4556-09-6Relevant articles and documents
Oxygen Atom Transfer Mechanism for Vanadium-Oxo Porphyrin Complexes Mediated Aerobic Olefin Epoxidation
Han, Qi,Huang, Jia-Ying,Ji, Hong-Bing,Liu, Xiao-Hui,Tao, Lei-Ming,Xue, Can,Yu, Hai-Yang,Zhou, Xian-Tai,Zou, Wen
supporting information, p. 115 - 122 (2021/12/04)
The development of catalytic aerobic epoxidation by numerous metal complexes in the presence of aldehyde as a sacrificial reductant (Mukaiyama epoxidation) has been reported, however, comprehensive examination of oxygen atom transfer mechanism involving free radical and highly reactive intermediates has yet to be presented. Herein, meso-tetrakis(pentafluorophenyl) porphyrinatooxidovanadium(IV) (VOTPFPP) was prepared and proved to be efficient toward aerobic olefin epoxidation in the presence of isobutyraldehyde. In situ electron paramagnetic resonance spectroscopy (in situ EPR) showed the generation, transfer pathways and ascription of free radicals in the epoxidation. According to the spectral and computational studies, the side-on vanadium-peroxo complexes are considered as the active intermediate species in the reaction process. In the cyclohexene epoxidation catalyzed by VOTPFPP, the kinetic isotope effect value of 1.0 was obtained, indicating that epoxidation occurred via oxygen atom transfer mechanism. The mechanism was further elucidated using isotopically labeled dioxygen experiments and density functional theory (DFT) calculations.
Selective C-H Allylic Oxygenation of Cycloalkenes and Terpenoids Photosensitized by [Cu(Xantphos)(neoc)]BF4
Kallitsakis, Michael G.,Gioftsidou, Dimitra K.,Tzani, Marina A.,Angaridis, Panagiotis A.,Terzidis, Michael A.,Lykakis, Ioannis N.
, p. 13503 - 13513 (2021/09/13)
We present herein for the first time the use of the [Cu(Xantphos)(neoc)]BF4 as a photocatalyst for the selective C-H allylic oxygenation of cycloalkenes into the corresponding allylic hydroperoxides or alcohols in the presence of molecular oxygen. The proposed methodology affords the products at good yields and has also been applied successfully to several bioactive terpenoids, such as geraniol, linalool, β-citronellol, and phytol. A mechanistic study involving also kinetic isotope effects (KIEs) supports the proposed singlet oxygen-mediated reaction. On the basis of the high chemoselectivity and yields and the fast and clean reaction processes observed, the present catalytic system, [Cu(Xantphos)(neoc)]BF4, has also been applied to the synthesis, at a laboratory scale, of the cis-Rose oxide, a well-known perfumery ingredient used in rose and geranium perfumes.
Are bis(pyridine)iodine(i) complexes applicable for asymmetric halogenation?
Andreasson, M?ns,Erdelyi, Mate,Németh, Flóra Boróka,Pápai, Imre,Sethio, Daniel,von der Heiden, Daniel
, p. 8307 - 8323 (2021/10/12)
Enantiopure halogenated molecules are of tremendous importance as synthetic intermediates in the construction of pharmaceuticals, fragrances, flavours, natural products, pesticides, and functional materials. Enantioselective halofunctionalizations remain
