A Cs2CO3-mediated simple and selective method for the alkylation and acylation of 3,4-dihydropyrimidin-2(1H)-thiones

Alkyl and acyl derivatives of 3,4-dihydropyrimidin-2(1H)-thiones were synthesized in good to excellent yields in the presence of Cs₂CO₃, a mild base. The method evidences a selective S-alkylation when using acyl chlorides as efficient acylating agents at room temperature on the 2-thioxo-dihydropyrimidone moiety. A possible mechanistic interpretation of the different selectivities in case of alkylation and acylation was done with the help of a geometry optimization process.     

A new method for making acyl fluorides using BrF3

While many carboxylic acids could be converted directly to acyl fluorides by using BrF₃, the reaction with acyl chlorides was found to be of a more general nature and yields better results. Surprisingly, reacting t-butyl esters with bromine trifluoride also resulted in acyl fluorides in reasonable yields. The reactions were completed in a few seconds at 0 °C.     

AlCl3-mediated tandem Friedel-Crafts reactions of vinylidenecyclopropanes with acyl chlorides: a facile synthetic method for the construction of 1-[2-(2,2-diarylvinyl)-1-phenyl-3H-inden-5-yl]ethanone derivatives

AlCl₃-mediated tandem Friedel-Crafts reaction of vinylidenecyclopropanes with acyl chlorides produced the corresponding 1-[2-(2,2-diarylvinyl)-1-phenyl-3H-inden-5-yl]ethanone derivatives in moderate to good yields under mild conditions within short reaction time.     

Acylation of aromatic alcohols and phenols over InCl3/montmorillonite K-10 catalysts

Montmorillonite K-10 clay supported InCl₃ is a highly active catalyst for the acylation of aromatic alcohols and phenols with different acyl chlorides. This catalyst can be reused in reactions a number of times without very significant loss of catalytic activity     

Convenient Synthesis of Thiol Esters from Acyl Chlorides and Disulfides Using Zn/AlCl3

 Various thiol esters were prepared by condensation of acyl chlorides with disulfides in the presence of Zn/AlCl₃. The advantages of this method are high yields under relatively mild conditions, simple work-up, lack of toxicity, and low costs.     

Rhenium complex-catalyzed acylative cleavage of ethers with acyl chlorides

It was found that rhenium complex was an efficient catalyst for the acylative cleavage of C-O bond of ethers with acyl chlorides. When acyclic ethers were allowed to react with acyl chlorides in the presence of a catalytic amount of ReBr(CO)₅, acylative cleavage of C-O bond of acyclic ethers smoothly proceeded to give the corresponding esters in moderate to good yields. Similarly, cyclic ethers were acylative cleaved by acyl chlorides to give the corresponding chloro substituted esters in good yields by the use of Re₂O₇ catalyst.     

Structural assignment of n3-acylated uridine derivatives by means of 13c nmr spectroscopy

Diisopropylethylamine was effective as a base for acylation of 2′,3′,5′-tri-O-acetyluridine with various acid chlorides. The ¹³C NMR spectra of the products and related compounds showed clearly that the acyl groups intoduced to the uracil moiety are attached to the N³-nitrogen.     

A general and efficient reduction of acyl chlorides to aldehydes by Sm(0)/Bu3P

A facile and efficient reduction of aromatic and aliphatic acyl chlorides to their corresponding aldehydes in the presence of Sm(0)/Bu₃P has been developed with broad scope. This method prevents over reduction of products, that is, the over-reduction of aldehydes to alcohols.     

Copper-catalyzed acylations of o-vinylbenzylzirconocene intermediate and synthetic application toward steroid skeleton

Benzylzirconocene intermediate, which was readily prepared by a reaction of o-alkoxymethylstyrene with `Cp₂Zr' under mild conditions, reacted with acyl chlorides in the presence of a catalytic amount of CuBr-SMe₂ to give ketone derivatives in moderate to good yields.     

A comparative study of the reactions of fluorinated oxi- and thiiranes with acyl chlorides

The CoCl₂-catalyzed reactions of fluorinated 1,2-oxi- and thiiranes with acyl chlorides were studied. It was found that a regioselective heterocycle opening reaction resulted in two isomers having normal and abnormal structure in a ratio predetermined by the substituents in both the starting heterocycles and acyl chlorides.     

An efficient method for chlorination of alcohols using PPh3/Cl3CCONH2

A new and convenient method for the chlorination of alcohols utilizing PPh₃/Cl₃CCONH₂ is addressed. Various alcohols could smoothly be converted into their corresponding alkyl chlorides in high yield under mild conditions with short reaction times. A mechanism is disclosed with the evidence of inversion of configuration of the analogous alkyl chloride derived from R-(−)-2-octanol.     

Synthetic studies on bafilomycin A1: stereoselective synthesis of the C12-C17 fragment and its coupling with the C1-C11 subunit

Stereoselective addition of (E)-1-lithio-2-tributylstannylethylene on a chiral cyclic di-t-butylsilyleneketal C₁₄-C₁₇ aldehyde afforded the required Felkin-Anh adduct for the synthesis of the C₁₂-C₁₇ fragment of bafilomycin A₁, the configuration of which was assigned unambiguously. After appropriate coupling with the enantiopure C₁-C₁₁ fragment, the C₁₂-C₁₇ subunit obtained here can be used for the study of the 16-membered macrolide formation either by an acyl activation or an intramolecular Stille reaction. Intermolecular esterification of the 15-OH with an acyl activation of the carboxylic acid of the C₁-C₁₁ fragment, in modified Yamaguchi's conditions, affords here an intermediate for examining an intramolecular Stille coupling.     

A convenient method for preparing aromatic ketones from acyl chlorides and arylboronic acids via Suzuki-Miyaura type coupling reaction

Aromatic ketones are synthesized efficiently via palladium-catalyzed cross-coupling reaction of boronic acids with acyl chlorides in the presence of K₃PO₄ hydrate in toluene. This allows the use of aliphatic acyl chlorides as the starting material. Hydrated water plays a significant role as an H₂O source to activate the catalytic system.     

New hydrofluoropolyethers: I. Synthesis and reaction pathway evaluation

A novel family of hydrofluoropolyethers (HFPEs) was obtained with 60-80% selectivity by hydrogenation of perfluoropolyether acyl chlorides with Pt/CaF₂. These compounds are characterized by a macromeric fluorinated body end-capped, on one or both sides, by a (1,1-difluoro)ethoxy group. A reaction pathway for the reduction was proposed consistently with the observed yields and side products. The hemiacetal originated by reaction of the aldehyde (first product of reduction) with the corresponding alcohol was postulated to be the key precursor leading to the HFPE. The metal appears to play a fundamental role promoting the hydrogenolysis of this unexpected intermediate. Exhaustive reduction of the alcohol, generally recognized as the path affording hydrocarbons in the hydrogenation of acyl chlorides, was excluded by products analysis and by specific experiments.     

Study on the Reductive Acylation of Azo Compounds by SmI2/THF in One Pot

Azobenzene compounds without big substituents were conveniently reduced by a system consisting of SmI₂/THF and successively reacted smoothly with analogous aliphatic acyl chlorides or acid anhydrides to afford corresponding mono‐acyl symmetrical hydrazobenzene under mild and neutral conditions in one pot; while other azo compounds reacted under similar conditions, amides were the terminate products.     

η2-acylcarbonylvanadium-verbindungen

Substituted vanadium carbonyl compounds with η²-bonded acyl ligands (η²-RCO)V(CO)₃

(

= ditertiary phosphines or arsines: dppe, dppp, dppm, diars, arphos, dpase) have been prepared by photochemical reaction of [V(CO)₄

] with various substituted benzoyl chlorides and cyclopropanylcarbonyl chloride.Effects of aromatic substituents and

upon the thermal stability of the η²-acylcarbonylvanadium compounds are discussed. IR ν(CO) force constants and ⁵¹V NMR signals are linearly correlated with Hammett's σ constants of the aromatic substituents.The preparation of V(CO)₂Cl(diars)₂ is described.     

Preparation du complexe cationique [η5-cyclopentadienyl fer-η6-pentamethylaniline]+ et de quelques amides et sulfonamides derives

The [η⁵-cyclopentadienyl-η⁶-pentamethylanilineiron]⁺ cation has been prepared from ligand exchange between ferrocene and pentamethylaniline. Acidic chlorides (CH₃COCl, C₆H₅COCl) and sulfonyl chlorides (p-CH₃C₆H₄SO₂Cl, camphorsulfonyl-d₁₀ chloride) react in situ with deprotonated species after treatment of this cation with t-BuOK in THF. An acid—base reaction between amide or sulfonamide derivatives and deprotonated species takes place and can limit the yield; the mechanism is discussed. Amide derivatives also have been prepared by direct action of acidic chlorides with [η⁵-C₅H₅Fe-η⁶-C₆-(CH₃)₅NH₂]⁺ in acetone solution. An optically active sulfonamide has been prepared.     

First synthesis of (1,2-C2)-monolignol glucosides

The monolignol glucosides (1,2-¹³C₂)-p-glucocoumaryl alcohol, (1,2-¹³C₂)-coniferin and (1,2-¹³C₂)-syringin, and the glucosides of (1,2-¹³C₂)-p-coumaric, (1,2-¹³C₂)-ferulic and (1,2-¹³C₂)-sinapic acids were synthesized by condensation of the corresponding aldehydes with (1,2,3-¹³C₃)-malonic acid. The free acids were converted to the acyl chlorides prior to their reduction to alcohols.     

The electrochemical fluorination of organic compounds: Further data in support of the ECbECn mechanism

Data in support of the four-stage mechanism EC_bEC_N result from the electrochemical fluorination of some acyl halides (benzoyl, n-butyryl and iso-butyryl, benzenesulphonyl and p-toluenesulphonyl chlorides) and amines (tripropylamine and N-methylmorpholine).     

Generation of Aryl and Heteroaryl Magnesium Reagents in Toluene by Br/Mg or Cl/Mg Exchange

The alkylmagnesium alkoxide sBuMgOR?LiOR (R=2‐ethylhexyl), which was prepared as a 1.5 m solution in toluene, undergoes very fast Br/Mg exchange with aryl and heteroaryl bromides, producing aryl and heteroaryl magnesium alkoxides (ArMgOR?LiOR) in toluene. These Grignard reagents react with a broad range of electrophiles, including aldehydes, ketones, allyl bromides, acyl chlorides, epoxides, and aziridines, in good yields. Remarkably, the related reagent sBu₂Mg?2 LiOR (R=2‐ethylhexyl) undergoes Cl/Mg exchange with various electron‐rich aryl chlorides in toluene, producing diorganomagnesium species of type Ar₂Mg?2 LiOR, which react well with aldehydes and allyl bromides.