A new synthesis of perfluoroacyl halides and anhydrides from perfluorocarboxylate salts. A synthetic study

The nucleophilic cleavage of difluorophosphine esters of perfluorocarboxylic acids by halide ions to form acyl halides has not been previously reported. Furthermore, the reactions between halophosphoryldifluorides or the anhydrides, P₂O₅F₂ and P₂O₃F₄, and perfluorocarboxylate salts produce acyl halides or acyl anhydrides, respectively.     

A versatile access to unsymmetrical and symmetrical α-diketones via organotin reagents

Unsymmetrical α -diketones have been obtained via cross coupling of acyltins with acyl halides under PdCl₂(PPh₃)₂ catalysis while symmetrical α -diketones have been readily obtained via “in situ” formation of acyltins using hexabutylditin and acyl chlorides under similar experimental conditions.     

Direct synthesis of fluorinated peroxides. V. The preparation of pentafluorosulfurperoxy esters by reactions of pentafluorosulfur hydroperoxide with acyl fluorides

The reaction of SF₅OOH with acyl fluorides in the presence of NaF has been investigated and found to yield new peroxy esters of the type RC(O)OOSF₅. An alternate method of synthesis using SF₅OOCl and acyl chlorides is discussed and the cesium fluoride catalyzed conversion of two of the esters to RCF(OF)OOSF₅ is described.     

A reactive rhodium(I) carbonyl dithiolate and the formation of acyl and hydride species

The rhodium(I) complex [Rh(CO)(PEt₃)(mnt)]^? (mnt = maleonitriledithiolate) reacts with a variety of alkyl halides to form acyl complexes isolated in the presence of excess PEt₃ as five-coordinate species of formula [Rh(COR)(PEt₃)₂(mnt)]. The structure of the complex for R = n-Pr has been determined by an X-ray analysis, and is found to be a square-based pyramid with the acyl group in the apical position. Addition of HClO₄ to the rhodium(I) anion in the presence of excess PEt₃ yields rhodium(III) hydride, [RhH(CO)(PEt₃)₂(mnt)], while addition of acid to the rhodium(I) complex in CH₃CN solution with ethylene present leads slowly to formation of an acyl complex which is isolated as [Rh(COEt)(PEt₃)₂(mnt)] upon phosphine addition. A novel alkyl group migration from the acyl carbon to a donor S atom is also observed in monophosphine systems.     

Analysis of the hydroxyacyldiacylglycerides of sea buckthorn seed oil

The TMS derivatives of the hydroxyacyldiacylglycerides of sea buckthorn seed oil have been analyzed by mass spectrometry. On the basis of characteristic fragments it has been established that an acyl residue of one of the seven hydroxy acids found previously in hydrolysis products by the GC-MS method is attached in one of the positions of the hydroxyacyldiacylglycerides. The remaining positions are substituted by acyl radicals of the C_18:1, C_18:2, C_18:3 and C_18:0 acids. The 24 most probable components of the triglycerides include these acyl and hydroxyacyl substituents. Features of the fragmentation of the components due to presence of polyunsaturated acids have been revealed.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 176–182, March–April, 1991.     

Rapid and efficient routes to phosphatidylinositol 3,4,5-trisphosphates via myo-inositol orthobenzoate

Efficient routes to two phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P₃] analogues with different acyl chains have been developed by using cheaply available myo-inositol as the starting material. The high yield of the orthobenzoate derivative, preferential formation of the required protected inositol diastereomer in its desymmetrization and ease of separation make the synthesis expedient, economical and high yielding. Due to the inherent problem of racemization of diacylglycerol (DAG), the synthesis of phosphatidylinositol phosphates [PIPns] with unambiguous stereochemical purity has always been difficult. Our methodology excludes the possibility of racemization in the DAG unit and thus provides access to PtdIns(3,4,5)P₃ of high optical purity. Since the acyl functionalities are introduced last, the methodology reported is amenable to the synthesis of PtdIns(3,4,5)P₃ with any acyl chain (or even a library of analogues).     

Mechanistic studies of carbonate macrocyclization

The kinetics of phenylchloroformate (PCF) reactions have been used to model some of the key chemical events in carbonate macrocyclization. Three reactions have been studied using stopped-flow FT-IR spectroscopy: formation of acyl ammonium salt from PCF and three different trialkylamines, the conversion of acyl ammonium salt to urethane, and the condensation reaction between acyl ammonium salt and 4-isopropylphenol. The rate dependence was studied for triethylamine (TEA), diethylmethylamine (DEMA) and tri-n-butylamine (TBA) at 0°C in anhydrous CH₂Cl₂. The reactivity order for acyl ammonium salt formation for TBA: TEA: DEMA is 1 : 2.7 : >444. By contrast, condensation and urethane formation are not sensitive to the structure of the amine. The rate of condensation is comparable to the rate of acyl ammonium salt formation for TEA and TBA, while the rate of urethane formation is the slowest process for all three amines. These results are consistent with the view that the yield of macrocyclic polycarbonates is related to the concentration of the acyl ammonium salt. The optimum amine concentration for obtaining high yields of cyclics varies with the amine structure and parallels the difference in the rates of acyl ammonium salt formation. © 1994 John & Sons, Inc.     

N‐(1‐Naphthyl­acetyl)­glycine phen­acyl ester and phen­acyl (1‐naphthyl­acetoxy)­acetate

The structures of the bichromophoric compounds N‐(1‐naphthyl­acetyl)­gly­cine phen­acyl ester, C₂₂H₁₉NO₄, (I), and its oxy­gen analogue, phen­acyl (1‐naphthyl­acetoxy)­acetate, C₂₂H₁₈O₅, (II), have been determined. The mol­ecules of (I) are held together by intermolecular N—H⋯O hydrogen bonds between the carbonyl and N—H groups, while compound (II) does not show any hydrogen bonding in the crystal.     

Transformatioms of cycloalkanes under the action of acyl halides in the presence of AIBr3.

Cycloalkanes have been found to react with acyl halides in the presence of AIBr₃, (mole ratio RCOX:AIBr₃ = 1:2) under very mild conditions affording products of hydrocarbon oxidative coupling or/and hydrocarbon acylation.     

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.     

Acyl Group Migration in Pyranosides as Studied by Experimental and Computational Methods

Acyl group migration affects the synthesis, isolation, manipulation and purification of all acylated organic compounds containing free hydroxyl groups, in particular carbohydrates. While several isolated studies on the migration phenomenon in different buffers have been reported, comprehensive insights into the overall migration process in different monosaccharides under similar conditions have been lacking. Here, we have studied the acyl migration in different monosaccharides using five different acyl groups by a combination of experimental, kinetic and theoretical tools. The results show that the anomeric configuration in the monosaccharide has a major influence on the migration rate, together with the relative configurations of the other hydroxyl groups and the nature of the migrating acyl group. Full mechanistic model, based on computations, demonstrates that the acyl migration proceeds through an anionic stepwise mechanism with linear dependence on the [OH⁻] and the pK_a of the hydroxyl group toward which the acyl group is migrating.     

Nature of the species responsible for the high activity of RCOX·2A1X3 complexes in reactions with alkanes and cycloalkanes

The reasons for the high reactivity of aprotic organic superacids (AOS) containing an acyl halide and a double molar excess of Lewis acid in reactions with saturated hydrocarbons are studied. The synthesis and spectral properties of two pairs of acyl salts are studied: MstCO⁺AlBr₄ ^– and MstCO⁺Al₂Br₇ ^– (Mst=2,4,6-Me₃C₆H₂) and Ac⁺SbF₆ ^– and Ac⁺Sb₂F₁₁ ^–. Comparison of the reactivities of these salts in cracking of alkanes and isomerization of trimethyl-enenorbornane demonstrated that the AOS activity is due to generation of acyl salts with a dimeric anion in the slightly polar solutions. Analysis of the¹³C NMR spectra suggests that the superacid properties of these salts are due to formation of species containing acyl cations coordinated to the Lewis acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2490–2496, November, 1990.     

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.     

Acylzirconocene Chloride as an “Unmasked” Acyl Anion

Under mild conditions the acyl group of acylzirconocene chloride 1 formed from an alkene or alkyne and [(C₅H₅)₂ZrHCl] reacts as an “unmasked” acyl anion. The Lewis acid mediated reactions with aldehydes that yield α-ketol products in high yields demonstrate the versatility of this reagent for C–C coupling.     

Highly efficient synthesis of capsaicin analogues by condensation of vanillylamine and acyl chlorides in a biphase H2O/CHCl3 system

Highly efficient synthesis of capsaicin analogues was developed using condensation of vanillylamine with acyl chlorides in a biphase H₂O/CHCl₃ system under mild conditions. For C4-C18 aliphatic or aromatic acyl chlorides, the yields were up to 93-96% with high purity after a simple work-up procedure, and only 1-1.16 equiv of acyl chloride was needed in the reaction.     

Nickel‐Catalyzed Decarbonylative Borylation of Amides: Evidence for Acyl C−N Bond Activation

A nickel/N‐heterocyclic carbene catalytic system has been established for decarbonylative borylation of amides with B₂nep₂ by C?N bond activation. This transformation shows good functional‐group compatibility and can serve as a powerful synthetic tool for late‐stage borylation of amide groups in complex compounds. More importantly, as a key intermediate, the structure of an acyl nickel complex was first confirmed by X‐ray analysis. Furthermore, the decarbonylative process was also observed. These findings confirm the key mechanistic features of the acyl C?N bond activation process.     

Isolation and structure of citreopyrone,a metabolite of penicillium citreo-viride biourge

Citreopyrone isolated from the mycelium of $\text{Penicillium citreo-viride}$ B. has been found to be 5-crotonoyl-4-methoxy-6-methyl-2-pyrone. This is the first naturally occurring pyrone with an acyl group at C₅-position.     

Selective removal of anomeric O-acetate groups in carbohydrates using HClO4-SiO2

A convenient methodology has been developed for the selective removal of the anomeric acyl group of carbohydrate derivatives using HClO₄-SiO₂ under acidic reaction conditions. Anomeric benzoyl groups can also be removed selectively following similar reaction conditions. The yields were excellent in all cases.     

Acyl iodides in organic synthesis: X. Reactions with triorganylsilanes and triphenylgermane

Reaction of acyl iodides RCOI (R = Me, Ph) with triorganylsilanes R′₂R″SiH in toluene gives 50–60% of the corresponding triorganyliodosilanes R′₂R″SiI. Triethylsilane reacts with the same acyl iodides under solvent-free conditions to afford the corresponding aldehyde and triethyliodosilane as primary products. Triethyliodosilane undergoes subsequent transformations into hexaethyldisiloxane and triethyl(acyloxy)silane Et₃SiOCOR (R = Me, Ph). Reactions of acyl iodides RCOI (R = Me, Ph) with triphenylgermane in the absence of a solvent lead to formation of iodo(triphenyl)germane in more than 90% yield.     

Iron–Carbonyl Aqueous Vesicles (MCsomes) by Hydration of [Fe(CO){CO(CH2)5CH3}(Cp)(PPh3)] (FpC6): Highly Integrated Colloids with Aggregation‐Induced Self‐Enhanced IR Absorption (AI‐SEIRA)

Self‐assembly of hydrophobic molecules into aqueous colloids contradicts common chemical intuition, but has been achieved through hydration of [Fe(CO){CO(CH₂)₅CH₃}(Cp)(PPh₃)] (FpC6). FpC6 has no surface activity, no NMR signals in D₂O and no critical aggregation concentration (CAC) in H₂O. The molecule, however, contains both acyl and terminal CO groups that are prone to being hydrated. By adding water to a solution in THF, self‐assembly of FpC6 can be initiated through water–carbonyl interactions (WCIs) with the highly polarized acyl CO groups. This aggregation subsequently enhances the hydration of the acyl CO groups and also induces the WCI of otherwise unhydrated terminal CO groups. The resultant metal–carbonyl aggregates have been proved to be bilayer vesicles with iron complexes exposed towards water and alkyl chains forming inner walls (MCsomes). These MCsomes show high structure integration upon dilution due to the hydrophobic nature of the building blocks. The highly polarized CO groups on the surface of the MCsomes result in a negative zeta potential (?65 mV) and create a local electric field, which significantly enhances the IR absorption of CO groups by more than 100‐fold. This is the first discovery of aggregation‐induced self‐enhanced IR absorption (AI‐SRIRA) without the assistant of external dielectric substrates. Highly integrated MCsomes are, therefore, promising as a novel group of materials, for example, for IR‐based sensing and imaging.