Preparation of Chromeno[b]quinoline Derivatives and Their Application for Lipid Droplets Markers

Functional dyes with a chromeno[b]quinoline skeleton (3a-d) were synthesized by one-step cyclization between coumarin derivatives and aromatic amines under the promotion of anhydrous aluminum chloride in 41.2-45.8% yields. Their maximum absorption and emission wavelengths locate at 358-396 and 420-603 nm with large Stokes shifts (168-231 nm), and their intramolecular charge transfer has been corroborated by density functional theory calculations. Cell experiments have proved that the probes 3a-c possess the ability to target lipid droplets.