Alkylation of C- and N-aminotriazoles with α-iodoketones

C- and N-Amino-1,2,4-triazoles react with 1-iodopropan-2-one in the absence of bases and phasetransfer catalysts (40°C, 9-12 h) to furnish 3-amino-1,4-bis(2-oxo-propyl)-4H-1,2,4-triazolium triiodide and 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium iodide. The alkylation of 1,2,4-triazol-4-amine with 1-iodopropan-2-one and 1,3-diiodopropan-2-one in the presence of elemental iodine led to the formation of 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium triiodide and 2-oxopropane-1,3-diylbis(4-amino-4H-1,2,4-triazolium) bis(triiodide). Triiodides are oily fluids possessing electric conductivity of 1.1 × 10^?3 Ω m^?1 opening the route to new types of electroconducting ionic liquids.     

A Practical Synthesis of β-Keto Phosphonates from Triethyl Phosphonoacetate

An efficient and practical preparation of β-keto phosphonates, via acylation reaction of triethyl phosphonoacetate with carboxylic acid chlorides in the presence of magnesium chloride-triethylamine followed by decarbethoxylation, is described.     

α-Enone by the Reaction of Aldehyde and α-Bromoketone with Tri-n-Butylstibine

α-Enones were readily obtained from the reaction of α-bromoketone with aldehydes mediated by tri-n-butylstibine.     

Palladium-Catalyzed Asymmetric Trifluoromethylated Allylic Alkylation of N-Substituted Glycine Ethyl Esters with α-(Trifluoromethyl)alkenyl Acetates

An efficient strategy for asymmetric trifluoromethylated allylic alkylation of easily available N-substituted glycine ethyl esters with α-(trifluoromethyl)alkenyl acetates has been developed. Catalyzed by a [Pd(C₃H₅)Cl]₂/(R)-BINAP, various trifluoromethyl-containing N-substituted glycine ethyl ester derivatives are afforded with good yields and excellent enantioselectivities. The product can be readily converted into diverse fluoro-substituted species, which shows the practicability of this method.     

Reactions of α,β-Dibromo-β-nitrostyrenes with Acetylacetone and Ethyl Acetoacetate

The reactions of ,-dibromo--nitrostyrenes with acetylacetone and ethyl acetoacetate were studied. The structures of the products were determined by ¹H NMR, IR, and UV spectroscopy. The products derived from acetylacetone were converted into copper chelates.     

Synthesis of 2-Oxazolines from Ethyl α-Cyanocinnamate Derivatives with Acetamide and N-Bromosuccinimide

An efficient method for the one-pot synthesis of 2-oxazolines from ethyl α-cyanocinnamate derivatives with acetamide and N-bromosuccinimide(NBS) in the presence of K₃PO₄ was developed. The reaction was performed smoothly and cleanly to give 2-oxazolines in good to excellent yields(up to 95%) in acetone at room temperature. Thirteen examples were investigated and the results indicated that a large range of α-cyanocinnamate derivatives could be suitable for this method. Based on the outcomes of experiment, a possible consecutive nucleophilic addition-cyclization pathway was proposed.     

Alkylation of 2-Sulfanylbenzoxazole with α-Iodoketones in the Absence of Bases

Reaction of 2-sulfanylbenzoxazole with 1-iodopropan-2-one, 2-iodo-1-phenylethanone, and 2-iodo-1-(thiophen-2-yl)ethanone without solvent and bases afforded bis(benzoxazol-2-yl)disulfonium derivatives in a single preparative stage. The reaction proceeds as a domino-process and includes the alkylation of a sulfanyl group of benzoxazole, the reduction of iodoketone with hydrogen iodide, the oxidation of 2-sulfanylbenzoxazole to disulfide, the alkylation of disulfide atoms of sulfur, and the formation of triiodideanions. The yield of disulfonium derivatives increases twice in the presence of equimolar amount of iodine.     

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.

     

Monofluoromethylation of Cyclic Sulfamidates and Sulfates with α-Fluorocarbanions of Fluorobis(phenylsulfonyl)methane and Ethyl 2-Fluoroacetoacetate

A regioselective fluoromethylation by ring-opening of cyclic sulfamidates and sulfates with α-fluorocarbanions and subsequent reductive desulfonylation is developed. Fluorobis(phenylsulfonyl)methane (FBSM) was explored as fluoromethide equivalent and the reaction was extended to the α-fluorocarbanion of ethyl 2-fluoroacetoacetate. This approach allows access to γ- and δ-fluoroamines as well as γ- and δ-fluoroalcohols in high yields.     

Alkylation of cyclododecanone with α,ω-dibromoalkanes under conditions of phase-transfer catalysis

Alkylation of cyclododecanone with ,-dibromoalkanes Br(CH) _n Br (n=3, 4, 5) under conditions of phase-transfer catalysis in the presence of KOH results in the formation of either bicyclic ketones forn=3 and 5 or a mixture of bicyclic and spirocyclic ketones forn=4.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1436–1438, August, 1994.     

Modified Wittig Reactions Using Triethylamine and Lithium Halides: Synthesis of α,β-Unsaturated Esters from Ketones and Ethyl Bis(Trifluoroethyl)Phosphonoacetate

A modified HWE reaction using triethylamine and lithium bromide with ethyl bis(trifluoroethyl)phosphonoacetate gives satisfactory yields of α,β-unsaturated esters from a variety of ketones.     

Tetrazoles: XLVI. Alkylation of 5-Substituted Tetrazoles with Methyl Chloromethyl Ether and α-Methylstyrene

Alkylation of 5-aryl(hetaryl)tetrazoles with methyl chloromethyl ether under conditions of phase-transfer catalysis leads to formation of isomeric 1- and 2-methoxymethyltetrazoles at a ratio of ~1 : 2. The reaction of 5-substituted tetrazoles with -methylstyrene in the presence of trichloroacetic acid gives the corresponding 2-(,-dimethylbenzyl)tetrazoles in high yield and with high regioselectivity.     

Diels-Alder Reactions of Ethyl α-Bromoacrylate with Open-chain Dienes——Synthesis of Ethyl 1,3-/1,4-Cyclohexadienecarboxylates

The Diels‐Alder reactions of ethyl α‐bromoacrylate 1 with open‐chain dienes 2 were conducted under thermal or Lewis acid‐catalysis conditions. In most cases, the cyclic adducts of 1‐bromocyclohex‐3‐enecarboxylates 3 were formed in high yields with good regio‐ and stereoselectivity. Subsequent E2‐elimination by treatment with DBU provided the corresponding 1,3‐ or 1,4‐cyclohexadienecarboxylates depending on the relative configuration of the products. Starting from myrcene (7‐methyl‐3‐methyleneocta‐1,6‐diene) the reaction sequence afforded the ester precursor of Georgywood with good yields.     

Studies of Birch Reductive Alkylation of Substituted α-Tetralones

A series of α-tetralones, with different degree of substitution, was submitted to the Birch reduction-alkylation procedure using various alkylating agents, to produce angularly substituted 1,4-unsaturated decalones. The stereoselectivity behavior of such dienones upon reduction is also described.     

An Efficient Synthetic Method to Nonnatural α- and β-Tryptophan Analogues via Friedel-Crafts Alkylation of Indoles with Nitroacrylates

The Friedel-Crafts alkylation of indoles with nitroacrylates could provide α- and β-tryptophan nitro-precursors, respectively, in moderate to good yields under Lewis acid catalysis. The diastereoselectivities of the reaction were enhanced by using 2-substituted indoles. The alkylation products could be easily transformed to nonnatural tryptophan derivatives.     

Reaction of nitroalkanes with levoglucosenone and its α-bromo and α-iodo derivatives. Cyclopentaannulation of α-halocyclenones

Michael reactions of levoglucosenone and its α-bromo and α-iodo derivatives with α,ω-dinitroalkanes were studied under conditions of chemical and electrochemical generation of base. Procedures were developed for stereospecific fusion of a cyclopentane ring to α-bromo- and α-iodolevoglucosenones, 2-iodocyclopent-2-en-1-one, and 2-iodocyclohex-2-en-1-one by the action of 2,2-dimethyl-1,3-dinitropropane.     

Dielectric Relaxation of Methyl Methacrylate and Ethyl Methacrylate on Complexation with Phenols

Dielectric absorption studies of H-bonded complexes of methyl methacrylate (MMA) and ethyl methacrylate (EMA) with p-cresol, p-chlorophenol, 2,4-dichlorophenol, and p-bromophenol were studied at microwave frequency 9.37 GHz in dilute solution of carbon tetrachloride at 308 K. Different dielectric parameters like dielectric constantε′ and dielectric loss ε″ at microwave frequency, static dielectric constant ε_0 and dielectric constant ε_∞ at optical frequency were determined. The validity of the single frequency equation of Higasi et al. for multiple relaxation time τ_(1) was found to be a function of the hydrogen bonding strength of phenolic hydrogen, whereas the group rotation relaxation time τ_(2) was a function of the steric interaction of proton donor. The relaxation time was the maximum at 50∶50 (molar ratio) of methacrylates with phenols.     

Generation of α-Boryl Radicals and Their Conjugate Addition to Enones: Transition-Metal-Free Alkylation of gem-Diborylalkanes

A transition-metal-free method for the alkylation of gem-diborylalkanes with α,β-unsaturated ketones has been developed. It is demonstrated that the α-boryl radicals can be generated efficiently from gem-diborylalkanes with the aid of catechol and oxidants. The α-boryl radicals formed through such process can be engaged in conjugate addition reaction with α,β-unsaturated ketones. This transformation is a straightforward method for the synthesis of γ-borylketones.     

Silver Fluoroborate Promoted Sulfur Alkylation of β-Silyl Ethyl Sulfides. Selective Synthesis of β-Thioglycosides

Silver (I) activation of α-glucosyl bromide in the presence of 2-trimethylsilylethyl sulfides as sulfur nucleophiles selectively provides β-thioglycosides.