4832-17-1Relevant articles and documents
Enhancing Chemo- And Stereoselectivity in C-H Bond Oxygenation with H2O2by Nonheme High-Spin Iron Catalysts- And Role of Lewis Acid and Multimetal Centers
Das, Abhishek,Jana, Rahul Dev,Paine, Tapan Kanti
, p. 5969 - 5979 (2021/05/04)
Spin states of iron often direct the selectivity in oxidation catalysis by iron complexes using hydrogen peroxide (H2O2) on an oxidant. While low-spin iron(III) hydroperoxides display stereoselective C-H bond hydroxylation, the reactions are nonstereoselective with high-spin iron(II) catalysts. The catalytic studies with a series of high-spin iron(II) complexes of N4 ligands with H2O2 and Sc3+ reported here reveal that the Lewis acid promotes catalytic C-H bond hydroxylation with high chemo- and stereoselectivity. This reactivity pattern is observed with iron(II) complexes containing two cis-labile sites. The enhanced selectivity for C-H bond hydroxylation catalyzed by the high-spin iron(II) complexes in the presence of Sc3+ parallels that of the low-spin iron catalysts. Furthermore, the introduction of multimetal centers enhances the activity and selectivity of the iron catalyst. The study provides insights into the development of peroxide-dependent bioinspired catalysts for the selective oxygenation of C-H bonds without the restriction of using iron complexes of strong-field ligands.
Ozonation of decalin as a model saturated cyclic molecule: A spectroscopic study
Bykov, Gennadii L.,Ershov, Boris G.,Krasovskiy, Vladimir G.,Kustov, Alexander L.,Kustov, Leonid M.,Panich, Nadezhda M.
, (2021/09/20)
Ozonolysis is used for oxidation of a model cyclic molecule-decalin, which may be consid-ered as an analog of saturated cyclic molecules present in heavy oil. The conversion of decalin exceeds 50% with the highest yield of formation of acids about 15–17%. Carboxylic acids, ketones/aldehydes, and alcohols are produced as intermediate products. The methods of UV-visible, transmission IR, at-tenuated total reflection IR-spectroscopy, NMR and mass-spectrometry were used to identify reaction products and unravel a possible reaction mechanism. The key stage of the process is undoubtedly the activation of the first C-H bond and the formation of peroxide radicals.
The debut of chiral cyclic (alkyl)(amino)carbenes (CAACs) in enantioselective catalysis
Pichon, Delphine,Soleilhavoup, Michele,Morvan, Jennifer,Junor, Glen P.,Vives, Thomas,Crévisy, Christophe,Lavallo, Vincent,Campagne, Jean-Marc,Mauduit, Marc,Jazzar, Rodolphe,Bertrand, Guy
, p. 7807 - 7811 (2019/08/30)
The popularity of NHCs in transition metal catalysis has prompted the development of chiral versions as electron-rich neutral stereodirecting ancillary ligands for enantioselective transformations. Herein we demonstrate that cyclic (alkyl)(amino)carbene (CAAC) ligands can also engage in asymmetric transformations, thereby expanding the toolbox of available chiral carbenes.