3009-97-0Relevant articles and documents
Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates
Adachi, Masaya,Akakabe, Mai,Ezawa, Tetsuya,Hashizume, Daisuke,Koshino, Hiroyuki,Sodeoka, Mikiko,Sohtome, Yoshihiro
supporting information, p. 9094 - 9104 (2021/07/01)
Reaction design in asymmetric catalysis has traditionally been predicated on a structurally robust scaffold in both substrates and catalysts, to reduce the number of possible diastereomeric transition states. Herein, we present the stereochemical dynamics in the Ni(II)-catalyzed diastereoconvergent (3 + 2) cycloadditions of isomerizable nitrile-conjugated nitrones with α-keto ester enolates. Even in the presence of multiple equilibrating species, the catalytic protocol displays a wide substrate scope to access a range of CN-containing building blocks bearing adjacent stereocenters with high enantio- and diastereoselectivities. Our computational investigations suggest that the enantioselectivity is governed in the deprotonation process to form (Z)-Ni-enolates, while the unique syn addition is mainly controlled by weak noncovalent bonding interactions between the nitrone and ligand.
Nano cobalt-copper ferrite catalyzed regioselective α-C(sp3)–H cyanation of amines: Secondary, tertiary, and drug molecules
Heidarian, Mahdi,Moghaddam, Firouz Matloubi,Pourkaveh, Raheleh
, (2020/11/03)
Oxidative cyanation of sp3C–H bonds at the α position of amines was achieved using CoCuFe2O4 as a catalyst and NaCN as an inexpensive cyanide source at room temperature. CoCuFe2O4 was found to be an active catalyst for Csp [3]-Csp coupling, efficiently delivering valuable α-aminonitriles from tertiary/secondary amines in good yields. The corresponding products were obtained with high selectivity toward α position. In addition, functional group tolerance offered the opportunity for application in late-stage functionalization of biologically active molecules. This transformation proceeds convenient on a gram-scale, and the catalyst can be reused for several runs with consistent catalytic activity.
Covalently hooked EOSIN-Y in a Zr(IV) framework as visible-light mediated, heterogeneous photocatalyst for efficient C–H functionalization of tertiary amines
Kumar, Gaurav,Solanki, Pratik,Nazish, Mohd,Neogi, Subhadip,Kureshy, Rukhsana I.,Khan, Noor-ul H.
, p. 298 - 304 (2019/02/26)
Herein, we report the synthesis of a novel heterogeneous photo-catalyst by utilizing post-synthetic modification of an amine functionalized Zr(IV) metal-organic framework (UiO-66-NH2) through covalent hooking of EOSIN-Y via dehydrating coupling. The characterization of the catalyst was accomplished by FT-IR, XRD, BET surface analysis, TGA, as well as TEM, SEM, XPS, DRS-UV–visible, and NMR spectroscopy, confirming successful covalent linking of EOSIN-Y with the pendent –NH2 functionality in the framework. That post-modified EY@UiO-66-NH2 acts as simple and green visible light mediated photo-catalyst for the C–H activation of tertiary amines with excellent yields. Importantly, the activity of dye incorporated heterogeneous photo-catalyst is found superior to that for the homogeneous photo-catalyst EOSIN-Y. Thus, separation difficulty of homogeneous catalysis, as well as the environmental adverse effects of toxic EOSIN-Y can be excluded by developing such photo-catalyst. Moreover, EY@UiO-66-NH2 catalyst could be consistently recycled up to 10 cycles, without any significant loss in activity. Based on literature report and experimental findings, we also propose a plausible mechanism for the reaction.
