Synthesis of dihydronaphthofurandiones and dihydrofuroquinolinediones with trypanocidal activity and analysis of their stereoelectronic properties

13C NMR studies of heterocyclic naphtho‐ and anthraquinones. Deshielding effect on the carbonyl carbon with methyl substitution

“…The methyl-deshielding effect is observed even in more complex heterocyclic quinones, such as pyrrole and thiophene derivatives (11)(12)(13). The chemical shift of C-5 in the 6-methyl derivative of benzopyrroloquinolinedione (12) is 2.2 ppm downfield with respect to that of C-10 in the same compound, which is consistent with the effect exerted by the nitrogen of the quinolinedione system.…”

“…[11] The azaanthraquinones (6-8) were obtained by reaction of quinoline-5,8-diones with the appropriate diene following a known procedure [13] ; spectral characteristics for all three compounds are in full accordance with those previously described [13] ; nevertheless, 13 C NMR data has not been reported before. A detailed experimental procedure for the preparation of benzopyrroloquinolinediones (11) and (12) has been presented recently.…”

“…[11] The azaanthraquinones (6-8) were obtained by reaction of quinoline-5,8-diones with the appropriate diene following a known procedure [13] ; spectral characteristics for all three compounds are in full accordance with those previously described [13] ; nevertheless, 13 C NMR data has not been reported before. A detailed experimental procedure for the preparation of benzopyrroloquinolinediones (11) and (12) has been presented recently. [12] Azaanthraquinones (9) and (10) were prepared through the following procedure (Scheme 1): AgO (180 mg) and HNO 3 (6 N, 530 µl) were added to a solution of 4-chloro-3-(2-chloroethyl)-5,8-dimethoxy-2-methylquinoline (14) [12] (0.3 mmol in 15 ml CH 3 CN).…”

“…[11,12] Therefore, we describe in this paper the 13 C NMR assignments for ten methyl substituted heterocyclic quinones. In every case, a downfield shift is observed for one of the carbonyl carbons, when compared to the same heterocycle in the absence of the methyl substitution.…”

Synthesis and Cytotoxic Evaluation of 6‐(3‐Pyrazolylpropyl) Derivatives of 1,4‐Naphthohydroquinone‐1,4‐diacetate

“…Also, they have diverse pharmacological activities such as anticancer [6 -9], antimicrobial [10,11], antiviral [12], and anti-inflammatory activities [13]. Their antitumor properties and mechanism of action are attributed to an inhibition of mitochondrial electron transport and decoupling of oxidative phosphorylation by the one-electron redox process of the quinone/ hydroquinone couple, involving semi-quinonic radicals which induce an increase in reactive oxygen species formation [2 -4, 14].…”