Herein, the development of a light-mediated
synthesis
of functionalized
indolines and tetrahydroquinolines is reported. These structural motifs
are considered as highly valuable targets, attributed to their widespread
occurrence in pharmaceuticals and natural products. The gold-mediated
approach offers a direct route to functionalized indolines in yields
of up to 81% under mild photochemical conditions. Thereby, easily
accessible Boc-protected N-aryl-allylamine and homoallylamine
derivatives were reacted with sp3-hybridized haloalkanes
in an intermolecular cascade cyclization reaction. A broad scope of
substrates, including a variety of different substituents on the aromatic
backbone as well as various haloalkanes, could be utilized. Indoline
derivatives, which are functionalized in position 2, are also accessible
by applying ortho-allylic anilines. Moreover, the synthetic appeal
was demonstrated for a total synthesis of the anti-inflammatory agent
AN669 in three reaction steps in an overall yield of 64%.