Absolute Conformation and Substituent Effects on Chiroptical Properties of 9-(2-Halo-1,1-dimethylethyl)-11,12- bis(methoxycarbonyl)-9,10-dihydro-9,10-ethenoanthracenes1,2

Optically active and inactive rotational isomers of 9-(1,1-dimethyl-3-butenyl)-11,12-bis(methoxycarbonyl)-9,10-dihydro-9,10-ethenoanthracene were isolated. The absolute conformations of these optically active conformers were determined by correlating them with those of camphorsultam amides of 9-(2-carboxy-1,1-dimethylethyl)-11,12-bis(methoxycarbonyl)-9,10-dihydro-9,10-ethenoanthracenes, the latter being determined by X-ray analysis. From the carboxylic acids, the title compounds, in which the halogen is a chloro, a bromo, or an iodo, were prepared. The CD spectra of the title compounds showed remote substituent effects on the Cotton effect at ca. 220 nm.