One-step construction of aminosquaraine backbone. (August 2016)

• Record Type: Journal Article
• Authors: Ying, Hanze; Cheng, Jianjun
• Is Part Of: Dyes and pigments. Volume 131(2016)
• Page Start: 264
• Page End: 267
• Publication Date: 2016-08
• Subjects: Squaraine -- Aminosquaraine -- One-step -- Amidation -- Oxidation -- Dye functionalization; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2016.04.024
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: One-step construction of the amino-substituted squaraine dye backbone was discovered unexpectedly in an amidation reaction. Under the catalysis of Mukaiyama's reagent, (4-dimethylamino)phenylacetic acid and bulky secondary amine 2, 2, 6, 6-tetramethylpiperidine give the reduced form of aminosquaraine instead of amide as the major product. The reduced form of aminosquaraine can be oxidized to a dark-colored conjugated aminosquaraine within seconds. The method provides a novel and facile way to functionalize the four-membered core of squaraine dye. Graphical abstract: Highlights: Amidation reaction unexpectedly gives reduced aminosquaraine as the major product. Reaction mechanism and substrate requirement are proposed and studied. The reduced aminosquaraine can be facilely oxidized to conjugated aminosquaraine.