Synthesis of 4-polyfluoroalkyl-1,3-dithiolanes via [3+2] cycloaddition of thiocarbonyl ylide to polyfluoroalkanethioamides

Chemistry of Heterocyclic Compounds - New 4-polyfluoroalkyl-1,3-dithiolanes were synthesized by reaction of polyfluoroalkanethioamides with thiocarbonyl ylide that was generated in situ by...     

Mechanism and stereoselectivity of the stepwise 1,3-dipolar cycloadditions between a thiocarbonyl ylide and electron-deficient dipolarophiles: a computational investigation

The 1,3-dipolar cycloadditions of a thiocarbonyl ylide to dimethyl 2,3-dicyanofumarate and 2,3-dicyanomaleate have been studied with DFT computations. The first C-C bond is formed via an anti attack to produce a very polar, zwitterionic diradical. The low stereoselectivity of the reaction was found to arise from rotations about single bonds in the intermediates that compete with cyclization. A distortion-interaction energy analysis was performed to compare the stepwise and concerted mechanisms, and to explain why the stepwise mechanism is favored in this unusual case.     

Synthesis of 4′-thionucleosides by 1,3-dipolar cycloadditions of the simplest thiocarbonyl ylide with alkenes bearing electron-withdrawing groups

Reactions of the simplest thiocarbonyl ylide with a variety of appropriate alkenes bearing electron-withdrawing substituents afforded the corresponding tetrahydrothiophenes, which could be easily elaborated into hydroxy and hydroxymethyl derivatives and then coupled with nucleobases to produce different 4′-thionucleosides. Particularly, α- and β-anomers of 1-[3,4-bis(hydroxymethyl)tetrahydro-2-thienyl]-thymine, -cytosine, -uracil and -fluorouracil were prepared with dimethyl fumarate and maleate, while 1-[4-(hydroxymethyl)tetrahydro-2-thienyl]- and 1-[4-(hydroxymethyl)tetrahydro-3-thienyl]-thymine, -cytosine, -uracil and -fluorouracil were prepared with a chiral α,β-unsaturated amide. These processes, simple in the experimental conditions and large availability of the starting materials, affording moderate to good yields of 4′-thionucleosides, represent an optimum alternative to those, already known, based on sugars, which often have the drawbacks of a higher number of steps and lower yields.     

New reaction of thiocarbonyl ylides. Interaction ofS-alkyl-N,N-dimethylthiobenzimidium salts with activated acetylene derivatives leading to (E,E)-divinyl sulfides

The reaction of thiocarbonyl ylides with activated acetylene derivatives gives (E,E)-divinyl sulfides in good yields. The reaction mechanism is discussed and evidence in favor of the formation of a thiirane intermediate is presented. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 791–795, April, 1997.     

New reaction of pyridinium ylide with 2,4,6‐trinitrofluorobenzene leading to stable heptatrienide moiety

A new reaction of pyridinium ylide ( 4 ) with 2,4,6‐trinitrofluorobenzene leading to stable negatively charged heptatriene moiety ( 6 ) is described. This reaction proceeds via a new route of decomposition of intermediate σ‐complex ( 5 ) occurring with the formation of ethylfluoroformate. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:421–424, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20315     

Dipolar 1,3-cycloaddition reaction of conjugated nitrones

Conclusions Some new isoxazolidines were synthesized by the 1,3-dipolar cycloaddition reactions of conjugated nitrones (–CH=CH–CH=N0) with activated dipolarophiles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 908–910, April, 1974.     

Synthesis and fragmentation-condensation reaction of 1,3-diethoxycarbonylallylidenetriphenylphosphononium ylide

Alkylidenephosphonium ylides with ethoxycarbonyl substituents in the α-position fragment in a $\text{retro}$-Michael fashion during condensation with aldehydes.     

AOT-based microemulsions accelerate the 1,3-cycloaddition of benzonitrile oxide to N-ethylmaleimide

We studied the 1,3-dipolar cycloaddition of benzonitrile oxide to N-ethylmaleimide in AOT/isooctane/water microemulsions at 25.0 degrees C and found the reaction rate to be roughly 150 and 35 times greater than that in isooctane and pure water, respectively. The accelerating effect of the microemulsion is the combined result of an increase in the local concentrations of the reactants through incorporation into the interface and of the intrinsic rate of the process through electrostatic interactions with the headgroups in the surfactant.     

Synthesis of spiropyrrolidinyl-benzoisothiazoline derivatives by 1,3-dipolar cycloaddition of benzoisothiazole-2,2-dioxide-3-ylidenes and azomethine ylide

The new spirocyclic compounds, spiropyrrolidinyl-benzoisothiazoline derivatives were synthesized by the 1,3-dipolar cycloaddition of benzoisothiazole-2,2-dioxide-3-ylidenes and azomethine ylide. The stereochemistry of 1,3-dipolar cycloaddition as well as the stereochemistry of Knoevenagel condensation of benzoisothiazole-2,2-dioxide with aldehydes were studied.     

Correlation between catalytic cyclopropanation and ylide generation

A linear correlation for catalytic effectiveness exists between cyclopropanation of n-butyl vinyl ether and ylide generation with allyl methyl sulfide in reactions with ethyl diazoacetate. Twenty-two representative transition metal compounds have been examined, and ruthenium is identified for the first time to exhibit catalytic potential comparable to copper and rhodium catalysts for carbene transformations.     

Effects of strong π-electron accepting substituents on structure preference for thiocarbonyl ylide or thiirane

Equilibrium between thiocarbonyl ylide and thiirane depends upon the π-electron accepting nature of the substituents. Four carbonyl and ester groups move the equilibrium far to the thiocarbonyl ylide side.     

A new approach to 2,2-disubstituted 1-(methylsulfanyl)vinyl phosphonates via an intermediate thiocarbonyl ylide

The reaction of methyl (diethylphosphoryl)dithioformate (6) with diaryldiazomethanes 7a-d in THF at −60 °C to room temperature followed by desulfurization is shown to be a convenient method for the preparation of 2,2-disubstituted 1-(methylsulfanyl)vinyl phosphonates 8a-d. The analogous reactions with 2-diazoacenaphthen-1-one (7f) or 2-diazocamphor (7g) in refluxing THF yield selectively the corresponding (Z)- and (E)-vinyl phosphonates 8f and 8g, respectively. These products can be easily oxidized to the vinylsulfoxides 13 and vinylsulfones 14. On the other hand, methyl (diethylphosphoryl)dithioformate (6) and 2-diazo-1,2-diphenylethanone (7e) in boiling THF react to give the 1,3-oxathiole 12. All these reactions occur via an intermediate thiocarbonyl ylide 11 followed by 1,3-dipolar electrocyclization and sulfur extrusion or 1,5-dipolar electrocyclization.     

Synthesis of thiocarbonyl and heterocyclic compounds from 2-methylene-1,3-dithietanes

2-Methyl-1,3-dithietanes bearing electron withdrawing groups on the methylene carbon atom were synthesized and their reactivities were studied. These compounds readily underwent a ring-opening reaction with a variety of nucleophic reagents such as amines, alcoholate and thiolate anions to yield thioamides, thionoesters and dithioesters, respectively. The products were applied for synthesis of heterocycles such as thiadiazoles, isothiazolones and pyrazoles.     

有机碲Ylide反应XII用碲Ylide合成双环丙烷衍生物

由相应的碲盐生成的某些碲ylide, 能顺利地和1, 4-双(3-取代苯基-3-酮-1-丙烯基)苯, 1, 5-二取代苯基-1, 4-戊二烯-3-酮反应生成双环丙烷衍生物, 反应具有高立体选择性, 产率为61.8-88.8%。     

A novel reaction cascade leading to a spontaneous intramolecular dipolar cycloaddition through simultaneous generation of 1,3-dipole and dipolarophile

Ornithine methyl ester reacts with aromatic aldehydes to generate bis-Schiff bases, which depending on the structure of the aromatic aldehyde, further undergo an intramolecular cycloaddition through the transient formation of a reactive 1,3-dipole.