The reactions between 3′-methyl-6-nitrospiro(2H-1-benzopyran-2,2-benzothiazolines] and 1,1-bis[4-(dimethylamino)phenyl]ethylene and the reactions of salicylaldehydes with 1,1-bis[4-(dimethylamino)phenyl]propene. A striking effect of an extra methyl group;