Substitution at the chiral bismuth center of optically pure diastereomeric iodobismuthanes bearing an intramolecular BiN coordination bond. Inversion of the configuration by aryl-Grignard reagents

Optically pure diastereomeric iodobismuthanes 3a and 3b underwent the substitution at the chiral bismuth center by 4-methylphenyl- and 4-chlorophenylmagnesium bromide to give bismuthane 4a and 4b as a single diastereomer, respectively. Each reaction was highly stereoselective. Comparison of 4a with 4b by 1H-NMR spectrum revealed that the chemical shifts of the aromatic ring protons are quite different from each other due to the anisotropic effect of the ferrocenyl group, which reflects the difference of the configuration around the chiral bismuth center. The differential 1H-NMR NOE experiments of 4a and 4b provided a critical evidence for the configuration in each compound. The X-ray crystallographic study of 4 demonstrated that the substitution proceeds with inversion of the configuration at the chiral bismuth center.