217. Chiral Near-Infrared Fluorophores by Self-Promoted Oxidative Coupling of Cationic Helicenes with Amines/Enamines
     Johann Bosson, Geraldine M. Labrador, Céline Besnard, Denis Jacquemin, Jérôme Lacour
     Angew. Chem. Int. Ed. 2021, 60, 8733-8738

In one pot, tertiary alkyl amines are oxidized to enamines by cationic dioxa [6]helicene, which further reacts as electrophile and oxidant to form mono or bis donor-π-acceptor coupling products. This original and convergent synthetic approach provides a strong extension of conjugation yielding chromophores that absorb intensively in far-red or NIR domains (λ_max up to 791 nm) and fluoresce in the NIR as well (λ_max up to 887 nm). Intense ECD properties around 790 nm with a |Δε| value up to 60 M^-1 cm^-1 are observed.

DOI : 10.1002/anie.202016643 

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