Syntheses and Infrared Spectra of α,β-Unsaturated-β-ketoamines and their Copper Chelates<sup>1</sup>

Holtzclaw, Henry F.; Collman, James P.; Alire, R.M.

doi:10.1021/ja01538a021

Cited by 134 publications

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“…5 However, the generally employed method for the preparation entails the reaction between ammonia or a primary or secondary amine with 1,3-dicarbonyl compound in benzene solution with azeotropic removal of the water formed. [6][7][8][9][10] We report here, a simple procedure for the synthesis of benamino esters and enaminoketones (1) starting from bketoesters or 1,3-diketones and primary amines in water as solvent (Scheme 1). The main advantages of this methodology are: (a) the reaction is simple to perform; (b) the reaction occurs at room temperature; (c) the yields are good to high, (d) acid catalysis is not necessary, (e) the reaction works for a variety of primary amines; and (f) purification of the enaminones is not necessary.…”

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confidence: 99%

An Easy Synthesis of Enaminones in Water as Solvent

Stefani¹,

Costa²,

Oliveira‐Silva³

2000

Synthesis

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Enaminones were prepared from b-ketoesters or 1,3-diketones and primary amines in water as solvent Enaminones and related compounds possessing the structural unit N-C=C-Z (Z = COR, CO 2 R, CN, etc.) are versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident eletrophilicity of enones. 1 Some procedures reported for the synthesis of b-enaminocarbonyl derivatives include the reaction of amines and 1,3-diketones supported over clay K 10 /ultra-sound 2 or silica under microwave irradiation, 3 reaction of b-amino ketones in the presence of triethylamine promoted by Pd(II), 4 and reactions of a-metalated imines with esters. 5 However, the generally employed method for the preparation entails the reaction between ammonia or a primary or secondary amine with 1,3-dicarbonyl compound in benzene solution with azeotropic removal of the water formed. [6][7][8][9][10] We report here, a simple procedure for the synthesis of benamino esters and enaminoketones (1) starting from bketoesters or 1,3-diketones and primary amines in water as solvent (Scheme 1). The main advantages of this methodology are: (a) the reaction is simple to perform; (b) the reaction occurs at room temperature; (c) the yields are good to high, (d) acid catalysis is not necessary, (e) the reaction works for a variety of primary amines; and (f) purification of the enaminones is not necessary. With secondary amines or simple carbonyl compounds, no reaction was observed. The reaction worked very well to soluble amines, but with less soluble amines the yield was moderated and it was necessary to use high excess of amine (3 equivalents). When b-ketoester and 1,3-diketones reacted with ethylene-diamine, diaminones were observed as products (1h and 1m). Scheme 1Since there are two carbonyl groups in the starting material and 2 equivalents of amine were added, there should be several products in this reaction, i.e., the amine may react with one or both of carbonyl groups. Thus, there should be three products from b-ketoester and two from 1,3-diketone, however, only enaminones were observed as products. This probably occurs because the acetyl portion of the starting dicarbonyl compounds is more reactive than the ester or aromatic conjugated carbonyl. When the enaminone is formed, it is stabilized by resonance, blocking the formation of other products. The conjugation effect also justifies the formation of only one product from acetylacetone.The probable explanation for the formation of enaminones in water is their tautomeric forms (A and B) associated with the hydrogen bond. 11,12 Enaminones of all types exist predominantly in the carbonyl form and are stabilized by the contribution of the zwitterionic form (C), 13 which can be solvated by water preventing hydrolysis of the formed enaminone. This explanation can be supported by the fact that no reaction was observed using secondary amines or simple carbonyl compounds (Scheme 2). Scheme 2In summary, we have provided a remarkably viable alternative route for the synthesi...

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confidence: 99%

An Easy Synthesis of Enaminones in Water as Solvent

Stefani¹,

Costa²,

Oliveira‐Silva³

2000

Synthesis

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“…Karl Fischer titration of the dry solvents showed values below 2 ppm. The ketoimine LH was prepared by literature method . 2,6‐dimethylphenol and dmap (Acros) were sublimed before use.…”

Section: Methodsmentioning

confidence: 99%

Synthesis, Structures, and Catalytic Activity of Homo‐ and Heteroleptic Ketoiminate Zinc Complexes in Lactide Polymerization

et al. 2018

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The heteroleptic complex LZnEt [(1); L = MeNacac = MeNC(Me)CHC(Me)O] containing the sterically less demanding N,O-chelating ketoiminate (MeNacac) ligand was synthesized by reaction of ZnEt 2 with an equimolar amount of MeNacacH, whereas the reaction with two equivalents MeNacacH gave the homoleptic complex L 2 Zn 5. 1 reacts with ArOH (Ar = 2,6-Me 2 -Ph) with ethane elimination and formation of LZnOAr (2). Addition of the Lewis base dmap (dmap = 4-dimethylamino pyridine) to 1 and 2 yielded the corresponding Lewis acid-base adducts dmap-Zn(L)Et 3 and dmap-Zn(L)OAr 4. Compounds 1-5 were characterized by heteronuclear NMR ( 1 H, 13 C) and IR spectroscopy, elemental analysis, and single-crystal X-ray dif-[a] Synthesis and Characterization The reaction of ketoimine LH [L = MeNacac = MeNC(Me)-CHC(Me)O] with an equimolar amount of diethylzinc in THF at -60°C occurred with elimination of ethane and formation of Scheme 1. Synthesis of 1-5.

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“…Increasing the size of substituent R 3 should lead to a destabilization of the E-isomers of deprotonated N-(3-oxoalkenyl)amides 3 due to steric interactions with the carbonyl group, and vice versa -a decrease in the size of R 3 should stabilize the E-isomers, like the enaminones. [39][40][41][42][43] Thus the charge distribution in mesomeric anion 9 as well as the isomerization Z-3k to E-3k prevent the intramolecular ring closure of N-(3-oxoalkenyl)amide 3k to a corresponding 2(1H)-pyridinone. Obviously, for this reason the cyclization of amides Z-3k does not occur under the action of potassium tert-butoxide in THF.…”

Section: N-(3-oxoalkyl)amides 2 and N-(3-oxoalkenyl)amides 3 Are Analmentioning

confidence: 99%

Intramolecular cyclization of N-(3-oxoalkenyl)phenylacetamides: synthesis of 3-phenyl-2(1H)-pyridones

Goncharov¹,

Garkushenko²,

Savelieva³

et al. 2015

Arkivoc

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3-Phenyl-2(1Н)-pyridinones were obtained by base-catalyzed intramolecular aldol-type cyclization of N-(3-oxoalkenyl)phenylacetamides. The effect of substituents in the starting compounds and the experimental conditions on the reaction course were established. It was shown that the transformations of N-(3-oxoalkenyl)amides in basic medium depend on structural and electronic factors as well as the reaction conditions.

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Syntheses and Infrared Spectra of α,β-Unsaturated-β-ketoamines and their Copper Chelates¹

Cited by 134 publications

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An Easy Synthesis of Enaminones in Water as Solvent

An Easy Synthesis of Enaminones in Water as Solvent

Synthesis, Structures, and Catalytic Activity of Homo‐ and Heteroleptic Ketoiminate Zinc Complexes in Lactide Polymerization

Intramolecular cyclization of N-(3-oxoalkenyl)phenylacetamides: synthesis of 3-phenyl-2(1H)-pyridones

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Syntheses and Infrared Spectra of α,β-Unsaturated-β-ketoamines and their Copper Chelates1

Cited by 134 publications

References 0 publications

An Easy Synthesis of Enaminones in Water as Solvent

An Easy Synthesis of Enaminones in Water as Solvent

Synthesis, Structures, and Catalytic Activity of Homo‐ and Heteroleptic Ketoiminate Zinc Complexes in Lactide Polymerization

Intramolecular cyclization of N-(3-oxoalkenyl)phenylacetamides: synthesis of 3-phenyl-2(1H)-pyridones

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Syntheses and Infrared Spectra of α,β-Unsaturated-β-ketoamines and their Copper Chelates¹