1,3-Dipolar Cycloaddition of 5-Substituted-1-Methyl-3-Oxidopyridiniums

5-Methoxy- and 5-dimethylamino-1-methyl-3-oxidopyridiniums were shown to give the 1,3-dipolar cycloadducts widely with methyl acrylate, acrylonitrile, N-phenylmaleimide, styrene, phenylacetylene, cyclopentadiene, cyclopentene, diethyl azodicarboxylate and singlet oxygen.     

Chemo- and Regioselective 1,3-Dipolar Cycloaddition of 2-Diazopropane over 1,4-Benzoquinone: Synthesis of New Pyrazoloquinones

Abstract

1,3-Dipolar cycloaddition reaction of 2-diazopropane 1 with 1,4-benzoquinone 2 carried out at ?20 °C led to a minor mono-cycloadduct 4 and mixture of bis-cycloadducts 6 and 7. The same addition realized with 3H-pyrazole 7 at ?60 °C for 2 h yields a mixture of compounds 8 and 9 and results in O-alkylation. The reaction of 3H-pyrazoles 4 and 7 with dimethylsulfoxide and oxalyl chloride under Swern conditions led to pyrazolenines 11 and 12.     

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.     

Three-Component Synthesis and 1,3-Dipolar Cycloaddition of Highly Functionalized Pyrans with Nitrile Oxides: Easy Access to 1,2,4-Oxadiazoles

Three-component reaction of 1-[(4-chlorophenyl)sulfanyl]acetone, malononitrile, and substituted aromatic aldehydes in the presence of sodium ethoxide under simple mixing at ambient temperature for 5–8 min afforded highly functionalized 4H-pyrans in good to excellent yields. 1,3-Dipolar cycloaddition of nitrile oxides over the nitrile functionality of the 4H-pyrans furnished 1,2,4-oxadiazoles in moderate yields.

Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for full experimental and spectral details.     

Stereoselectivity in the 1,3-dipolar cycloaddition of nitrones to 1-substituted 3,3-methylene-5,5-dimethyl-2-pyrrolidinones

Summary The stereoselectivity of the nitrone cycloaddition with 1-substituted 3,3-methylene-5,5-dimethyl-2-pyrrolidinones1 is discussed. C,N-Diarylnitrones give mixtures of diastereomeric spirocycloadducts3 and4, in which3 always dominates. In contrast, N-methylnitrones react under the formation of4 as major products. Cycloaddition of C-benzoyl nitrones7 with1 affords exclusively single isoxazolidines8. Semi-empirical quantum mechanical methods (AM1) were used to rationalize the regio- and stereoselectivity of the reactions.

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Stereoselektivität der 1,3-dipolaren Cycloaddition von Nitronen an 1-substituierte 3,3-Methylen-5,5-dimethyl-2-pyrrolidinone

Zusammenfassung Die Stereoselektivität der Cycloaddition von Nitronen mit 1-substituierten 3,3-Methylen-5,5-dimethyl-pyrrolidinonen (1) wird diskutiert. C,N-Diarylnitrone ergeben Mischungen der diastereomeren Spirocycloaddukte3 und4, wobei3 immer überwiegt. Im Gegensatz dazu entsteht bei der Reaktion von N-Methylnitronen4 als Hauptprodukt. Die Cycloaddition von C-Benzoylnitronen (7) mit1 liefert ausschließlich Isoxazolidine vom Typ8. Zum besseren Verständnis der Regio- und Stereoselektivität der Reaktionen wurden semiempirische quantenmechanische Berechnungen (AM1) durchgeführt.

     

Diastereoselective Synthesis of 1,10-Dihydropyrrolo [ 1,2-a] [1,10]phenanthroline Derivatives via 1,3-Dipolar Cycloaddition Reaction

The functionalized 1,10-dihydropyrrolo[1,2-a][1,10]phenanthroline derivatives were synthesized in good yields and with high diastereoselectivity by 1,3-dipolar cycloaddition reactions of N-phenacylphenanthrolinium bromides or N-ethoxycarbonylmethylene phenanthrolinium bromide with various nitrostyrenes in acetonitrile at room temperature in the presence of triethvlamine,     

Asymmetric Synthesis of Tetrahydroisoquinoline Derivatives through 1,3-Dipolar Cycloaddition of C,N-Cyclic Azomethine Imines with Allyl Alkyl Ketones

A [3 + 2] 1,3-Dipolar cycloaddition of C,N-cyclic azomethine imines with allyl alkyl ketones has been achieved. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. An array of tetrahydroisoquinoline derivatives is generally constructed with good diastereoselectivities and enantioselectivities (up to >25:1 dr, >95% ee). Moreover, the absolute configuration of the product was previously determined by using the quantum electronic circular dichroism calculation and ECD spectrum method.     

Synthesis of Novel Discotic C60-triphenylene Derivative by 1, 3-Dipolar Cycloaddition

1 IntroductionFullerene 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 C60 and for constructing supramolecular architectures[4-6].Among all kinds of C60 derivatives,the diseotic molecule-substituted C60 derivatives show interesting properties,especially,liquid crystal properties.Up to now,few C60 derivatives with discotic-molecular groups and their liquid crystal properties have been studied.In 1996,Deschenaux et al.[7]reported the first mesomorphic C60-ferrocene derivative.Tian et al.[8]synthesized a C60-perylene derivative in 2004.Nakanishi et al.[9]prepared a series of uncommon liquid C60derivatives with 2,4,6-tris(alkyloxy)benzal groups in 2006.Lately,Geerts et al.[10]described the synthesis of mesogenic phthalocyanine-C60.     

1,3-偶极环加成合成双-1,2,4-噁二唑啉衍生物及单晶结构

2-苯基-1,2,3-三唑基-4-甲醛与1,3-丙二胺或对苯二胺缩合, 形成新的双席夫碱3和4, 然后分别与氯代肟在三乙胺条件下发生1,3-偶极环加成, 得到新型双-1,2,4-噁二唑衍生物6a～6f和7a～7f. 结构经元素分析, IR, 1H NMR和MS确证, 并用X射线衍射法测定了化合物6e的晶体结构. 化合物6e属于单斜晶系, C2/c空间群, 晶胞参数 a＝3.5134(8) nm, b＝0.50575(11) nm, c＝2.0598(5) nm, α＝90°, β＝102.02(8)°, γ＝90°, Mr＝756.81, V＝3.5798(14) nm3, Dc＝1.404 g/cm3, Z＝4, F(000)＝1576, μ＝0.095 mm－1, R＝0.0787, wR＝0.2093.     

ConjugatedSchiff's bases, 19 Cycloaddition of heterocumulenes to sterically congested 1,4-diazabutadiene 4N-oxides

Reactions of aryl isocyanates with sterically congested 1,4-diazabutadiene 4N-oxides representing bifunctional nitrones, proved to be 1,3-dipolar cycloadditions in which the nitrone 1,3-dipol manifested its predominant reactivity in comparison with the 1,4-diazabutadiene system. 3-Substituted 5-oxadiazolidinones resulted from these cycloadditions. Acidic hydrolysis of these products was also investigated.

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Konjugierte Schiff-Basen, 19. Mitt.: Cycloaddition von Heterokumulene an sterisch gehinderten 1,4-Diazabutadien-4N-oxiden

Zusammenfassung Die Reaktionen von Arylisocyanaten mit sterisch gehinderten 1,4-Diazabutadien-4N-oxiden als Vertretern bifunktioneller Nitrone erwies sich als eine 1,3-dipolare Cycloaddition, bei der sich der Nitron-1,3-Dipol in seiner Reaktivität im Vergleich mit dem 1,4-Diazabutadiensystem bevorzugt zeigte. Es wurden bei diesen Cycloadditionen 3-substituierte 5-Oxadiazolidinone erhalten. Die saure Hydrolyse dieser Produkte wurde ebenfalls untersucht.

     

Synthesis of Novel Spiro Pyrrolidine and Pyrrolizine Derivatives by 1,3-Dipolar Cycloaddition

The 1,3‐dipolar cycloaddition of azomethine ylides derived from isatin and amino acids viz. sarcosine and proline to 2‐arylmethylidene‐5,6‐dihydroimidazo[2,1‐b]thiazol‐3(2H)‐ones afforded novel spiro pyrrolidines and pyrrolizidines regio‐ and stereoselectively in moderate yields. The products were characterized thoroughly by IR, MS, NMR together with elementary analysis.     

One-Pot Tandem Synthesis of Tetrasubstituted Pyrazoles via 1,3-Dipolar Cycloaddition Between Aryl Hydrazones and Ethyl But-2-ynoate

1,3,4,5-Tetrasubstituted pyrazoles are rapidly and regioselectively synthesized in a one-pot, three-step sequence consisting of condensation, nitrilimine generation, and cycloaddition using mercuric acetate. Newly synthesized compounds were characterized by spectral studies. Regiochemistry of compounds 6a and 8a was determined as 1,4- and 1,5-regioisomers respectively by X-ray crystallography.     

Synthesis of 5-Fluoroalkyl Isoxazolidines via 1,3-Dipolar Cycloaddition of Ethyl 2-Hydropolyfluoroalk-2-enoates with Nitrones

1,3-Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were described. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at room temperature to give the corresponding 5-fluoroalkylisoxazolidines regioselectively as a mixture of two diastereoisomers (trans and cis) in high yields, while longer reaction time and higher temperature were needed in the case of non-cyclic nitrones. Under similar conditions the reaction of quinoline N-oxide (14) with 1 did not give the expected adducts and a ring-opening product was obtained.     

Regio- and stereoselectivity in the 1,3-dipolar cycloaddition of C,N-diarylnitrones to 3,3-methylene-5,5-dimethyl-2-pyrrolidinone

Summary Regio- and stereoselectivity of the nitrone cycloaddition with 3,3-methylene-5,5-dimethyl-2-pyrrolidinone ((1) is discussed. Nitrones react regioselectively with1 to give a mixture of diastereoisomeric spiro-cycloadducts3 and4, in which3 always dominates. Both3 and4 result from the approach which binds the carbon of the nitrone with the exocyclic carbon of1 and the oxygen to the spiro carbon. The structure and steric configuration of the adducts have been assigned on the basis of¹H- and¹³C-NMR spectroscopy, mainly by nuclear Overhauser effect difference spectroscopy. AM1 calculations of the reactants were performed, the regio- and stereochemistry of the cycloaddition seems to be controlled by steric effects.

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Regio- und Stereoselektivität bei der 1,3-dipolaren Cycloaddition von C,N-Diarylnitronen an 3,3-Methylen-5,5-dimethyl-2-pyrolidinon

Zusammenfassung Es wird die Regio- und Stereoselektivität der Cycloaddition von Nitronen an 3,3-Methylen-5,5-dimethyl-2-pyrolidinon (1) diskutiert. Nitrone reagieren mit1 regioselektiv zu einer Mischung von diastereomeren Spirocycloaddukten3 und4, wobei3 stets dominierend ist. Sowohl3 als auch4 resultieren aus der gleichen Reaktionsanordnung unter Bindung des Nitron-Kohlenstoffatoms an das exocyclische Kohlenstoffatom von1 und des Sauerstoffatoms an den Spiro-Kohlenstoff. Die Stereochemie der Addukte wurde auf Basis von¹H- und¹³C-NMR-Spektroskopie, insbesondere aus Differenz-Nuclear-Overhauser-Messungen, abgeleitet. Es wurden auch AM1-Rechnungen durchgeführt. Die Regio- und Stereochemie der Cycloaddition scheint von sterischen Effekten bestimmt zu sein.

     

Facile One-Pot Synthesis of Ferrocene-Based Spiropyrrolidines and Pyrrolizidines Through 1,3-Dipolar Cycloaddition Reaction

A facile and efficient synthesis of ferrocene-based spiroacenaphthenone pyrrolidines and pyrrolizidines through a one-pot, three component 1,3-dipolar cycloaddition reaction is described.     

Synthesis of Novel Dispiro 1,4-Benzothiazine Hybrid Heterocycles Through 1,3-Dipolar Cycloaddition

The 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the reaction of acenaphthylene-1,2-dione or isatins and α-amino acids to (E)-methyl/ethyl 2-(3-oxo-3,4-dihydro-2H-benzo[b][1,4]thiazin-2-ylidene)acetate led to the stereoselective formation of novel dispiro 1,4-benzothiazine hybrid heterocycles in good yields.     

微波促进的葡萄糖烯与硝酮的1,3-偶极环加成反应

在微波辐射下, 葡萄糖烯(1)与硝酮2环加成反应的效率大大提到, 在乙二醇二甲醚溶液中, 200 ℃封管反应2 min, 环加成反应产物的收率可高达96%, 而且反应的立体选择性无明显变化. 利用环加成产物可进一步合成各种含官能团的碳糖苷衍生物, 找到了一种合成碳糖苷衍生物中间体的简便有效方法.     

含氮Ylide对C_(60)的1,3-偶极环加成反应法合成含吡咯环C_(60)衍生物

利用肌氨酸与对位含不同取代基的苯甲醛、共轭烯烃醛类及酮类反应生成的含氮Ylide对C60的加成反应，合成并分离、纯化制得了一系列含不同取代基的C60吡咯环纯衍生物，并用1HNMR、13CNMR、FDMS、FT－IR、UV－Vis等光谱手段确定了它们的分子结构．     

1,3-Dipolar cycloaddition route to novel isoxazole-type derivatives related to combretastatin A-4

A series of compounds related to combretastatin A-4, containing a five-membered heterocyclic ring interposed between the two phenyl groups have been prepared. Synthetic approach involves 1,3-dipolar cycloaddition of various 3,4,5-trimethoxyphenyl units with an in situ generated nitrile oxide from a suitable aldoxime using sodium hypochlorite. Depending on the nature of the dipolarophile, 3,5-diarylisoxazole derivatives were obtained along with the 3,4-regioisomeric isomers.