Fe-Catalyzed Olefin Hydroamination with Diazo Compounds for Hydrazone Synthesis

Zheng, Jing; Qi, Jifeng; Cui, Sunliang

doi:10.1021/acs.orglett.5b03317

Cited by 68 publications

(35 citation statements)

References 57 publications

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“…Taking into account the combined results of our mechanistic studies and previous reports, [10c,20] a plausible mechanism for this formal cycloaddition is illustrated in Figure 1. The reaction is initiated by the iron‐catalyzed decomposition of TBHP to form the tert ‐butoxy radical III , which undergoes hydrogen atom transfer (HAT) from TBHP to deliver the selective tert ‐butylperoxy radical IV .…”

Section: Methodssupporting

confidence: 70%

Generation of Diazomethyl Radicals by Hydrogen Atom Abstraction and Their Cycloaddition with Alkenes

Dong

Zheng

et al. 2021

Angew Chem Int Ed

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A general catalytic methodology for the synthesis of pyrazolines from α‐diazo compounds and conjugated alkenes is reported. The direct hydrogen atom transfer (HAT) process of α‐diazo compounds promoted by the tert‐butylperoxy radical generates electrophilic diazomethyl radicals, thereby reversing the reactivity of the carbon atom attached with the diazo group. The regiocontrolled addition of diazomethyl radicals to carbon‐carbon double bonds followed by intramolecular ring closure on the terminal diazo nitrogen and tautomerization affords a diverse set of pyrazolines in good yields with excellent regioselectivity. This strategy overcomes the limitations of electron‐deficient alkenes in traditional dipolar [3+2]‐cycloaddition of α‐diazo compounds with alkenes. Furthermore, the straightforward formation of the diazomethyl radicals provides umpolung reactivity, thus opening new opportunities for the versatile transformations of diazo compounds.

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Section: Methodssupporting

confidence: 70%

Generation of Diazomethyl Radicals by Hydrogen Atom Abstraction and Their Cycloaddition with Alkenes

Dong

Zheng

et al. 2021

Angew Chem Int Ed

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“…2b) 20 source to form oximes 21 . Since Mukaiyama and coworkers 22 reported the iron-catalyzed hydroamination of unactivated alkenes via HAT, using phenyl silane as a reductant and butyl nitrite as an aminating reagent, various aminating reagents, such as azo compounds [23][24][25][26] , nitro compounds 27,28 , diazo compounds 29 , azides 24,30 , and amides 31,32 have been explored by many research groups, which offers a great opportunity for retrosynthetic possibility of new transformations. Although simple 1,3-dicarbonyl metal complexes could promote the reactions, stoichiometric amount or high loading of these complexes used to be necessary 20,33 .…”

mentioning

confidence: 99%

Ligand-promoted cobalt-catalyzed radical hydroamination of alkenes

Shen

Chen

et al. 2020

Nat Commun

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Highly regio-and enantioselective intermolecular hydroamination of alkenes is a challenging process potentially leading to valuable chiral amines. Hydroamination of alkenes via metalcatalyzed hydrogen atom transfer (HAT) with good regioselectivity and functional group tolerance has been reported, however, high enantioselectivity has not been achieved due to the lack of suitable ligands. Here we report a ligand-promoted cobalt-catalyzed Markovnikovtype selective radical hydroamination of alkenes with diazo compounds. This operationally simple protocol uses unsymmetric NNN-tridentate (UNT) ligand, readily available alkenes and hydrosilanes to construct hydrazones with good functional group tolerance. The hydrazones can undergo nitrogen-nitrogen bond cleavage smoothly to deliver valuable amine derivatives. Additionally, asymmetric intermolecular hydroamination of unactivated aliphatic terminal alkenes using chiral N-imidazolinylphenyl 8-aminoquinoline (IPAQ) ligands has also been achieved to afford chiral amine derivatives with good enantioselectivities.

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“…Among these instances is the synthesis of hydrazones through an iron-catalyzed hydroamination as an alternative to olefin hydroaminations that use NaN 3 (Scheme 29). 69 This reaction used Fe(acac) 3 (10 mol%) and PhSiH 3 for the hydroamination of various alkenes with a wide scope of acceptor/acceptor and donor/acceptor diazo compounds in moderate and high yields. An intramolecular hydroamination of a variety of olefin-containing diazo compounds allowed access to 6-, 7-, and 8-membered cyclic hydrazones in good yields (up to 85%).…”

Section: Miscellaneousmentioning

confidence: 99%

The Power of Iron Catalysis in Diazo Chemistry

Carreras¹,

Tanbouza²,

Ollevier³

2020

Synthesis

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The use of iron catalysis to enable reactions with diazo compounds has emerged as a valuable tool to forge carbon–carbon or carbon–heteroatom bonds. While diazo compounds are often encountered with toxic and expensive metal catalysts, such as Rh, Ru, Pd, Ir, and Cu, a resurgence of Fe catalysis has been observed. This short review will showcase and highlight the recent advances in iron-mediated reactions of diazo compounds.1 Introduction2 Insertion Reactions2.1 Insertion into B–H Bonds2.2 Insertion into Si–H Bonds2.3 Insertion into N–H Bonds2.4 Insertion into S–H bonds3 Ylide Formation and Subsequent Reactions3.1 Doyle–Kirmse Rearrangement3.2 [1,2]-Stevens and Sommelet–Hauser Rearrangements3.3 Olefination Reactions3.4 Cycloaddition Reactions3.5 gem-Difluoroalkenylation4 Three-Component Reactions5 Miscellaneous6 Conclusion

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Fe-Catalyzed Olefin Hydroamination with Diazo Compounds for Hydrazone Synthesis

Cited by 68 publications

References 57 publications

Generation of Diazomethyl Radicals by Hydrogen Atom Abstraction and Their Cycloaddition with Alkenes

Generation of Diazomethyl Radicals by Hydrogen Atom Abstraction and Their Cycloaddition with Alkenes

Ligand-promoted cobalt-catalyzed radical hydroamination of alkenes

The Power of Iron Catalysis in Diazo Chemistry

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