Sulfonic acid supported on hydroxyapatite-encapsulated-γ-Fe2O3 nanocrystallites as a magnetically separable catalyst for one-pot reductive amination of carbonyl compounds
A novel, environmentally friendly procedure has been developed for the preparation of secondary or tertiary amines by one-pot reductive amination of carbonyl compounds using sodium borohydride in the presence of a magnetically recoverable sulfonic acid supported on hydroxyapatite-encapsulated-γ-Fe2O3 [γ-Fe2O3@HAP-SO3H] at room temperature. The catalyst was easily separated from the reaction mixture by applying an external magnet and reused for six cycles without significant loss of catalytic activity.
A Reusable Co Catalyst for the Selective Hydrogenation of Functionalized Nitroarenes and the Direct Synthesis of Imines and Benzimidazoles from Nitroarenes and Aldehydes
作者:Tobias Schwob、Rhett Kempe
DOI:10.1002/anie.201608321
日期:2016.11.21
presence of highly hydrogenation‐sensitive functional groups, as well as the direct synthesis of imines from nitroarenes and aldehydes or ketones in the presence of such substituents. Furthermore, we introduce the first base‐metal‐mediated direct synthesis of benzimidazolesfrom nitroarenes and aldehydes. Functional groups that are easy to hydrogenate are again well tolerated.
Hydroxyl‐substituted benzaldimines underwent a RhIII‐catalyzed C−Hactivation and annulation with alkynes to provide novel mesoionicisoquinoline derivatives in moderate to excellent yields using oxygen as an internal anion source. This simple and efficient approach has a broad substrate scope.
Catalytic Asymmetric Inverse-Electron-Demand (IED) [4+2] Cycloaddition of Salicylaldimines: Preparation of Optically Active 4-Aminobenzopyran Derivatives
The catalyticasymmetricinverse-electron-demand (IED) [4+2] cycloaddition of various salicylaldehyde-derived N-arylimines with electron-rich alkenes in the presence of chiral BINOL-derived phosphoric acid catalysts has been studied with the aim of obtaining opticallyactive4-aminobenzopyranderivatives. Dienophiles such as 2,3-dihydro-2H-furan, benzyl N-vinylcarbamate and 2-vinylindole have been
Diastereospecific Coupling of Imines by Low-Valent Titanium: An Experimental and Computational Study
作者:Akshai Kumar、Ashoka G. Samuelson
DOI:10.1002/ejoc.201001256
日期:2011.2
phenylsilane (PhSiH3) and titanium(IV) isopropoxide Ti(OiPr)(4)] generates low-valenttitanium alkoxides that reduce and reductively couple imines. The C-C coupling reaction is diastereospecific, with exclusive formation of the (+/-)-isomer. The yield is dependent on the concentration of titanium(IV) isopropoxide used. Using imines with varying electronic demand revealed that the coupling is most efficient