Asymmetric phase-transfer catalysed β-addition of isoxazolidin-5-ones to MBH carbonates

Capaccio, Vito; Zielke, Katharina; Eitzinger, Andreas; Massa, António; Palombi, Laura; Faust, Kirill; Waser, Mario

doi:10.1039/c8qo01057a

Cited by 29 publications

(25 citation statements)

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“…Having identified high yielding and highly diastereoselective racemic phase transfer-catalysed conditions for the (3 + 2)-cyclisation between 3a and 6a , we next screened a variety of different chiral ammonium salt phase transfer catalysts under different conditions for this reaction. 20,23 Unfortunately however, all these efforts were rather disappointing, as we were not able to obtain any reasonable enantioselectivity for this reaction. Scheme 2 gives the best result obtained with a Cinchona alkaloid-based chiral phase transfer catalyst, but a variety of other catalyst systems under different conditions were tested as well, but none of them gave any satisfying selectivity (as shown in the online ESI†).…”

Section: Resultsmentioning

confidence: 96%

Synthesis of α-CF₃-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

et al. 2019

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Section: Resultsmentioning

confidence: 96%

Synthesis of α-CF₃-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

et al. 2019

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“…Inspired by an earlier work of O'Donnell, 38 Waser and co-workers developed in 2018 an enantioselective S N 2′ substitution of isoxazolidin-5-ones 81 with MBH carbonates 40 catalysed by the chiral quaternary ammonium salt 82 (Scheme 13B). 39 The best results were obtained using 5 mol% of 82 together with 3 equivalents of caesium carbonate as Brønsted base in isopropyl ether at -20 °C. This protocol allows the synthesis of a broad range of chiral -amino acid derivatives 83 in moderate to high yields and enantioselectivities and good E/Z control.…”

Section: Scheme 12 Regiodivergent -And -Allylation Of Hydrazides Wimentioning

confidence: 99%

Unconventional Transformations of Morita–Baylis–Hillman Adducts

Calcatelli

Cherubini‐Celli²,

Carletti³

et al. 2020

Synthesis

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Morita–Baylis–Hillman (MBH) adducts are versatile starting materials widely employed in Lewis base catalysis. A myriad of different transformations have been reported based on either allylic alkylations with stabilised nucleophiles or annulations with diverse dipolarophiles. Apart from these two conventional types of reactivity, MBH adducts have recently been implemented in alternative and complementary catalytic strategies, including: (i) one-pot and cascade transformations, where additional chemical bonds are formed following the asymmetric allylic alkylation event in a single synthetic operation; (ii) regioselective α-allylations for the synthesis of trisubstituted alkenes; and (iii) dual activation strategies, involving Lewis base catalysis together with transition metal complexes or light, enabling allylic alkylations with nonstabilised nucleophiles and cascade processes. The present Short Review summarises the most significant unconventional catalytic transformations of racemic MBH adducts reported within the last decade.1 Introduction2 Multi-Step Single-Vessel Transformations (path iii)2.1 One-Pot Transformations2.2 Cascade Transformations3 α-Allylations (path iv)3.1 SN2′ Mechanism3.2 SN2′–SN2 Mechanism3.3 Miscellaneous Mechanisms4 Dual Activation (path v)4.1 MBH Adduct as Electrophile4.2 MBH Adduct as Nucleophile5 Summary and Outlook

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“…The use of electrophiles other than π‐allyl ones can afford a variety of β 2,2 ‐amino acids in a similar fashion. Despite the efforts made by the groups of Brière (2018), Shibasaki (2018, 2019), and Waser (2018), who employed different carbon‐based electrophiles, further development is necessary for practical applications because of insufficient selectivities and/or narrow substrate scope.…”

Section: C(α)–h/r Bond Formationmentioning

confidence: 99%

Recent Advances in the Catalytic Asymmetric Synthesis of β²‐ and β^2,2‐Amino Acids

Noda

Shibasaki

2019

Eur J Org Chem

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The importance of -amino acids for peptidomimetics and their presence in numerous natural products and pharmaceuticals make the development of the corresponding synthetic procedures a task of high practical significance. Herein, we focus on the recent developments in the catalytic asymmetric synthesis of 2 -and 2,2 -amino acids. The examples are arranged according to strategic bond disconnections. Despite the abundance of feasible approaches, only a handful of reaction [a] Dr. 2350 types can effectively furnish 2 -and 2,2 -amino acid derivatives with sufficient enantioselectivity suitable for peptide applications. These include asymmetric hydrogenation or conjugate addition of acrylates, α-functionalization of -amino acid enolate precursors, and aminomethylation of carbonyl compounds. Hence, future research directions are discussed considering these literature precedents.fied so far, -peptides -oligomers of -amino acids -have attracted considerable attention due to their structural similarity to native α-peptides and the conformational rigidity and chemical stability bestowed by the unnatural residues. [2] Contemporary research has further diverged into the use of γ-amino acids and α/ -hybrid peptides. [3] -Amino acids are also found in many natural products and pharmaceutical agents such as -lactams, [4] rendering the development of corresponding synthetic procedures an important task of synthetic organic chemistry.-Amino acids are homologated variants of α-amino acids, which are structurally categorized by their side-chain substitution patterns. The nomenclature for -amino acids is as follows: 3 denotes those with a substituent at the -position, 2 at the α-position, 2,3 at both αand -positions, and so on (Figure 1). Cyclic -amino acids are also classified in a similar fashion. 3 -Amino acids can be synthesized from the corresponding Minireview 2352 Scheme 3. Rh-catalyzed enantioselective hydrogenation of -phthalimide acrylates 5 reported by Zheng. Scheme 4. Rh-catalyzed enantioselective hydrogenation of (α-aminomethyl)acrylates 7 reported by Qiu. Scheme 16. Organocatalytic asymmetric conjugate addition of pyrrolidin-2,3dione 30 for the synthesis of 2,2 -peptidic compounds reported by Palomo.acid derivative 33, followed by the asymmetric protonation of the resulting enolate of the 5-membered ring to afford 4-substituted isoxazolidin-5-ones 35 (Scheme 17). [49] Although the selectivities need further improvement for practical applications, this work is one of the rare examples of the synthesis of 2 -amino acids bearing functionalized side chains (e.g., 35d).Scheme 17. Organocatalytic asymmetric protonation for the synthesis of 4-substituted isoxazolidin-5-ones 35 reported by Brière.

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Asymmetric phase-transfer catalysed β-addition of isoxazolidin-5-ones to MBH carbonates

Abstract: A novel high yielding, enantio- and diastereoselective protocol for the synthesis of α-allylated highly functionalised β-amino acid derivatives by adding isoxazolidin-5-ones to MBH carbonates under asymmetric phase-transfer catalysis has been developed.

Cited by 29 publications

References 40 publications

Synthesis of α-CF₃-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

Synthesis of α-CF₃-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

Unconventional Transformations of Morita–Baylis–Hillman Adducts

Recent Advances in the Catalytic Asymmetric Synthesis of β²‐ and β^2,2‐Amino Acids

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Asymmetric phase-transfer catalysed β-addition of isoxazolidin-5-ones to MBH carbonates

Abstract: A novel high yielding, enantio- and diastereoselective protocol for the synthesis of α-allylated highly functionalised β-amino acid derivatives by adding isoxazolidin-5-ones to MBH carbonates under asymmetric phase-transfer catalysis has been developed.

Cited by 29 publications

References 40 publications

Synthesis of α-CF3-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

Synthesis of α-CF3-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

Unconventional Transformations of Morita–Baylis–Hillman Adducts

Recent Advances in the Catalytic Asymmetric Synthesis of β2‐ and β2,2‐Amino Acids

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Synthesis of α-CF₃-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

Synthesis of α-CF₃-proline derivatives by means of a formal (3 + 2)-cyclisation between trifluoropyruvate imines and Michael acceptors

Recent Advances in the Catalytic Asymmetric Synthesis of β²‐ and β^2,2‐Amino Acids