Catalytic, Z-Selective, Semi-Hydrogenation of Alkynes with a Zinc–Anilide Complex

Baker, Greg; White, Andrew; Casely, Ian; Grainger, Damian; Crimmin, Mark R.

doi:10.26434/chemrxiv-2022-3tcn2-v2

Cited by 4 publications

(6 citation statements)

References 14 publications

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“…Similarly, compound 1 reacted with benzyl alcohol ( 8a ) at the above reaction condition to produce CBG zinc alkoxide complex, [LZnO–CH 2 –C 6 H 5 ] 2 ( Zn-5 ) as confirmed by NMR, HRMS, and X-ray single crystal analysis (Scheme ). To our knowledge, a few examples of structurally characterized zinc-anilide and zinc alkoxide complexes are known in the literature …”

Section: Resultsmentioning

confidence: 99%

Zinc Catalyzed Hydroelementation (HE; E = B, C, N, and O) of Carbodiimides: Intermediates Isolation and Mechanistic Insights

et al. 2023

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The conjugated bis-guanidinate (CBG) supported zinc hydride, [{LZnH} 2 ; L = {(ArHN)(ArN)-C�N−C�(NAr)-(NHAr); Ar = 2,6-Et 2 -C 6 H 3 }] (1) (pre)-catalyzed addition of E− H (E = B, C, N, and O) to carbodiimides is presented. Compound 1 catalyzed the reduction of carbodiimides with pinacolborane (HBpin), terminal alkynes, primary amines, and alcohols, gave a series of N-boryl formamidines, propiolamidines, guanidines, and isoureas with high conversions. All these reactions display good tolerance of functional groups. These reactions proceeded through the active catalysts and intermediate of zinc amidinate (Zn-1, Zn-1′, and Zn-3), zinc alkynyl (Zn-2, and Zn-2′), zinc anilide (Zn-4), and zinc alkoxide (Zn-5) complexes, which have been characterized by multinuclear NMR and HRMS analyses. Moreover, compounds Zn-1′, Zn-2′, Zn-4, and Zn-5 were confirmed by singlecrystal X-ray diffraction studies. Complete catalytic cycles have been proposed based on well-defined intermediates and stoichiometric experiments.

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Section: Resultsmentioning

confidence: 99%

Zinc Catalyzed Hydroelementation (HE; E = B, C, N, and O) of Carbodiimides: Intermediates Isolation and Mechanistic Insights

et al. 2023

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“…Related hydrozincation reactions of acyclic alkenes with 2 have recently been reported by our group. 22 …”

Section: Resultsmentioning

confidence: 99%

“…Related hydrozincation reactions of acyclic alkenes with 2 have recently been reported by our group. 22 Crystals of 5b and 5c suitable for single crystal X-ray diffraction were grown from n-pentane solution (Fig. 2).…”

Section: Hydrometallation Of Methylidene Cycloalkanesmentioning

confidence: 99%

Understanding the role of ring strain in β-alkyl migration at Mg and Zn centres

et al. 2023

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“…10 A σ-bond metathesis between H 2 and the terminal Zn−N HMDS of 1 or the Zn−C Et of 2 could be a possibility. 35 But both 1 and 2 are inert toward H 2 (1 atm), at least up to 60 °C.…”

Section: ■ Introductionmentioning

confidence: 97%

2-Anilidomethylpyridine-Derived Three-Coordinate Zinc Hydride: The Journey Unveils Anilide Backbone’s Reactive Nature

Mandal,

Joshi,

Das

et al. 2023

Inorg. Chem.

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Low-coordinate heteroleptic zinc hydrides are catalytically important but rare and synthetically challenging. We herein report three-coordinate monomeric zinc hydride on a 2anilidomethylpyridine framework ( NN L). The synthetic success comes through systematically screening a few different routes from different precursors. During the process, the ligand's anilide backbone interestingly appears to be more reactive than Zn's terminal site to electrophilic Lewis and Brønsted acids. The proligand NN LH reacts with [Zn{N(SiMe 3 ) 2 } 2 ] and ZnEt 2 to give [( NN L)ZnA] (A = N(SiMe 3 ) 2 (1), Et(2)). Both are inert to PhSiH 3 and H 2 but react with HBpin only through the internal Zn−N anilide bond to give the borylated ligand NN LBpin (3). The reactions of 1 and 2 with Ph 3 EOH (E = C, Si) afford a series of divergent compounds like [( NN LH)Zn(OSiPh 3 ) 2 ] (4), [Zn 3 (OSiPh 3 ) 4 Et 2 ] (5), and [EtZn(OCPh 3 )] (6). But in all cases, it is invariably the Zn−N anilide bond protonated by the −OH with equal or higher preference than the terminal Zn−N or Zn−C bonds. A DFT analysis rationalizes the origin of such a reactivity pattern. Realizing that an acidfree route might be the key, reacting [( NN L)Li] with ZnBr 2 gives [( NN L)Zn(μ-Br)] 2 (7), which on successively treating with KOSiPh 3 and PhSiH 3 gives the desired [( NN L)ZnH] (8) as a three-coordinate monomer with a terminal Zn−H bond. Estimating the ligand steric in 8 shows the openness in Zn's coordination sphere, a desired criterion for efficient catalysis. This and a positive influence of the pyridyl sidearm is reflected in 8's superior activity in hydroborating PhC(O)Me by HBpin in comparison to Jones' two-coordinate anilido zinc hydride.

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Catalytic, Z-Selective, Semi-Hydrogenation of Alkynes with a Zinc–Anilide Complex

Cited by 4 publications

References 14 publications

Zinc Catalyzed Hydroelementation (HE; E = B, C, N, and O) of Carbodiimides: Intermediates Isolation and Mechanistic Insights

Zinc Catalyzed Hydroelementation (HE; E = B, C, N, and O) of Carbodiimides: Intermediates Isolation and Mechanistic Insights

Understanding the role of ring strain in β-alkyl migration at Mg and Zn centres

2-Anilidomethylpyridine-Derived Three-Coordinate Zinc Hydride: The Journey Unveils Anilide Backbone’s Reactive Nature

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