Revisiting Biginelli-like reactions: solvent effects, mechanisms, biological applications and correction of several literature reports.

This study critically reevaluates reported Biginelli-like reactions using a Kamlet-Abboud-Taft-based solvent effect model. Surprisingly, structural misassignments were discovered in certain multicomponent reactions, leading to the identification of pseudo three-component derivatives instead of the expected MCR adducts. Attempts to replicate literature conditions failed, prompting reconsideration of the described MCRs and proposed mechanisms. Electrospray ionization (tandem) mass spectrometry, NMR, melting points, elemental analyses and single-crystal X-ray analysis exposed inaccuracies in reported MCRs and allowed for the proposition of a complete catalytic cycle. Biological investigations using both pure and "contaminated" derivatives revealed distinctive features in assessed bioassays. A new cellular action mechanism was unveiled for a one obtained pseudo three-component adduct, suggesting similarity with the known dihydropyrimidinone Monastrol as Eg5 inhibitors, disrupting mitosis by forming monoastral mitotic spindles. Docking studies and RMSD analyses supported this hypothesis. The findings described herein underscore the necessity for a critical reexamination and potential corrections of structural assignments in several reports. This work emphasizes the significance of rigorous characterization and critical evaluation in synthetic chemistry, urging a careful reassessment of reported synthesis and biological activities associated with these compounds.

Synthesis and evaluation of quinonoid compounds against tumor cell lines.

Thirty two compounds were synthesized in moderate to high yields and showed activity against cancer cells HL-60 (leukemia), MDA-MB435 (melanoma), HCT-8 (colon) and SF295 (central nervous system), with IC(50) below 2 µM for some compounds. The ß-lapachone-based 1,2,3-triazoles showed the best cytoxicity profile and emerge as promising anticancer prototypes. Insights about the reactive oxygen species (ROS) mechanism of anticancer action for some compounds were obtained by addition of 1-bromoheptane that deplete reduced glutathione (GSH) content and by using N-acetylcysteine that protects cells against apoptotic cellular death, as well by analysis of thiobarbituric acid reactive substances (TBARS) formation, and oxidative DNA damage after treatment detected by the comet assay with the bacterial enzymes formamidopyrimidine DNA-glycosylase (FPG) and endonuclease III (ENDOIII).

3-(2,4-Dibromo-anilino)-2,2-dimethyl-2,3-dihydro-naphtho[1,2-b]furan-4,5-dione: a new substituted aryl-amino nor-ß-lapachone derivative.

The title compound, C(20)H(15)Br(2)NO(3), shows the furan ring to adopt a half-chair conformation and the two ring systems to be approximately perpendicular [dihedral angle = 71.0 (2)°]. In the crystal structure, inter-molecular C-H⋯O contacts link the mol-ecules.