Synthesis of New Enantiopure Fluorinated Phenylcyclopropanecarboxylates – Potential Chiral Dopants for Liquid‐Crystal Compositions

The reaction of α‐fluorostyrene ( 1a ) with methyl phenyldiazoacetate in the presence of Rh 2 (OAc) 4 gave a 64:36 mixture of diastereomeric monofluorinated cyclopropanes 5a and 6a . When using chiral Rh II catalysts Rh 2 (TBSP) 4 ( 7 ) and Rh 2 (DOSP) 4 ( 8 ), the products were obtained enantioselectively in up to >99 % ee for both (1 R ,2 R )‐ 5a and (1 R ,2 S )‐ 6a . The fluorocyclopropane derivatives are of interest as dopants to induce chirality in liquid‐crystal mixtures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)