Synthesis of Carbo[6]helicene Derivatives Grafted with Amino or Aminoester Substituents from Enantiopure [6]Helicenyl Boronates

Enantiopure carbo[6]helicenyl boronates were synthesized using a photocyclization reaction as the key step. These compounds were further converted to various amino derivatives using copper-catalyzed azidation or amination and reductive alkylation of benzylazide by a helicenyl dichloroborane. Asymmetric Petasis condensation with glyoxylic acid and morpholine controlled by the helical chirality afforded the corresponding amino esters.