T. Zimmermann, O. Brede
Jul 1, 2003
Citations
0
Influential Citations
5
Citations
Journal
Journal of Heterocyclic Chemistry
Abstract
The synthesis of the novel 2,4,6-triaryl-1-(spiro[2H-1-benzopyran-2,2′-indoline]-6-yl)pyridiniumper-chlorates 4 by reaction of 5-nitrosalicylaldehydes 6 with 1,3,3-trimethyl-2-methyleneindoline (7) to 6-nitro-spiro[2H-1-benzopyran-2,2′-indolines] 1, their stannous chloride reduction to the 6-amino derivatives 8, followed by a 2,6-[C5+N] ring transformation with 2,4,6-triarylpyrylium perchlorates 9, is reported. UV irradiation experiments in twenty solvents of different polarity prove their photochromic properties and show that the photochemically generated negative solvatochromic dyes 5, formed by ring opening of the benzopyran moiety of 4, are rather merocyanine than pyridinium phenolate betaine dyes.