Experimental and Computational Investigation of the Oxime Bond Stereochemistry in c-Jun N-terminal Kinase 3 Inhibitors 11H-Indeno[1,2-b]quinoxalin-11-one Oxime and Tryptanthrin-6-oxime

Abstract

11H-Indeno[1,2-b]quinoxalin-11-one oxime (IQ-1) and tryptanthrin-6-oxime are potent c-Jun N-terminal kinase 3 (JNK-3) inhibitors demonstrating neuroprotective, anti-inflammatory and anti-arthritic activity. However, the stereochemical configuration of the oxime carbon–nitrogen double bond (E- or Z-) in these compounds was so far unknown. In this contribution, we report the results of the determination of the double bond configuration in the solid state by single crystal X-ray diffraction and in solution by 1D and 2D NMR techniques and DFT calculations. It was found that both in the solid state and in solution, IQ-1 adopts the E-configuration stabilized by intermolecular hydrogen bonds, in contrast to previously assumed Z-configuration that could be stabilized only by an intramolecular hydrogen bond.

Chemistry, Synthesis, and Structure Activity Relationship of Anticancer Quinoxalines

“…It is a low-melting solid (29-30 • C), soluble in water, and a weak base (pKa = 0.56) [15]. Several studies were performed and displayed a wide range of pharmacological activities for quinoxaline derivatives (Figure 1) [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Additionally, quinoxalines are used for crop protection as a component of insecticides, herbicides, and fungicides [31][32][33][34][35].…”