Stereospecific 1,4-Metallate Shift Enables Stereoconvergent Synthesis of Ketoximes
Qiuling Song presents a stereospecific 1,4-metallate shift enabling the stereoconvergent synthesis of ketoximes.
Stereochemically pure oximes are ubiquitous structural motifs in drugs, bioactive molecules and food additives. They are also very important starting materials for the Beckmann rearrangement, which has been successfully employed for the industrial production of many valuable fine chemicals. The prototypical ketoxime synthesis involves condensation of ketones with hydroxylamine or tautomerization of C-nitroso species, as well as reduction of nitro compounds. However, the ratio of the resulting E/Z-isomers is under thermodynamic control and depends on the nature of the substrates, which usually causes major problems when it comes to isolating a single geometric isomer, unless the two substituents of the ketoximes are structurally very different. Therefore, according to Professor Qiuling Song from Fuzhou University (P. R. of China), the practical and universal direct stereoselective synthesis of stereochemically pure ketoximes, especially of thermodynamically less-stable ones, remained thus far an unsolved challenge in modern chemical transformations.
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