Biconcave and Convex–Concave Tribenzotriquinacene Dimers

A new
chiral tribenzotriquinacene bearing an ortho-bromoaniline
nucleus was synthesized and optically resolved. The
individual enantiomers, the absolute configuration of which was confirmed
by single-crystal X-ray structure analysis, were stereoselectively
converted into the same pyrazine-fused syn-bis-TBTQ
derivative by chirality-assisted Buchwald–Hartwig amination.
The corresponding diastereomeric anti-dimer was obtained
alongside the syn-dimer from the racemic sample under
similar reaction conditions. X-ray structure analysis of the dimers
confirmed the mutual biconcave and convex–concave configuration
of their TBTQ moieties and the preservation of the orthogonal orientation
of the indane wings within each of them.