Protonation of acyl anion equivalents generated from acylphosphonates: nonhydride access to the aldehyde oxidation state from the carboxylic acid oxidation state

Acylphosphonates, which are easily available from carboxylic acids, are potent acyl anion precursors and undergo cyanide ion promoted phosphonate-phosphate rearrangement to provide the corresponding acyl anion equivalents as reactive intermediates. The protonation of these acyl anion equivalents furnished cyanohydrin O-phosphates in good yields. For the high yield formation of cyanohydrin O-phosphates from arylphosphonates THF should be used and from alkylphosphonates DME was used.     

Reactions of acyl anions generated from acid chlorides and diiodosamarium

Acid chlorides react with SmI₂ to give α-diketones. Various experiments show that the initially formed acyl radical is rapidly transformed into an acyl anion which is thus generated by quite an unusual route.This species acylates acid chlorides, aldehydes and ketones in situ to give α-diketones and α-ketols. There are some limitations to this acyl anion chemistry but the reactions are realized with a good efficiency at room temperature in THF solution.     

Rh(I)-catalyzed carbonylative ring opening of diazabicycles with acyl anion equivalents

A catalytic desymmetrization of strained alkenes by ring-opening of meso-diazabicycles with acyl anion nucleophiles is reported. Densely functionalized trans-1,2-hydrazinoacyl cyclopentene building blocks are obtained stereoselectively. The acyl anion equivalent is generated in situ under very mild conditions from readily available organoboron precursors.     

Intermolecular Cross-Acyloin Reactions by Fluoride-Promoted Additions of O-Silyl Thiazolium Carbinols

The addition of acyl anion equivalents to aliphatic aldehydes (crossed-acyloin reaction) has been developed. Cesium fluoride with isopropanol as solvent promotes the addition of O-silyl thiazolium carbinols to various aliphatic aldehydes in moderate to good yields. These reactions represent a general procedure for the selective coupling of aliphatic aldehydes by an acyl anion reaction which have been problematic until now.     

Reductive Cleavage of the S-Si Bond in Phenylthio-trimethylsilane:A Novel Method for the Synthesis of Thiolesters

TheaPPlicationofsamariumdiiodideinorganicSyntilesishasreceivedmoreandmoreattenhoninthelastdecade.'-'Itisapowerfulone-electrontr~ferreducest.Recently,wehaveconsideredthattheS-Stbondmightbereductivelycleavedwithsamariumdiiodide.Thiolestersareusefulintermediatesinorgbocchemistry.'-'Manynewmethodshavebeendevelopedforthepreparationoftlilolestersinrecentyears,'-"forexample,tilereachonbetWeensodiumthiobenzoateandarenediazoniumtetaluoroborates,'beatmentofnitrosoamidesornitroamideswithinercaptansint…     

Studies on alkylation of acyl anion equivalents: unsymmetrical ketone synthesis by use of diethyl 1-trimethylsilyloxy-alkylphosphonates

Novel acyl anion equivalents, lithiated diethyl 1-trimethylsilyloxy-alkylphosphonates, were successfully alkylated and converted to the corresponding ketones. The mechanism of the alkylation is discussed in connection with the Brook-Wittig rearrangement.     

Reductive Cleavage of S-S Bond in Diphenyl Disulfide by Samarium Diiodide: A Novel Method for the Synthesis of Thiolesters

Diphenyl disulfide is reduced by samarium diiodide to yield samarium phenylthiolate. This new thiolate anion species mildly reacts with acyl chlorides to give thiolesters in good yields.     

The thiazolium-catalyzed Sila-Stetter reaction: conjugate addition of acylsilanes to unsaturated esters and ketones

A new acyl anion addition reaction between acylsilanes and alpha,beta-unsaturated conjugate acceptors promoted by a nucleophilic organic catalyst has been disclosed. The 1,4-dicarbonyl products produced in this reaction are highly useful synthons. Neutral carbenes (or zwitterions) generated in situ from commercial thiazolium salts are used as effective catalysts for the reaction which is in contrast to established anionic catalysts typically employed to promote the required Brook rearrangement (1,2-silyl shift from carbon to oxygen) involved in the reported reaction. This process successfully utilizes acylsilanes as tunable acyl anion progenitors and is tolerant of a wide range of structural diversity on the acylsilane or the conjugate acceptor.     

Stereocontrolled acylation of (η4-cycloheptatriene)iron tricarbonyl

The anion derived by deprotonating (cycloheptatriene)Fe(CO)₃ reacts with acid chlorides to give exo C-7 substitution. The acyl group is readily isomerized to C-5 on treatment with base. The C-7 acylated products can be deprotonated; the resulting anions react at oxygen with acyl chlorides and Me₃SiCl, and at carbon with MeI.     

Process Improved Preparation of a Versatile α-Ketoester Acyl Anion Synthon

An improved scalable procedure for preparation of an α-ketoester acyl anion synthon is described.     

中心碳极性反转的酰基化试剂的理论研究Ⅱ: H~2C=C(OH)Na 的理论研究

用MP2/6-31+G^*解析梯度方法,研究乙酰基负离子等效物CH~2=C(OH)Na的结构,得到了四个平衡构型。偏位取代的三元环结构1最稳定,将是最易存在的结构。H~2C=C(OH)Na具有双重反应性,结构4是发生亲核反应的中间体,发生类卡宾反应时经过类似构型2的中间状态。同H~2C=C(OH)Li相比较,H~2C=C(OH)Na碳负离子反应将更突出,发生类卡宾反应则更加困难。     

Acyl furans from cyclohexane-1,3-diones – A synthesis of hibiscone C

A direct route to acyl furans was developed using dithiane anion addition followed by deprotection/aromatization. This led to an efficient synthesis of hibiscone C.     

Monoacylglycerols as transmembrane Cl- anion transporters

We report that the amphiphilic natural product, monoacylglycerol 1, functions as a transmembrane Cl(-)/NO(3)(-) anion transporter. The 1,2-diol group is crucial for the transport function since diacylglycerol and triacylglycerol analogs are not anion transporters. Furthermore, adding another hydrogen bond donor to the glycerol head-group and perfluorination of the acyl tail gave synthetic analogs with improved Cl(-) membrane transport properties.     

α-Aminonitriles—I: A simple synthesis of deoxybenzoins

A method is described, involving an acyl anion equivalent, for the preparation of deoxybenzoins that are inaccessible by the more usual methods.     

Addition of trifluoromethyltrimethylsilane to acyl phosphonates: synthesis of TMS-protected 1-alkyl-1-trifluoromethyl-1-hydroxyphosphonates and 1-aryldifluoroethenyl phosphates

Addition reactions of nucleophilic CF3TMS to acyl phosphonates were investigated. Various acyl phosphonates reacted readily with CF3TMS in the presence of K2CO3 in DMF at rt to give 1-alkyl-2,2,2-trifluoro-1-trimethylsilyloxyethylphosphonate in 70-90% yields. When benzoyl phosphonates were used as starting material, after addition of CF3, the formed alcoholate undergoes phosphonate-phosphate rearrangement to form the acyl anion, followed by elimination of F- to give 1-aryldifluoroethenyl phosphates in 87-97% yields. As a representative example, vinylphosphate 6a was converted into 2,2-difluoro-1-phenylethanone 7 with 6 N HCl/EtOH/reflux or CAN/NaOH/MeOH/0 degrees C in 82-90% yields.     

Derivatives and reactions of glutacondialdehyde IV 1-substituted-3-formyl-2(1H)-pyridinethiones

The reaction of the glutacondialdehyde anion with alkyl and acyl isothiocyanates has been investigated. Whereas alkyl isothiocyanates give rise to 1-alkyl-3-formyl-2(1$\text{H}$)-pyridinethiones, $\text{O}$-acylated glutacondialdehyde derivatives are formed from acyl isothiocyanates in most cases. The reaction courses may be understood on the basis of the principle of hard and soft acids and bases.     

二(芳砜基)甲烷作极性逆转试剂:醛的一个简便合成法

二(芳砜基)甲烷的亚甲基被两个砜基活化,它的酸性大于硫代缩醛.使用较弱的碱性试剂即可使它形成相应的α-碳阴离子,发生烃化反应,继而还原,水解,从而提供醛的简便合成方法.     

Cyanide ion promoted addition of acyl phosphonates to ethyl cyanoformate: synthesis of tertiary carbinols via tandem carbon-carbon bond formations

New cyanation/phosphonate-phosphate rearrangement/C-acylation reactions of cyanophosphate anion with cyanoformate esters are described. Phase-transfer cocatalysts facilitate cyanide-catalyzed reactions between acyl phosphonates and cyanoformates to afford protected tertiary carbinol products in good to excellent yields (74-95%). Ethyl cyanoformate is used as a cyanide source and electrophile. The scope of the reaction was investigated by using a number of benzoyl and acyl phosphonates along with ethyl cyanoformate. Representative chemoselective reduction of the product 5a afforded ethyl 3-amino-2-hydroxy-2-phenylpropanoate (13) in good yield.     

Properties of various phosphatidylcholines as emulsifiers or dispersing agents in microparticle preparations for drug carriers

We investigated characteristics of various phosphatidylcholines (PCs) used as dispersing agents and emulsifiers. Six PCs with different lengths of acyl hydrocarbon chains and different degrees of unsaturated acyl hydrocarbon chains were selected to examine influences of a lipophillic part of phosphatidylcholines in emulsion and dispersion systems. Vesicles and oil-in-water emulsions were prepared by sonication under several ambient temperature conditions. Mean diameters of vesicles and oil droplets in emulsions were measured by a submicron particle sizer. In vesicles that are generated by hydration of the PCs and have a bilayer form, particle size was influenced by length and degree of unsaturation of acyl hydrocarbon chains of a PC. PCs with shorter acyl hydrocarbon chains or unsaturated bonds are considered more potent dispersing agents. Preparation temperature of the PC is also a factor affecting potency of dispersion. In O/W emulsions in which PCs were absorbed at water-oil interfaces and which have a single layer form or liquid-crystal layer form, particle size was also influenced by length and degree of unsaturation of acyl hydrocarbon chains of a PC. PCs with shorter and saturated acyl hydrocarbon chains are considered more potent emulsifiers. Unsaturation of acyl hydrocarbon chains weaken the ability of emulsification due to vulnerable double bonds. For stable emulsions, it is considered beneficial for PCs to form small oil droplets and lamellae liquid-crystal phase. From this perspective, saturated PCs with short hydrocarbon chains, i.e., DLPC and DMPC, may have advantages in preparing a stable emulsion not only by giving a smaller droplet size but also by forming lamellae liquid-crystal phase. When considering characteristics of PCs as emulsifiers, their characteristics as dispersing agents is also useful information.     

Acylation of salts of dinitromethane

Conclusions When the ambient anion of dinitromethane is reacted with acyl chlorides (acetyl or benzoyl chloride) the acylation of this anion occurs only at the oxygen atom, with the formation of the O-acyl derivatives of dinitromethane. The latter, being very reactive compounds, undergo a number of further transformations during the reaction process.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2045–2049, September, 1971.