Release Time:2019-03-12  Hits:

Indexed by: Journal Article

Date of Publication: 2018-06-26

Journal: CHEMISTRY-A EUROPEAN JOURNAL

Included Journals: SCIE、PubMed

Volume: 24

Issue: 36

Page Number: 9041-9050

ISSN: 0947-6539

Key Words: benzotrisoxazoles; benzotristhiazoles; C-H arylation; cyclotrimerization; star-shaped molecules

Abstract: Star-shaped pi-extended molecules comprising discotic aromatic cores and peripheral pi-conjugated arms have attracted significant attention as diverse optoelectronic materials in terms of their large pi-surface, tunable self-assembly, enhanced charge transport and fluorescence, and liquid crystallinity. Although many efforts have been made in the construction of various aromatic discotic cores, a new class of C-3-symmetric star-shaped discotic pi-molecules consisting of electron-deficient benzotristhiazole and benzotrisoxazole cores, which are expected to exhibit distinct optoelectronic properties, remains unexplored owing to the unachievable synthetic approaches involved in their synthesis. Herein, we report a novel and highly efficient Pd-catalyzed cyclotrimerization of the functionalized thiazoles or oxazoles for the construction of a new class of discotic molecules of benzotristhiazole and benzotrisoxazole central cores with star-shaped pi-conjugated arms. The combination of [Pd-2(dba)(3)]/XPhos (dba=dibenzylideneacetone) catalyst systems with the 4-bromo-substituted thiazole enables the formation of a sufficiently stable thiazole-Pd species that participates in the subsequent C-H arylations consecutively to form the corresponding cyclic trimer products. This new class of star-shaped discotic pi-extended products showed tunable energy levels and high fluorescence quantum yields that make them promising candidates for optoelectronic applications.