Synthesis of Saturated Five‐Membered Nitrogen Heterocycles via Pd‐Catalyzed CN Bond‐Forming Reactions

Wolfe, John P.; Neukom, Joshua D.; H., Duy

doi:10.1002/9783527633388.ch1

Cited by 5 publications

(2 citation statements)

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“…Palladium-catalyzed alkene arylamination and hydroamination have emerged as useful methods to prepare α-substituted pyrrolidines and other N-heterocycles (Figure ). Readers can find the updated and detailed reviews in recent publications …”

Section: Synthesis Of Saturated N-heterocycles Contaning One Heteroatommentioning

confidence: 99%

Synthesis of Saturated N-Heterocycles

2014

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Saturated N-heterocycles are prevalent in biologically active molecules and are increasingly attractive scaffolds in the development of new pharmaceuticals. Unlike their aromatic counterparts, there are limited strategies for facile construction of substituted saturated N-heterocycles by convergent, predictable methods. In this Synopsis, we discuss recent advances in the synthesis of these compounds, focusing on approaches that offer generality and convenience from widely available building blocks.

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Section: Synthesis Of Saturated N-heterocycles Contaning One Heteroatommentioning

confidence: 99%

Synthesis of Saturated N-Heterocycles

2014

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“…While linear and trigonal carbon can be activated fairly easily, tetrahedral carbon atoms are (with a few exceptions) the least reactive ones, those in allylic positions being activated more easily than the remaining atoms. In particular, Rh, Ru, and Pd catalyses , allow the direct allylic amination of an alkene. − …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Study of the Direct Intramolecular Allylic Amination Reaction Catalyzed by Palladium(II)

2016

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DFT calculations (PBE1PBE/6-31G(d,p), Def2-TZVPPD) were performed to study the intramolecular C−H amination of an unsaturated carbamate catalyzed by [Pd(LL)(OAc) 2 ] (2), where LL is the bis(sulfoxide) ligand PhS(O)(CH 2 ) 2 S(O)Ph. The coordination takes place by an associative path over a trigonal-bipyramidal transition state. The LL ligand undergoes a coordination shift from κ 2 S,S to κ 1 S, leaving an open position for binding of the substrate (C C). In the next step, the C−H activation, the transition state for the hydrogen abstraction from the substrate to form the σallyl complex has an energy of 124.0 kJ mol −1 , which is the highest energy in the whole mechanism (TOF-determining transition state). The σ-allyl converts easily in the π-allyl, the acetic acid molecule leaving the coordination sphere. The remaining acetate receives the second hydrogen from the NH group, while the newly formed acetic acid molecule is replaced by the pendant arm of the LL ligand, and the cyclization takes place (nucleophilic attack). During these changes, the metal is reduced to Pd(0) in the form of the Pd(0) complex of the oxazolidinone product, the most stable species in the cycle (TOF-determining intermediate). Either the C−H activation or the Pd(0) oxidation may be the step determining the energy span of the reaction, depending on reaction conditions.

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Dormant versus Evolving Aminopalladated Intermediates: Toward a Unified Mechanistic Scenario in Pd^II‐Catalyzed Aminations

Rajabi

Lorion

et al. 2014

Chemistry A European J

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Pd(II)-catalyzed alkene aminopalladation and allylic C-H activation are two competing reaction sequences sharing the same reaction conditions. This study aimed at understanding the factors that bias one or the other path in the intramolecular oxidative cyclization of two types of N-tosyl amidoalkenes. The results obtained are in accord with the initial generation of a high-energy cyclic (5- or 6-membered) aminopalladated intermediate. However, this latter species can evolve only if the following specific conditions are met: the availability of distocyclic β-H elimination pathway, the presence of a strong terminal oxidant, or the availability of a carbopalladation pathway. Conversely, the cyclic alkylpalladium complex is only a latent species in equilibrium with the initial substrate and cannot evolve. Such a reactivity hurdle leaves the way open for alternative reactivities such as allylic C-H activation of the olefinic substrate to generate a η(3)-allyl complex followed by its interception by the nitrogen nucleophile, [3,3]-sigmatropic rearrangement, or decomposition. This study proposes a unifying mechanistic picture that connects these competing mechanisms.

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Synthesis of Saturated Five‐Membered Nitrogen Heterocycles via Pd‐Catalyzed CN Bond‐Forming Reactions

Cited by 5 publications

References 231 publications

Synthesis of Saturated N-Heterocycles

Synthesis of Saturated N-Heterocycles

Mechanistic Study of the Direct Intramolecular Allylic Amination Reaction Catalyzed by Palladium(II)

Dormant versus Evolving Aminopalladated Intermediates: Toward a Unified Mechanistic Scenario in Pd^II‐Catalyzed Aminations

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Synthesis of Saturated Five‐Membered Nitrogen Heterocycles via Pd‐Catalyzed CN Bond‐Forming Reactions

Cited by 5 publications

References 231 publications

Synthesis of Saturated N-Heterocycles

Synthesis of Saturated N-Heterocycles

Mechanistic Study of the Direct Intramolecular Allylic Amination Reaction Catalyzed by Palladium(II)

Dormant versus Evolving Aminopalladated Intermediates: Toward a Unified Mechanistic Scenario in PdII‐Catalyzed Aminations

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Dormant versus Evolving Aminopalladated Intermediates: Toward a Unified Mechanistic Scenario in Pd^II‐Catalyzed Aminations