1-carboxyethyl-3,3-dibutyl-2-methylindolenium iodide 、
1-(4-N,N-dioctylaminophenyl)-2-hydroxycyclobutene-3,4-dione 以
正丁醇 、
苯 为溶剂,
以35%的产率得到4-[[3,3-Dibutyl-1-(2-carboxyethyl)indol-1-ium-2-yl]methylidene]-2-[4-(dioctylamino)phenyl]-3-oxocyclobuten-1-olate