Palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate

Highly efficient palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate is reported. This procedure does not use carbon monoxide and affords one-carbon-elongated carboxylic acid phenyl esters in excellent yields. The reaction proceeds smoothly under mild conditions and tolerates a wide range of functional groups including aldehyde, ether, ketone, ester, and cyano groups. Furthermore, a variety of heteroaromatic bromides can be converted to the corresponding phenyl esters in high yields.     

“Palladium complexes-KF / alumina” catalysed exchange of allylic groups of esters with phenol

In the presence of KF / alumina and catalytic amounts of palladium complexes, phenol reacts with allylic esters under mild conditions to give the corresponding allyl phenyl ethers.     

Solvolysis of 1-Chloro-1-Alkenyl Phenyl Sulfides. Synthesis of α-Bromo Phenyl Thiocarboxylic Esters, α-Bromo Alkyl Carboxylic Esters and α-Phenylthio Methyl Carboxylic Esters

1-chloro-1-alkenyl phenyl sulfides treated with bromine followed by hydrolysis or methanolysis give α-bromo phenyl thiocarboxylic esters and α-phenyl-thio methyl carboxylic esters. Direct oxidative solvolysis with bromine and alcohol give α-bromo alkyl carboxylic esters.     

Direct conversion of carboxylic acids and carboxylic esters into S,S′-diphenyl acetals and phenyl sulfides with thexylphenylthioborane

Reaction of carboxylic acids with thexylphenylthioborane in methylene chloride at room temperature gives S,S′-diphenyl acetals in high yields and carboxylic esters are converted into phenyl sulfides in the presence of zinc iodide under similar conditions.     

O‐Arylation of Carboxylic Acids using (Phenyl)[2‐(trimethylsilyl)phenyl]iodonium Triflate as a Precursor of Arynes

Using (phenyl)[2‐(trimethylsilyl)phenyl]iodonium triflate as a precursor of arynes, Larock's method for O‐arylation of carboxylic acids and arynes was developed. A variety of acids including simple aliphatic carboxylic acids, aromatic carboxylic acids, allenoic acids, and p‐toluenesulfonic acid under mild reaction conditions could generate the aryl esters.     

A facile synthesis of p- and m-(amidinomethyl)phenyl esters derived from amino acid and tryptic hydrolysis of these synthetic inverse substrates

A facile synthetic method for p- and m-(amidinomethyl)phenyl esters derived from a variety of amino acids is presented. We analyzed the kinetic behavior of trypsin towards these synthetic esters, which are inverse substrates. The substituent (meta- and para-isomers) and isosteric effects of (amidinomethyl)phenyl esters are discussed.     

Carbonylation of aryl chlorides with oxygen nucleophiles at atmospheric pressure. Preparation of phenyl esters as acyl transfer agents and the direct preparation of alkyl esters and carboxylic acids

A mild, functional group tolerant method of the preparation of phenyl esters from aryl chlorides via palladium-catalyzed carbonylation is described using atmospheric pressure of carbon monoxide. Phenyl esters are shown to be useful acylating agents, delivering libraries of carbonyl derivatives, including alkyl, allyl and thioesters, under very mild conditions. Direct preparation of alkyl esters and carboxylic acids is also demonstrated, providing the first method for the preparation of methyl and ethyl esters from aryl chlorides without pressured reactors.     

Studies on aryl H-phosphonates. 3. Mechanistic investigations related to the disproportionation of diphenyl H-phosphonate under anhydrous basic conditions

Diphenyl H-phosphonate undergoes under anhydrous reaction conditions a base-promoted disproportionation to triphenyl phosphite and phenyl H-phosphonate. On the basis of ³¹P NMR data the most likely mechanism for this transformation was proposed. In order to substantiate these findings and to get a deeper insight into the chemistry of aryl H-phosphonate esters, we carried out also some studies on activation of phenyl and diphenyl H-phosphonates with various condensing agents. We found that aryl vs alkyl esters of phosphonic acid often follow different reaction pathways during the activation, and this can most likely be traced back to higher electrophilicity of the phosphorus centre and to higher reactivity of the P-H bonds in aryl H-phosphonate derivatives.     

Enantio- and diastereoselective hydrogenation via dynamic kinetic resolution by a cationic iridium complex in the synthesis of beta-hydroxy-alpha-amino acid esters

Anti-selective asymmetric hydrogenation of alpha-amino-beta-keto esters via dynamic kinetic resolution under low hydrogen pressure has been achieved by an easily-handled cationic iridium complex with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF) as a counterion.     

Alkylation d'α-nitroacetates catalysee par les complexesn3 du palladium

Nitroacetic esters react with allyl phenyl ethers and allyl carbonates in the presence of Pd (dppe)₂ as catalyst to give C-alkylated products in good yieds (70–90%), under mild conditions.     

Phenyl esters, preferred reagents for mono-acylation of polyamines in the presence of water

In the presence of water, several diamines and one triamine were mono-acylated at ambient to moderate temperatures using phenyl esters and a phenyl carbonate as acylation agents in good to excellent isolated yields. Both linear and cyclic polyamines were suitable substrates, and the acylating agents can be aryl and alkyl carboxylic acid esters.     

Role of aggregates in Claisen acylation reactions of imidazole, pyrazole, and thioesters with lithium enolates in THF

[formula: see text] Although phenyl esters react with both monomers and dimers or tetramers of two lithium enolates in THF, the reactions of phenyl thiobenzoates are relatively much faster with the monomers. Similarly, imidazole esters react primarily with the monomers but pyrazole esters react with monomers and aggregates. The results are rationalized by a mechanism in which coordination with two lithium cations within an enolate aggregate is required for the reaction of aggregates to compete with monomers.     

丙烯酸酯在苯肼存在下的氧化和聚合研究

苯肼存在下丙烯酸酯的吸氧和氧化速度迅速增加,苯肼浓度约0.1—1.0％范围时,并发生聚合。 不同结构丙烯酸酯在苯肼存在下的吸氧与聚合的次序为:甲基丙烯酸 2-甲氧基乙酯>甲基丙烯酸羟基丙酯>甲基丙烯酸甲酯。我们认为苯肼存在下丙烯酸酯的氧化机构可能是苯肼结合丙烯酸酯醚键或双键α位碳原子上的氢,形成负碳离子或疏松离子对,从而在氧作用下生成过氧化合物。     

Effects of silica surface and external magnetic field on photochemical reaction of phenyl esters

Photolysis of phenyl phenylacetate and its derivatives in homogeneous solutions results in photo-Fries rearrangement products, phenols and diphenylethane as well as phenyl benzyl ethers. Photolysis of these esters adsorbed on silica surface leads only to the formation of or/tho-hydroxyphenones and phenyl benzyl ethers. This observation demonstrates that silica surfaces suppress diffusion and rotation of the photogenerated radicals. Application of a weak external magnetic field upon photolysis of these esters adsorbed on silica surface results in no change in the product distribution, suggesting that the photochemical reaction of these esters originates from the excited singlet state. The rate of the formation of the ortho rearrangement product from the geminate radical pairs adsorbed on silica surfaces is estimated to be 2.0 x 10⁸ s^-1.     

New synthetic routes to β-fluoro β-phenyllactic acid derivatives and β-fluorocyanohydrins

Alkyl phenyl 2,3-epoxycarboxylates from the well-known Darzens glycidic esters synthesis react under very mild conditions with pyridinium-poly-hydrogen fluoride to give corresponding 3-fluoro 3-phenyllactates in almost quantitative yields with a high regio and stereoselectivity.This method can be applied successfully to other glycidic derivatives : glycidoamides, glycidonitriles, glycidoiminoesters…The spectrometric propertities (IR, NMR) are presented.     

Some three-ring esters containing a pyrazine ring. A comparison of their liquid crystal properties

Two novel series of pyrazine-containing esters, together with an analogous phenyl system have been prepared, and their liquid crystalline phase behaviour compared in order to establish how the replacement of a phenyl ring by a pyrazine ring affects the liquid crystal behaviour of these esters. Both of the heterocyclic-containing ester series show significant suppression of the smectic phases, and some suppression of the nematic phase, when compared with the non-heterocyclic series.     

Samarium diiodide induced reductive cleavage of the Te–Si bond in phenyltellurotrimethylsilane: A novel method for the synthesis of alkylphenyl tellurides,telluroesters, and β‐phenyltelluro esters (nitriles)

Phentyltellurotrimethylsilane (1) was reduced by samarium diiodide in tetrahydrofuran (THF) to produce samarium phenyltellurolate. This new tellurolate anion reacted smoothly with alkyl and benzyl halides to give alkyl and benzyl‐phenyl tellurides in good yields under mild and neutral conditions. The samarium tellurolate also reacted with acyl halides or anhydrides to give telluroesters, and the 1,4‐addition of samarium tellurolate to α, β‐unsaturated esters (nitriles) gave β‐phenyltelluro esters (nitriles). © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 471–474, 1999     

Synthesis and antimicrobial activity of tris phosphonates

Syntheses of novel [{(3‐dialkoxy‐phosphoryl)‐(substituted‐phenyl‐methyl)‐2‐oxo‐2‐phenyl‐2,3‐dihydro‐2λ⁵–benzo [1,3,2] diazaphosphol‐1‐yl}‐(substituted‐phenyl)‐methyl]‐phosphonic acid diethyl/dimethyl esters ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j ) were conveniently accomplished by cyclocondensation of [(2‐{(dimethoxy‐phosphoryl)‐phenyl‐methyl)‐amino}‐phenyl amino)‐phenyl‐methyl]phosphonic acid diethyl/dimethyl esters ( 2a , 2b , 2c , 2d , 2e , 2f , 2g , 2h , 2i , 2j ) with phenyl phosphonic dichloride in dry toluene in the presence of triethylamine at 40°C. The title compounds were characterized by physicospectral techniques. All the synthesized compounds were found to possess antimicrobial properties. J. Heterocyclic Chem., 2011.     

Thermal stability of phthalate esters: Effect of substituents on the β-carbon atom

In order to clarify the mechanism conferring heat resistance on phthalate esters, those with a substituent on the β-carbon atom, such as bis(2-aminobutyl) phthalate, bis(2-nitrobutyl) phthalate, bis(2,4-diphenylbutyl) phthalate and dineopentyl phthalate, were synthesized and their thermal stabilities were studied by thermogravimetry and differential thermal analysis. The analytical results for these phthalate esters were compared with those for dibutyl phthalate, with a straight alkyl chain. As the temperatures required for a 3% weight loss of phthalate esters with a substituent, an electron-donating group (amino group) or an electron-accepting group (nitro group) on the β-carbon atom move to the higher end of the range, the effect of the adjacent group was recognized. The presence of a phenyl group in phthalate esters considerably improved the heat resistance. It is considered that the high heat resistance of bis(2,4-diphenylbutyl) phthalate is due to the obstruction of the planar configuration for cis elimination by the phenyl group and hindrance by the phenyl group of the formation of the six-membered cyclic transition state owing to the interaction between non-bondable molecules.     

Facile preparation of thiol esters from organotin mercaptides and acyl chlorides

Organotin mercaptides condense with acyl chlorides to give thiol esters in excellent yield. Of note are efficient syntheses of $\text{t}$-butyl and phenyl thiol esters.