Iron‐catalyzed Cross‐Coupling of Propargyl Carboxylates and Grignard Reagents: Synthesis of Substituted Allenes

Kessler, Simon N.; Bäckvall, Jan‐E.

doi:10.1002/anie.201511139

Cited by 85 publications

(35 citation statements)

References 86 publications

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“…The same is true for nonradical processes, where iron cross coupling also becomes particularly valuable wherever it opens possibilities beyond the canon of palladium chemistry. 123−128 An instructive case is depicted in Scheme 11.…”

Section: Radical Approaches and Tasks Beyond Reach Of The Noble Cousinsmentioning

confidence: 99%

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

2016

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The current status of homogeneous iron catalysis in organic chemistry is contemplated, as are the reasons why this particular research area only recently starts challenging the enduring dominance of the late and mostly noble metals over the field. Centered in the middle of the d-block and able to support formal oxidation states ranging from −II to +VI, iron catalysts hold the promise of being able to encompass organic synthesis at large. They are expected to serve reductive as well as oxidative regimes, can emulate “noble tasks”, but are also able to adopt “early” transition metal character. Since a comprehensive coverage of this multidimensional agenda is beyond the scope of an Outlook anyway, emphasis is laid in this article on the analysis of the factors that perhaps allow one to control the multifarious chemical nature of this earth-abundant metal. The challenges are significant, not least at the analytical frontier; their mastery mandates a mindset that differs from the routines that most organic chemists interested in (noble metal) catalysis tend to cultivate. This aspect notwithstanding, it is safe to predict that homogeneous iron catalysis bears the chance to enable a responsible paradigm for chemical synthesis and a sustained catalyst economy, while potentially providing substantial economic advantages. This promise will spur the systematic and in-depth investigations that it takes to upgrade this research area to strategy-level status in organic chemistry and beyond.

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Section: Radical Approaches and Tasks Beyond Reach Of The Noble Cousinsmentioning

confidence: 99%

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

2016

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“…[1] Pd, [2] Cu, [3] Rh, [4] Fe, [5] and Ni [6] derivativesh ave been used as catalysts in these reactions for the activation of propargylh alides, esters, carbonates,a nd phosphonates. [1] Pd, [2] Cu, [3] Rh, [4] Fe, [5] and Ni [6] derivativesh ave been used as catalysts in these reactions for the activation of propargylh alides, esters, carbonates,a nd phosphonates.…”

Section: Introductionmentioning

confidence: 99%

Ni^I Catalyzes the Regioselective Cross‐Coupling of Alkylzinc Halides and Propargyl Bromides to Allenes

Soler‐Yanes

Arribas-Álvarez

Guisán‐Ceinos

et al. 2017

Chemistry A European J

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We describe the unprecedented formation of allenes by Ni-catalyzed cross-coupling of propargyl bromides with alkylzinc halides. The reaction regioselectivity is complementary to the previously reported formation of propargyl-coupled compounds. Experiments support the formation of Ni complexes as the active species and the participation of radical intermediates. Kinetic studies showed that the reaction is first order with respect to the electrophile, zero-order with respect to the nucleophile (fast transmetalation), and one-half order with respect to the metal catalyst. Mechanistic studies support a bimetallic Ni -based pathway that involves fast homolytic cleavage of the C-Br bond by an alkyl-Ni complex, followed by radical coordination to Ni that determines the observed regioselectivity.

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“…(b)]. [18] In summary,w eh ave developed ag eneral and scalable strategy to synthesize 2-allenylindoles by aC À Ha ctivation strategy.F or the first time,e arth-abundant manganese was utilized as the catalyst and various synthetically useful functional groups such as ester,n itro and halide groups were tolerated. No apparent kinetic isotope effect (k H /k D = 1.05) was observed from parallel reactions of 1a and [D]-1a with 2c,w hich suggests that cleavage of the CÀHbond is likely not involved in the rate-determining step (for details,s ee the Supporting Information).…”

mentioning

confidence: 99%

Manganese(I)‐Catalyzed Regioselective C−H Allenylation: Direct Access to 2‐Allenylindoles

et al. 2017

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A Mn -catalyzed regioselective C-H allenylation is reported that allows a broad range of 2-allenylindoles to be synthesized regioselectively on a gram scale under simple conditions. Notably, a highly efficient chirality transfer was observed (up to 93 % ee) in this transformation. This procedure was further found to allow, for the first time, the direct preparation of ketones by Mn -catalyzed C-H activation. Mechanistic investigations revealed that the precoordination of the oxygen atom to the manganese center as well as the congested tertiary carbon atom in the propargylic carbonates play a crucial role.

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Iron‐catalyzed Cross‐Coupling of Propargyl Carboxylates and Grignard Reagents: Synthesis of Substituted Allenes

Cited by 85 publications

References 86 publications

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

Ni^I Catalyzes the Regioselective Cross‐Coupling of Alkylzinc Halides and Propargyl Bromides to Allenes

Manganese(I)‐Catalyzed Regioselective C−H Allenylation: Direct Access to 2‐Allenylindoles

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Iron‐catalyzed Cross‐Coupling of Propargyl Carboxylates and Grignard Reagents: Synthesis of Substituted Allenes

Cited by 85 publications

References 86 publications

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

NiI Catalyzes the Regioselective Cross‐Coupling of Alkylzinc Halides and Propargyl Bromides to Allenes

Manganese(I)‐Catalyzed Regioselective C−H Allenylation: Direct Access to 2‐Allenylindoles

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Ni^I Catalyzes the Regioselective Cross‐Coupling of Alkylzinc Halides and Propargyl Bromides to Allenes