CC Coupling with NO<sub>2</sub>/Alkyl Substitution at the Vinylic Carbon by Reaction of 2‐Aryl‐l‐nitro‐1‐alkenes with Dialkylzinc Compounds—A Novel Reaction

Seebàch, Dieter; Schäfer, Harald; Schmidt, Beat; Schreiber, Martin

doi:10.1002/anie.199215871

Cited by 27 publications

(19 citation statements)

References 10 publications

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“…The reaction is accompanied by the simultaneous elimination of a small molecule containing NO 2 residue. To the best of our knowledge, the first transformations of this kind were independently reported by Seebach and Russell in 1992 ( Scheme 2 and Scheme 3 ) [ 17 , 18 ]. Ever since, the transformation rapidly grew into an emerging field of organic synthesis, providing an exciting alternative to the traditional cross-couplings.…”

Section: Nitrostyrene Cross-coupling—the Background and Mechanismsmentioning

confidence: 99%

“…Although each proposal differs in detail, the main three characteristic steps feature in all proposals. Firstly, carbon- or heteroatom-centered radical 4 is generated in situ by various methods from precursors 6 – 33 [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. These include a thermal homolytic cleavage of labile bonds, metal-catalyzed and photochemically initiated processes.…”

Section: Nitrostyrene Cross-coupling—the Background and Mechanismsmentioning

confidence: 99%

“…During the investigation of enantioselective Michael additions of diethylzinc to nitrostyrenes, Seebach made a surprising discovery [ 17 ]. Instead of the expected 1,4-addition, he observed the formation of 1-phenylbut-1-ene (3a), the product of the substitution of the vinylic nitro group by ethyl group ( Scheme 2 ).…”

Section: Nitrostyrenes In Denitrative C(sp 2 )-mentioning

confidence: 99%

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Denitrative Cross-Couplings of Nitrostyrenes

et al. 2020

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Interestingly, β-nitrostyrenes, typically bench stable compounds, are highly promising cross-coupling partners, due to their excellent availability and well understood reactivity. In this review, we report on the discovery and advancements, in the field of stereoselective, denitrative cross-couplings of β-nitrostyrenes with miscellaneous organic reagents. The rapidly expanding field offers alternative access to a broad range of functionalized alkenes, including β-alkylated styrenes, chalcones, stilbenes, cinnamic acids, and conjugated sulfones and phosphonates. The most important mechanistic pathways are briefly discussed, to familiarize readers with the elementary reactions occurring during the coupling.

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Section: Nitrostyrene Cross-coupling—the Background and Mechanismsmentioning

confidence: 99%

Section: Nitrostyrene Cross-coupling—the Background and Mechanismsmentioning

confidence: 99%

Section: Nitrostyrenes In Denitrative C(sp 2 )-mentioning

confidence: 99%

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Denitrative Cross-Couplings of Nitrostyrenes

et al. 2020

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“…This ipso-type substitution (vinylic substitution) usually takes place, when nitroolefins bearing an acceptor group are used together with 'soft' nucleophiles. 25,26 In contrast, dialkylzinc compounds or mixed diorganozinc compounds (TMSM)ZnR have been found to smoothly add to nitroolefins and other Michael acceptors in a mixture of THF and the polar co-solvent N-methylpyrrolidone (NMP) in the absence of any copper or transition metal catalyst. 14 Formation of the ipso-product of type 11 (Scheme 4) has not been observed under these conditions.…”

Section: Conjugate Addition Of Alkyl Trimethylsilylmethylzinc Compoundsmentioning

confidence: 99%

Conjugate Addition of Organozinc Compounds to Nitroolefins

Rimkus¹,

Sewald²

2003

Synthesis

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Symmetrical (R 2 Zn) or mixed diorganozinc compounds (R 1 ZnR 2 ) smoothly react with a series of nitroolefins in the presence of catalytic amounts of copper(I) salts and provide synthetically versatile nitro compounds in moderate to good yields. Simple alkyl groups, functionalized residues, or mixed trimethylsilylmethyl organozinc compounds (TMSM)ZnR may be employed for conjugate addition, while the TMSM group is not being transferred. ipso-Substitution is observed in absence of the copper(I) salt.Enantiomerically pure copper(I) complexes with BINOL based chiral phosphoramidite ligands efficiently catalyze the addition of dialkylzinc compounds to nitroalkenes. For instance, diethylzinc addition occurs with high yields and excellent enantioselectivity. Nitrostyrene, 3-nitroacrolein dimethylacetal, and 3-nitroacrylates have been used as substrates. The nitroolefin moiety predominates over the acrylate moiety and acts as the more powerful Michael acceptor. 2-Alkyl-3-nitropropanoates are exclusively obtained with excellent yield and enantioselectivity. The products can easily be transformed into b 2 -homoamino acids, compounds of high relevance for different areas of preparative organic chemistry.

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“…Although the method avoided the use of toxic CN -ion in the reaction, the amount of Cu(OAc) 2 used was still stoichiometric. In this paper, we report that the nitro group of 1-aryl-2-nitroethenes can be substituted by organozinc halides under the catalysis of Ni(acac) 2 and a tertiary amine to give 1-aryl-1-alkenes in excellent yields (Scheme 1, Table I). A survey of the literature shows that a nitro group on an aromatic ring can be readily substituted by many organic nucleophiles 9 , and the nitro group of 1-aryl-2-nitroethenes can be replaced by dialkylzincs 10 .…”

mentioning

confidence: 99%

Nickel(II) Catalyzed Substitution Reactions of Nitro Group on 1-aryl-2-nitroethenes by Organozinc Halides

1998

Synlett

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The nitro group of 1-aryl-2-nitroethenes was readily substituted by the organic moiety of organozinc halides in the presence of a catalytic amount of Ni(acac) 2 and tertiary amine to give 1-aryl-1-alkenes in excellent yields.Organozinc reagents (R 2 Zn and RZnX) have proved to be versatile synthetic reagents in the last decades 1 . Complex functionalized organozinc reagents have great potential for natural-product synthesis 2 . Unfortunately they are relatively poor nucleophiles and do not react directly with most useful electrophiles such as aldehydes, ketones and organic halides. In 1978, Mukaiyama first reported that Et 2 Zn could add smoothly to benzaldehyde in the presence of aminoalcohols 3 . After this report, much attention has been given to the reaction 4 , especially the enantioselective addition reaction 5 of dialkylzinc compounds with aldehydes and ketones. In 1988, P. Knochel showed 6 that functional organozinc iodides R-ZnI could be transmetallized into organozinccopper reagents R-Cu(CN)ZnI with THF soluble copper salt CuCN · 2LiCl, and then coupled with acyl chlorides or conducted 1,4-addition reaction with enones. This report greatly extended the application range of organozinc reagents in organic synthesis. Now these reagents have been successfully used in coupling reactions with organic halides, 1,2-addition reactions with aldehydes or ketones and 1,4-addition reactions with β-unsaturated carbonyl compound or nitro olefins 1,4,7 . However, stoichiometric CuCN · 2LiCl must be used in most of their reactions. In our previous report 8 , we used Cu(OAc) 2 / LiCl as copper salt to carried out the 1,4-addition reaction with enones. Although the method avoided the use of toxic CN -ion in the reaction, the amount of Cu(OAc) 2 used was still stoichiometric. In this paper, we report that the nitro group of 1-aryl-2-nitroethenes can be substituted by organozinc halides under the catalysis of Ni(acac) 2 and a tertiary amine to give 1-aryl-1-alkenes in excellent yields (Scheme 1, Table I). A survey of the literature shows that a nitro group on an aromatic ring can be readily substituted by many organic nucleophiles 9 , and the nitro group of 1-aryl-2-nitroethenes can be replaced by dialkylzincs 10 . Scheme 1The organozinc reagents were obtained following P. Knochels procedure 6 , and then added into a mixture of Ni(acac) 2 and tertiary amine at room temperature. The substitution reactions were carried out at -18 o C to room temperature. In the course of the reactions, the reaction mixture would become slightly brown from milky white. In the experiment, we find that the structure of nitro compounds have great influence on the reaction. When the nitro group is attached to an aromatic ring or a saturated carbon atom, the reactions are absolutely prohibited. For example, using nitrobenzene or 1-nitro-2-phenylheptane as substrate, over 95% will be recovered after reacting with R-ZnI for 20 hours. This indicates that the nitro group is not reduced in the course of the reaction. In the absence of Ni(acac) 2 and ter...

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CC Coupling with NO₂/Alkyl Substitution at the Vinylic Carbon by Reaction of 2‐Aryl‐l‐nitro‐1‐alkenes with Dialkylzinc Compounds—A Novel Reaction

Cited by 27 publications

References 10 publications

Denitrative Cross-Couplings of Nitrostyrenes

Denitrative Cross-Couplings of Nitrostyrenes

Conjugate Addition of Organozinc Compounds to Nitroolefins

Nickel(II) Catalyzed Substitution Reactions of Nitro Group on 1-aryl-2-nitroethenes by Organozinc Halides

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CC Coupling with NO2/Alkyl Substitution at the Vinylic Carbon by Reaction of 2‐Aryl‐l‐nitro‐1‐alkenes with Dialkylzinc Compounds—A Novel Reaction

Cited by 27 publications

References 10 publications

Denitrative Cross-Couplings of Nitrostyrenes

Denitrative Cross-Couplings of Nitrostyrenes

Conjugate Addition of Organozinc Compounds to Nitroolefins

Nickel(II) Catalyzed Substitution Reactions of Nitro Group on 1-aryl-2-nitroethenes by Organozinc Halides

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CC Coupling with NO₂/Alkyl Substitution at the Vinylic Carbon by Reaction of 2‐Aryl‐l‐nitro‐1‐alkenes with Dialkylzinc Compounds—A Novel Reaction