On the [1,4] sigmatropic rearrangement of ammonium benzylides

Zdrojewski, Tadeusz; Jończyk, A.

doi:10.1016/0040-4039(94)02476-r

Cited by 16 publications

(29 citation statements)

References 4 publications

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“…An alternate fate for the aziridinium ylide INT2 is suggested by the computations in Scheme 3 and involves a rare pseudo- [1,4]sigmatropic rearrangement of INT2 via TS2′. This pathway has never been observed for an aziridinium ylide; however, a single example of a [1,4]-rearrangement of an ammonium benzylide has been reported 69,70 . According to our calculations, this path proceeds with a lower barrier than the competing cheletropic extrusion (ΔΔG ≠ = 5.3 kcal/mol).…”

Section: Scope Of the [3+3] Ring Expansionmentioning

confidence: 99%

Intermolecular [3+3] ring expansion of aziridines to dehydropiperi-dines through the intermediacy of aziridinium ylides

et al. 2020

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The importance of N-heterocycles in drugs has stimulated diverse methods for their efficient syntheses. Methods that introduce significant stereochemical complexity are attractive for identifying new bioactive amine chemical space. Here, we report a [3 + 3] ring expansion of bicyclic aziridines and rhodium-bound vinyl carbenes to form complex dehydropiperidines in a highly stereocontrolled rearrangement. Mechanistic studies and DFT computations indicate that the reaction proceeds through formation of a vinyl aziridinium ylide; this reactive intermediate undergoes a pseudo-[1,4]-sigmatropic rearrangement to directly furnish heterocyclic products with net retention at the new CC bond. In combination with asymmetric silver-catalyzed aziridination, enantioenriched scaffolds with up to three contiguous stereocenters are rapidly delivered. The mild reaction conditions, functional group tolerance, and high stereospecificity of this method are well-suited for appending piperidine motifs to natural product and complex molecules. Ultimately, our work establishes the value of underutilized aziridinium ylides as key intermediates for converting small, strained rings to larger N-heterocycles.

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Section: Scope Of the [3+3] Ring Expansionmentioning

confidence: 99%

Intermolecular [3+3] ring expansion of aziridines to dehydropiperi-dines through the intermediacy of aziridinium ylides

et al. 2020

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“…24,26 Recently, this common co-occurrence has been attributed to the relatively loose transition states usually found for the pericyclic [2,3]-process, which may dynamically lead to bond cleavage, thus fueling the stepwise [1,2]-migration. 6 An earlier in silico study by Ghigo 50,51 Moreover, a strong dependence of the ratio of the obtained products on the reaction conditions was observed.…”

Section: Scheme 21 Synthesis Of (+)-Dihydroantirhinementioning

confidence: 85%

Rearrangements of Nitrile-Stabilized Ammonium Ylides

Lahm¹,

Pacheco²,

Opatz³

2014

Synthesis

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Rearrangements of nitrile-stabilized ammonium ylides are useful reactions for the construction of alkylamines, nitrogen heterocycles, or carbonyl compounds. In spite of their attractive synthetic potential, they are much less frequently used than rearrangements of ammonium ylides either carrying charge-stabilizing carbonyl groups or being devoid of additional stabilization of the negative charge. This review focuses on different classes of rearrangements of nitrile-stabilized ammonium ylides as well as their application in synthetic organic chemistry.

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“…NH,-CH,C12 (B), and solid NaHC0,-DMF ( C ) . The expected products 6, 7 and 8, 9 are formed by [1,4], [ 1,2] or [2,3], [ 1,2] rearrangements of the isomeric ylides 4'and 5'-respectively (Scheme 3).…”

Section: R2mentioning

confidence: 99%

“…Recently we have shown that ylides generated from suitably substituted benzylammonium salts underwent [2,3] (Sommelet-Hauser), [ 1,2] (Stevens) and hitherto unknown [ 1,4] ('reverse' Sommelet-Hauser) rearrangements '-3 (Scheme 1). We have now studied sigmatropic rearrangements of ylides generated from the structurally related allylammonium salts 3a-c (see the framed skeleton in Scheme 1).…”

mentioning

confidence: 99%

“…We have now studied sigmatropic rearrangements of ylides generated from the structurally related allylammonium salts 3a-c (see the framed skeleton in Scheme 1). Unlike the behaviour of ylides generated from benzylammonium salts,'-, [ 1.41 rearrangement (which accompanied [ 1,2] (OEt),"] by means of a base, or CsF6y9 and tetrabutylammonium fluoride' (TBAF) in the case of silyl substituted salts, usually proceeded in a [2,3] fashion. In rearrangements of ylides generated by desilylation of these salts, both vinylic and aromatic n: electrons participated in reorganization of the skeleton.6 A literature search"" showed that reactions of ylides generated from allylammonium salts substituted with R3, Z = EWG, have not been earlier investigated.…”

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confidence: 99%

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