Condensed Isoquinolines. 18. Enamine Properties of Benzimidazo[1,2-b]isoquinolin-11(5H)-one in the Michael Reaction

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

“…Several nitrogen-rich π-extended acenaphthylenes have been obtained, characterized by the presence of one or two N atoms at the junction of five- and six-membered rings. Such systems, which typically contain ketone or lactam functionalities, were reported by Schefczik ( C52.1 , Chart ), Kappe and co-workers ( C52.2 , C52.3 , C52.5 ), Möhrle and Seidel ( C52.4 ), Gharagozloo et al ( C52.6 ), Kovtunenko et al ( C52.7 ), and Koutentis et al ( C52.8 ) . In contrast to C52.1 – 7 , which were synthesized by classical condensation methods, compound C52.8 was obtained via Ag I -mediated Pd-catalyzed cyclizations, of either oxidative or nonoxidative character.…”

Condensed isoquinolines 25. Alkylation of 6,11-dihydro-13H-isoquino[3,2-b]quinazolin-13-one

“…3,9-dioxo-3H,9H,11H-benzo [5,6] We have previously studied alkylation, one of the characteristic reactions of enamines, using benzimidazo[1,2-b]isoquinolin-11(5H)-one [2,3] and 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one [4,5] as examples. It seemed of interest to investigate the characteristics of this reaction for the linear isomer -6,11-dihydro-13H-isoquino [3,2-b]quinaxolin-13-one (1) which had been shown previously [1] to be ambident as nucleophilic agent with the example of reactions with carbonyls.…”

“…It should be noted that in the case of isoquino [3,2-b]quinazoline 1 this reaction occurs quite easily (20-40 min at 120-150°C) and with high yield (60-80%). Whereas for other condensed 3-aminoisoquinolines -benzimidazo[1,2-b]isoquinolin-11(5H)-one, which exists predominantly in the "enamine" form [3] and 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one, which exists as a mixture of tautomers [7] -alkylation products were not formed with these olefins. One possible reason for this is the difference in reactivity of these heterocycles as proton donors in reaction with proton acceptors -anhydride and imides of dicarboxylic acids.…”

“…However, the enumerated data do not allow an unambiguous conclusion on the structures of the products as products of C-alkylation or N-alkylation. Although it is known [3,10,11] that alkylation of natural products (cyclic "imines" and "enamines") with derivatives of cyanocinnamic acid occurs predominantly at carbon atoms, it should be taken into consideration an alternate structure 10 as a product of C-alkylation and N-alkylation. The final choice of 9 resulted from a study of the structure of by-products of this reaction.…”