Nucleophilic properties of a nonstabilized azomethine ylide derived from sarcosine and cyclohexanone. A novel domino reaction leading to substituted 4-aryl-2-pyrrolidones

A nonstabilized asymmetric azomethine ylide derived from sarcosine and cyclohexanone reacts with 3-substituted coumarins and ethyl benzylidene malonate to give 4-aryl-2-pyrrolidones in moderate yields, and the adducts of classical 1,3-dipolar cycloadditions as the minor products. The main reaction proceeds via a domino process, starting with 1,4-nucleophilic addition to the conjugated double bond, and represents the first example of the nucleophilic properties of a nonstabilized azomethine ylide.     

Nonstabilized azomethine ylides in the synthesis of aryl cucurbitine derivatives

Nonstabilized azomethine ylides react with 4-arylidene-2-phenyloxazol-5(4H)-ones to form diazaspiro[4.4]nonenes, which were hydrolyzed to aryl cucurbitine derivatives in 35–67% overall yield.     

亚甲胺叶立德参与的[3＋2]环加成反应的最新进展

综述了亚甲胺叶立德的制备、它参与的[3＋2]环加成反应的反应机理、反应选择性及在天然产物全合成中的应用等方面的最新进展.     

Cyclocondensation between fatty acid hydrazides and 1,1,1-trifluoro-4-alkoxy-3-alken-2-ones: Introducing a trifluoromethylated head onto fatty acid moieties

This paper reports the regioselective synthesis of new trifluoromethylated lipid derivatives, namely, 1-(5-hydroxy-5-trifluoromethyl-3-alkyl-4,5-dihydro-1H-pyrazol-1-yl)alkan-1-ones, through cyclocondensation reactions between a series of fatty hydrazides (palmitoyl, stearoyl, and oleoyl hydrazides) obtained from fatty acids from renewable resources (1,1,1-trifluoro-4-alkoxy-3-alken-2-ones [F₃CC(O)CH?C(R¹)OR, where R¹?=?H and R?Et; R¹?=?–(CH₂)₆CH₃, –(CH₂)₆CH₃, –(CH₂)₈CH₃, –(CH₂)₉CH₃, –(CH₂)₁₀CH₃, –(CH₂)₁₂CH₃, –(CH₂)₂Ph], and R?Me). Experimental observations showed that the lipophilic characteristic of 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-pyrazoles (5–7) prevent the acid catalyzed dehydration to aromatization of 1H-pyrazole ring, although in some cyclocondensations a proportion of the aromatic derivative 1-(5-trifluoromethyl-3-alkyl-1H-pyrazol-1-yl)alkan-1-one was obtained. All products were characterized using multinuclear (¹H, ¹³C, ¹⁹F) NMR spectroscopy.     

Synthesis and Structure Elucidation of Novel Spirooxindole Linked to Ferrocene and Triazole Systems via [3 + 2] Cycloaddition Reaction

In the present work, a novel heterocyclic hybrid of a spirooxindole system was synthesized via the attachment of ferrocene and triazole motifs into an azomethine ylide by [3 + 2] cycloaddition reaction protocol. The X-ray structure of the heterocyclic hybrid (1″R,2″S,3R)-2″-(1-(3-chloro-4-fluorophenyl)-5-methyl-1H-1,2,3-triazole-4-carbonyl)-5-methyl-1″-(ferrocin-2-yl)-1″,2″,5″,6″,7″,7a″-hexahydrospiro[indoline-3,3″-pyrrolizin]-2-one revealed very well the expected structure, by using different analytical tools (FTIR and NMR spectroscopy). It crystallized in the triclinic-crystal system and the P-1-space group. The unit cell parameters are a = 9.1442(2) Å, b = 12.0872(3) Å, c = 14.1223(4) Å, α = 102.1700(10)°, β = 97.4190(10)°, γ = 99.1600(10)°, and V = 1484.81(7) ų. There are two molecules per unit cell and one formula unit per asymmetric unit. Hirshfeld analysis was used to study the molecular packing of the heterocyclic hybrid. H···H (50.8%), H···C (14.2%), Cl···H (8.9%), O···H (7.3%), and N···H (5.1%) are the most dominant intermolecular contacts in the crystal structure. O···H, N···H, H···C, F···H, F···C, and O···O are the only contacts that have the characteristic features of short and significant interactions. AIM study indicated predominant covalent characters for the Fe–C interactions. Also, the electron density (ρ(r)) at the bond critical point correlated inversely with the Fe–C distances.     

Oligonucleotides containing arylacetylene residues: Synthesis and post-synthetic modification via [3+2] cycloaddition

The synthesis of a phosphoramidite reagent for 5′-modification of oligonucleotides by introducing an arylacetylene residue has been described. Using the reaction with 3-(perylen-3-yl)propyl azide as an example, it was shown that the acetylene derivatives of oligonucleotides synthesized using this reagent undergo Cu^I-catalyzed [3+2] dipolar cycloaddition. Fluorescent conjugates were obtained in high yields and characterized by mass spectra. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1220–1226, July, 2006.     

Synthesis of 2-azaspiro[4.4]nonan-1-ones via phosphine-catalysed [3+2]-cycloadditions

The phosphine-catalyzed [3+2]-cycloaddition of the 2-methylene γ-lactams 4 and 5 and the acrylate 6 with the ylides derived from the ethyl ester, the amide or the chiral camphor sultam derivative of 2-butynoic acid (7a-c) give directly, or indirectly after reductive cyclization, spiro-heterocyclic products. The acid 32 underwent Curtius rearrangement and then acid hydrolysis to give two novel spiro-cyclic ketones, 41 and 42.     

Total Synthesis of Proposed Structure of Yuremamine and All Diastereomers Using [3+2]‐Cycloaddition of Platinum‐Containing Azomethine Ylide

Total synthesis of the proposed structure of yuremamine has been achieved for the first time based on the intermolecular [3+2]‐cycloaddition reaction of the platinum‐containing azomethine ylide. All the possible diastereomers of yuremamine were also synthesized via the common intermediate. Through these syntheses, it was confirmed that the proposed structure of yuremamine and the diastereomers differ from the natural product.     

Synthesis and unusual [2+2]-cycloaddition reactions of ethyl 4-chloro-2-oxobut-3-ynoate with unactivated alkenes

The highly activated acetylenes, ethyl 4-chloro-2-oxobut-3-ynoate and ethyl 4-bromo-2-oxobut-3-ynoate, were prepared from readily available bis(trimethylstannyl)acetylene in two steps with high overall yield. An unusual ability of the former to furnish [2+2]-cycloadducts with 1,1-disubstituted alkenes in the absence of irradiation and catalysts was discovered. The cycloaddition of ethyl 4-chloro-2-oxobut-3-ynoate to the 1,2-disubstituted alkenes was shown to be effectively catalyzed with stannic chloride.     

One-pot synthesis of dihydroquinazolinethione-based polycyclic system

A one-pot and diastereoselective synthesis of quinazoline-2(1H)-thione-containing polycyclic compounds is introduced. The reaction process includes [3?+?2] cycloaddition of azomethine ylides for pyrrolidines, Staudinger-aza-Wittig reaction of azides for iminophosphoranes, formation of isothiocyanates, and finally cyclization of amines to isothiocyanates for dihydroquinazolinethiones.     

[3+2]‐Cycloaddition for Fully Decorated Vinyl‐1,2,3‐Triazoles: Design,Synthesis and Applications

The s mall heterocyclic ring of the 1,2,3‐triazole module is one of the most widely investigated compounds in numerous applications of biological, medicinal, pharmaceutical and materially important molecules. In this regard, a large number of synthetic methodologies and approaches have already been reported to construct such a heterocyclic core structure in a selective manner. However, the vinyl‐substituted 1,2,3‐triazole moiety is another privileged segment in heterocyclic chemistry. The selective introduction of simple vinyl and functionalized vinyl groups onto the three different positions of the 1,2,3‐triazole framework can significantly improve the properties of the molecule. Accordingly, high‐yielding efficient approaches for the selective construction of vinyl‐containing 1,2,3‐triazoles becomes a promising branch of chemistry among practitioners of industry and academia. In this minireview, we have discussed recent advances in the construction of highly selective three different vinyl‐containing 1,2,3‐triazoles. In addition, representative synthetic methodologies and approaches for the corresponding three different classes of vinyl‐1,2,3‐triazoles and their applications have been described as well in this review.     

Synthesis and structure of 1,3-dialkyl-4-(sulfonylimino)imidazolidin-2-ones

The reactions of 1,3-dialkyl-4,5-dihydroxyimidazolidin-2-ones with alkyl sulfamides have been studied and previously undescribed 1,3-dialkyl-4-(alkylaminosulfonylimino)imidazolidin-2-ones have been obtained. The structure of 1,3-dimethyl-4-(benzenesulfonylimino)imidazolidin-2-one was investigated by X-ray structural analysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1159–1166, August, 2007.     

3-Cyanochromones in [3+2] cycloadditions with an azomethine ylide derived from sarcosine and formaldehyde. A short synthesis of 1-benzopyrano[2,3-c:3,4-c′]dipyrrolidines

Reactions of 3-cyanochromones with sarcosine and paraformaldehyde proceed diastereoselectively to give 1-benzopyrano[2,3-c]pyrrolidines and tetrahydro-1H-spiro[chromeno[2,3-c]pyrrol-9,5′-oxazolidine]-9a-carbonitriles, depending on the reactant ratio, as a result of a 1,3-dipolar cycloaddition of the intermediate nonstabilized azomethine ylide at the double bond and carbonyl group of the chromone system. The latter undergoes demethylenation and recyclization into a novel hexahydrochromeno[2,3-c:3,4-c′]dipyrrole tetracyclic system on heating with hydrochloric acid.     

Synthesis of unsaturated silyl nitronates via the silylation of conjugated nitroalkenes

A new method for the synthesis of conjugated silyl nitronates from nitroalkenes is described. The procedure has wide substrate scope and is compatible with in situ generation of the substrates from 2-nitroalcohols or 2-chloro-nitroalkanes. A cascade transformation to give 3,4,5,6-tetrahydropyridine N-oxide derivatives was disclosed.     

由N-苯基[1,3]苯并噁嗪正离子与烯烃[4+2]反应合成喹啉并[1,2-c][1,3]苯并噁嗪-6-酮衍生物

以BF3·OEt2 为催化剂, 在室温下通过4-羟基-N-苯基[1,3]苯并噁嗪-2-酮的脱羟基产生N-苯基[1,3]苯并噁嗪正离子, 然后与富电子烯烃发生Diels-Alder反应, 合成出了一系列喹啉并[1,2-c][1,3]苯并噁嗪-6-酮和喹啉并[1,2-c][1,3]萘并噁嗪-6-酮衍生物.     

Reaction of 4-Methylene-1,3-dioxolan-2-ones with Hydrazines

The structure of the products of the reaction of 4-methylene-1,3-dioxolan-2-ones with hydrazines is a function of the structure of the starting hydrazine. 1,3,4-Oxadiazin-2-one derivatives are obtained from hydrazine hydrate. 3-Arylaminooxazolidin-2-ones are obtained from monoarylhydrazines, while mixtures of these derivatives are obtained from aliphatic monoalkylhydrazines.     

Catalytic Asymmetric [2, 3]－Sigmatropic Rearrangement of Sulfur Ylides Generated from Carbenoids and Allenic 2－Methylphenyl Sulfide

The first investigation on catalytic asymmetric [2,3]-sigmatropic rearrangement of sulfur ylides generated from carbenoids and allenic phenyl sulfide was carried out. Up to 55% ee value was obtained.     

Synthesis and Complexing Ability of Azacrownophanes: The Cyclodextrin Catalysis of the Photochemical Cyclization Reaction

Azacrownophanes were efficiently prepared by the irradiation of precursor ammonium chlorides in the presence of -CD (-cyclodextrin) in aqueous solution, by repressing the amino group-quenching effect by inclusion of the styrene moieties in -CD. In liquid–liquid extraction, azacrownophanes (6 and 7) showed affinity toward both Ag⁺ and Pb²⁺ cations in a series of heavy metal nitrates. Both 6 and 7 formed 1:1 complexes with the above two cations, according to ¹³C NMR titration and ESI-MS analysis.     

A simple two-step synthesis of 2-(alkylamino)-1-arylethanols,including racemic adrenaline,from aromatic aldehydes via 5-aryloxazolidines

Benzaldehydes react smoothly with nonstabilized azomethine ylides, generated in situ from sarcosine/formaldehyde or N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine, to give 5-aryloxazolidines as intermediates. These were converted into 2-(alkylamino)-1-arylethanols in good yields by simple heating in methanol with hydrochloric acid, or by treatment with hydrazine hydrate in ethanol.     

6-Aryl-2,2-dimethyl-1,3-dioxin-4-ones: Synthesis and Chemical Characteristics. (Review)

Methods for the production of 6-aryl-2,2-dimethyl-1,3-dioxin-4-ones and their thermolysis in the presence of nucleophiles and dienophiles are discussed