S. Toppet, W. Quintens, G. Smets
1975
Citations
0
Influential Citations
18
Citations
Journal
Tetrahedron
Abstract
Abstract The 1H NMR spectra of some 1′3′3′-trimethylindolino-6,8-disubstituted-spirobenzopyranes in equilibrium with more than 5% of their merocyanine isomer were taken at different temperatures in dimethylsulfoxide d6. This presents evidence of a fast inversion process at the asymmetric spiro carbon-2. It is shown that the intermediate responsible for the inversion process is certainly not the merocyanine but more likely the open ring cis isomer of the spiropyran.