Palladium-Catalyzed Oxidative Nonclassical Heck Reaction of Arylhydrazines with Allylic Alcohols via C–N Bond Cleavage: Access to β-Arylated Carbonyl Compounds

Wang, Xiaoshuo; Wang, Xiaojing; Pan, Hongwu; Ming, Xiayi; Zhang, Zhenming; Wang, Tao

doi:10.1021/acs.joc.2c01115

Cited by 6 publications

(5 citation statements)

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“…16 Recently, our group has been greatly interested in the dehydrazination couplings of monosubstituted hydrazines, and reported an electrochemical sulfonylative oxycyclization via dehydrazination of sulfonyl hydrazides 17 and a palladiumcatalyzed nonclassical Heck reaction via dehydrazination of arylhydrazines. 18 Encouraged by Breit and Kwong and our previous works, we conjectured that the use of phosphine ligand would provide a satisfactory solution to the above challenges. To verify our hypothesis, a palladium-catalyzed allylic substitution reaction of 1-phenylallyl acetate (1a) and phenyl hydrazines (2a) was designed, which employed 5 mol% Pd 2 (dba) 3 as a catalyst and 10 mol% DPPPy (L4) as a ligand in DCM at room temperature under an open system.…”

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confidence: 99%

“…Some challenges in regio- and chemoselectivity for both the arylhydrazines and allylic substrates could be met: (1) carbon–nitrogen bond cleavage of arylhydrazines, which resulted in a palladium-catalyzed Heck or analogous reaction; (2) selectivity of two nitrogen atoms on arylhydrazines as nucleophilic reaction sites; (3) selectivity of allylic substrates for the construction of branched or linear products . Recently, our group has been greatly interested in the dehydrazination couplings of monosubstituted hydrazines, and reported an electrochemical sulfonylative oxycyclization via dehydrazination of sulfonyl hydrazides and a palladium-catalyzed nonclassical Heck reaction via dehydrazination of arylhydrazines . Encouraged by Breit and Kwong and our previous works, we conjectured that the use of phosphine ligand would provide a satisfactory solution to the above challenges.…”

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confidence: 99%

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N¹-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

Wang

Shu

et al. 2023

Org. Lett.

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A direct and efficient method for constructing N,Ndisubstituted hydrazines via a palladium-catalyzed allylic substitution of allyl acetates with arylhydrazines as nucleophiles has been developed. This method is highly selective in terms of both chemoand regio-selectivity and is carried out under an open-air system with the use of the DPPPy phosphine ligand. Additionally, this reaction is compatible with a wide variety of substrates, including those bearing reactive groups such as Cl, Br, and I, to afford various N 1 -allylation products in moderate to good yields under simple and mild reaction conditions. N,N-Disubstituted hydrazines are a class of important scaffolds, which have been widely found in biologically active natural products and pharmaceutical molecules 1 and are also useful building blocks for the synthesis of N-substituted indoles in organic synthesis. 2 Therefore, tremendous effort has been dedicated to constructing N,N-disubstituted hydrazine frameworks. 3 Classical synthesis methods for access to these scaffolds could be classified into two categories, N−N bond formation reactions of secondary amines and direct N 1functionalization of monosubstituted hydrazines. The former mainly focused on reduction of N-nitrosamines, formed by nitrosation of secondary amines in presence of nitrous acid. 4 The later involved reductive amination of carbonyl compounds 5 and nucleophilic substitution of halides. 6 Despite significant advances, these methods still existed with some limitations, including harsh and complex conditions, multistep reaction processes, and narrow substrate scope.Recently, transition-metal catalyzed direct N-functionalization of hydrazines has been considered a powerful method for the synthesis of substituted hydrazines. 7 For example, Pd-and Cu-catalyzed coupling reactions of N-Boc hydrazine or hydrazine with aryl halides have been reported for the construction of polysubstituted hydrazines. 8 However, to our knowledge, transition-metal catalyzed N 1 -functionalization of arylhydrazines remains challenging, because arylhydrazines are prone to undergoing dehydrazination reactions under transition-metal catalytic conditions. 9 To address this issue, phosphine ligands have been employed to lower the rate of carbon−nitrogen bond cleavage of arylhydrazines. In this field, the Breit group developed a N 1 -allylation reaction of arylhydrazines with allenes using [Rh(COD)Cl] 2 with a chiral phosphine ligand (L1 or L2) in 2015 (Scheme 1, eq 1), 10 and the Kwong group reported a N 1 -arylation reaction of arylhydrazines with aryl tosylates using Pd(TFA) 2 and a phosphine ligand (L3) in 2020 (Scheme 1, eq 2). 11 By employing this approach, we herein present a novel Pd-

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N¹-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

Wang

Shu

et al. 2023

Org. Lett.

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“…The authors proposed that, following rhodium-catalyzed C(sp 3 )–H bond activation, an allylic alcohol can coordinate to the rhodium catalyst, thereby bringing it in close proximity to the coupling partner and enabling a facile 1,2-migratory insertion to generate a new C–C bond. In general, allyl alcohols have been highly explored in C–C bond-forming Heck-type pathways controlled by the directing capacity of alkoxide, and modern advances have seen the employment of new metal catalysts and an expanded range of coupling partners. − …”

Section: Chain Functionalizationmentioning

confidence: 99%

Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

Cook,

Newman

2024

Chem. Rev.

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Alcohols are abundant and attractive feedstock molecules for organic synthesis. Many methods for their functionalization require them to first be converted into a more activated derivative, while recent years have seen a vast increase in the number of complexity-building transformations that directly harness unprotected alcohols. This Review discusses how transition metal catalysis can be used toward this goal. These transformations are broadly classified into three categories. Deoxygenative functionalizations, representing derivatization of the C−O bond, enable the alcohol to act as a leaving group toward the formation of new C−C bonds. Etherifications, characterized by derivatization of the O−H bond, represent classical reactivity that has been modernized to include mild reaction conditions, diverse reaction partners, and high selectivities. Lastly, chain functionalization reactions are described, wherein the alcohol group acts as a mediator in formal C−H functionalization reactions of the alkyl backbone. Each of these three classes of transformation will be discussed in context of intermolecular arylation, alkylation, and related reactions, illustrating how catalysis can enable alcohols to be directly harnessed for organic synthesis.

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“…Under certain conditions, arylhydrazines can react with anilines, arenethiols and quinoline‐4‐ones via C−N bond cleavage [3] . Mechanistically, dehydrazination process involving C−N bond cleavage typically begin with the generation of phenyl radicals and the release of N 2 [2a,3a,c,4] . However, direct dehydrazination reactions have received limited attention.…”

Section: Introductionmentioning

confidence: 99%

Potassium tert‐Butoxide‐Promoted Aerobic Dehydrazination of Arylhydrazines: From Arylhydrazines to Substituent Aromatics

Zhang,

Tan,

et al. 2024

Eur J Org Chem

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An efficiently aerobic dehydrazination of arylhydrazines promoted by potassium tert‐butoxide (tBuOK) is detailed in this study. This method smoothly produces aromatics analogues from arylhydrazines using catalytic amount of tBuOK under practical conditions, exhibiting excellent functional group tolerance and a broad substrate scope. The application potential of this approach is further demonstrated through the preparation of deuterated, iodinated and brominated aromatics. Moreover, it shows that this aerobic base‐mediated dehydrazination could be utilized to prepare unsymmetrical aryl sulfides, selenides and tellurides with high efficiency.

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Palladium-Catalyzed Oxidative Nonclassical Heck Reaction of Arylhydrazines with Allylic Alcohols via C–N Bond Cleavage: Access to β-Arylated Carbonyl Compounds

Cited by 6 publications

References 68 publications

N¹-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

N¹-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

Potassium tert‐Butoxide‐Promoted Aerobic Dehydrazination of Arylhydrazines: From Arylhydrazines to Substituent Aromatics

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Palladium-Catalyzed Oxidative Nonclassical Heck Reaction of Arylhydrazines with Allylic Alcohols via C–N Bond Cleavage: Access to β-Arylated Carbonyl Compounds

Cited by 6 publications

References 68 publications

N1-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

N1-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

Potassium tert‐Butoxide‐Promoted Aerobic Dehydrazination of Arylhydrazines: From Arylhydrazines to Substituent Aromatics

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N¹-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

N¹-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution