High-yielding synthesis of 2-arylacrylamides via homogeneous catalytic aminocarbonylation of α-iodostyrene and α,α′-diiodo-1,4-divinylbenzene

Highly reactive iodoalkenes (α-iodostyrene and α,α′-diiodo-1,4-divinylbenzene) were prepared and used as substrates in palladium-catalysed aminocarbonylation reaction. Regardless of the type of amine nucleophile the corresponding N-substituted phenylacrylamides have been formed chemoselectively in nearly quantitative yields. High isolated yields (up to 83%) have been achieved both with unfunctionalised simple amines and amino acid methyl esters under mild reaction conditions.     

New syntheses of α-oximno-α-haloketones : reactions of α-haloketones with alkyl thionitrites

α-Oximino-α-haloketones were readily synthesized in good yields by treating α-haloketones with alkyl thionitrites under mild conditions.     

Synthesis of α,α-difluoro-γ-butyrolactones via ethyl iododifluoroacetate

A novel synthesis of α,α-difluoro-γ-butyrolactones was realized by the alkaline hydrolysis of the adducts of ethyl iododifluoroacetate and alkenes. Ethyl iododifluoroacetate reacted with alkenes in the presence of sodium dithionite to give the addition products in 62-78% yields. The products were hydrolyzed in 10% aqueous sodium carbonate solution to give α,α-difluoro-γ-butyrolactones in 93-98% yields.     

α,ω-Dihydroxyalkan-α,α-diphosphonsäuren durch Desaminierung von ω-Aminoalkandiphosphonsäuren

α,ω-Dihydroxyalkane-α,α-diphosphonic Acids by Desamination of ω-Aminoalkanediphosphonic Acids The title compounds represent a new group of complexing diphosphonic acids which are synthesized by desamination of ω-amino-α-hydroxyalkane-α,α-diphosphonic acids. In case of α,ω-dihydroxypropane-α,α-diphosphonic acid ( 1 ) a phosphonylated phostone is formed by dehydration. In contrast, the ω-phenyl drivative of ( 1 ) yields in a smooth reaction under the same conditions 2-hydroxy-5-phenyl-3-phosphono-1.2-oxaphosphol-3-en-2-oxide ( 6 ).     

Practical and Efficient Method for α-Sialylation with an Azide Sialyl Donor Using a Microreactor

Efficient α-sialylation with a C5 azide sialyl donor was investigated under microfluidic conditions using a microreactor composed of a Comet X-01 micromixer and a tube reactor. Precise temperature control realized excellent α-selectivity, and Siaα(2,6)Gal, Siaα(2,3)Gal, and Siaα(2,9)Sia disaccharides were obtained in moderate to good yields.     

Umlagerungen der Phenylthiogruppe in Trimethylsilyl-enoläthern von α,α-dialkyl-α-phenylthio-ketonen

Rearrangements of the Phenylthio Group of Trimethylsilyl-enolethers of α,α-Dialkylated α-Phenylthio-ketones Trimethylsilyl-enolethers of α,α-dialkylated α-phenylthio-ketones undergo a photochemically induced 1,3-phenylthio shift leading to isomeric enolethers in high yields. The rearrangement can also be carried out under thermal conditions, but the results are less satisfying.     

First iodocyclization of β-allenic phosphonates: a novel synthesis of α-difluoromethylenephostones

Six-membered α-difluoromethylenephostones were prepared in moderate to good yields with high regioselectivities under mild conditions from the iodocyclization reaction of diethyl β-allenic α,α-difluorophosphonates using I₂ or ICl as the electrophile.     

Chiral phosphoric acid catalyzed aza-Friedel-Crafts alkylation of indoles with cyclic aryl α-ketimino esters

A highly enantioselective aza-Friedel-Crafts alkylation of indoles with cyclic aryl α-ketimino esters catalyzed by a chiral phosphoric acid has been developed, the corresponding α,α-disubstituted unnatural α-amino ester derivatives were obtained in moderate to high yields (67–85%) with high enantioselectivities (up to 93% ee) under mild reaction conditions.     

A simple nitration of electrophilic alkenes with tetranitromethane in the presence of triethylamine. Synthesis of functionalized β-nitroalkenes

A convenient method for the preparation of functionalized β-nitroalkenes based on the nitration of α,α-di- and α,α,β-trisubstituted unsaturated aldehydes, ketones and esters with tetranitromethane in the presence of triethylamine is described. Series of substituted β-nitroalcohols and β-nitroalkenes are obtained in good yields under mild conditions.     

A simple and efficient method for α-bromination of carbonyl compounds using N-bromosuccinimide in the presence of silica-supported sodium hydrogen sulfate as a heterogeneous catalyst

α-Bromination of carbonyl compounds (cyclic and acyclic ketones, amides and β-ketoesters) has been achieved efficiently by treatment with N-bromosuccinimide (NBS) and catalyzed by silica-supported sodium hydrogen sulfate (NaHSO₄·SiO₂). The products were formed in high yields under mild reaction conditions and in short reaction times.     

The Reaction of α,α-Dichlorobenzyltrimethylsilane with Aldehydes and Ketones

The reaction of α,α-dichlorobenzyltrimethylsilane with carbonyl compounds in the presence of fluoride ion fails to give reasonable yields of the α,α-dichlorobenzyl adducts except when carried out in the presence of zinc iodide and in HMPA as solvent. Under these conditions moderate yields of the adducts can be obtained with cyclohexanone, cyclohexenone, benzaldhyde and trans cinnamaldehyde. These reactions were compared with those of α,α-dichlorobenzyllithium.     

Samarium Diiodide Mediated Coupling of Aroyl Chlorides

α, α'‐Stilbenediol dibenzoate compounds were synthesized in moderate to good yields through the coupling of aroyl chloride promoted by samarium diiodide under mild conditions.     

Reaction of Fluoro(phenyl)carbene with Schiff Bases: Synthesis of 2-Fluoro-2-phenylaziridines

Fluoro(phenyl)carbene generated by reaction of α-bromo-α-fluorotoluene with potassium tert-butoxide reacts with Schiff bases to afford the corresponding 2-fluoro-2-phenylaziridines. The latter were isolated in low yields due to their instability under the carbene generation conditions. Although the reaction of α,α-dibromo-α-fluorotoluene with zinc and lead involves formation of fluoro(phenyl)carbene, this procedure is not suitable for the synthesis of 2-fluoro-2-phenylaziridines.     

Reactivity of n-aryl-α, α-dichlorinated arylketimines

N-Aryl-α,α-dichloroalkylarylketimines are formed from N-aryl-alkylarylketimines with N-chloro succinimide in carbon tetrachloride. Reaction of N-1-(2,2-dichlor-1-arylpropylidene)anilines with sodium methoxide the latter compounds formally involves migration of the notrogen atom from the 1- to the 3-position. The reaction of higher substituted N-aryl-α,α-dichloroalkylarylketimines with sodium methoxide leads mainly to α-chloro-α,β-unsaturated ketones. In the case of long-chain α,α-dichloroketimines, a formal γ-functionalization was observed. The reaction mechanisms are discussed in detail.     

Electrolytic partial fluorination of organic compounds 84: Anodic mono- and difluorination of benzylphosphonate derivatives

Anodic fluorination of benzylphosphonate derivatives was carried out under various electrolytic conditions to provide the corresponding α-mono- and/or α,α-difluoro-products in moderate to good yields. It was found that the selectivity of fluorinated products was depending on the molecular structures of the starting substrates and the electrolytic conditions.     

Straightforward synthesis of alkynyl imines via 1,2-elimination of α,α-dichloroketimines

Alkylation of α,α-dichloroketimines at the α-position with benzyl bromides afforded β-arylated α,α-dichloroketimines in good yields. The latter imines could be easily transformed to the corresponding alkynyl imines, a synthetically important class of compounds, via 1,2-elimination of HCl upon treatment with 2 equiv of sodium hydride in DMSO or potassium tert-butoxide in THF.     

Synthesis of arylglycine and mandelic acid derivatives through carboxylations of α-amido and α-acetoxy stannanes with carbon dioxide

Incorporation reactions of carbon dioxide (CO(2)) with N-Boc-α-amido and α-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected α-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO(2) pressure. α-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO(2) pressure. Both transformations enabled the synthesis of α-tertiary and α-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-α-amido stannanes was transferred with up to 90% inversion of configuration at 100 °C.     

Photo-irradiation of α-halo carbonyl compounds: a novel synthesis of α-hydroxy- and α,α′-dihydroxyketones

The reaction of α-halo ketones (α-iodocycloalkanones, α-bromocycloalkanones, α-iodo-β-alkoxy esters, and α-iodoacyclicketones) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketones in good yields. For α-bromoketones, it was found that α-hydroxylation does not occur. However, α-bromoketones were converted into α-hydroxyketones in the presence of KI. In the case of α,α′-diiodo ketones, α,α′-dihydroxyketones, which up to now have scarcely been reported, were obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′-dihydroxyketones.     

The Sulfinatodehalogenation Reaction of α ,α -Difluorobenzyl Halides with Sodium Dithionite

The sulfinatodehalogenation reaction of α,α-difluorobenzyl halides, ArCF2X ( Ar = C6F5, C6H5; X = Br, I ), with sodium dithionite took place readily in aqueous acetonitrile under mild conditions, giving the corresponding sodium sulfinate. The 1:1 adducts were obtained when alkenes were added to the reaction system in some cases.     

Base-controlled reaction of α,β-unsaturated trifluoromethyl ketone and dialkyl phosphite

Base-controlled selective reactions of α,β-unsaturated trifluoromethyl ketones with dialkyl phosphites were achieved. In the presence of DABCO, the Pudovik reaction took place readily to give the corresponding α-hydroxy phosphonates in high yields under mild conditions. While using DBU as base, the Phospha-Brook rearrangement of α-hydroxy phosphonates formed in the reaction occurred to afford phosphates as final products.