Reactions of α-aminoazoles with diethyl benzylidenemalonate

Cyclocondensations of diethyl benzylidenemalonate with 3-amino-5-methylpyrazole, 3,5-diamino-1,2,4-triazole, 3,4,5-triamino-1,2,4-triazole, and 2-amino-benzimidazole in alcohols take a single route and lead to the formation of functionally substituted partially hydrogenated pyrazolo-, triazolo[1,5-a]-pyrimidin-5-ones and pyrimido[1,2-a]benzimidazol-2-one respectively. From reaction mixtures involving 3-amino-1,2,4-triazole and its 5-methylsulfanyl analog in methanol the intermediate products of heterocyclization were isolated forming as a result of alkylation with the β-carbon of the unsaturated ester the endocyclic nucleophilic sites of aminoazoles. The structure of one among the products obtained, diethyl(3-amino-5-methylsulfanyl-1,2,4-triazol-2-yl)benzylmalonate was proved by X-ray crystallography. In DMF the same reagents yielded mixtures of partially hydrogenated triazolo[1,5-a]pyrimidin-5-ones.     

Reactions of 4-oxobenz[1,3-e]oxazinium perchlorates with α-aminoazoles

Reactions of 4-oxo benz[1,3-e]oxazinium perchlorates with 1-R¹-3-R²-5-aminopyrazoles lead to the formation of derivatives of pyrazolo[3,4-d]pyrimidine and pyrazolo[1,5-a]1,3,5]triazine series, and with 3-amino-1,2,4-triazole, to [1,2,4]triazolo[1,5-a][1,3,5]triazines.     

Reactions of α-nitroacrylates with thiophenols

Reactions of α-nitroacrylates with aromatic thiols like 4-methyl- and 4-chlorothiophenols afford a series of new 3-arylsulfanyl-2-nitropropanoates. The latter were isolated as diastereomerically pure substances or mixtures of two diastereomers. Structures of the obtained S-adducts were confirmed by IR, ¹H and ¹³C-{¹H} NMR spectroscopy using HMQC and HMBC experiments.     

Reactions of α-halonitrosoalkanes with resorcinol

-Halonitrosoalkanes react with resorcinol as nitrosylating agents to form 3-hydroxy-N-(2,4-dihydroxyphenyl)-1,4-quinone imine.Translated fromIzvestiya Akademioi Nauk. Seriya Khimicheskaya, No. 3, pp.773–774, March, 1996.     

Reactions of CF3-substituted boranes with α-diazocarbonyl compounds

Boranes substituted with a CF₃-group can be generated from methyl boronic esters RB(OMe)₂ and Me₃SiCF₃/KF followed by treatment with Me₃SiCl. These boranes are stable only in coordinating solvents, and due to the increased Lewis acidity of boron, react rapidly with α-diazocarbonyl compounds to give the products of transfer of the organic group from boron. Alkyl, aryl, vinyl, and alkynyl boronic esters can be used in this reaction.     

Reactions of cyclic α-methoxy nitrones with nucleophilic reagents

Reactions of cyclic -methoxy nitrones, which are derivatives of imidazole or dihydroimidazole N-oxides, with amines, KOH, or KSH result in the replacement of the MeO group to form cyclic -amino nitrones, hydroxamic acids, or thiohydroxamic acids, respectively. Analogous reactions occur with C-nucleophiles.     

Reactions of Phosphorodiamidous Acid Esters with α-Halocarbonyl Compounds

Reactions of ethyl and tert-butyl phosphorodiamidites with chloroacetone, bromoacetone, and -chloroethyl acetate were studied. The reaction pathway is determined by the structure of the intermediate quasiphosphonium compound responsible for the formation of the Arbuzov product as well as for the occurrence of the amonalous reaction yielding vinyl phosphate.     

Reactions of Lithium Acylates α-Carbanions with 1,2-Diiodoethane

Russian Journal of General Chemistry - The interaction of lithium acylates α-carbanions (obtained via metallation of acetic, butyric, and isobutyric acids with lithium diisopropylamide) with...     

Reactions of α-aminoazoles with (2<Emphasis Type="Italic">E</Emphasis>)-3-phenylacryloyl chloride

Reaction of 5-amino-3-methylpyrazole, 3-amino-, 5-amino-3-methylsulfanyl-1,2,4-triazole and 5-amino-1,2,4-triazole-3-thione with 3-phenylacryloyl-chloride under mild conditions is characterized by low selectivity and does not lead to the formation of fused heterocyclic systems but gives mixtures of products of mono- and diacylation of the nucleophilic sites in the molecules of α-aminoazoles. Endocyclic monoacyl derivatives of aminotriazoles in DMF undergo a transacylation at the exo-amino-group followed by cyclization into dihydro-1,2,4-triazolo[1,5-a]-pyrimidin-5-ones.     

Reactions of α-fluorine-containing β-functionalized vinyl sulfides with N-nucleophiles

-Fluorine-containing -functionalized vinyl sulfides readily react with N-nucleophiles to form -fluorine-substituted products. The reactions with phenylhydrazines and amidines of acids are accompanied by cyclization at the functional group. Thermal cyclization of cyanotrifluoromethylketene N,S-acetals proceeds at the trifluoromethyl group to give substituted 3-cyanoquinolin-4-ones.     

Reactions of α-chloro β-oxo aldehydes with CH-acid anions

The reactions of α-chloro and α,α-dichloro β-oxo aldehydes with carbanions are accompanied by the cleavage of the carbon-carbon bond in the chloro aldehydes and result in formylation of CH-acids. These electrophiles react with carbanions, which are generatedin situ from CH-acids in the presence of AcONa in aprotic solvents, to form polyfunctional hydroxy compounds.     

Reactions of organometallics with oximes. Synthesis of α-N-hydroxy amino acids

Reaction of organolithium reagents with glyoxylate and pyruvate derived oximes provides a direct route for the synthesis of unusual α-N-hydroxy amino acids.     

Effects of Phosphorus Substituents on Reactions of α-Alkoxyphosphonium Salts with Nucleophiles

The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph(3) P with Grignard reagents was observed to take place in the presence of O(2) to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments.     

Effects of Phosphorus Substituents on Reactions of α-Alkoxyphosphonium Salts with Nucleophiles

The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph₃P with Grignard reagents was observed to take place in the presence of O₂ to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments.     

Low-Temperature Reactions of α-Bromopropanoyl Chloride with Lithium Derivative of Ethyl Acetate

The reaction of 2-bromopropanoyl chloride with lithium ethyl acetate generated in situ by the reaction of equimolar amounts of lithium diisopropylamide with ethyl acetate forms, depending on the conditions (temperature, time, reagent ratio), diethyl 2,2′-(3-methyloxirane-2,2-diyl)diacetate, 2,2-dibromo-N,N-diisopropylpropanamide, and ethyl (5-methyl-4-oxo-4,5-dihydrofuran-2-yl)acetate as minor by-products along with the expected acylation product ethyl 4-bromo-3-oxopentanoate. The reaction with 2 or 5 equiv of lithium ethyl acetate (–78°C → –20°C) gave, together with the mentioned α-bromo ester, ethyl (5-methyl-4-oxo-4,5-dihydrofuran-2-yl)acetate formed as a result of transformations of the adduct of the second LiCH₂CO₂Et molecule and ethyl-4-bromo-3-oxopentanoate. The reaction 2-bromopropanoyl chloride with sodium malonic ester involves acylation of enol form of the primary expected acylation product to afford dimethyl |2-bromo-1-[(2-bromopropanoyl)oxy]propylidene-malonate.

     

Reactions of α-Sulfenyl-N-anions at the Nitrogen Atom. Reactions of N-Substituted Arenesulfenamide Sodium Salts with Isocyanates

N-Arylsulfonylarenesulfenamide sodium salts react with isocyanates in acetone to give N-arylsul- fonyl-N-arylsulfenyl-N'-substituted urea sodium salts which are converted into the corresponding ureas by the action of mineral acids.     

Reactions of β-Sulfinyl α,β-Unsaturated Ketones with Dienes

β-Sulfinyl α,β-unsaturated ketones (2a-f) reacted in a regioselective manner with dienes such as butadiene (3a) and 1,3-pentadiene (3b) to give 1,4-cyclohexadiene derivatives (4-8) with the concomitant elimination of sulfenic acid, while the ketones (2a-c) reacted with cyclopentadiene (3c) to yield the norbornenes (9).     

Reactions of α-nitrocinnamic acids esters with indole and its derivatives

Reactions of α-nitrocinnamic acids esters with indole and its derivatives lead to the formation of the products of alkylation at the C₃-reaction center of the heterocycle. The hydrogenation of the adduct of 1-methylindole and α-nitro-β-phenylacrylate on the Raney nickel catalyst afforded indolylaminopropanoate, that was used for the synthesis of ethyl 2-acetylamino-3-(1-methylindol-3-yl)-3-phenylpropanoate, a precursor of the methylated in the indole ring phenyl-substituted tryptophan.