Synthesis, Structures, and Solid State Self-Assemblies of Formyl and Acetyl Substituted Triptycenes and Their Derivatives

Starting from triptycene, 2-, (2,6- or 2,7-)­di-, and
(2,6,14- or 2,7,14-)­triformyl or acetyl substituted triptycenes were
selectively synthesized. The derivatization of the formyl or acetyl
substituted triptycenes was then investigated. Consequently, it was
found that the formyl-substituted triptycenes could be transformed
into cyano substituted triptycene derivatives by the aldoxime formation
and dehydration. Acetoxyl- and acetamino-substituted triptycenes were
synthesized by Baeyer–Villiger oxidation of acetyl-substituted
triptycenes and Beckmann rearrangement of acetyl-oxime triptycenes,
respectively. Deacetylation of triacetaminotriptycene provided an
alternative way to the synthesis of triaminotriptycene. In addition,
2-ethynyltriptycene could be conveniently synthesized by Corey–Fuchs
reaction of 2-formyltriptycene, and 1,3,5-tritriptycenebenzene was
obtained in high yield by the dehydration cyclotrimerization of 2-acetyltriptycene.
The different functionalized triptycene derivatives and their regioisomers
were well characterized by the FT-IR, 1H NMR, 13C NMR, MS spectra, and single crystal X-ray analyses. Moreover, it
was also found that 2,6,14-triacetaminotriptycene with the three amide
groups paralleled to their connected aromatic rings could self-assemble
into a 2D layer with porous structure, and further 3D microporous
architecture by the hydrogen-bond network in the solid state.