1,3-Dipolar cycloaddition reactions of 2-(2′-thienyl)aziridines

Lown, J. W.; Matsumoto, Kazuo

doi:10.1139/v70-570

Cited by 22 publications

(11 citation statements)

References 8 publications

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“…It is noteworthy that in the experiments involving deuterium labelled aziridines in acetonitrile in this study, quantitative transfer of the deuterium was often observed. This is in contrast to previous work in nonpolar solvents where appreciable leakage of deuterium label was observed (10,(13)(14)(15)(16).…”

Section: Ch Chcontrasting

confidence: 99%

Thermal Decomposition of Stereoisomeric 3-Aroyl- and 3-Carbomethoxyaziridines in Acetonitrile

Lown¹,

Akhtar²

1972

Can. J. Chem.

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The thermal decomposition of I-alkyl-3-benzoyl-2-(m-nitrophenyl)aziridines in dry acetonitrile results in a series of autocatalytic hydrolytic cleavages, 1,3-dipolar additions, condensations, and rearrangements to give products including oxazolidines, 1,2-dihydropyrazines, pyrrolo-[3,4-4-4-oxazolines, and a-aminoketones.The marked differences in product type and distribution from cis-and trans-aziridines are ascribed to preferential hydrolytic opening at the aziridinium ion stage. Complete equilibration of the stereoisomeric azomethine ylides takes place prior to 1,3-dipolar additions.Thermal decomposition of cis-and trans-methyl I-isopropyl-2-(m-nitrophenyl)aziridine-3-carboxyates in acetonitrile is not autocatalytic (and can be suppressed) and produces three stereoisomeric oxazolidines in identical yields and ratios, and methyl N-isopropylglycine by selective hydrolytic attack at the 2-aziridine position. This result is ascribed to equilibration of the stereoisomeric aziridines prior to hydrolytic cleavage by adventitious moisture only.La decomposition thermique des alkyl-l benzoyl-3 m-nitrophknyl-2 aziridines dans I'acttonitrile sec conduit a une strie de clivages hydrolytiques autocatalysts, d'additions dipolaires-1,3, de condensations et de rearrangements donnant des produits comprenant des oxazolidines, des dihydro-1,2 pyrazines, des pyrroles[3,4-dl oxazolines-4 et des a-aminodtones. Les differences notables dans le type de produit et leur distribution A partir des aziridines cis et trans sont attribuees a I'ouverture prkferentielle par hydrolyse au stade de I'ion aziridinium. L'kquilibration compltte des ylures azomkthine stertoisomtres se fait avant les additions dipolaires-1,3. La decomposition thermique des carboxylates d'isopropyl-l m-nitrophknyl-2 aziridine-3 de mkthyle cis et trans, n'est pas autocatalytique (et peut &re supprimke) et conduit trois oxazolidines stireoisomtres dans des rapports et des rendements identiques et a la mtthyl-N-isopropylglycine par hydrolyse selective sur la position-2 de I'aziridine. Ce resultat est attribue a I'tquilibration des aziridines st6reoisomtres avant clivage par hydrolyse causte seulement par une humiditt accidentelle.

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Section: Ch Chcontrasting

confidence: 99%

Thermal Decomposition of Stereoisomeric 3-Aroyl- and 3-Carbomethoxyaziridines in Acetonitrile

Lown¹,

Akhtar²

1972

Can. J. Chem.

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“…A welldocumented drawback of this method is that this type of unstabilized azomethine ylide does not readily undergo cycloaddition with unactivated dipolarophiles. 6 Pyrrolidines whose requisite alkenes were unreactive under the acid-catalyzed conditions required a different preparation. A survey of the chemical literature unearthed a little used, but powerful method wherein a reactive unstabilized azomethine ylide can be generated by treating trimethylamine N-oxide 4 with lithium diisopropylamide at low temperature.…”

Section: Scheme 1 Acid-catalyzed [3+2]-cycloaddition Reactionmentioning

confidence: 99%

Remarkable [3+2] Annulations of Electron-Rich Olefins with Unstabilized Azomethine Ylides

Davoren¹,

Gray²,

Harris³

et al. 2010

Synlett

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Herein we would like to communicate that an unstabilized azomethine ylide generated from commercial trimethylamine N-oxide will undergo a remarkable 1,3-dipolar cycloaddition in good yield with electron-rich and unpolarized olefins. A broad range of substituents on the alkenes are tolerated provided they are compatible with excess LDA. This demonstration of novel reaction scope should encourage others to try trimethylamine N-oxide as an azomethine ylide precursor in the synthesis of challenging 3,4-disubstituted pyrrolidines.Substituted pyrrolidines are common structural motifs present in a wide variety of natural products, 1 chiral ligands, 2 and biologically active compounds. 3 One of the most prevalent and reliable methods for the diastereoselective construction of 3,4-substituted architecture is the 1,3-dipolar cycloaddition reaction of an azomethine ylide and an appropriately substituted alkene. 4During the course of our research we became interested in constructing novel 3,4-disubstituted pyrrolidine ring systems. Since we did not require substitution on the 2-and 5-positions of the pyrrolidine ring, the azomethine ylide derived from the acid-catalyzed decomposition of commercial N-methoxymethyl-N-trimethylsilyl methyl phenyl methanamine (1) 5 was deemed a suitable choice (Scheme 1). Scheme 1 Acid-catalyzed [3+2]-cycloaddition reactionIn general, with compatible substrates, we found this wellprecedented chemistry to be operationally simple and scalable. In several cases we obtained multigram quantities of the corresponding N-benzyl pyrrolidine. A welldocumented drawback of this method is that this type of unstabilized azomethine ylide does not readily undergo cycloaddition with unactivated dipolarophiles. 6Pyrrolidines whose requisite alkenes were unreactive under the acid-catalyzed conditions required a different preparation. A survey of the chemical literature unearthed a little used, but powerful method wherein a reactive unstabilized azomethine ylide can be generated by treating trimethylamine N-oxide 4 with lithium diisopropylamide at low temperature. 7 Under these strongly basic conditions, ylide formation is thought to proceed by deoxygenation of the N-oxide. The resultant intermediate is extremely reactive and can be trapped by simple alkenes such as hex-1-ene, cyclopentene, styrene, and stilbene. 8 Scheme 2 Basic [3+2]-cycloaddition reactionHerein we would like to report that this cycloaddition reaction furnished targeted N-methyl pyrrolidines in yields ranging from good to excellent in nearly all cases examined. 9 A broad range of substituents on the alkenes were tolerated in this transformation provided that functionalities were compatible with excess LDA. Among the successful dipolarophiles were several examples of electronrich olefins including those that failed under the acid conditions (specifically products 8-10, Table 1). We found this reaction to be operationally straightforward with cycloadditions generally reaching completion in less than one hour.

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“…Examination of the orbital symmetry controlled generation of azomethine ylides from aziridines and exploration of their synthetic potential via 1,3-dipolar cycloaddition to a wide variety of multiple and heteromultiple bonds has recently proved extremely fruitful (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). The isoelectronic carbonyl ylides which are of equal importance have not received as much attention (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29).…”

Section: Introductionmentioning

confidence: 99%

Reactions of Carbonyl Ylides

Lown¹,

Matsumoto²

1971

Can. J. Chem.

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2,3-Diphenylindenone oxide 1 undergoes thermal 1,3-dipolar cycloadditions via a carbonyl ylide with symmetrical olefinic dipolarophiles to give (i) with cis addends mixtures of endo and exo adducts in which endo adducts generally predominate in agreement with results obtained with l-cyclohexyl-6-(cyclohexylimino)-la-phenylindano[l,2-b]aziridine and (ii) with trans addends adducts in which the 2-exo-3-endo product predominates. The pyrilium oxide 4is efficiently trapped with benzyne. 1,3-Diphenylisobenzofuran reacts with cis-addends to give endo-exo mixtures in which the endo adducts generally predominate. 2-Acetyl-5,5-pentamethylene-2-phenyl-A3-l,3,4-oxadiazoline undergoes regiospecific cycloaddition via a carbonyl ylide with unsymmetrical olefinic dipolarophiles in accordance with substituent electronic effects, and with 1,4-naphthoquinone a previously postulated type of intermediate adduct is isolated. L'oxyde de diphenylindenone-2,3 1 peut reagir pour donner des cycloadditions dipolaires-1,3 thermiques, par l'intermediaire d'une ylure de carbonyle possedant des dipolarophiles olefiniques symetriques. On obtient ainsi (i) avec des melanges endo et exo des produits cis, des produits d'addition oh la forme endo predomine habituellement, en accord avec les resultats obtenus avec le cyclohexyl-1 (cyclohexylimino)-6 phenylindano-la aziridine[l,2-b] et (ii) avec les produits trans, des produits d'addition oh la forme exo-2-endo-3 predomine. L'oxyde de pyrilium 4 peut &tre recueilli efficacement dans le benzene. Le diphCnylisobenzofuranne reagit avec les produits cis pour donner des melanges endo-exo, oil les produits d'addition endo prkdominent generalement. Le 2-acetyl-5,5 pentamethylene-2 phenyl-A3-1,3,4-oxadiazoline peut reagir pour donner des cycloadditions rtgiospecifiques, via une ylure de carbonylepossedant des dipolarophiles olefiniques non-symetriques, selon les effets dlectroniques du substituant; avec la naphthoquinone-1,4, on isole un produit d'addition intermediaire postule precedemment.

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1,3-Dipolar cycloaddition reactions of 2-(2′-thienyl)aziridines

Cited by 22 publications

References 8 publications

Thermal Decomposition of Stereoisomeric 3-Aroyl- and 3-Carbomethoxyaziridines in Acetonitrile

Thermal Decomposition of Stereoisomeric 3-Aroyl- and 3-Carbomethoxyaziridines in Acetonitrile

Remarkable [3+2] Annulations of Electron-Rich Olefins with Unstabilized Azomethine Ylides

Reactions of Carbonyl Ylides

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