Asymmetric [2,3]-Rearrangement of Glycine-Derived Allyl Ammonium Ylids

Workman, James; Garrido, Neil P.; Sançon, Julien; Roberts, Edward; Wessel, Hans Peter; Sweeney, Joseph B.

doi:10.1021/ja043768i

Cited by 73 publications

(44 citation statements)

References 11 publications

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“…In most cases, the diastereoselectivity is modest, 16-18 with only a few examples of high selectivity in auxiliary mediated processes. 19,20 We now report the results of our studies on the diastereoselectivity at the migration terminus of the [2,3]rearrangement of several unstabilized, lithionitrogen ylides (Eq 5), in which we find that the rearrangement is highly stereoselective. Note: Strictly speaking, the ylide is the zwitterion having a positive nitrogen and a negative carbon.…”

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confidence: 87%

Stereoselective [2,3]‐Sigmatropic Rearrangements of Unstabilized Nitrogen Ylides.

Gawley

Moon

2007

ChemInform

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The steric course of the [2,3]-rearrangement of several unstabilized nitrogen ylides has been investigated. The reactions proceed cleanly through an anti transition state, affording modest to good yields of a single diastereomer of the product. In two examples containing an N-cinnamyl group, a competing [1,2]-rearrangement affords a minor product.Electrophilic substitution reactions of α-alkoxy-and α-aminoorganolithium compounds (Eq 1) have been extensively studied, and constitute an important class of synthetic methods, with hundreds of applications reported so far. 1,2 A second class of carbon-carbon bond forming reactions utilizing these reactive intermediates is sigmatropic rearrangements. 3,4 In 1978, Still and Mitra reported the first example of a [2,3]-rearrangement of an organolithium generated by tin-lithium exchange, 5 which was later shown to be invertive at the lithium-bearing carbon (Eq 2). 6-8(1) with butyllithium in THF at −78 °C for 1 h, quenching with methanol, and silica gel chromatography afforded a 69% yield of tetrabutyltin, indicating that transmetalation to the ylide is facile in this system. Quaternization of racemic 1 with E-crotyl bromide, and E-and Z-cinnamyl bromide affords ammonium salts 2a-c, as shown in Scheme 1. For some compounds, anion exchange from halide to hexafluorophosphate facilitated handling, provided a salt that was less hygroscopic, and increased solubility in organic solvents (see Supporting Information).As illustrated in Scheme 2, stannylammonium ions 2a-c were treated with butyllithium in THF at −60 °C to effect transmetalation and stirred at that temperature for 20-24 h. After workup and column chromatography, amines 5a-c were obtained in the yields shown in Table 1, entries 1-3.Of interest in these rearrangements is the possibility of two transition state conformers, syn and anti 4a-c, which would afford diasteromeric products 5 or 6, and possibly [1,2]-rearrangement product 7. In all cases, only one diastereomer was isolated. Independent synthesis of 5b and 5c established the relative configurations (see Supporting Information). It appears that the [2,3]-rearrangement prefers the anti transition state 4, independent of alkene geometry, even though anti 4c having a Z double bond appears somewhat more congested. The lower yield from the Z-cinnamyl intermediate 3c may indicate that steric crowding in the anti transition state slows the rearrangement, allowing pathways toward nonproductive decomposition to become more competitive; in this case, there were numerous unidentified polar byproducts. It is noteworthy that under these conditions, none of the [1,2]-products 7a-c were detected.If R 2 and R 3 in Eq 5 are different, then the nitrogen is a stereocenter and the stereoselectivity of the rearrangement will rely on the stereoselective quaternization of the nitrogen. To probe the diastereoselectivity of the rearrangement in cyclic systems, we chose racemic N-methyl-2-(tributylstannyl)-piperidine, 8. Based on precedent from a single example in an earlier repor...

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Stereoselective [2,3]‐Sigmatropic Rearrangements of Unstabilized Nitrogen Ylides.

Gawley

Moon

2007

ChemInform

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“…For these reasons, synthetic applications of the Sommelet-Hauser rearrangement and its asymmetric versions have been limited. [5] Herein, we report a unique example of a Sommelet-Hauser rearrangement of carbonyl-stabilized ammonium ylides that is not accompanied by the [1,2] Stevens rearrangement to a detectable extent.…”

Section: Eiji Tayama* and Hiroshi Kimuramentioning

confidence: 97%

“…Recently, we reported that the [1,2] Stevens rearrangement of ammonium salt 1, which is derived from (2S)-N-(4-tert-butoxycarbonyl)benzyl proline tert-butyl ester, proceeds with a perfect level (greater than 99 %) of N-to-C chirality transfer to give the a-benzylated proline tert-butyl ester 2 (Scheme 1).…”

Section: Eiji Tayama* and Hiroshi Kimuramentioning

confidence: 99%

“…

[5] Herein, we report a unique example of a Sommelet-Hauser rearrangement of carbonyl-stabilized ammonium ylides that is not accompanied by the [1,2] Stevens rearrangement to a detectable extent.

Recently, we reported that the [1,2] Stevens rearrangement of ammonium salt 1, which is derived from (2S)-N-(4-tert-butoxycarbonyl)benzyl proline tert-butyl ester, proceeds with a perfect level (greater than 99 %) of N-to-C chirality transfer to give the a-benzylated proline tert-butyl ester 2 (Scheme 1).

[2b] However, when the rearrangement was performed in THF at À40 8C using potassium tert-butoxide (1.5 equiv) as a base, the Sommelet-Hauser rearrangement (concerted [2,3] sigmatropic process) proceeded exclusively to give the corresponding a-aryl proline [6] derivative 3 in 96 % yield.

…”

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Asymmetric Sommelet–Hauser Rearrangement of N‐Benzylic Ammonium Salts

Tayama

Kimura

2007

Angew Chem Int Ed

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The Stevens and Sommelet-Hauser rearrangements of ammonium ylides are known as useful transformations for organic synthesis because they convert a readily accessible CÀN bond into a new CÀC bond.[1] The Stevens rearrangement has been widely used for the asymmetric synthesis of aamino acid derivatives, [2,3] whereas the Sommelet-Hauser rearrangement is much less common because it usually competes with the [1,2] Stevens rearrangement.[4] For example, the base-induced rearrangement of carbonyl-stabilized ammonium ylides such as those derived from N-benzylic aamino esters almost exclusively undergoes the [1,2] Stevens rearrangement to give the a-benzylated amino acid derivatives. For these reasons, synthetic applications of the Sommelet-Hauser rearrangement and its asymmetric versions have been limited.[5] Herein, we report a unique example of a Sommelet-Hauser rearrangement of carbonyl-stabilized ammonium ylides that is not accompanied by the [1,2] Stevens rearrangement to a detectable extent.Recently, we reported that the [1,2] Stevens rearrangement of ammonium salt 1, which is derived from (2S)-N-(4-tert-butoxycarbonyl)benzyl proline tert-butyl ester, proceeds with a perfect level (greater than 99 %) of N-to-C chirality transfer to give the a-benzylated proline tert-butyl ester 2 (Scheme 1).[2b] However, when the rearrangement was performed in THF at À40 8C using potassium tert-butoxide (1.5 equiv) as a base, the Sommelet-Hauser rearrangement (concerted [2,3] sigmatropic process) proceeded exclusively to give the corresponding a-aryl proline [6] derivative 3 in 96 % yield. The 1 H NMR analysis of 3 showed a new singlet peak from benzylic methyl protons (d = 2.27 ppm in CDCl 3 ), three proton signals from aromatic protons, and the disappearance of the benzylic methylene protons. The enantiomeric excess was determined to be greater than 99 % by chiral HPLC analysis after reduction of 3 to the amino alcohol with lithium aluminum hydride.[7] The R configuration of 3 was assigned by analogy with the reported examples of [2,3] Stevens rearrangement of proline-derived ammonium salts. [2d, e]

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“…In this regard, particular attention is drawn to the Stevens rearrangement of ammonium ylides with allylic type groups, which allow obtaining compounds of different classes, including unsaturated tertiary amines [6][7][8][9]. The latter are used for the synthesis of surface-active substances, drugs, biologically active compounds, etc.…”

Section: Letters To the Editormentioning

confidence: 99%

Synthesis of New Unsaturated Amines by The Stevens Rearrangement

et al. 2018

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Abstract-Monoalkylation of 1,4-dichlorobut-2-ene with prop-2-yn-1-ol under phase-transfer catalysis conditions led to the formation of 1-(prop-2-yn-1-yloxy)-4-chlorobut-2-ene. The latter reacted with dimethylamine to afford N,N-dimethyl-4-(prop-2-yn-1-yloxy)but-2-enyl-1-amine. Its quaternization afforded new ammonium salts containing 4-(prop-2-yn-1-yloxy)but-2-enyl group. Unsaturated tertiary amines formed as a result of Stevens 3,2-rearrangement of quaternary salts.

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Asymmetric [2,3]-Rearrangement of Glycine-Derived Allyl Ammonium Ylids

Cited by 73 publications

References 11 publications

Stereoselective [2,3]‐Sigmatropic Rearrangements of Unstabilized Nitrogen Ylides.

Stereoselective [2,3]‐Sigmatropic Rearrangements of Unstabilized Nitrogen Ylides.

Asymmetric Sommelet–Hauser Rearrangement of N‐Benzylic Ammonium Salts

Synthesis of New Unsaturated Amines by The Stevens Rearrangement

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