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.     

A Practical Synthesis of β-Keto Phosphonates from Triethyl Phosphonoacetate

An efficient and practical preparation of β-keto phosphonates, via acylation reaction of triethyl phosphonoacetate with carboxylic acid chlorides in the presence of magnesium chloride-triethylamine followed by decarbethoxylation, is described.     

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.     

Condensation of 5-Aminopyrazoles Unsubstituted in Position 1 with β-Keto Esters

Condensation of -keto esters with 5-aminopyrazoles unsubstituted in position 1 gives 7-oxopyrazolo[1,5-a]pyrimidines.     

Photocatalytic Synthesis of β-Keto Primary Chlorides by Selective Chlorocarbonylation of Olefins

Functionalized primary alkyl chlorides are precursors to a plethora of scaffolds but their access from chemical feedstocks remains challenging. Herein, we report a concise dual Ni/photoredox catalytic protocol for regioselective chlorocarbonylation of unactivated alkenes that enables rapid access to β-keto primary chlorides. The catalytic process features an extensive substrate scope, scalability and functional group tolerance. The Ni/photocatalytic Cl⋅ generation and subsequent cross-coupling is implicated for the process based on the control experiments and DFT study. The synthetic utility of the protocol has been further corroborated through functionalization of complex substrates and modifications of the product.     

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.     

Transition-Metal-Free α-Arylation of β-Keto Amides via an Interrupted Insertion Reaction of Arynes

Direct α-arylation reactions of secondary β-keto amides with arynes, generated by fluoride-induced elimination of ortho-silyl aryltriflates, are described. The transformation proceeds via an interrupted insertion reaction of arynes and leads to densely functionalized aromatic compounds exhibiting a chiral 'all carbon' quaternary center under transition-metal-free conditions. An organocatalytic asymmetric version of the reaction also proved possible, affording the proof of concept that arynes can be involved in enantioselective transformations.     

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.     

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.     

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.     

Microwave-Induced Solvent-free Synthesis of β-Keto Esters Using Montmorillonite KSF and K10 Clays as Efficient and Recyclable Heterogeneous Solid Acids

Montmorillonite KSF and K10 clays catalyzed effectively the reaction of methyl diazoacetate with various aldehydes using microwave irradiation under solvent-free conditions affording the corresponding β-keto esters in good yields and short reaction time. The present method is an improvement for the previous known synthetic methods and has many obvious advantages compared to them including the high efficiency, generality, high yields, operational simplicity, environmental benignity, and possibility of recycling the natural solid clays.     

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.     

Lewis Base Organocatalyzed Enantioselective Hydrosilylation of α-Keto Ketimines

A chiral Lewis base organocatalyzed enantioselective hydrosilylation ofa-keto ketimines was investigated.The reactions afforded various enantioenriched a-amino ketones with good yields（up to 95％） in moderate to good enantioselectivities（up to 98％ e.e.）.Furthermore,one of the products was reduced to a chiral 1,2-amino alcohol.Following cyclization of it with triphosgene generated a cannabinoid receptor 1 （CB 1） inhibitor with good diastereoselectivity.     

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.