2983-48-4Relevant articles and documents
Yolk-Shell-Mesostructured Silica-Supported Dual Molecular Catalyst for Enantioselective Tandem Reactions
Wu, Liang,Li, Yilong,Meng, Jingjing,Jin, Ronghua,Lin, Jingrong,Liu, Guohua
, p. 861 - 867 (2018)
Yolk-shell-mesostructured silica was used as a support in the development of an active-site-isolated bifunctional catalyst that can mediate a sequential organic transformation. Herein, through immobilization, the location of two catalytic species is controlled: a base functionality is anchored in the channels of the outer silica shell and a chiral ruthenium/diamine functionality is anchored on the inner silica yolk. The result is a yolk-shell-mesostructured silica-supported active-site-isolated dual molecule catalyst. Structural analysis through solid-state carbon 13C NMR spectroscopy reveals its well-defined single-site dual active centers. Electron microscopy investigations disclose its uniformly distributed mesoporous nanoparticles. As envisaged, this bifunctional catalyst enables a controllable aza-Michael addition/asymmetric transfer hydrogenation catalytic sequence, where the base-catalyzed aza-Michael addition of enones and amines to aryl-substituted β-secondary amino ketones is followed by a Ru-catalyzed asymmetric transfer hydrogenation. Various aryl-substituted γ-secondary amino alcohols are obtained in high yields and enantioselectivities via this one-pot enantioselective organic transformation. Furthermore, the heterogeneous catalyst can be applied in a continuous-flow process, which was shown to be particularly attractive for the practical preparation of aryl-substituted γ-secondary amino alcohols in an environmentally friendly medium.
Hydrogen-Atom-Transfer-Mediated Acceptorless Dehydrogenative Cross-Coupling Enabled by Multiple Catalytic Functions of Zwitterionic Triazolium Amidate
Minami, Kodai,Ohmatsu, Kohsuke,Ooi, Takashi
, p. 1971 - 1976 (2022/02/07)
An unconventional cooperative catalysis for hydrogen-atom-transfer-mediated acceptorless dehydrogenative cross-coupling is described. The combined use of zwitterionic 1,2,3-triazolium amidate and an Ir-based photosensitizer as catalysts enables C-H/C-H cross-couplings between heteroatom-containing C-H donors and enamides or 1,1-diarylethenes under visible-light irradiation without the need for any oxidants, hydrogen evolution catalysts, or electrodes. A key to establishing this catalysis is the susceptibility of the conjugate acid of the triazolium amidate, amide triazolium, toward single-electron reduction to complete the catalytic cycle.
Gold-Catalyzed Hydroamination of Propargylic Alcohols: Controlling Divergent Catalytic Reaction Pathways to Access 1,3-Amino Alcohols, 3-Hydroxyketones, or 3-Aminoketones
Laserna, Victor,Porter, Michael J.,Sheppard, Tom D.
, p. 11391 - 11406 (2019/09/30)
A versatile approach to the valorization of propargylic alcohols is reported, enabling controlled access to three different products from the same starting materials. First, a general method for the hydroamination of propargylic alcohols with anilines is described using gold catalysis to give 3-hydroxyimines with complete regioselectivity. These 3-hydroxyimines can be reduced to give 1,3-amino alcohols with high syn selectivity. Alternatively, by using a catalytic quantity of aniline, 3-hydroxyketones can be obtained in high yield directly from propargylic alcohols. Further manipulation of the reaction conditions enables the selective formation of 3-aminoketones via a rearrangement/hydroamination pathway. The utility of the new chemistry was exemplified by the one-pot synthesis of a selection of N-arylpyrrolidines and N-arylpiperidines. A mechanism for the hydroamination has been proposed on the basis of experimental studies and density functional theory calculations.
Domino Synthesis of α,β-Unsaturated γ-Lactams by Stereoselective Amination of α-Tertiary Allylic Alcohols
Xie, Jianing,Xue, Sijing,Escudero-Adán, Eduardo C.,Kleij, Arjan W.
, p. 16727 - 16731 (2018/11/23)
Tertiary allylic alcohols equipped with a carboxyl group can be smoothly aminated under ambient conditions by a conceptually new and stereoselective protocol under palladium catalysis. The in situ formed Z-configured γ-amino acid cyclizes to afford an α,β-unsaturated γ-lactam, releasing water as the only byproduct. This practical catalytic transformation highlights the use of a carboxyl group acting as an activating and stereodirecting functional group to provide a wide series of pharma-relevant building blocks. Various control reactions support the crucial role of the carboxyl group in the substrate to mediate these transformations.
