Synthesis and application of 4,5-disubstituted carbazoles

Alotaibi, Alya ORCID: 0000-0002-5081-5625 (2023). Synthesis and application of 4,5-disubstituted carbazoles. University of Birmingham. Ph.D.

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Abstract

Carbazoles are widely exploited for their interesting photophysical and electronic properties. However, (4,5-) functionalisation is challenging, and previously inaccessible through carbazole C-H activation. There is limited literature on the direct synthesis of substituted carbazoles, in particular
at the 4,5 positions. In 2021, the Grainger group reported a direct and convenient method to synthesise 4,5-disubstituted carbazoles.This thesis expands on this new protocol for the regioselective synthesis of 4,5-disubstituted carbazoles, and extends it to fluorenes, through direct C-H functionalization.
4,5-Disubstituted carbazoles and fluorenes were synthesised from N-TIPS carbazole 56 and 9,9-dimethyl fluorene 176 using a dilithiation methodology (n-BuLi and TMEDA) and quenching with different electrophiles. Subsequent reactions towards potential applications of these compounds were investigated. The novel 4,5 disubstituted carbazoles obtained are potentially useful in a range of fields.
X-ray crystal structures of select 4,5-disubstituted carbazole derivatives were obtained, and data analysed with respect to potential twisting and other deviations from the planar aromatic carbazole ring system. Photophysical properties were investigated for sulfur and selenium functionalised 4,5-disubstituted carbazoles and compared with the corresponding 3,6- disubstituted carbazoles.
4,5-Disubstituted dicarboxylate dibenzyl ammonium carbazole and fluorene salts were synthesized and crystallised.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):