Abstract A novel synthesis of aminosquarylium cyanine dyes, based on the methylation of readily available squarylium dyes with methyl triflate, followed by nucleophilic substitution with appropriate aliphatic amines, was disclosed. By this procedure several new aminosquarylium cyanine dyes bearing benzothiazole, benzoselenazole and quinoline nuclei were prepared.
![Quinolinium,1-ethyl-2-[[3-[(1-ethyl-2(1H)-quinolinylidene)methyl]-2-hydroxy-4-oxo-2-cyclobuten-1-ylidene]methyl]-,inner salt结构式](https://image.chemsrc.com/caspic/219/23475-74-3.png)