Stereochemical properties of N-benzoylated carbazole derivatives

The atropisomeric properties of 2′,6′-disubstituted N-benzoylated carbazole derivatives were investigated. It was found that the bulky t-butyl and iodo groups restricted rotation about the N–C7′ and C7′–C1′ bonds to separate four stereoisomers, in which rotation about the C7′–C1′ bond was in perfect concert with rotation about the N–C7′ bond. The relation of the rotation of the N–C7′ and C7′–C1′ axes was investigated by comparing the stereochemistry of variously 2′,6′-disubstituted N-benzoyl-carbazole derivatives. It was suggested that the concerted rotation of the N–C7′ and C7′–C1′ axes might occur even in less hindered compounds.

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