Diphenylamine Moieties Research Articles

Hydrolytic breakdown of meso-diphenylamine substituted heptamethine dye IR140 and isomerism of the merocyanine breakdown product

Nucleophilic attack by hydroxyl ions is found to occur preferentially at the C 2 position of the benzothiazolium heterocyclic moiety of the laser dye IR140, and not at the eneamine functionality that consists of the mesocarbon atom and the adjacent diphenylamine moiety, which is the other electrophilic site on the dye. The temperature-dependence of the absorption spectrum of the merocyanine breakdown product suggests that similar ground state isomerism is present in the breakdown product, as is found in the initial dye IR140. It is concluded that the non-fluorescent majority conformer of the merocyanine breakdown product is the one in which the meso-amine substituent is twisted so as to withdraw electron density by induction, and that the fluorescent minority conformer is that in which themeso-amine substituent is conjugated to act as an electron donor by resonance.

The synthesis of pyrido [4,3-b]carbazoles from diphenylamine derivatives: alternative routes to and relay syntheses of ellipticines and olivacines

Two new synthetic routes to pyrido [4,3-b]carbazoles are described. In the first, Goldberg-type coupling of various aryl sulfonamides with aryl bromides in the presence of copper and potassium carbonate gives N,N-diaryl sulfonamides. UV irradiation of these, in ethanol, removes the toluene-p-sulfonyl protecting groups and cyclises the diphenylamine moiety to the corresponding carbazoles. These carbazoles are established intermediates in the synthesis of several ellipticines (5,11 -dimethyl-pyrido[4,3-b]carbazoles).