RESUMEN
One-handed helical oligo(p-benzamide)s were induced via the domino effect based on the planar-axial-helical chirality relay triggered by a planar chiral transition-metal complex at the terminal position as the single chiral source.
Asunto(s)
Benzamidas/química , Dicroismo Circular , Cristalografía por Rayos X , Modelos Moleculares , Estructura Molecular , Espectrofotometría , EstereoisomerismoRESUMEN
The thermal chromium tricarbonyl migration reaction induced axially chiral N-C bonds of N-aryl acridane and related complexes in good yield with outstanding enantiomeric excess.
Asunto(s)
Acridinas/química , Carbono/química , Cromo/química , Nitrógeno/química , Complejos de Coordinación/química , Conformación Molecular , Estereoisomerismo , TemperaturaRESUMEN
N-Aryl indoles with axially chiral N-C bonds were synthesized by stereoselective nucleophilic aromatic substitution reactions of planar chiral tricarbonyl(2,6-disubstituted-1-fluorobenzene)chromium complexes. The stereochemistry of the products is highly dependent on the position of the substituent in the indole. When indoles devoid of a substituent at the 2-position were used, N-aryl indole chromium complexes having anti orientation with respect to the tricarbonylchromium fragment were obtained diastereoselectively. In contrast, 2-substituted indoles gave the N-aryl indoles with syn orientation between the tricarbonylchromium fragment and the benzene ring of the indole. These results demonstrate that we have succeeded in synthesizing both enantiomers of N-aryl indoles utilizing an identical planar chiral arene chromium complex.
Asunto(s)
Química Orgánica/métodos , Indoles/síntesis química , Carbono/química , Compuestos de Cromo/química , Indoles/química , Espectroscopía de Resonancia Magnética , Estructura Molecular , Nitrógeno/química , EstereoisomerismoRESUMEN
We newly prepared para- and meta-linked alkynylpyrene oligomers and examined their photophysical properties. Oligomerization of monomeric building blocks was performed by CuI-promoted oxidative coupling reaction. The resulting oligomers mainly consist of 2-mer to 6-mer that were assigned on the basis of MALDI-TOF mass spectra, and the 2-mer, 3-mer, and 4-mer were isolated and fully characterized. From their absorption and fluorescence spectra, the para-linked oligomers were found to be somewhat pi-conjugated compared with meta-linked ones, and the fluorescence quantum yields decreased with increasing oligomer length (Phif = 0.79-0.55).