Microwave-assisted, zinc-mediated peptide coupling of N-benzyl-α,α-disubstituted amino acids

Cianci, Julia; Baell, Jonathan B.; Harvey, Andrew J.

doi:10.1016/j.tetlet.2007.06.109

Cited by 11 publications

(5 citation statements)

References 13 publications

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“…After 24 h, the crude mixture was directly adsorbed onto diatomaceous earth and purified by flash column chromatography (20% ethyl acetate in hexanes up to 100% ethyl acetate and then 10% acetone in hexanes for the first isolation; 10% acetone hexanes, twice for second isolation). The product was obtained as a colorless oil containing 5% lactone byproduct and 10% Ullmann coupling byproduct (18.9 mg, 27%). R f = 0.33 (20% ethyl acetate in hexanes).…”

Section: Methodsmentioning

confidence: 99%

Copper-Catalyzed Three-Component Carboiminolactonization of Electron-Deficient Olefins

Wendlandt,

Trammel,

Kohler

et al. 2024

J. Org. Chem.

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Herein we report the three-component copper-catalyzed carboiminolactonization of α,β-unsaturated carbonyl derivatives. In the presence of a Cu(I) catalyst, α-haloesters, electron-deficient alkenes, and primary amines couple to generate γiminolactones in a single step. The scope of the reaction is explored with respect to the three coupling partners. Nineteen examples are presented with yields of these hydrolytically labile heterocycles of up to 69%. Mechanistic investigations support the formation of an oxocarbenium by way of an atom transfer radical addition (ATRA) intermediate.

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Section: Methodsmentioning

confidence: 99%

Copper-Catalyzed Three-Component Carboiminolactonization of Electron-Deficient Olefins

Wendlandt,

Trammel,

Kohler

et al. 2024

J. Org. Chem.

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“…155.7–155.9 °C (ref. m.p. 156–157 °C); 1 H NMR (300 MHz, D 2 O): δ =4.18 (q, J= 7.2 Hz, 2 H; CH 2 ), 1.49 (s, 6 H; C(CH 3 ) 2 ), 1.19 ppm (t, J= 7.2 Hz, 3 H; CH 2 C H 3 ); 13 C NMR (75.5 MHz, CDCl 3 ): δ =172.5 (C=O), 63.7 (CO 2 C H 2 ), 56.8 ( C (CH 3 ) 2 ), 22.9 (C( C H 3 ) 2 ), 13.1 ppm (CO 2 CH 2 C H 3 ).…”

Section: Methodsmentioning

confidence: 99%

New Amino‐Acid‐Based β‐Phosphorylated Nitroxides for Probing Acidic pH in Biological Systems by EPR Spectroscopy

et al. 2016

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There is increasing attraction of measuring pH in biological studies using nitroxides having pHdependent electron paramagnetic resonance (EPR) spectra. Aiming to improve the spectral sensitivity, a X , of these probes (i.e. the difference between limiting EPR hyperfine splittings (hfs) in their protonated and unprotonated forms), we present here a series of novel linear -carboxy, '-diethoxyphosphoryl nitroxides constructed on an amino acid core and featuring a ( or ')-C−H bond.In buffers the three main hfs (a N , a H and a P ) of their X-band EPR spectra vary reversibly with pH and, when it is inferred from a P or a H titration curves, a 2−4-fold increase in sensitivity is achieved vs reference imidazoline or imidazolidine nitroxides. Lead crystallized carboxylate 10b (pK a ≈ 3.6), which demonstrated low cytotoxicity and good resistance to bioreduction, was applied to probe the stomach acidity in rats. The results pave the way to a novel generation of highly sensitive EPR pH markers.

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“…76 Also, microwaves assisted zinc dust mediated coupling involving highly hindered α,α-dialkylamino acids and cyclic as well as acyclic α,α-dialkylamino acids has lead to their assembly in good yields of 79-90%. 228 Preparation of hindered peptides possessing up to four successive diphenylglycine or Aib residues was accomplished by using azido acid chloride method. 133 After coupling the azide Also Fmoc-amino acid chloride/KOBt protocol has been utilized for the synthesis of peptides containing α,α-dialkyl amino acids as well as N-methyl amino acids (tables 12,13).…”

Section: Coupling Mediated By Agcnmentioning

confidence: 99%

Amino acid chlorides: a journey from instability and racemization toward broader utility in organic synthesis including peptides and their mimetics

et al. 2015

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The review provides a broad overview of amino acid chlorides in peptide chemistry, classified into different sections comprising reagents, N-protected amino acid chlorides (preparation and properties), coupling employing various protocols and applications in difficult and hindered couplings. The recent developments include their applications in synthesis of various amino acid derivatives, peptidomimetics, heterocycles and biologically active molecules.

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Microwave-assisted, zinc-mediated peptide coupling of N-benzyl-α,α-disubstituted amino acids

Cited by 11 publications

References 13 publications

Copper-Catalyzed Three-Component Carboiminolactonization of Electron-Deficient Olefins

Copper-Catalyzed Three-Component Carboiminolactonization of Electron-Deficient Olefins

New Amino‐Acid‐Based β‐Phosphorylated Nitroxides for Probing Acidic pH in Biological Systems by EPR Spectroscopy

Amino acid chlorides: a journey from instability and racemization toward broader utility in organic synthesis including peptides and their mimetics

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