100 × 4.6 mm i.d. Chiralpak IB-3 column and subsequently scaled up to a
250 × 10.0 mm i.d. Chiralpak IB column. In the optimized semipreparative
conditions, about 34 mg of pure (P) and (M) enantiomers per hour could be
produced.