Search results for "3-Dipolar"

Regioselective Synthesis of Mono- and Dispiropyrazoline Derivatives via 1,3-dipolar Cycloaddition with Nitrilimines

2016

The 1,3-dipolar cycloaddition reaction of (E,E)-1,3-bis(arylidene)indan-2-one with diarylnitrilimines, generated in situ via dehydrohalogenation of the corresponding hydrazonoyl chlorides , affords predominantly monospiropyrazolines and as a mixture of diastereoisomers. Also dispiropyrazolines are formed in moderate yields. The structure and stereochemistry of cycloadducts were confirmed by 1H and 13C-NMR spectroscopy, elemental analyses data, and single-crystal X-ray diffraction studies of and .

PdII-mediated integration of isocyanides and azide ions might proceed via formal 1,3-dipolar cycloaddition between RNC ligands and uncomplexed azide

2016

Reaction between equimolar amounts of trans-[PdCl(PPh3)2(CNR)][BF4] (R = t-Bu 1, Xyl 2) and diisopropylammonium azide 3 gives the tetrazolate trans-[PdCl(PPh3)2(N4t-Bu)] (67%, 4) or trans-[PdCl(PPh3)2(N4Xyl)] (72%, 5) complexes. 4 and 5 were characterized by elemental analyses (C, H, N), HRESI+-MS, 1H and 13C{1H} NMR spectroscopies. In addition, the structure of 4 was elucidated by a single-crystal X-ray diffraction. DFT calculations showed that the mechanism for the formal cycloaddition (CA) of N3− to trans-[PdCl(PH3)2(CNMe)]+ is stepwise. The process is both kinetically and thermodynamically favorable and occurs via the formation of an acyclic NNNCN-intermediate. The second step of the fo…

Synthesis of Isoxazole and 1,2,3-Triazole Isoindole Derivatives via Silver- and Copper-Catalyzed 1,3-Dipolar Cycloaddition Reaction.

2016

International audience; The CuI-or Ag 2 CO 3-catalyzed [3+2] cycloaddition of propargyl-substituted dihydroisoindolin-1-one (3) with arylnitrile oxides 1a-d (Ar = Ph, p-MeC 6 H 4 , p-MeOC 6 H 4 , p-ClC 6 H 4) produces in good yields novel 3,5-disubstituted isoxazoles 4 of the ethyl-2-benzyl-3-oxo-1-((3-arylisoxazol-5yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylate type. With aryl azides 2a-d (Ar = Ph, p-MeC 6 H 4 , p-OMeC 6 H 4 , p-ClC 6 H 4), a series of 1,4-disubstituted 1,2,3-triazoles 6 (ethyl-2-benzyl-3-oxo-1-((1-aryl-1H-1,2,3-triazol-4-yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylates) was obtained. The reactions proceed in a regioselective manner affording exclusively racemic adduc…

Synthesis and characterization of new 1,4 and 1,5-disubstituted glucopyranosyl 1,2,3-triazole by 1,3-dipolar cycloaddition

2009

Abstract A series of 1,4 and 1,5-disubstituted 1-(β- d -glucopyranosyl)-1,2,3-triazoles has been prepared in an efficient manner with excellent yields using the intermolecular 1,3-dipolar cycloaddition of 1-azido-2,3,4,6-tetra-O-acetyl-β- d -glucopyranose 2 to a variety of substituted alkynes phenylacethylene 3, propargyl alcohol 4, 2-butyn-1,4-diol, 5, 3-propargylbenzimidazole 6 and propargylpyrazole 7 in toluene. The reaction takes place with the formation of both 4- and 5-regioisomers.

1,3-Dipolar cycloadditions in the synthesis of annelated diazines: design of new scaffolds for anticancer and antimicrobial agents

2008

Pyrazolo[3,4-d][1,2,3]triazolo[1,5-a]pyrimidine: a new ring system through Dimroth rearrangement

2008

Abstract Derivatives of the new ring system pyrazolo[3,4- d ][1,2,3]triazolo[1,5- a ]pyrimidine were synthesized from the corresponding angular isomers, through a Dimroth rearrangement, in quantitative yields. Preliminary computational studies demonstrated that this class of compounds could be a good candidate as DNA intercalating agents.

Reactions of the hydrofluoroborate salts of open-chain analogues of Reissert compounds with some α,β-ethylenic esters

1999

The reaction of the hydrofluoroborate salt of an open-chain analogue of a Reissert compound with some α,β-ethylenic esters does not give a [4 + 2] cycloadduct, as previously described in the case of ethyl acrylate. The reaction starts with a 1,3-dipolar cycloaddition of a munchnone imine 5c, d. The [3 + 2] cycloadducts 13 evolve via a rearrangement–condensation sequence to give a substituted 2-pyridone derivative 18 or 19. The proposed mechanism has been verified by the isolation and structural X-ray analysis of some compounds of the reaction sequence.

1,3-Dipolar Cycloaddition Reactions of Indan-1-one Enamines across Arylnitrile Oxides Leading to Novel Cyclic Isoxazoline Derivatives

2013

Synthesis of a series of cyclic fused-isoxazolines has been accomplished by regioselective and diastereoselective 1,3-dipolar cycloaddition of 3-methylindan-1-one enamines (1a, 1b, 1c) and 3-phenylindan-1-one enamines (2a, 2b, 2c) to arylnitrile oxides (3d, 3e, 3f, 3g, 3h). The structure of the cycloadducts was elucidated by 1H and 13C NMR spectroscopy. The proposed regio- and stereochemistry of fused-compounds (4) and (5) has also been corroborated by two single-crystal X-ray diffraction studies carried out on 4-methyl-8b-morpholinyl-3-(p-tolyl)-4H-3a,8b-dihydroindeno[2,3-d]isoxazoline (4be) and 3-(p-anisyl)-4-phenyl-8b-pyrrolidinyl-4H-3a,8b-dihydroindeno[2,3-d]isoxazoline (5af) and by mea…

[1,2,3]Triazolo[1,5-a]piridinas y compuestos relacionados : aplicaciones en química supramolecular : actividad biológica

2013

Los heterociclos nitrogenados son moléculas clave dentro de numerosos campos científicos. En concreto, los triazoles han encontrado numerosas aplicaciones en química médica como antifúngicos (fluconazol, posaconazol), antidepresivos (trazodona) o anticancerígenos (triazoloacridonas). En este contexto se decidió sintetizar nuevos derivados de [1,2,3]triazolo[1,5-a]piridinas con el fin de explorar su capacidad de interaccionar con ADN y su actividad leishmanicida y antichagásica. Con este objetivo se ha utilizado la química clásica de las triazolopiridinas (reacción de litiación regioselectiva de este heterociclo, seguida de adición de un electrófilo), para obtener nuevos derivados con estruc…

Synthesis, characterization and X-ray structure of glycosyl-1,2-isoxazoles and glycosyl-1,2-isoxazolines prepared via 1,3-dipolar cycloaddition

2013

Abstract A convenient preparative method of a series of glycosyl-1,2-isoxazoles ( 6–11 ) and glycosyl-1,2-isoxazolines ( 15–20 ) by a simple and efficient 1,3-dipolar cycloaddition of a series of aryl nitrile oxide, generated in situ from aryl oximes ( 4–5 ), with a variety of O -propargyl glycosyles ( 1 – 3 ) or O -allyl glycosyles ( 12–14 ) respectively, is reported. The carbohydrate-containing 1,2-isoxazoles and 1,2-isoxazolines compounds were isolated in excellent yields (81–91%) and they were fully characterized by 1 H, 13 C NMR and mass spectrometry. The relative stereochemistry of the glycosyl-1,2-isoxazole 10 was confirmed by single crystal X-ray analysis. The molecular structure of…