Synthesis of novel dispiro-oxindoles via 1,3-dipolar cycloaddition reactions of azomethine ylides

The 1,3-dipolar cycloaddition of 1-allyl-5-haloisatin derivatives as dipolarophiles with the azomethine ylides generated in situ from N-allylisatin and l-proline to furnish novel dispiro-oxindoles has been investigated. The structures and relative stereochemistry of both types of cycloadducts were confirmed by single crystal X-ray diffraction, ¹H and ¹³C NMR spectroscopy and mass spectrometry.     

Synthesis of glucosylspiro-oxindole derivatives via one-pot three-component cycloaddition of azomethine ylides

Highly regio- and stereoselective synthesis of glucosylspiro-oxindole/acenaphthenone derivatives was accomplished through 1,3-dipolar cycloaddition (1,3-DC) reaction. The glucosyl α,β-unsaturated-7,3-lactone (a sugar lactone) derived from d-glucose was used as a chiral dipolarophile in 1,3-DC reaction for the first time. The azomethine ylides generated from sarcosine/l-proline/thiazolidine-4-carboxylic acid/piperidine-2-carboxylic acid with isatin and acenaphthoquinone were trapped by the sugar lactone to give a series of glucosylspiro-pyrrolidine derivatives in good yields.     

Asymmetric construction of trifluoromethylated pyrrolidines via Cu(I)-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with 4,4,4-trifluorocrotonates

Trifluoromethylated pyrrolidines have been synthesized via catalytic asymmetric 1,3-dipolar cycloaddition with excellent stereoselectivity for the first time. Epimerization of the endo-pyrrolidines obtained from cis-4,4,4-trifluorocrotonate into the exo-pyrrolidines was also revealed.     

1,3-Dipolar cycloaddition reactions of azomethine ylides and alkynes

Chemistry of Heterocyclic Compounds - In this review, we consider 1,3-dipolar cycloaddition reactions between azomethine ylides and alkynes, resulting in the formation of pyrroles, as well as their...     

1,3-Dipolar cycloaddition reactions of cyclooctyne with azomethine ylides

Cyclooctyne smoothly underwent 1,3-dipolar cycloaddition with aziridines and pyridinium ylides to afford the corresponding pyrroles and indolizines in moderate to good yields.     

1,3-dipolar cycloaddition reactions of porphyrins with azomethine ylides

[reaction: see text] The behavior of porphyrins as dipolarophiles in 1,3-dipolar cycloadditions with azomethine ylides was studied. Depending on the nature of the substituent groups on the porphyrin macrocycles, the reaction can give monoadducts (chlorins) or bisadducts (isobacteriochlorins and bacteriochlorins). When a large excess of azomethine ylide is used, trisadducts can also be obtained. Mixed isobacteriochlorin derivatives were prepared from the reaction of azomethine ylides with the chlorin monoadducts previously obtained via Diels-Alder reactions.     

亚甲胺叶立德参与的不对称1,3-偶极环加成构建含连续季碳中心的螺四氢吡咯衍生物

Cu(I)催化的亚甲胺叶立德和亚环丙基乙酸乙酯参与的不对称endo-1,3-偶极环加成反应,高效构建了多官能化、含有多个连续季碳中心的5-氮杂-[2,4]庚烷化合物.此反应具有广泛的底物适用性,α-取代的和α-非取代的亚甲胺叶立德和亚环丙基乙酸乙酯都能很好的参与反应,并以很高的产率、优秀的非对映选择性(95:5–98:2 d.r)和对映选择性(87%–98%ee)生成相应的在2,3,4位上含有连续季碳中心的螺四氢吡咯化合物.     

Asymmetric construction of substituted pyrrolidines via 1,3-dipolar cycloaddition of azomethine ylides and chiral acrylates derived from biomass

The first application of chiral auxiliaries synthesized from levoglucosenone (a biomass-derived anhydrosugar) in asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides is herein reported. The corresponding pyrrolidinic cores were obtained in excellent levels of regio and stereocontrol, good to excellent π-facial selectivities, and could be isolated enantiomerically pure by column chromatography. Unexpected NMR observations coupled with DFT calculations allowed the stereochemical assignment of the synthesized adducts. The stereochemical assignment performed in silico was further unambiguously validated by structural X-ray diffraction analysis.     

Synthesis of bioactive fluoropyrrolidines via copper(i)-catalysed asymmetric 1,3-dipolar cycloaddition of azomethine ylides

Chiral pyrrolidinyl units are important building blocks in biologically active natural products and drugs, and the development of efficient methods for the synthesis of diverse structured pyrrolidine derivatives is of great importance. Meanwhile, incorporating fluorine containing groups into small molecules often changes their activities to a great extent due to the special physicochemical properties of fluorine atoms. Herein, we report an efficient route to obtain enantioenriched 3,3-difluoro- and 3,3,4-trifluoropyrrolidinyl derivatives by Cu(i)-catalysed enantioselective 1,3-dipolar cycloaddition of azomethine ylides with less active 1,1-difluoro- and 1,1,2-trifluorostyrenes. A series of new fluorinated pyrrolidines have been prepared in high yields (up to 96%) and with excellent stereoselectivities (up to >20 : 1 dr and 97% ee), and these unique structural blocks could be readily introduced into some natural compounds and pharmaceuticals. Additionally, antifungal activity investigation against four common plant fungi showed that some products possess general and high biological activities; comparison with the low antifungal activities of corresponding nonfluorinated compounds revealed that the fluorine atoms at the pyrrolidinyl rings play a crucial role in the antifungal activity.

Chiral fluoropyrrolidines were synthesized by Cu(i)-catalyzed enantioselective 1,3-dipolar cycloaddition of azomethine ylides with less active fluorinated styrenes, with broad substrate scope and high yield, stereoselectivity and biological activity.     

A new chiral phosphine oxide ligand for enantioselective 1,3-dipolar cycloaddition reactions of azomethine ylides

A new set of phosphorus-containing chiral ligands has been synthesized and used with silver(I) for the catalytic asymmetric 1,3-dipolar cycloaddition reaction of azomethine ylides. One of these ligands (POFAM6) was found to produce an effective catalyst for the asymmetric 1,3-dipolar cycloaddition reaction of azomethine ylides with electron deficient dipolarophiles to form pyrrolidines in up to 97% yield and 89% ee.     

1,3-Dipolar cycloadditions of azomethine ylides with dipolarophiles. II. Synthesis of pyrrolizidines

Substituted pyrrolizidines have been synthesized by 1,3-dipolar cycloaddition of various dipolarophiles with the azomethine ylide generated by treatment of proline with benzaldehyde in dimethylsulfoxide. The regio- and stereochemical outcome of the reaction as well as the stability of the isomers obtained are discussed.     

Diastereoselective synthesis of pyrrolidines via 1,3-dipolar cycloaddition of a chiral azomethine ylide

1,3-Dipolar cycloaddition of d-glucose-derived azomethine ylides for the synthesis of chiral pyrrolidines accompanied an unexpected 1,2-elimination in the furanose moiety of the products. The C3′ alkoxy/hydroxy group of the furanose moiety was invariably eliminated under the reaction conditions. Also, in contrast to the previous reports, moderate to good exo-diastereoselectivity was observed in the reaction products.     

Organocatalytic enantioselective (3+2) cycloaddition using stable azomethine ylides

We have developed a highly efficient procedure for carrying out the catalytic enantioselective (3+2) cycloaddition between enals and stable azomethine ylides such as isoquinolinium and phthalizinium methylides. Under the optimized reaction conditions highly substituted chiral pyrroloisoquinolines and pyrrolophthalazines have been obtained in high yields and excellent diastereo- and enantioselectivities.     

Synthesis of new enantiomerically pure spirooxindolopyrrolizidines via a three-component asymmetric 1,3-dipolar cycloaddition reaction of azomethine ylides derived from isatin

An efficient, one-pot, three-component procedure for the synthesis of a small library of new chiral spirooxindolopyrrolizidines with high regio-, diastereo-, and enantioselectivity, from the 1,3-dipolar cycloaddition of azomethine ylides and optically active cinnamoyl oxazolidinone is described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the absence of any Lewis acids. The oxazolidinone chiral auxiliary is removed in a non-destructive manner. The reaction mechanism is discussed on the basis of the assignment of the absolute configuration of the cycloadducts, and on theoretical calculations.     

Cu(I)/DTBM-BIPHEP-catalyzed exo-selective 1,3-dipolar cycloaddition of azomethine ylides with cis-trifluorocrotonate for asymmetric construction of trifluoromethylated pyrrolidines

A direct and facile access to highly substituted exo-pyrrolidines bearing a unique trifluoromethyl group is developed via Cu(I)/DTBM-BIPHEP-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with cis-4,4,4-trifluorocrotonate for the first time.     

Highly enantioselective copper(I)-fesulphos-catalyzed 1,3-dipolar cycloaddition of azomethine ylides

The catalyst system formed by Cu(CH3CN)4ClO4 and the planar chiral P,S-ligand Fesulphos behaves as a very efficient chiral Lewis acid in the catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides. This catalyst shows a remarkable reactivity at low catalyst loading (0.5-3 mol %), affording in good yields the endo adducts with exceptional levels of enantioselectivity (up to >99% ee). This catalytic asymmetric procedure has a broad structural scope with regard to both azomethine and dipolarophile substitution. The first examples of catalytic asymmetric 1,3-dipolar cycloaddition with ketimine-derived azomethines are reported.     

Synthesis of indazole-N-oxides via the 1,7-electrocyclization of azomethine ylides

The first examples of the 1,7-electrocyclization of azomethine ylides onto a nitro group, to give benz-1,2,6-oxadiazepine intermediates are reported. Subsequent ring contraction results in the formation of indazole-N-oxides.     

Asymmetric synthesis of spirocyclohexanone-pyrrolidine via AgI-catalysed asymmetric 1,3-dipolar cycloaddition of azomethine ylides

Cinchonine was effectively used in an AgOAc-catalysed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with 2,6-bis(arylmethylidene) cyclohexanones, affording spiropyrrolidine derivatives with excellent yields (up to 99%), diastereoselectivities (up to 96:04 dr), and enantioselectivities (up to 99% ee).     

Axially chiral BINIM and Ni(II)-catalyzed highly enantioselective 1,3-dipolar cycloaddition reactions of azomethine ylides and N-arylmaleimides

Axially chiral BINIM-Ni(II) complexes are effective catalysts in the asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides and N-arylmaleimides to give the corresponding adducts in good yields and up to 95% enantiomeric excesses.