Stereoisomerism in Nanohoops with Heterogeneous Biaryl Linkages of <i>E/Z</i>- and <i>R/S</i>-Geometries

The stereochemistry of cycloarylene nanohoops gives rise to unique cyclostereoisomerism originating from hoop-shaped molecular shapes. However, cyclostereoisomerism has not been well understood despite the ever-increasing number of structural variants. The present work clarifies the cyclostereoisomerism of a cyclophenanthrenylene nanohoop possessing both <i>E/Z</i>- and <i>R/S</i>-geometries at the biaryl linkages. Involvement of the <i>R/S</i> axial chirality in the nanohoop leads to the deviation of the structure from a coplanar belt shape and allows for structural variations with 51 stereoisomers with <i>E/Z</i>- and <i>R/S</i>-geometries. Experimental investigations of the dynamic behaviors of the cyclophenanthrenylene nanohoop revealed the presence of two-stage isomerization processes taking place separately at the <i>E/Z</i>- and <i>R/S</i>-linkages. Consequently, despite the presence of <i>E/Z</i>-fluctuations, the <i>R/S</i> axial chirality resulted in a separable pair of enantiomers. The structural information reported here, such as geometric descriptors and anomalous dynamics, may shed light on the common structures of various nanohoops

Correction to Helicenes from Diarylmaleimides

Correction to Helicenes from Diarylmaleimide

Helicenes from Diarylmaleimides

Perkin condensations of arylglyoxylic acids with arylacetic acids, followed by the addition of alkylamine, yield diarylmaleimides in a one-pot procedure. The arylglyoxylic acids are obtained by arene acylation with ClCOCO₂Et and reduced with NaI and hypophosphorous acid to the arylacetic acids. With 2,7-di-<i>tert-</i>butyl-pyren-4-yl or chrysen-6-yl as the aryl, photocyclodehydrogenation of the diarylmaleimides yields substituted helicenes which can be reduced to stable anions. The helicenes combine bathochromically shifted absorption with hypsochromically shifted fluorescence with respect to their precursors

Helicenes from Diarylmaleimides

Perkin condensations of arylglyoxylic acids with arylacetic acids, followed by the addition of alkylamine, yield diarylmaleimides in a one-pot procedure. The arylglyoxylic acids are obtained by arene acylation with ClCOCO₂Et and reduced with NaI and hypophosphorous acid to the arylacetic acids. With 2,7-di-<i>tert-</i>butyl-pyren-4-yl or chrysen-6-yl as the aryl, photocyclodehydrogenation of the diarylmaleimides yields substituted helicenes which can be reduced to stable anions. The helicenes combine bathochromically shifted absorption with hypsochromically shifted fluorescence with respect to their precursors