Dual Catalysis Involving Organoboron Compounds

Ji, Xin; Liu, Lu

doi:10.1002/ejoc.202200853

Cited by 3 publications

(2 citation statements)

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“…1,2 The use of organoboranes as catalysts has also received significant attention whereby the interaction of the Lewis acidic boron atom with a pair of nonbonding electrons or -electron pairs is employed to activate the substrate. [3][4][5] Recent attention has focused on more electron-deficient organoboranes, such as B(C 6 F 5 ) 3 , in catalysis. These more Lewis acidic species can also interact with (C-H) bonds, resulting in hydride abstraction and the formation of a formal carbocation and a borohydride counterion.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

Elsherbeni

Winfrey

Lei

et al. 2023

Synlett

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C‒H functionalization is widely regarded as an important area in the development of synthetic methodology, enabling the design of more time- and atom-efficient syntheses. The ability of electron-deficient organoboranes to mediate hydride abstraction from α-amino C‒H bonds is therefore of great interest, as the reactive iminium and hydridoborate moieties generated are able to participate in a range of synthetically useful transformations. In this review update, we cover the recent advances made in organoborane mediated hydride abstraction, with particular focus on the catalytic applications of electron deficient boranes for α- or β- functionalization, α,β-difunctionalization, and the dehydrogenation of amines.

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Section: Introductionmentioning

confidence: 99%

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

Elsherbeni

Winfrey

Lei

et al. 2023

Synlett

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“…In two catalytic systems, a simple swap of the metal salt from Ni(OTf) 2 to InCl switches the enamine-imine tautomerism, giving the 1 H- pyrazolo[3,4- b ]pyridines 4 in up to 97% yield in an oxidation of enamines and 4,5-dihydro-1 H -pyrazolo[3,4- b ]pyridines 5 as imines in up to 92% yield and with up to >99% ee, respectively. In fact, compared to other metal salts, − reactions catalyzed by either Ni II or In I have been rather less successful in the presence of phosphoric acid. − …”

mentioning

confidence: 99%

Switchable Chemoselectivity in [3 + 3] Annulation of β,γ-Unsaturated α-Ketoesters and 1H-Pyrazol-5-amines by Cooperative Acid Catalysis with Ni^II and In^I

Tang,

Wang,

et al. 2024

Org. Lett.

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The exchange of the metal ion from Ni(II) to In(I) leads to a switch in the chemoselectivity of the [3 + 3] annulation of β,γunsaturated α-ketoesters and 1H-pyrazol-5-amines in the presence of phosphoric acid 1, affording functionalized 1H-pyrazolo [3,4-b]pyridines 4 in up to 97% yields and highly enantioselective 4,5-dihydro-1Hpyrazolo [3,4-b]pyridines 5 in up to 92% yield and 99% ee. pyridine and dihydro-1H-pyrazolo[3,4-b]pyridine derivatives are privileged structural motifs, occurring frequently in numerous natural products, pharmaceuticals, and biologically active molecules (Figure 1). 1−3 Therefore, numerous efforts have been devoted to developing efficient catalysts for the selective addition of α,β-unsaturated carbonyls with 1H-pyrazol-5-amines. 4−11 Although many efforts have focused on the α,β-unsaturated carbonyls in formal [3 + 3] cycloaddition with enamines, 12−14 the exploitation of β,γunsaturated α-ketoesters remains less studied. 15−18 This is speculatively attributed to chemoselectivity issues arising from the differentiation of 1,2-and 1,4-addition pathways. In 2010, we first developed asymmetric binary-acid catalysis, 19 which resulted in a synergistic effect for catalysis in regio-, 20 diastereo-, 21 and enantiodivergent 22,23 reactions. Herein, we report a metal salt-regulated strategy for the manipulation of the chemoselectivity in cooperative acid-catalyzed [3 + 3] annulation of β,γ-unsaturated α-ketoesters and 1H-pyrazol-5-amines (Scheme 1), which was initiated via 1,4-addition. In two catalytic systems, a simple swap of the metal salt from Ni(OTf) 2 to InCl switches the enamine-imine tautomerism, giving the 1H-pyrazolo [3,4-b]pyridines 4 in up to 97% yield in an oxidation of enamines and 4,5-dihydro-1H-pyrazolo [3,4b]pyridines 5 as imines in up to 92% yield and with up to >99% ee, respectively. In fact, compared to other metal

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Ultraviolet-Light-Induced P–H Insertion of α-Halocarbenes

Liu,

Zhang,

et al. 2024

Org. Lett.

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An intriguing P−H insertion of arylhalodiazirines with H-phosphorus oxides under ultraviolet-light irradiation is described. This methodology provides an efficient and straightforward route to the construction of a variety of α-halophosphorus oxides in good yields (≤95%), which represents a unique example of P−H insertion of α-halocarbenes for C−P bond formation. The metal-free protocol features the advantages of mild reaction conditions, high atom economy, and environmental friendliness.

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Dual Catalysis Involving Organoboron Compounds

Abstract: In recent years, organoboron compounds has attracted much attention due to their unique chemical properties. In this Review, we summarize catalytic reactions via the dual catalysis of boron and another catalyst, which showed specific catalytic activity in organic transformations.

Cited by 3 publications

References 82 publications

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

Switchable Chemoselectivity in [3 + 3] Annulation of β,γ-Unsaturated α-Ketoesters and 1H-Pyrazol-5-amines by Cooperative Acid Catalysis with Ni^II and In^I

Ultraviolet-Light-Induced P–H Insertion of α-Halocarbenes

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Dual Catalysis Involving Organoboron Compounds

Abstract: In recent years, organoboron compounds has attracted much attention due to their unique chemical properties. In this Review, we summarize catalytic reactions via the dual catalysis of boron and another catalyst, which showed specific catalytic activity in organic transformations.

Cited by 3 publications

References 82 publications

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

Switchable Chemoselectivity in [3 + 3] Annulation of β,γ-Unsaturated α-Ketoesters and 1H-Pyrazol-5-amines by Cooperative Acid Catalysis with NiII and InI

Ultraviolet-Light-Induced P–H Insertion of α-Halocarbenes

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Switchable Chemoselectivity in [3 + 3] Annulation of β,γ-Unsaturated α-Ketoesters and 1H-Pyrazol-5-amines by Cooperative Acid Catalysis with Ni^II and In^I