Transient imine directing groups for the C–H functionalisation of aldehydes, ketones and amines: an update 2018–2020

Higham, Joe I.; Bull, James A.

doi:10.1039/d0ob01587c

Cited by 96 publications

(25 citation statements)

References 110 publications

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“…Recent efforts have focused on transient auxiliaries or a combination of coordinating functional groups and exogenous ligands as a powerful alternative for selective functionalization that circumvent the need for harsh cleavage steps. A full discussion of this field is beyond the scope of this review and we would like to point the reader towards excellent recent publications in this area [193–196] . These approaches are often complementary to covalent directing group chemistry, and there is clearly still a need for mild, efficient methods for directing group cleavage at this time.…”

Section: Discussionmentioning

confidence: 99%

A Guide to Directing Group Removal: 8‐Aminoquinoline

Fitzgerald

O’Duill

2021

Chemistry A European J

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The use of directing groups allows high levels of selectivity to be achieved in transition metal‐catalyzed transformations. Efficient removal of these auxiliaries after successful functionalization, however, can be very challenging. This review provides a critical overview of strategies used for removal of Daugulis’ 8‐aminoquinoline (2005–2020), one of the most widely used N,N‐bidentate directing groups. The limitations of these strategies are discussed and alternative approaches are suggested for challenging substrates. Our aim is to provide a comprehensive end‐users’ guide for chemists in academia and industry who want to harness the synthetic power of directing groups—and be able to remove them from their final products.

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Section: Discussionmentioning

confidence: 99%

A Guide to Directing Group Removal: 8‐Aminoquinoline

Fitzgerald

O’Duill

2021

Chemistry A European J

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“…Very recently, the newly emerged transient directing group (TDG) strategy was found to be an ideal option to circumvent the aforementioned inherent obstacles. 8 Since the breakthrough work from Yu's group, 9 a large number of TDG-assisted direct C−H functionalizations has been implemented for benzaldehydes. 10 However, heterocyclic aldehydes have been rarely focused on, and the only two examples concerned C−H arylation.…”

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confidence: 99%

Transient Directing Group Strategy as a Unified Method for Site Selective Direct C4–H Halogenation of Indoles

et al. 2021

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A unified method for direct C4–H halogenation of indoles has been accomplished with the assistance of anthranilic acids as suitable transient directing groups. Exclusive site selectivity (one out of five potential reactive sites) as well as good functional group tolerance was obtained to install three kinds of halogen atoms (Cl, Br and I, respectively) by using inexpensive N-halosuccinimides (NXS) as halogen sources under mild conditions. Taking advantage of the rich functional groups in the product, a diversity of nitrogen-containing heterocycles were facily constructed via one-step late-stage derivations.

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“…The domain of transition metal‐catalyzed C−H activation has now grown to the potential for introducing carbon−carbon and carbon−heteroatom bonds in a streamlined and simplified fashion leading to concise synthesis of natural products and pharmaceuticals [11,12] . Site‐selective C−H activation is often achieved by employing directing groups, transient directing groups, non‐covalent interactions in order to deliver the metal catalyst in close proximity to the target C−H bond leading to cyclometallation [13–19] . The common directing groups include carbonyl derivatives, aromatic N ‐heterocycles, hydroxy group, oximes, nitriles, etc [14,15] .…”

Section: Introductionmentioning

confidence: 99%

Catalytic C−H Activation via Four‐Membered Metallacycle Intermediate

Bhagat

Biswas

Dutta

2022

Helvetica Chimica Acta

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C−H Activation by transition metals has revolutionized the field of modern synthetic organic chemistry thereby enabling efficient and atom‐economical construction of complex organic frameworks in reduced number of steps. Various ways are being explored in order to maximize efficiency of the approach and construct previously unknown molecules. The major challenge in this aspect is the ubiquitous presence of C−H bond in an organic molecule that demands sophistication to achieve site‐selective functionalization. Directing group approach provided the most viable solution which operates through formation of a thermodynamically preferred metallacycle. Although, five and six membered metallacycles are known to be thermodynamically most favorable, there exists ingenious methodologies that operates through a four‐membered metallacycle in order to achieve site‐selectivity. In this review article, we summarize the C−H activation reactions evidenced to proceed via four‐membered metallacycle intermediate to achieve synthetically relevant transformations.

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Transient imine directing groups for the C–H functionalisation of aldehydes, ketones and amines: an update 2018–2020

Abstract: The use of pre-installed directing groups has become a popular and powerful strategy to control site selectivity in transition metal catalysed C–H functionalisation reactions. However, the necessity for directing group...

Cited by 96 publications

References 110 publications

A Guide to Directing Group Removal: 8‐Aminoquinoline

A Guide to Directing Group Removal: 8‐Aminoquinoline

Transient Directing Group Strategy as a Unified Method for Site Selective Direct C4–H Halogenation of Indoles

Catalytic C−H Activation via Four‐Membered Metallacycle Intermediate

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