Rhenium-Catalyzed Addition of Carbonyl Compounds to the Carbon−Nitrogen Triple Bonds of Nitriles: α-C−H Activation of Carbonyl Compounds

Abstract

The ReH(7)(PPh(3))(2)-catalyzed addition of carbonyl compounds to the carbon-nitrogen bond of nitriles proceeds efficiently and selectively to give the corresponding (Z)-enamines, which are important synthetic intermediates. The key step of the reaction is the chemoselective alpha-C-H activation of carbonyl compounds induced by the alpha-heteroatom effect in the presence of nitriles.

Development of biomimetic catalytic oxidation methods and non-salt methods using transition metal-based acid and base ambiphilic catalysts

“…Thus, the ReH 5 (P i Pr 3 ) 2 -catalyzed reaction of carbonyl compounds with nitriles gives the corresponding (Z)-ketoenamines selectively. 42) This is a clean and salt-free catalytic Blaise reaction and is advantageous compared to the conventional Blaise reaction, where the carbonyl compound is converted into the corresponding bromide, and then treated with zinc in a Reformatskii-type reaction. The addition of carbonyl compounds to a carbon–nitrogen triple bond can be carried out chemo-selectively in the presence of carbonyl compound.…”

Title Pages

“…Ruthenium-catalyzed cross-metathesis has been applied to the synthesis of 2,6-cis-substituted 2-vinyl-4-hydroxytetrahydropyrans by reaction with allyl bromide and intramolecular O-allylation in one-pot 29 . ReH 7 (PPh 3 ) 2 -Catalyzed addition of carbonyl compounds (ketones, 2-benzofuranone) to nitriles gives the corresponding (Z)-enamines 30 . 1,2,3-(Benzo)triazole-gold(I) complexes display improved stability and reactivity for intermolecular hydroamination of alkynes 31 .…”

Solution and Solid‐State Structure of the First NHC‐Substituted Rhenium Heptahydrides

“…the catalyst showed a resting state with an activated C-H bond in α-position to the C=O group of the carbonyl compound. [5] Furthermore, this complex could selectively catalyze the conversion of cycloalkanes into cycloalkenes, which also involved C-H activation. [6] We decided to study the synthetic access to N-heterocyclic carbene (NHC) substituted heptahydride rhenium complexes [ReH 7 (NHC) 2 ] to see whether they were somehow structurally related to both the [ReH 7 (PR 3 ) 2 ] complexes and to the [ReH 9 ] 2anion in which two hydride ligands are then replaced by two NHC's.…”

“…Later Chart and Coffey prepared the stable [ReH 7 (PR 3 ) 2 ] complexes (R = PEt 2 Ph, PEtPh 2 or PPh 3 ) replacing two hydride ligands of the [ReH 9 ] 2– anion with two phosphines . The [ReH 7 (PPh 3 ) 2 ] turned recently out to be an efficient catalyst for the addition of carbonyl compounds to the carbon–nitrogen triple bonds of nitriles in a reaction, in which the catalyst showed a resting state with an activated C–H bond in α‐position to the C=O group of the carbonyl compound . Furthermore, this complex could selectively catalyze the conversion of cycloalkanes into cycloalkenes, which also involved C‐H activation .…”