Conformationally Flexible C-3-Symmetric 1,3-Oxazoles as Molecular Scaffolds

Flexible-arm, C-3-symmetric tris-oxazoles are synthesized for their applications in supramolecular chemistry and materials science. The C-3-symmetry is introduced starting from 1,3,5-trimethylbenzene and carrying out threefold reactions at each stage of the synthesis. The applicability of these tris-oxazoles is demonstrated by transforming a representative example into a highly fluorescent material. This is accomplished by conjugation with an aromatic moiety via palladium(0)-catalyzed direct arylation at C-2 of the oxazole. A unique molecular arrangement in the crystal structure is observed.