6948-01-2Relevant articles and documents
Oxidation Under Reductive Conditions: From Benzylic Ethers to Acetals with Perfect Atom-Economy by Titanocene(III) Catalysis
Funk, Pierre,Richrath, Ruben B.,Bohle, Fabian,Grimme, Stefan,Gans?uer, Andreas
supporting information, p. 5482 - 5488 (2021/02/03)
Described here is a titanocene-catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines, respectively, with pendant epoxides. The reaction proceeds by catalysis in single-electron steps. The oxidative addition comprises an epoxide opening. An H-atom transfer, to generate a benzylic radical, serves as a radical translocation step, and an organometallic oxygen rebound as a reductive elimination. The reaction mechanism was studied by high-level dispersion corrected hybrid functional DFT with implicit solvation. The low-energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate. An interesting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions.
ZIF-67 Derived Co/NC Nanoparticles Enable Catalytic Leuckart-type Reductive Amination of Bio-based Carbonyls to N-Formyl Compounds
Li, Chuanhui,Meng, Ye,Yang, Song,Li, Hu
, p. 5166 - 5177 (2021/10/25)
It is of great significance to develop non-precious metal catalysts with excellent catalytic activity, stability, and acid resistance for biomass valorization. Herein, catalytic amination of biomass carbonyl compounds was achieved via a Leuckart-type reaction over Co nanoparticles (NPs) embedded N-doped carbon catalyst, which was prepared by thermolysis of ZIF-67 precursor at different temperatures in the N2 atmosphere. The Co/NC-800 catalyst exhibited excellent catalytic activity and recyclability in furfural reductive amination to mono-substituted formamide, which was attributed to the synergistic catalytic action of Co NPs and nitrogen base sites of the catalyst. The reductive amination mechanisms were elucidated by theoretical calculations, and showed that the initial formation of C?N bond was derived from the condensation of furfural and formamide, followed by dehydration to form C=N double bond, which was then reduced by hydrogen species Co?H? and NH+. The developed catalytic system was applicable to different carbonyls for the synthesis of corresponding N-formyl compounds with up to 99 % yield.
Preparation and catalytic evaluation of a palladium catalyst deposited over modified clinoptilolite (Pd&at;MCP) for chemoselective N-formylation and N-acylation of amines
Amirsoleimani, Mina,Khalilzadeh, Mohammad A.,Zareyee, Daryoush
, (2020/08/22)
Novel palladium nanoparticles stabilized by clinoptilolite as a natural inexpensive zeolite prepared and used for N-formylation and N-acylation of amines at room temperature at environmentally benign reaction conditions in good to excellent yields. Pd (II) was immobilized on the surface of clinoptilolite via facile multi-step amine functionalization to obtain a sustainable, recoverable, and highly active nano-catalyst. The structural and morphological characterizations of the catalyst carried out using XRD, FT-IR, BET and TEM techniques. Moreover, the catalyst is easily recovered using simple filtration and reused for 7 consecutive runs without any loss in activity.