Anthracene–acetylene cyclic dimers having a methoxy or an ethoxy group at the intra-annular position were synthesized by cross-coupling reactions. DFT calculations suggested that the alkoxy–alkyl groups were perpendicular to the planar rigid framework leading to a chiral structure. The enantiomers were resolved by chiral HPLC and their chiroptical properties were characterized by optical rotation and CD spectral measurements. Their absolute stereochemistries were assigned by the theoretical calculation of CD spectra by using the TDDFT method. Kinetic measurements revealed that the barriers to enantiomerization were 122 and >142 kJ mol−1 for the methoxy and ethoxy compounds, respectively. The structures and stereochemistries are compared with those of intra-annular alkyl derivatives.
2013 The Chemical Society of Japan