Overcrowded molecules. Part IX. Fatigue-free photochromic systems involving (E)-2-Isopropylidene-3-(mesitylmethylene)succinic anhydride and N-phenylimide
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- p. 923-927
- https://doi.org/10.1039/p19740000923
Abstract
(E)-2-Isopropylidene-3-(mesitylmethylene)succinic anhydride and N-phenylimide undergo reversible photochemical conrotatory ring closure reactions to form 1,8a-dihydronaphthalene intermediates, which do not experience ring opening up to 160°. This is presumably because of steric interactions between the 1 - and 8a-methyl substituents which must occur in the allowed disrotatory mode. Neither a methyl shift nor elimination of ethane occurs at this temperature; these thermally stable photochromic systems thus do not exhibit irreversible side reactions.Keywords
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