Reactions of N-halo-N-methylbenzylamines with sodium methoxide-methanol and potassium tert-butoxide-tert-butyl alcohol. Effects of .beta.-carbon substituent and base-solvent system upon the imine-forming transition state
Fe(BF4)2·6H2O/2,6-pyridinedicarboxylic acid catalysed nitrosation of a wide variety of substituted styrenes has been developed in the presence of t-BuONO/NaBH4 under H2 pressure (10 bar) in MeOH–H2O (5 : 1) to afford corresponding oximes in good to excellent yields.
A novel cationic [IrH(THF)(P,N)(imine)] [BArF] catalyst containing a P-stereogenic MaxPHOX ligand is described for the direct asymmetrichydrogenation of N-methyl and N-alkyl imines. This is the first catalytic system to attain high enantioselectivity (up to 94% ee) in this type of transformation. The labile tetrahydrofuran ligand allows for effective activation and reactivity, even at low temperatures
A combined computational and experimental approach allowed us to develop the most selective catalysts for the direct hydrogenation of N‐methyl and N‐alkyl imines described to date. Iridium catalysts with a cyclometallated cyclic imide group provide selectivity of up to 99% enantiomeric excess. Computational studies show that the selectivity results from the combined effect of H‐bonding of the imide C=O with the substrate iminium ion and a stabilizing π‐π interaction with the cyclometallated ligand. The cyclometallated ligand thus exhibits a unique mode of action, serving as a template for the H‐bond directed approach of the substrate which results in enhanced selectivity. The catalyst (2) has been synthesized and isolated as a crystalline air‐stable solid. X‐ray analysis of 2 confirmed the structure of the catalyst and the correct position of the imide C=O groups to engage in an H‐bond with the substrate. 19F‐NMR real‐time monitoring showed the hydrogenation of N‐methyl imines catalyzed by 2 is very fast, with a TOF of approx. 3500 h‐1.
Copper-catalyzed asymmetric 1,2-arylboration of enamines: access to chiral borate-containing 3,3′-disubstituted isoindolinones
An enantioselective Cu-catalyzed 1,2-arylboration reaction of N-(o-iodobenzoyl)enamines with bis(pinacolato)diboron (B2pin2) is developed to access chiral borate-containing 3,3′-disubstituted isoindolinones.