75171-67-4Relevant academic research and scientific papers
Studies on quinones. Part 40: Synthesis and cytotoxicity evaluation of anthraquinone epoxides and isomerization products
Valderrama, Jaime A.,Espinoza, Omar,González, M. Florencia,Tapia, Ricardo A.,Rodríguez, Jaime A.,Theoduloz, Cristina,Schmeda-Hirschmann, Guillermo
, p. 2631 - 2638 (2007/10/03)
Aerobic oxidation of 1,4,4a,10a-tetrahydro-1,4-alkano-5,10-anthraquinones and thiophene-analogues in dichloromethane-DBU yielded the corresponding dihydroalkanoquinones which, depending on their structures, react with in situ generated hydroperoxide anion to give quinone epoxides and/or hydroperoxides. The calcium hydroxide-induced rearrangement of quinone epoxides yielded furan-containing angular quinones. The cytotoxic activities of quinone epoxides and their isomerization products were evaluated in vitro against normal human lung fibroblasts (MRC-5) and human cancer gastric epithelial cells (AGS).
Electronic Control of Stereoselectivity. 6. Directionality of Singlet Oxygen Addition to 1,4-Dimethoxynaphthalenes Laterally Fused to Bridged Bicyclic Systems
Paquette, Leo A.,Bellamy, Francois,Boehm, Michael C.,Gleiter, Rolf
, p. 4913 - 4921 (2007/10/02)
The photooxygenation in methanol solution of 1,4-dimethoxynaphthalene derivatives having bridged bicyclic systems fused at C2, C3 with rose bengal as sensitizer leads to formation of stereoisomeric epoxynaphthoquinone monoketals.These products, which are readily hydrolyzed in acid solution to the epoxynaphthoquinones, possess an epoxide oxygen which serves as a stereochemical marker for the directionality of singlet oxygen addition.For the norbornyl and norbornenyl cases, endo bonding by 1O2 is preferred; the reverse is true for the pair of bicyclooctenyl derivatives studied.This contrasting stereoselection was compared to the stereochemical consequences of alkaline hydroperoxidation of the corresponding naphthoquinones.In each instance, the reaction course was opposite to that observed with singlet oxygenation.Both processes are analyzed from the theoretical viewpoint, use being made of the photoelectron spectra of the substrate molecules, detailed evaluation of frontier orbital effects, and prevailing ?/? interactions.While the alkaline hydroperoxidation results can be interpreted in terms of standard kinetic and steric control, an understanding of the directionality of 1O2 capture appears dependent on our appreciation of the contributions made by the ? electrons of the bicyclic moieties upon the aromatic ? orbitals.The tilting caused by such interactions is thought to be source of the experimentally observed exo/endo ratios.
