H. Shitara et al., Synthesis of optically active 2-methylchroman derivatives and application to chiral dopants for nematic liquid crystals, B CHEM S J, 73(1), 2000, pp. 259-265
Chiral 2-methylchroman-2-carboxylic acid derivatives were prepared as new c
hiral dopants for nematic liquid crystals. The starting material, optically
active 6-benzyloxy-2-methylchroman-2-carboxylic acid, was newly synthesize
d as a rigid core structure and resolved by a diastereomeric salt formation
method. Its absolute configuration was determined by comparing its circula
r dichroism spectrum with that of the commercially available (S)-6-hydroxy-
2,5,7,8-tetramethylchroman-2-carboxylic acid derivative. The helical twisti
ng power of the new dopants was determined and the relationship between the
ir functional groups and flexible terminal structures was studied.