Polystyrene-supported nickel complex catalysed deprotection of allylic tertiary amine with sodium borohydride

Bao, Lingxiang; Liang, Honggang; Zhang, Haonan; Yan, Zhibin; Sun, Chia‐Chung; Pang, Siping

doi:10.1088/1757-899x/772/1/012101

Cited by 2 publications

(3 citation statements)

References 14 publications

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“…Both Ni and Pd have been previously reported to deallylate amines. 55,56 Although the isomerization of 1t is observed using Ni/Zr(OH) 4 •nH 2 SO 4 , the low E/Z selectivity and the competing side reaction deem this catalytic system less effective than the Ni/SZO 300-insitu system. This indicates that SZO 300 is indeed required for broadly applicable alkene isomerization activity, stereoselectivity, and chemoselectivity.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…After 24 h, 1 H NMR analysis of the crude reaction indicates 9% of unreacted 1t , 59% of 2t with low E / Z selectivty of 5.9:1 ( E / Z ), and deallylated 1t to form TsN(Me)H, S1 (compare to the results with Ni/SZO 300‑insitu : E / Z = 24:1, 97% yield, no deallylation observed) (Figure S16, Table S11). Both Ni and Pd have been previously reported to deallylate amines. , Although the isomerization of 1t is observed using Ni/Zr(OH) 4 · n H 2 SO 4 , the low E / Z selectivity and the competing side reaction deem this catalytic system less effective than the Ni/SZO 300‑insitu system. This indicates that SZO 300 is indeed required for broadly applicable alkene isomerization activity, stereoselectivity, and chemoselectivity.…”

Section: Resultsmentioning

confidence: 99%

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Alkene Isomerization Using a Heterogeneous Nickel-Hydride Catalyst

Chang,

Kascoutas,

Valentine

et al. 2024

J. Am. Chem. Soc.

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Transition metal-catalyzed alkene isomerization is an enabling technology used to install an alkene distal to its original site. Due to their well-defined structure, homogeneous catalysts can be fine-tuned to optimize reactivity, stereoselectivity, and positional selectivity, but they often suffer from instability and nonrecyclability. Heterogeneous catalysts are generally highly robust but continue to lack active-site specificity and are challenging to rationally improve through structural modification. Known single-site heterogeneous catalysts for alkene isomerization utilize precious metals and bespoke, expensive, and synthetically intense supports. Additionally, they generally have mediocre reactivity, inspiring us to develop a heterogeneous catalyst with an active site made from readily available compounds made of Earth-abundant elements. Previous work demonstrated that a very active homogeneous catalyst is formed upon protonation of Ni[P(OEt)3]4 by H2SO4, generating a [Ni–H]+ active site. This catalyst is incredibly active, but also decomposes readily, which severely limits its utility. Herein we show that by using a solid acid (sulfated zirconia, SZO300), not only is this decomposition prevented, but high activity is maintained, improved selectivity is achieved, and a broader scope of functional groups is tolerated. Preliminary mechanistic experiments suggest that the catalytic reaction likely goes through an intermolecular, two-electron pathway. A detailed kinetic study comparing the state-of-the-art Ni and Pd isomerization catalysts reveals that the highest activity and selectivity is seen with the Ni/SZO300 system. The reactivity of Ni/SZO300, is not limited to alkene isomerization; it is also a competent catalyst for hydroalkenylation, hydroboration, and hydrosilylation, demonstrating the broad application of this heterogeneous catalyst.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Alkene Isomerization Using a Heterogeneous Nickel-Hydride Catalyst

Chang,

Kascoutas,

Valentine

et al. 2024

J. Am. Chem. Soc.

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show abstract

“…Both Ni and Pd have been previously reported to deallylate amines. 55,56 Although the isomerization of 1t is observed using Ni/Zr(OH)4•nH2SO4, the low E/Z selectivity and the competing side reaction deem this catalytic system less effective than the Ni/SZO300-insitu system. This indicates that SZO300 is indeed required for broadly applicable alkene isomerization activity, stereoselectivity, and chemoselectivity.…”

Section: Substrate Scopementioning

confidence: 99%

Alkene Isomerization using a Heterogeneous Nickel-Hydride Catalyst

Chang,

Kascoutas,

Valentine

et al. 2024

Preprint

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Transition metal-catalyzed alkene isomerization is an enabling technology used to install an alkene distal to its original site. Due to their well-defined structure, homogeneous catalysts can be fine-tuned to optimize reactivity, stereoselectivity, and positional selectivity, but they often suffer from instability and non-recyclability. Heterogeneous catalysts are generally highly robust but continue to lack active-site specificity and are challenging to rationally improve through structural modification. Known single-site heterogeneous catalysts for alkene isomerization utilize precious metals and bespoke, expensive, and synthetically intense supports. Additionally, they generally have mediocre reactivity, inspiring us to develop a heterogeneous catalyst with an active site made from readily available compounds made of Earth-abundant elements. Previous work demonstrated that a very active homogeneous catalyst is formed upon protonation of Ni[P(OEt)3]4 by H2SO4, generating a [Ni–H]+ active site. This catalyst is incredibly active, but also decomposes readily, which severely limits its utility. Herein we show that by using a solid acid (sulfated zirconia, SZO300), not only is this de-composition prevented, but high activity is maintained, improved selectivity is achieved, and a broader scope of functional groups is tolerated. Preliminary mechanistic experiments suggest that the catalytic reaction likely goes through an intermolecular, two-electron pathway. A detailed kinetic study comparing the state-of-the-art Ni and Pd isomerization catalysts reveals that the highest activity and selectivity is seen with the Ni/SZO300 system. The reactivity of Ni/SZO300, is not limited to alkene isomerization; it is also a competent catalyst for hydroalkenylation, hydroboration, and hydrosilylation, demonstrating the broad application of this heterogeneous catalyst.

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Polystyrene-supported nickel complex catalysed deprotection of allylic tertiary amine with sodium borohydride

Cited by 2 publications

References 14 publications

Alkene Isomerization Using a Heterogeneous Nickel-Hydride Catalyst

Alkene Isomerization Using a Heterogeneous Nickel-Hydride Catalyst

Alkene Isomerization using a Heterogeneous Nickel-Hydride Catalyst

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