Preparation of Carbodiimides with One-Handed Axial Chirality

The axial chirality of carbo­diimide was proposed in 1932, but the synthesis of carbo­diimide with one-handed axial chirality has not been achieved because of the low barrier of racemization. This work presents a strategy to use a conformationally restrained cyclic structure for creating carbo­diimides whose biases of the axial chirality (labeled as SNCN/RNCN) are higher than 100:1, as determined by vibrational circular dichroism spectroscopy and density functional theory calculations.