Studies on New Additions to 5-Methoxy-2 (5H)-Furanone: 1, 4-Addition of Grignard Reagents, and 1,3-Dipolar Cycloaddition of Silyl Nitronates

1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of preparing fused heterocyclic compounds was offered by 1,3-dipolar cycloaddition reaction of silyl nitronates to 1.

Synthesis of Novel Discotic C_(60)-triphenylene Derivative by 1,3-Dipolar Cycloaddition

1 Introduction Fullerene has received considerable attention and a great researching interest due to its unique structure and interesting properties[1―3]. Many functional groups have been introduced, often region- or stereo-selectively, for tuning the physical properties of C60and for constructing supramoleculararchitectures^[4-6].

Asymmetric 1,3-Dipolar Cycloaddition of the Chiral Nitronic Esters with Acrylate

Asymmetric 1,3-dipolar cycloaddihon of the chiral nitronic esters with acrylate giving the enantiomerically pure novel chiral bisheterocyclic compounds is describcd

1,3-Dipolar Cycloaddition Reaction between Vinyl Acetate and N-Alkyl Hydroxypyridinium Halide

1, 3 Dipolar cycloaddition reaction between vinyl acetate and 3-hydroxypyridiniun betaine was performed under solid-liquid phase transfer catalytic condition, This reaction has been successfully used on the synthesis of an analogue of Bao-Gong-Teng A.

ASYMMETRIC 1,3-DIPOLAR CYCLOADDITION REACTION BY A CHIRAL SOURCE,5-(1-MENTHYLOXY)-2(5-H)-FURANONE

5-(1-Menthyloxy)-2(5-H)-furanone is used as s chiral dipolarophile for thermal asymmetric 1,3-dipolar cycloaddition reaction with C-phenyl-N-phenyl nitrone to give the diastereomerically pure cycloaddition product.

A FACILE SYNTHESIS OF 2-TRIFLUOROMETHYLPYRROLE VIA 1,3-DIPOLAR CYCLOADDITION REACTION OF 2-TRIFLUOROMETHYLOXAZOLONE AND THE ACTIVATED CARBON-CARBON MULTIPLE BOND

The 1.3-dipolar cycloaddition reaction of 2-trifluoromethyl- oxazolone and the activated carbon-carbon multiple bond was studied and gave a convenient way to synthesize 2-trifluoromethylpyrrole derivatives.

An expeditious synthesis of isoxazoline using cetyltrimethylammonium cerium nitrate:A phase transferring oxidative 1,3-dipolar cycloaddition

An expeditious and effective method for synthesis of isoxazoline from aldoximes and activated alkenes using cetyltrimethylammonium cerium nitrate at room temperature is described.Reaction was completed within short time period in high yields at room temperature.

Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides withβ-trifluoromethyl-substituted alkenyl heteroarenes

Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo-and regioselectivity(up to 99%yield,>20:1 rr,>20:1 dr,and up to 95%ee).Notably,substratecontrolled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis withα-aryl substituted aldimine esters as the dipole precursors.Systematic DFT studies were conducted to explore the origin of the stereo-and regioselectivity of this 1,3-dipolar cycloaddition,and suggest that copper(Ⅱ)salt utilized in this catalytic system could be reduced in-situ to the active copper(Ⅰ)species and might be responsible for the observed high stereo-and regioselectivity.

Synthesis and thermal properties of novel calix[4]arene derivatives containing 1,2,3-triazole moiety via K_2CO_3-catalyzed 1,3-dipolar cycloaddition reaction

Two calix[4]arene derivatives containing 1,2,3-triazole moiety were synthesized via K2CO3-catalyzed1,3-dipolar cycloaddition reaction between calix[4]arene-based azide and active methylene compounds in good yields.The structures of the two compounds synthesized herein were fully confirmed by 1HNMR,,（13）C NMR,and MS（ESI）.The thermal analysis showed that the mass losses of the synthesized compounds 4 and 5 containing 1,2,3-triazole groups are similar to each other.

Synthesis of novel N-pyridylpyrazole derivatives containing 1,2,4-oxadiazole moiety via 1,3-dipolar cycloaddition and their structures and biological activities

A series of novel 1,2,4-oxadiazole-containing N-pyridylpyrazole derivatives 12 a-h were efficiently synthesized with pivaldehyde,pyridylpyrazole carboxylic acid and arylamine as raw materials via 1,3-dipolar cycloaddition.Their structures were identified by melting points,1 H NMR,13 C NMR and elemental analysis or HRMS.The exploration on the single-crystal structures of 12 c and 12 g revealed the stereochemical and substituent oriental characteristics,and the relevance of the structure and the reaction activity of this type of compounds.The preliminary bioassays indicated that several compounds had good insecticidal activities,among which 12 c showed a lethality rate of 80%towards Mythimna separata Walker at 200μg/mL;some of the compounds exhibited favorable fungicidal activities at 50μg/mL against Physalospora piricola,Rhizoctonia cereal,Sclerotinia sclerotiorum,etc.Among which,12 a,12 b,12 c and 12 h could be considered as new fungicidal leading compounds for further structural optimization.These discoveries along with the structure-activity relationship analysis in this paper will provide useful guidance for the innovative studies on new pyridylpyrazole derivatives and their applications in agrochemical area.

A Facile Access to Fluorinated Pyrrolidines via Catalytic Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Ylides with Methyl a-Fluoroacrylate

Asymmetric 1,3-dipolar cycloaddition of methyl a-fluoroacrylate with azomethine ylides for the construction of optically active fluorinated pyrrolidines bearing one unique fluorinated quaternary and two tertiary stereogenic cen- ters has been achieved with Cu（CH3CN）4BF4/TF-BiphamPhos complexes for the first time. This catalytic system performs well over a broad scope of substrates, providing the synthetically useful adducts in good yields and excel- lent diastereoselectivities and good to high enantioselectivities.

Solvent-free 1,3-Dipolar Cycloaddition of Azomethine Imines with Terminal Alkynes Promoted by Calcium Fluoride Under the Ball Milling Condition

A convenient and efficient procedure for the synthesis ofN, N-bicyclic pyrazolidinone derivatives has been developed via the reaction of azomethine imines with terminal alkynes under the ball milling condition without sol- vent, which was promoted by calcium fluoride with a catalyst of copper（I） salt. The cyclization reactions exhibited moderate to high yields.

The Chemistry of Tetrafluoroallene:One-pot Synthesis of Trifluoromethylindolizines from 1,3-Diiodo-1,1,3,3-tetrafluoropropane by 1,3-Dipolar Cycloaddition

Heating a mixture of 1, 3-diiodo-1 ,1,3, 3-tetrafluoropropane (2), K2CO3, pyridinium bromides (3) in CH3CN at 65℃ for 10 h gives the corresponding trifluoromethylindolizines.

Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides: Efficient access to chiral pyrrolidine-3-sulfonyl fluorides

Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide range of chiral pyrrolidine-3-sulfonyl fluorides with good to excellent results(up to 87% yield,>20:1 dr, 94% ee). Some other chiral sulfonyl derivatives, such as sulfonamide and sulfonate, were easily accessible through simple transformations with high yields, which demonstrated that the cycloaddition products could be synthetically useful in the sulfur(VI) fluoride exchange(Su FEx) chemistry.

Synthesis of Novel Fuctionalized Glycosides Based on 1,3-Dipolar Cycloaddition

1 Results 1,3-Dipolar cycloaddition reaction is one of the most common methods for preparing various five membered heterocycles,and provides a conveniet protocols for constructing C-C bond with functional groups.The reaction has also been successfully used in the syntheses of C-glycosides and other sacharride derivatives.We wish to present herein our recent approaches on the synthesis of novel C-amino-glycosides,C-aminodisaccharides,spiro heterocyclic glycosides and heterocycle linked C-disaccharides,et...

Stereoconvergent and stepwise 1,3-dipolar cycloadditions of nitrile oxides and nitrile imines

The first example of stereoconvergent 1,3-dipolar cycloaddition of nitrile oxides and nitrile imines with E/Z isomeric mixture of electron-deficient olefins is reported,delivering isoxazolines and pyrazolines bearing two vicinal stereogenic tertiary and trifluoromethylated quaternary carbon centers with perfect regioand diastereoselectivities.The possibility of concerted cycloaddition/epimerization sequence under basic condition to form the thermodynamically stable diastereomers is excluded through some control experiments and DFT calculations,and a stepwise mechanism is proposed.

Asymmetric catalytic 1,3-dipolar cycloaddition ofα-diazoesters for synthesis of 1-pyrazoline-based spirochromanones and beyond

A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97%yield,98%ee with>95:5 dr).Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switchingα-substituted diazoesters toα-diazoacetates.The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well.

Soluble Polymer-Supported Synthesis of Pyrazoles via 1,3-Dipolar Cycloaddition Strategy

Rapid parallel liquid-phase synthesis of pyrazoles has first been developed. The 1,3-dipolar cycloaddition be-tween nitrilimines generated in situ and soluble polymer-supported alkynyl or alkenyl dipolarophiles in parallel one-pot fashion gave the corresponding PEG-supported regioisomeric pyrazoles or regiospecific pyrazolines. The latter was assuredly oxidated by DDQ to PEG-supported regiospecific pyrazoles. Cleavage from the support under mild conditions afforded pyrazoles in good yields and high purity.

1,3-Dipolar cycloaddition for selective synthesis of functionalized spiro[indoline-3,3’-pyrrolizines]

The 1,3-dipolar cycloaddition reaction of dimethyl hex-2-en-4-ynedioate with azomethine ylides derived from reaction of L-proline with various isatins in methanol selectively resulted in the formation of functionalized spiro[indoline-3,3’-pyrrolizine]acrylates as main products and spiro[indoline-3,3’-pyrrolizine]propiolates as minor products.This result indicated that the electron-deficient alkyne has higher reactivity than that of electron-deficient alkene in 1,3-dipolar cycloaddition reaction.

Design, Synthesis and Properties of Novel C60-Crown Dyads by 1,3-Dipolar Cycloaddition

Based on the 1,3-dipolar cycloaddition of azomethine ylide generated in situ from aldehyde and sarcosine attached to C60,two novel benzo-15-crown-5/C60 dyads with a different linking chain in each were designed and synthesized in yields of 30％ and 38％,respectively.It was found that their UV-Vis absorption spectra could be regulated hypsochromically by metal ions complexed.The long and soft linking chain was favorable for cooperate interaction of crown ether unit and C60 unit.