1,3,3-Trimethyl spiro indoline

The numbering of spiropyrans adopted throughout this review is indicated in Figure 1.2. The nomenclature of the spiropyran 1 is given as 1, 3, 3 -trimethyl-spiro[2H-l-benzopyran-2,2 -indoline] it is referred to as spiroindolinobenzopyran and abbreviated as BIPS. 

I. I. Chuev, O. S. Filipenko, S. M. Aldoshin, and O. A. Kozina, Molecular structure of l, 3, 3-trimethyl-6-[(trifluoromethyl)sulfonyl]spiro[indoline-22,2 -benzo[i>]pyran], Russ. Chem. Bull. 43, 1857-1859 (1994). 

Hovery, R.J., Chu, N.Y., Piusz, P.G., and Eudsmann, C.H., Photochromic Compounds, U. S. Patent 4342, 668, 1982 Kawanishi, Y, Seki, K., Tamaki, T, Sakuragi, M., and Suzuki, Y, Tuning reverse ring closure in the photochromic and thermochromic transformation of l, 3, 3 -trimethyl-6-nitro-spiro[2H-l-benzopyran-2,2 -indoline] analogues by ionic moieties, /. Photochem. Photobiol., A Chem., 109, 237, 1997. 

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