Substituent effects on the rate of formation of azomethine ylides. A computational investigation

Banks, Harold D.

doi:10.1039/c1ob05588g

Cited by 4 publications

(3 citation statements)

References 105 publications

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“…Many routes have been extensively studied experimentally − and computationally − for the synthesis of the requisite starting materials (Figure ). For example, many of the most popular approaches, including desilylation, N-metalation, and decarboxylation, are dependent on specific auxiliary groups, requiring additional steps along with an intrinsically decreased reaction scope .…”

Section: Introductionmentioning

confidence: 99%

Multi-Ion Bridged Pathway of N-Oxides to 1,3-Dipole Dilithium Oxide Complexes

et al. 2021

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Roussi's landmark work on the generation of 1,3dipoles from tertiary amine N-oxides has not reached its full potential since its underlying mechanism is neither well explored nor understood. Two competing mechanisms were previously proposed to explain the transformation involving either an iminium ion or a diradical intermediate. Our investigation has revealed an alternative mechanistic pathway that explains experimental results and provides significant insights to guide the creation of new Noxide reagents beyond tertiary alkylamines for direct synthetic transformations. Truhlar's M06-2x functional and Møller−Plesset second-order perturbation theory with Dunning's [jul,aug]-cc-pv[D,T]z basis sets and discrete-continuum solvation models were employed to determine activation enthalpies and structures. During these mechanistic explorations, we discovered a unique multiion bridged pathway resulting from the rate-determining step, which was energetically more favorable than other alternate mechanisms. This newly proposed mechanism contains no electrophilic intermediates, strengthening the reaction potential by broadening the reagent scope and limiting the possible side reactions. This thoroughly defined general mechanism supports a more direct route for improving the use of N-oxides in generating azomethine ylide−dilithium oxide complexes with expanded functional group tolerance and breadth of chemistry.

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Section: Introductionmentioning

confidence: 99%

Multi-Ion Bridged Pathway of N-Oxides to 1,3-Dipole Dilithium Oxide Complexes

et al. 2021

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“…As outlined in Scheme , there are several different synthetic strategies for the generation of N-protonated azomethine ylides ( 289 ) and their N-alkylated cousins ( 290 ) including (1) ring-opening reactions, (2) deprotonation, (3) 1,2-prototropic rearrangement, (4) decarboxylation, (5) disilylation/destannylation, and (6) via carbenes and carbenoids. The most classical method involves the thermal (or photochemical) retro -pericyclic ring opening of aziridines ( 291 ). − The mechanism of this ring-opening process and the ensuing 1,3-dipolar cycloaddtions have been investigated thoroughly. − More recent innovations include the use of Lewis acids to mediate the ring-opening of aziridines to azomethine ylides at lower temperatures. − Dihydrooxazoles ( 292 , X = O), ,− dihydrothiazoles ( 292 , X = S), and related heterocycles ,, also can produce N -alkyl azomethine ylide dipoles via ring-opening processes.…”

Section: Azomethine Ylidesmentioning

confidence: 99%

2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides

et al. 2018

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This review covers the use of 2-azaallyl anions, 2-azaallyl cations, and 2-azaallyl radicals in organic synthesis up through June 2018. Particular attention is paid to both foundational studies and recent advances over the past decade involving semistabilized and nonstabilized 2-azaallyl anions as key intermediates in various carbon–carbon and carbon–heteroatom bond-forming processes. Both transition-metal-catalyzed and transition-metal-free transformations are covered. Azomethine ylides, which have received significant attention elsewhere, are discussed briefly with the primary focus on critical comparisons with 2-azaallyl anions in regard to generation and use.

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“…The 1,3-dipolar cycloaddition of azomethine ylides (AMYs) [1][2][3][4][5][6] is a powerful method for the synthesis of bioactive pyrrolidine-containing compounds and natural product analogs [7][8][9][10][11][12][13][14][15]. AMYs generated from the reaction of aldehydes and α-amino esters (via dehydration) or α-amino acids (via decarboxylation) could be classified based on the substitution groups on the N atom to: 1) N-substituted (N-R type), 2) hydrogen containing (N-H type), and 3) metal complexes (N-M type) (Figure 1) [16,17]. These AMYs could also be classified as stabilized (A1-A4) which contain an electron-withdrawing group (EWG), semi-stabilized (B1-B4) which have an aryl (Ar) substituent, and non-stabilized (C1 and C2) which have neither an Ar group nor an EWG on the α-carbon atoms.…”

Section: Introductionmentioning

confidence: 99%

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

Zhang,

Ma,

Zhang

2023

Beilstein J. Org. Chem.

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The [3 + 2] cycloadditions of stabilized azomethine ylides (AMYs) derived from amino esters are well-established. However, the reactions of semi-stabilized AMYs generated from decarboxylative condensation of α-amino acids with arylaldehydes are much less explored. The [3 + 2] adducts of α-amino acids could be used for a second [3 + 2] cycloaddition as well as for other post-condensation modifications. This article highlights our recent work on the development of α-amino acid-based [3 + 2] cycloaddition reactions of N–H-type AMYs in multicomponent, one-pot, and stepwise reactions for the synthesis of diverse heterocycles related to some bioactive compounds and natural products.

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Substituent effects on the rate of formation of azomethine ylides. A computational investigation

Cited by 4 publications

References 105 publications

Multi-Ion Bridged Pathway of N-Oxides to 1,3-Dipole Dilithium Oxide Complexes

Multi-Ion Bridged Pathway of N-Oxides to 1,3-Dipole Dilithium Oxide Complexes

2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

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