Optically Active Triptycenes. IV. Synthesis of Optically Active 2- or 5-Substituted 7-Carboxytriptycenes

Abstract

Abstract Starting from anthraquinone-1-carboxylic acid (I), 2-methoxy- and 5-methoxy-7-carboxytriptycenes (VIIa and VIIb) have been synthesized. Optical resolution of the triptycenecarboxylic acids with brucine afforded (+)-VIIa and (+)-VIIb. The absolute configuration of (+)-VIIa was determined to be 1R,6R by the chemical correlation with (+)-2,5-dimethoxy-7-methoxycarbonyltriptycene. From a comparison of the CD spectrum of (+)-5-methoxy-7-carboxytriptycene (VIIb) with that of (+)-2-acetoxy-5-methoxy-7-methoxycarbonyltriptycene (XIIIb), 1R,6R absolute configuration was assigned to (+)-VIIb. (+)-2-Hydroxy-5-phenylazo-7-carboxytriptycene (XIIa) was derived from (+)-VIIa. (+)-2-Chloro- and (+)-5-chloro-7-carboxy triptycenes (XVIIIa and XVIIIb) have been prepared from 5-chloro- and 8-chloro-1-carboxyanthraquinones (XIVa and XIVb). The absolute configuration of (+)-XVIIIa was determined to be 1R,6R by the chemical correlation with (−)-VIIa via (+)-2-chloro-5-methoxytriptycene (XIX).