Synthesis of a Double-Helical Naphthotetraindole Core via an Intramolecular Dehydrogenative Homocoupling Reaction

A novel naphthotetraindole (NTI) core was synthesized in two steps via the McMurry reaction and a [Cu]/[Ag]-promoted intramolecular dehydrogenative homocoupling reaction. NTI shows a unique X-shaped double-helical structure as determined by single-crystal X-ray diffraction analysis. The hole-transport mobility of the bare NTI core was measured to be 2.3 × 10–5cm2V–1s–1, which is comparable with the commonly used Spiro-OMeTAD.