Pick and choose: Novel cationic diaza‐, azaoxo‐, and dioxo[6]helicenes are readily prepared and functionalized selectively by orthogonal aromatic electrophilic and vicarious nucleophilic substitutions (see scheme). Reductions, cross‐coupling, or condensation reactions introduce additional diversity and allow tuning of the absorption properties up to the near‐infrared region. The diaza salts can be
Chiral Near‐Infrared Fluorophores by Self‐Promoted Oxidative Coupling of Cationic Helicenes with Amines/Enamines
作者:Johann Bosson、Geraldine M. Labrador、Céline Besnard、Denis Jacquemin、Jérôme Lacour
DOI:10.1002/anie.202016643
日期:2021.4.12
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 (λmax up to 791 nm) and fluoresce in the NIR as well (λmax up to 887 nm). Intense ECD properties around 790 nm with
在一个罐中,叔烷基胺被阳离子二氧杂[6]螺旋氧化为烯胺,后者进一步以亲电子和氧化剂反应,形成单或双供体-π-受体偶联产物。这种原始的和会聚的合成方法提供了在远红或近红外域集中吸收缀合得到的发色团的强烈的扩展(λ最大高达791纳米)和发荧光在NIR以及(λ最大高达887纳米)。围绕790nm的强烈ECD性质与|Δ ε | 观察到高达60 M -1 cm -1的值。