A novel route for the synthesis of α,β-unsaturated esters,ketones and nitriles using dibutyl telluride

In the presence of dibutyl telluride, α-halo-ester, nitrile, and ketone were found to condense easily with aromatic aldehydes to afford α,β-unsaturated esters, nitriles and ketones in high yields as one-pot reaction. A possible reaction machanism was proposed.     

LiClO4-Accelerated Three-Component Mannich-Type Reaction of Diethyl Malonate with Imines: An Efficient Synthesis of β-Amino Esters Under Solvent-Free Conditions

LiClO₄ is used as catalyst for direct Mannich-type reaction of aryl aldehydes, aryl amines, and diethyl malonic ester under solvent-free conditions. This three-component reaction afforded the corresponding β-amino esters in good yields with simple and environmentally benign procedure.     

E -型α, β-不饱和酰胺的立体选择合成

本文报道了在钯及二丁基碲存在下, 溴代乙酰胺与醛的亲卤缩合反应, 提供了E型α, β-不饱和酰胺的立体选择合成。     

A FACILE SYNTHESIS OF HETEROCYCLE SUBSTITUTED CHALCONE AND 5-NITROFURANYL OLEFIN DERIVATIVES

Reaction of heterocycle substituted telluronium salts with aroma-tic aldehydes under mild conditions gave corresponding chalcones.In thepresence of dibutyl telluride,2-bromomethyl-5-nitrofuran condensed easilywith aromatic aldehydes in THF to afford corresponding olefin derivativesas one-pot reaction.     

用碲ylide合成杂环查尔酮,二烯酮和杂环烯类衍生物

最近,我们用碳酸钾作碱从碲盐在含微量甲酰胺的乙腈中,手室温条件下十分简便地合成了2-或2,4-不饱和腈,酮,酯和酰胺。杂环查尔酮和5-硝基呋喃烯类化合物都是具有生理活性的化合物。为扩大碲ylide的应用并研究杂环基团引入对碲ylide反应活性的影     

A Practical,efficient, and atom economic alternative to the Wittig and Horner–Wadsworth–Emmons reactions for the synthesis of (E)-α,β-unsaturated esters from aldehydes

We describe a highly efficient new methodology for the synthesis of (E)-α,β-unsaturated esters from aldehydes. In our DMAP-catalyzed reaction, both aromatic as well as aliphatic aldehydes furnish the desired products highly regio- and stereoselectively if treated with commercially available or synthetically easily accessible malonic acid half ester. A large scale application in the synthesis of p-methoxycinnamates, which are of use as sunscreen ingredients, is described.     

Nouvelle methode de decarbomethoxylation

Heterocycles substituted by two carbomethoxy groups on the same carbon lose one of these groups when reacted with piperidine. This reaction has been extended to substituted malonic and cyanacetic esters. The mechanism of this reaction is discussed. Piperidine also causes the decarboxylation of substituted malonic and cyanacetic acids.     

A FACILE METHOD FOR DEBROMINATION OF VICINAL DIBROMIDES

In the presence of equimolar triethylamine,vicinal dibromideswere found to be easily debrominated by dibutyl telluride,forming the co-rresponding olefins.     

A ‘one-pot’ synthesis of α-1,2,4-oxadiazolo esters from malonic diesters and amidoximes under solvent-free conditions

A ‘one-pot’ procedure for synthesis of α-1,2,4-oxadiazolo esters from malonic diesters and amidoximes under solvent-free conditions is described. It is likely that this reaction goes through a ketene intermediate generated from the malonic diester by elimination of a molecule of alcohol.     

α-Amidoalkylation of CH-Acids by Means of N-(1,2,2,2-Tetrachloroethyl)-amides

The reaction of α-amidoalkylation of malonic and acetoacetic esters as well as tert. butylacetate, arylacetic acids and benzylcyanide with different N-(1,2,2,2-tetrachloroethyl)-amides was investigated and 2-substituted 3-acylamino-3-trichloromethyl propionic acids and esters were synthezised.     

Practical selective monohydrolysis of bulky symmetric diesters

The highly efficient selective monohydrolysis reaction we previously reported has been applied to monohydrolysis of several bulkyl symmetric diesters, including diethyl esters, dipropyl esters, and dibutyl esters. A greater proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH appear to help improve the reactivity of bulky diesters compared to the corresponding dimethyl esters. The procedure is mild and practical, yielding the corresponding half-esters in high yields under simple conditions.     

Novel 2-pyridone synthesis via nucleophilic addition of malonic esters to alkynyl imines

[reaction: see text] A novel 2-pyridone synthesis via nucleophilic addition of malonic esters to alkynyl imines has been developed. The reaction of dialkylalkyl sodiomalonates with alkynyl imines provided 2-pyridones in good to excellent yields.     

An efficient synthesis of β-amino esters via Zn(OTf)2-catalyzed Mannich-type reaction

A Zn(OTf)₂-catalyzed Mannich-type reaction of the electron-deficient aromatic amines with the electron-deficient aromatic aldehydes and diethyl malonic ester was described. This three-component reaction afforded the corresponding β-amino esters in good yields.     

Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters

Abstract

In this paper, we report the application of chiral complexes of La(III) with pyBOX ligands as Lewis acid catalysts in the conjugate addition of malonic esters to N-tosyl imines derived from β,γ-unsaturated α-keto esters to give the corresponding chiral α,β-dehydroamino esters. pyBOX complexes with La(III), Yb(III), Sc(III), and In(III) triflates were assessed in this reaction but only La(III) showed good activity and enantioselectivity, while Yb(III) provided the expected product with low yield and stereoselectivity, and the Sc(III) and In(III) complexes were completely inactive. The complex of La(OTf)₃ with the diphenyl-pyBOX ligand prepared in situ provided the best results and allowed obtaining chiral α,β-dehydroamino esters 3 with excellent yields, E:Z diastereomeric ratios (29:71–99:1) and high enantiomeric excesses (20–95%). The reaction could be applied to imines having a substituted aromatic ring or a heterocycle attached to the double bond, although the presence of electron-withdrawing groups on the aromatic ring was detrimental for stereoselectivity. The reaction products were obtained with the S configuration at the stereogenic center and the Z configuration at the enamine double bond as determined by NOESY experiments and X-ray analysis. Based on the experimental results a stereochemical model involving a nine-coordinate La(III) species has been proposed.     

TBAI/TBHP‐Promoted Generation of Malonyl Radicals: Oxidative Coupling with Styrenes Leads to γ‐Keto Diesters

A metal‐free protocol for oxidative coupling of malonic esters with styrenes to form γ‐keto diesters has been developed. Key to the success of this process is the generation of malonyl radicals from unfunctionalized malonic esters under organo‐catalysis conditions with TBAI and TBHP. This process tolerates both terminal and internal olefins with diverse malonic esters. It provides a new green metal‐free alternative to traditional metal mediated process for generation of malonyl radicals and there by γ‐keto diesters.     

The Knoevenagel-Doebner reaction on 1,2-O-(2,2,2-trichloroethylidene) derivatives of D-gluco- and D-manno-furanose

The synthesis of new α,β-unsaturated furanuronic acid derivatives of α-gluco-, β-gluco- and β-manno-chloraloses via a convenient one pot procedure using the Knoevenagel-Doebner reaction approach are described. The dialdofuranose derivatives were reacted with malonic acid under Knoevenagel-Doebner reaction conditions and (E)-α,β-unsaturated furanuronic acid derivatives were obtained.     

A mild,rapid and convenient esterification of half esters of malonic acid

A new method for the esterification of half esters of malonic acid with chloroformates is described. The reaction proceeds $\text{via}$ the mixed anhydride followed by spontaneous decarboxylation.     

Simple modification in hexakis-addition for efficient synthesis of c(60)-centered dendritic molecules bearing multiple aromatic chromophores

In the templated hexakis-addition reaction of malonic esters with C(60) to prepare dendritic macromolecules that are terminated symmetrically with 12 derivatized pyrenes, a simple modification to use a much larger excess of the bromination agent resulted in dramatic increases in the product yields. [structure: see text]     

One-pot carbon-carbon bond formation at the β-position of cyclic ketones: oxidative Michael addition with alkyl malonates

A carbon-carbon bond was formed at the β-position of cyclic ketones in a one-pot manner by oxidation with N-tert-butylbenzenesulfinimidoyl chloride, followed by the reaction of malonic acid esters or potassium cyanide.     

Malonic to Acetic Ester Transformation by Boric Acid

One of our synthetic projects involves a step of removing a carbalkoxy group from a substituted malonic ester. For accomplishing that goal, Krapcho's method¹ was deemed unsuitable, because the malonic ester contains an allylic halogen which is liable to attack by dimethyl sulfoxide (Kornblum reaction). Our recent work on using iodotrimethylsilane² to achieve decarbal-koxylation of such esters was partly impelled by that need; however, the prohibitive economics associated with even a medium-scale preparation forced us to develop a less expensive alternative.