Atropisomerism about a heptafluoroisopropyl to aryl bond in 5-amino-4-heptafluoroisopropyl indazole

The atropisomerism about a heptafluoroisopropyl to aryl bond in 5-amino-4-heptafluoroisopropyl indazole is reported. The through-space hydrogen fluorine coupling of the indazole H-3 proton with the tertiary F atom is shown to be useful to distinguish the two rotamers. The same atropisomerism is also observed in the analogous indole, benzofuran, and naphthaline derivatives.