Condensation of 1-Substituted 5-Aminopyrazoles with β-Dicarbonyl Compounds

Condensation of N-substituted 5-aminopyrazoles with -diketones occurs with the formation of pyrazolo[4,5-b]pyridines. Depending on the conditions, their reaction with -keto acids can give either 6-oxo- or 4-oxopyrazolo[4,5-b]pyridines.     

Selective Cleavage of β-Keto and Vinylogous β-Keto Esters by 3-Quinuclidinol

As a result of a continuing study utilizing nitrogenous bases^2–6, we now wish to report that the base 3-quinuclidinol (13) is useful for the cleavage of β-keto and vinylogous β-keto esters.     

Solvent-Free Microwave-Assisted Organic Reactions Preparation of β-Keto Esters

Microwave technique has been utilised in the preparation of β-keto esters. Two different procedures are described: transesterification of β-keto esters and ring opening of 2,2,6-trimethyl-1,3-dioxin-4-one.     

pH-Independent Transfer Hydrogenation in Water: Catalytic, Enantioselective Reduction of β-Keto Esters

A pH-independent asymmetric transfer hydrogenation of β-keto esters in water with formic acid/sodium formate is described. The reaction is conducted open to air and gives access to β-hydroxy esters in excellent yields and selectivities.     

Catalytic Activity of Homogeneous Mixtures of Metal Chelates of Polyfluorinated β-Keto Esters with Tertiary Amines in Urethane Formation

A series of Cu(II), Co(II), Mn(II), Fe(III), and La(III) chelates with unsymmetrical fluorinated -keto esters, taken separately and in mixtures with tertiary amines, were tested as catalysts in urethane formation and in synthesis of network elastomers.     

Efficient Syntheses of 2-Substituted Benzimidazoles and Benzoxazoles from β-Keto Esters

An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzo- xazoles with β-keto esters as starting materials under mild reaction conditions, during which other functional groups are bearable from reactants to products.     

Selective α-Bromination of β-Keto Esters in Reusable PEG-400 under Mild and Catalyst-free Conditions

An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） at room temperature to selectively afford the corresponding α-monobromination products in excellent yields. It is noteworthy that the reaction was conducted under mild, environmentally benign and catalyst-free conditions.     

Condensation of p-Benzoquinone with Anilides of β-Aminocrotonic Acid

Benzofuranone derivatives have been synthesized by the condensation of p-benzoquinone with anilides of -aminocrotonic acids under the conditions of the Nenitzescu reaction.     

Condensation of polyfluorinated β-diimines with aromatic aldehydes

Polyfluorinated 2-arylpyrimidines were synthesized by the reaction of polyfluorinated -diimines with aromatic aldehydes.     

Iodine-catalyzed Efficient Synthesis of β-Keto Esters from Aldehydes and Ethyl Diazoacetate Under Solvent-free Conditions

An efficient procedure for the synthesis of β-keto esters from the reaction of aldehydes and ethyl diazoa-cetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic procedure has the advantages of easily available catalyst,mild reaction conditions,high yields,and easy work-up.     

Synthesis of β-Stannyl Esters

A synthesis of β-stannyl esters from ester enolates and iodomethyl (tri-n-butyl) stannane (3) is described.     

Photoinduced Reaction of α-Bromoacetophenone with Thiosulfonate: Synthesis of β-Keto Thiosulfone

A photoinduced synthesis of β-keto thiosulfone/β-keto selenosulfone by the reaction of α-bromoacetophenone with thiosulfonate/selenosulfonate under metal-free and visible light irradiation conditions is developed. Two C−S bonds or one C−S bond and one C−Se bond were constructed simultaneously.     

Synthesis of Pyrazoles by the Condensation of C(α)- and Trianions with Esters

In addition to our previous papers^2,3 on the preparation of pyrazoles from the C(α), N-dianions of phenylhydrazones and C(α), N, N-trianions of hydrazones, we wish to report preliminary results on (I) the preparation and condensation of methylhydrazone dianions with methyl benzoate followed by acid cyclization, (II) the condensation of the dianions of phenylhydrazone with methylformate, and the preparation and condensation of the trianions of cyclopentanone (III) and α - tetralone (IV) hydrazones.     

Synthesis of 3- and 5-Alkyl-6-alkyl(aryl)tetrahydropyran-2,4-diones by the Condensation of β-Oxo Acid Esters with Aldehydes and Ketones

A method is proposed for obtaining 3- and 5-alkyl-6-alkyl(aryl)tetrahydropyran-2,4-diones based on the condensation of the dianion of alkyl(dialkyl)acetoacetic ester with aldehydes and ketones.     

General and Efficient Transesterification of β-Keto Esters with Various Alcohols Using Et3N as a Brønsted Base Additive

Transesterification of β-keto esters with a wide variety of allyl, benzyl, propargyl, and alkyl alcohols using, for the first time, commercially available and inexpensive Et₃N as a Brønsted base additive, is efficiently performed in toluene at reflux. The corresponding esters are exclusively obtained in 57–98% yields with no trace amounts of γ,δ-ketones, usually expected from the decarboxylative Carroll rearrangement.     

Synthesis of Azaphenanthrene Derivatives by Condensation of 2-Methyleneaminonaphthalene with Cyclic β-Diketones

2-Methyleneaminonaphthalene smoothly reacts with cyclic -diketones to afford azaphenanthrene derivatives in high yield. The dihydropyridine ring in the products can be oxidized to pyridine ring. The oxidation products, unlike their precursors and analogs having an aryl substituent in the -position with respect to the nitrogen atom, react with hydroxylamine at the carbonyl group to give the corresponding oximes and in some cases undergo Knoevenagel condensation with malononitrile. Hydrolysis of the condensation product yields the respective diamide.