D. J. Zwanenburg, T. Maas
Sep 2, 2010
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Recueil des Travaux Chimiques des Pays-Bas
Abstract
The reactions between 1,1-bis[4-(dimethylamino)phenyl]ethylene (Michler's ethylene, 4) and 3′-methyl-6-nitrospiro[2H-1-benzopyran-2,2′-benzothiazoline] (5, which exists in the open merocyanine form3), and its 3-methyl derivative 10, respectively, were studied. The methyl group in the 3-position in 10 has a great influence on the reactivity of this spiropyran at the 4-position; 5 reacts with 4 giving 2,2-bis[4-(dimethylamino)phenyl]-4-{2,2-bis[4-(dimethylamino)phenyl]vinyl}-6-nitrochroman (9), whereas no change of the starting products was observed in the reaction of 10 with 4. The same striking effect of an extra methyl group was found in the reaction of salicylaldehydes with 1,1-bis[4-(dimethylamino)phenyl]propene (11). In these cases we isolated the 1:1 products, 2,2-bis-[4-(dimethylamino)phenyl]-3-methyl-2H-chromenes (13) whereas reactions of salicylaldehydes with 1,1-bis[4-(dimethylamino)phenyl]ethylene give only 1:2 products.