22028-15-5Relevant academic research and scientific papers
Formation of reactive o-quinone methides from the reaction of trimethylsilyl(methyl)-substituted 1,4-benzoquinones with nucleophiles
Ezcurra, John E.,Karabelas, Kostas,Moore, Harold W.
, p. 275 - 286 (2007/10/03)
o-Quinone methides are formed from the reaction of nucleophiles with trimethylsilyl(methyl)-1,4-benzoquinones. These reactive intermediates are trapped by excess nucleophile to form substituted quinones following oxidation. In addition, varying amounts of a symmetrical dimer and a xanthen derivative were observed. The influence of different nucleophiles and ring substituents on the rate of reaction have been studied, and are consistent with rate-limiting formation of a vinylogous enolate initiated by attack of the nucleophile on the silyl group. Graphical Abstract.
Rearrangement of 4-Alkynylcyclobutenones. A New Synthesis of 1,4-Benzoquinones
Foland, Lafayette D.,Karlsson, J. Olle,Perri, Steven T.,Schwabe, Rudolf,Xu, Simon L.,et al.
, p. 975 - 989 (2007/10/02)
A new convergent synthesis of 1,4-benzoquinones from 4-alkynyl-4-alkoxy(or hydroxy or trimethylsilyloxy)cyclobutenones is described.The required cyclobutenones are prepared from squaric acid and converted to the quinones upon mild thermolysis.The reaction proceeds via electrocyclic ring opening of the required cyclobutenones to (2-alkynylethenyl)ketenes, which then ring close to unique diradical intermediates.These then give the quinone products.The scope and mechanism of this unusual rearrangement are discussed.
Isolation, Structure, and Synthesis of Combretastatin C-1
Singh, Sheo Bux,Pettit, George R.
, p. 4105 - 4114 (2007/10/02)
A new cell growth inhibitory (PS ED50 2.2 μg/mL) phenanthraquinone designated combretastatin C-1 (2) has been isolated from the African tree Combretum caffrum.The structure (2) assigned combretastatin C-1 was based on high-resolution mass and NMR spectral analyses and confirmed by total syntheses.Synthetic routes 5b -> 6b -> 2 and especially 5c -> 6c -> 2 proved to be quite practical.
