Tackling <i>N</i>‐Alkyl Imines with 3d Metal Catalysis: Highly Enantioselective Iron‐Catalyzed Synthesis of α‐Chiral Amines

Blasius, Clemens K.; Heinrich, Niklas F.; Vasilenko, Vladislav; Gade, Lutz H.

doi:10.1002/ange.202006557

Cited by 7 publications

(1 citation statement)

References 78 publications

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“…Asymmetric catalysis employing various acyclic N -alkyl imines afforded α-chiral amines in excellent yields. 41 The Schmidt group recently reported a cationic [(iminophosphine)nickel(allyl)] + complex in the hydroboration of N -allylimines (5 mol%). However, no successful hydroboration of ketimine is reported by this catalyst.…”

Section: Introductionmentioning

confidence: 99%

Iron-catalysed hydroboration of non-activated imines and nitriles: kinetic and mechanistic studies

2021

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Section: Introductionmentioning

confidence: 99%

Iron-catalysed hydroboration of non-activated imines and nitriles: kinetic and mechanistic studies

2021

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Reaction Pathways and Redox States in α‐Selective Cobalt‐Catalyzed Hydroborations of Alkynes

et al. 2020

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Cobalt(II) alkyl complexes supported by a monoanionic NNN pincer ligand are pre-catalysts for the regioselective hydroboration of terminal alkynes, yielding the Markovnikov products with a:b-(E) ratios of up to 97:3. A cobalt(II) hydride and a cobalt(II) vinyl complex appear to determine the main reaction pathway. In a background reaction the highly reactive hydrido species specifically converts to a coordinatively unsaturated cobalt(I) complex which was found to re-enter the main catalytic cycle.

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Cobalt‐Catalysed Asymmetric Addition and Alkylation of Secondary Phosphine Oxides for the Synthesis of P‐Stereogenic Compounds

Weng

Cheng

et al. 2021

Angewandte Chemie

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The catalytic asymmetric synthesis of P-chiral phosphorus compounds is an important way to construct Pchiral ligands. Herein, we report a new strategy that adopts the pyridinyl moiety as the coordinating group in the cobaltcatalysed asymmetric nucleophilic addition/alkylation of secondary phosphine oxides. A series of tertiary phosphine oxides were generated with up to 99 % yield and 99.5 % ee, and with broad functional-group tolerance. Mechanistic studies reveal that (R)-secondary phosphine oxides preferentially interact with the cobalt catalysts to produce P-stereogenic compounds.Chiral phosphorus compounds play important roles as ligands [1] or organic catalysts [2] in asymmetric catalysis. Compared to the synthesis of axial-, planar-, and carboncentered chiral phosphorus compounds, the synthesis of Pstereogenic phosphines has been less investigated. The main recent strategies for the preparation of P-chiral compounds involve the use of chiral auxiliary materials or the resolution of racemates. [3] These classical methods require stoichiometric chiral agents or generate an equivalent amount of compound with an opposite configuration. [4] Recently, several asymmetric catalytic methods were developed based on the desymmetrization of phosphine oxides via CÀH bond activation, [5] asymmetric addition, [6] ring-closing metatheses, [7] and [2+2+2] cycloaddition processes. [8] In addition, secondary phosphines have been used as nucleophiles in asymmetric conjugate addition, [9] alkylation, [10] and arylation reactions. [11] However, in this process, the strong coordination ability of the secondary phosphines may lead to deactivation of the metal catalyst, thereby reducing the enantioselectivity. Therefore, the development of alternative methods for the synthesis of P-chiral compounds is still highly necessary.Compared with secondary phosphines, secondary phosphine oxides (SPOs) are more stable in air and have low toxicity to metal catalysts. Nonetheless, only a few synthetic examples have been reported for the preparation of optically active tertiary phosphine oxides (TPOs) from SPOs. In 2016, Gaunt and co-workers reported a new strategy in which Cu combined with chiral pyridine-2,6-bis(oxazolines) ligand (pybox) was applied for the enantioselective arylation of SPOs with diaryliodonium salt, affording P-chiral tertiary phosphorus compounds with up to 98 % ee (Scheme 1 a). [12] The Cai group reported a Pd-catalysed arylation of SPOs with aryl iodides with moderate to high ee (Scheme 1 b). [13] Recently, Zhang and co-workers also reported Pd-catalysed asymmetric arylation and alkenylation reactions of SPOs (Scheme 1 c), in which products were obtained in up to 99 % ee. [14] In addition to the above examples, the Qing-Wei Zhang group developed a Ni-catalysed kinetic resolution of SPOs via an allylic substitution process, providing a series of Pstereogenic compounds with high enantioselectivity (Scheme 1 d). [15] However, the SPOs in the abovementioned examples usually contain one aryl and one alkyl group. Substrates b...

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Tackling N‐Alkyl Imines with 3d Metal Catalysis: Highly Enantioselective Iron‐Catalyzed Synthesis of α‐Chiral Amines

Cited by 7 publications

References 78 publications

Iron-catalysed hydroboration of non-activated imines and nitriles: kinetic and mechanistic studies

Iron-catalysed hydroboration of non-activated imines and nitriles: kinetic and mechanistic studies

Reaction Pathways and Redox States in α‐Selective Cobalt‐Catalyzed Hydroborations of Alkynes

Cobalt‐Catalysed Asymmetric Addition and Alkylation of Secondary Phosphine Oxides for the Synthesis of P‐Stereogenic Compounds

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