Über die Darstellung von <i>N</i>‐(Arylmethylen)dehydroalanin‐methylestern sowie ihre Eignung als Bausteine in der Aminosäuresynthese

Wulff, Günter; Böhnke, Helmut; Klinken, H. T.

doi:10.1002/jlac.198819880604

Cited by 13 publications

(4 citation statements)

References 25 publications

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“…37 Wulff and co-workers developed cuprate and other nucleo-philic additions to Z-type 2-azadienes. 38 The Tarzia group has also disclosed the addition of several classes of nucleophiles to azadienes to prepare -amino acids. 39 Most previous research involving C-type 2-azadienes has largely focused on employing these reagents as heterodienes in cycloadditions; due to the lower reactivity of Ctype azadienes, electron-deficient dienophiles have often been employed for these reactions (e.g., aldehydes, 40 dialkyl azodicarboxylates, 41 isocyanates, 41 or maleimides).…”

Section: Scheme 5 Enantioselective Cu-box-catalyzed [4+2]-cycloadditions Of X-type 2-azadienesmentioning

confidence: 99%

2-Azadienes as Enamine Umpolung Synthons for the Preparation of Chiral Amines

Malcolmson¹,

Shao

2019

Synlett

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The development of new strategies for the preparation of chiral amines is an important objective in organic synthesis. In this Synpacts, we summarize our approach for catalytically accessing nucleophilic aminoalkyl metal species from 2-azadienes, and its application in generating a number of important but elusive chiral amine scaffolds. Reductive couplings with ketones and imines afford 1,2-amino tertiary alcohols and 1,2-diamines, respectively, whereas fluoroarylations of gem-difluoro-2-azadienes deliver α-trifluoromethylated benzylic amines.1 Introduction2 Background: Umpolung Strategies for Preparing Chiral Amines3 Background: 2-Azadienes4 Reductive Couplings of 2-Azadienes5 Fluoroarylations of gem-Difluoro-2-azadienes6 Summary and Outlook

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Section: Scheme 5 Enantioselective Cu-box-catalyzed [4+2]-cycloadditions Of X-type 2-azadienesmentioning

confidence: 99%

2-Azadienes as Enamine Umpolung Synthons for the Preparation of Chiral Amines

Malcolmson¹,

Shao

2019

Synlett

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“…136,137 The 3-alkoxycarbonyl-2-azabuta-1,3-dienes 256 were prepared via a reaction of arylimines 255, derived from serine esters, and CDI, followed by a base-induced elimination (Scheme 76). [138][139][140] The abovementioned studies revealed that the 4-unsubstituted 3-alkoxycarbonyl-2-azabuta-1,3-dienes 256 are quite unstable compounds. When left in solution for a short time at room temperature, dimerisation was observed with formation of tetrahydropyridine 257.…”

Section: Synthesis and Reactivity Of 1-sulfinyl-1-azabuta-13-dienesmentioning

confidence: 99%

“…Especially when diorganocopper(I) reagents (R 2 CuLi) were used, the desired Michael addition was strongly preferred (Scheme 78). 138 Later, Gilchrist and co-workers evaluated the reactivity of 3-alkoxycarbonyl-2-azabuta-1,3-dienes in hetero-Diels-Alder reactions. [142][143][144][145][146] They synthesized several of these azadienes using the abovementioned methods.…”

Section: Synthesis and Reactivity Of 1-sulfinyl-1-azabuta-13-dienesmentioning

confidence: 99%

“…[142][143][144][145][146] They synthesized several of these azadienes using the abovementioned methods. 135,138,139 The DA cycloaddition reactions took place with both electron-rich dienophiles (enamines) and electron-deficient dienophiles (enones) and were shown to be regioselective but not stereoselective. For example, reaction of the cysteine methyl ester with ethyl and methyl pyruvate led to the formation of the corresponding thiazolidines 261.…”

Section: Synthesis and Reactivity Of 1-sulfinyl-1-azabuta-13-dienesmentioning

confidence: 99%

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Electron-deficient 1- and 2-azabuta-1,3-dienes: a comprehensive survey of their synthesis and reactivity

2011

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Electron-deficient 1- and 2-azabuta-1,3-dienes are reagents intrinsically able to provide a wide range of cyclic and acyclic N-containing building blocks. Depending on their substitution, they behave as dienes for Diels-Alder reactions, as partners for [4+1], [3+2], [2+2]-cycloadditions, for aziridinations and as electrophiles for 1,2 and 1,4-additions. Nowadays, they are a very versatile family of compounds, despite their usual instability and complex reactivity. Four decades of research in this challenging area are reviewed in this critical review: their synthetic aspects and their reactivity towards a wide range of dienophiles, dipoles and nucleophiles are described as well. The introduction focuses on their electronic properties in order to get a clear picture of their reactivity (190 references).

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Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

1992

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Well over a decade ago, two reviews were contributed to the Organic Reactions series covering substitution and conjugate addition reactions in organocopper chemistry. Their appearance, which highlighted most of the early work in this field, served not only as a source of invaluable references to original literature reports, but also stimulated a vast number of subsequent studies on the properties and uses of organocopper complexes. The work cited in this chapter, which dates from ca. 1975, concerns in large measure uses of organocopper complexes originating from either catalytic or stoichiometric quantities of a copper(I) halide together with a Grignard (RMgX) or organolithium (RLi) reagent. These combinations form either neutral organocopper reagents RCu ( 1 ) or copper(I) monoanionic salts R 2 CuM (M = Li or MgX), commonly referred to as “lower‐order” species. The latter ate complexes with lithium as gegenion ( 2 ) are also known as “Gilman reagents” in recognition of their origins. Copper(I) cyanide is also an excellent precursor, affording homogeneous mixtures of lower order cyanocuprates RCu(CN)Li, ( 3 ), upon treatment with an equivalent of an organolithium. The strength of the CuCN linkage presumably accounts for direct cuprate formation with 1 equivalent of the organolithium, rather than the metathesis that occurs with copper(I) chloride, bromide, or iodide. While use of reagents ( 1 ), ( 2 ) and ( 3 ) alone can be aptly classified as broad‐based and intense, their importance has further encouraged extensive development of variations on these themes (i.e., their composition and reactivity profiles). Reagents ( 1–3 ) have been found to be unexpectedly compatible with certain electrophilic additives at low temperatures, which substantially alter their reactivity. Rather than forming ( 2 ) from 2 equivalents of the same RLi, different organolithiums can be utilized to give R T R R CuLi, ( 4 ), conserving potentially valuable RLi. This scenario raises the question of controlling the selectivity of transfer of the desired ligand R T rather than the anticipated residual (or “dummy”) group R R from copper to electrophilic carbon. Fortunately, many solutions to this problem now exist. Admixture of 2RLi (or R T Li + R R Li) with copper(I) cyanide proceeds beyond the stage of ( 3 ) to ultimately arrive at copper(I) dianionic complexes 5 , the so‐called “higher‐order” cyanocuprates. Undoubtedly it is the cyano ligand, with its π‐acidic nature, which enables copper to accept a third negatively charged ligand. Although reagents ( 5 ) do not yet share in all of the benefits offered by time in comparison with their lower‐order counterparts, they nicely complement prior art. Moreover, as with species ( 1–4 ), they continue to evolve, providing the synthetic community with alternatives for highly selective and efficient means of making key carbon–carbon bonds.

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Über die Darstellung von N‐(Arylmethylen)dehydroalanin‐methylestern sowie ihre Eignung als Bausteine in der Aminosäuresynthese

Cited by 13 publications

References 25 publications

2-Azadienes as Enamine Umpolung Synthons for the Preparation of Chiral Amines

2-Azadienes as Enamine Umpolung Synthons for the Preparation of Chiral Amines

Electron-deficient 1- and 2-azabuta-1,3-dienes: a comprehensive survey of their synthesis and reactivity

Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

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