Regiospezifische acylierung von ketonen zu 1.3 - diketonen über metallierte dimethylhydrazone

Enders, Dieter; Weuster, Peter

doi:10.1016/s0040-4039(01)94881-6

Cited by 21 publications

(5 citation statements)

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“…10,11,51,[76][77][78][79][80] It was shown that hydrazones, acting like aza analogues of the parent carbonyl compounds, could be R-deprotonated (lithiated with LDA or n-BuLi) and reacted with a number of electrophiles (in particular alkyl halides). The pioneering studies have shown that N,N-dialkylhydrazones (mostly N,Ndimethylhydrazones) could be important intermediates in the synthesis of R-substituted aldehydes and ketones, and also in other C-C bond forming reactions.…”

Section: Short History Of Synthetic Applicationsmentioning

confidence: 99%

“…77 Claisen-type substitution on sp 2 carbon atoms of acid chlorides by azaenolates followed by hydrazone hydrolysis provides an access to 1,3-diketones. 80,102 Various applications of hydrazone azaenolates (1-azaallylic anions) toward the synthesis of heterocyclic structures have previously been reviewed. 103…”

Section: Reactions Of Azaenolates With Electrophiles: Carbon-carbon B...mentioning

confidence: 99%

“…Despite the early reports, N , N -dialkylhydrazones did not gain widespread application in synthesis until the landmark papers on alkylation of metalated N , N -dimethylhydrazones (described also as metal azaenolates) were published by Corey and Enders in the years 1976−1978. ,,,− It was shown that hydrazones, acting like aza analogues of the parent carbonyl compounds, could be α-deprotonated (lithiated with LDA or n -BuLi) and reacted with a number of electrophiles (in particular alkyl halides). The pioneering studies have shown that N , N -dialkylhydrazones (mostly N , N -dimethylhydrazones) could be important intermediates in the synthesis of α-substituted aldehydes and ketones, and also in other C−C bond forming reactions.…”

Section: Short History Of Synthetic Applicationsmentioning

confidence: 99%

“…1,4-Addition of hydrazone anions to α,β-unsaturated carbonyl compounds, esters, nitriles, alkenyl sulfones, and alkenyl phosphonates results in various Michael-type adducts (Scheme ) . Claisen-type substitution on sp 2 carbon atoms of acid chlorides by azaenolates followed by hydrazone hydrolysis provides an access to 1,3-diketones. , …”

Section: Reactions Of Azaenolates With Electrophiles: Carbon−carbon B...mentioning

confidence: 99%

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N,N-Dialkylhydrazones in Organic Synthesis. From Simple N,N-Dimethylhydrazones to Supported Chiral Auxiliaries

2009

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Section: Short History Of Synthetic Applicationsmentioning

confidence: 99%

Section: Reactions Of Azaenolates With Electrophiles: Carbon-carbon B...mentioning

confidence: 99%

Section: Short History Of Synthetic Applicationsmentioning

confidence: 99%

Section: Reactions Of Azaenolates With Electrophiles: Carbon−carbon B...mentioning

confidence: 99%

See 2 more Smart Citations

N,N-Dialkylhydrazones in Organic Synthesis. From Simple N,N-Dimethylhydrazones to Supported Chiral Auxiliaries

2009

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“…Y, I H , HOOC(1)); 4,49 (t, J = 6, 2 H, 2 H-C(4)); 2,73-2,22 (m, 4 H, 2 H-C(2) und 2 H-C(3)). -MS.: 133 (2, M* (C4H7N04)), 116(9), 115(6), 91(4).87 (16), 85(21), 74 (12), 69 (lo), 59 (lo), 55 (18), 45 (IUO),…”

mentioning

confidence: 99%

Herstellung von 1, 3‐Diketonen und von Nitro‐diketonen durch (1:1)‐Acylierungen von Lithiumenolaten mit Acylchloriden

Seebàch

Weller

Protschuk

et al. 1981

Helvetica Chimica Acta

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Slow addition of precooled solutions of lithium enolates in THF (Fig. 1 ) to solutions of equimolar amounts of acyl chlorides in the same solvent at temperatures between -80 and -100" furnishes 1,3-diketones in acceptable to good yields (Tables 1-3). Even 3-nitropropionyl and 4-nitrobutyryl chloride can be employed for the (1 : 1)-acylation of enolates to give the synthetically useful 5and 6-nitro-l,3diketones 13 and 25, respectively. The scope and the limitations of this method of preparing 1,3-diketones are given and are compared with alternative methods. 1. Einleitung. -Zur Acylierung von Ketonen zu 1.3-Dicarhonylverbindungen sind prinzipiell viele Methoden bekannt [l] [2]. Beim Einsatz von Enolaten liegt die Schwierigkeit vor allem darin, aus einem Mol-Aquivalent Keton-enolat und einem Mol-Aquivalent Acylierungsmittel moglichst hohe Ausbeuten an 1,3-Diketonen zu erzielen, also eine Deprotonierung des Diketons durch das Ausgangsenolat zu vermeiden. Um Enolate ganz zu umgehen, wurden an deren Stelle 2.B. Silylenolather [3], metallierte Hydrazone [4] oder Enamine [5] [6] verwendet. Die erste Methode ist beziiglich der Acylchloride nur bedingt anwendbar [3] (es wurden lediglich Di-und Trichloracetylchlorid umgesetzt), und die oftmals energischen Hydrolysebedingungen in der Folge der beiden letztgenannten Verfahren bedeuten eine Beschrankung beziiglich der Anwesenheit weiterer funktioneller Gruppen.Der ambidente Charakter und die gegeniiber den zu bildenden 1,3-Diketonen hohe Basizitat von Enolaten lassen Schwierigkeiten wie 0-Acylierung, Umprotonierung, doppelte Acylierung und damit nicht zuletzt niedrige Ausbeuten an

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N , N ‐Dimethylhydrazine

Ho¹,

Fieser²,

Fieser³

et al. 2006

Fieser and Fieser's Reagents for Organic Synthesis

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Regiospezifische acylierung von ketonen zu 1.3 - diketonen über metallierte dimethylhydrazone

Cited by 21 publications

References 8 publications

N,N-Dialkylhydrazones in Organic Synthesis. From Simple N,N-Dimethylhydrazones to Supported Chiral Auxiliaries

N,N-Dialkylhydrazones in Organic Synthesis. From Simple N,N-Dimethylhydrazones to Supported Chiral Auxiliaries

Herstellung von 1, 3‐Diketonen und von Nitro‐diketonen durch (1:1)‐Acylierungen von Lithiumenolaten mit Acylchloriden

N , N ‐Dimethylhydrazine

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