Site-Selective C-H Bond Activation/Functionalization of Alpha-Amino Acids and Peptide-Like Derivatives

2018 ◽  
Vol 2018 (44) ◽  
pp. 6050-6067 ◽  
Author(s):  
Tobias Brandhofer ◽  
Olga García Mancheño
Keyword(s):  
Amino Acids ◽  
Bond Activation ◽  
Site Selective

Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands

2017 ◽  
Author(s):  
Haibo Ge ◽  
Lei Pan ◽  
Piaoping Tang ◽  
Ke Yang ◽  
Mian Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Bond Functionalization ◽  
Aliphatic Ketones ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Site Selective

Transition metal-catalyzed selective C–H bond functionalization enabled by transient ligands has become an extremely attractive topic due to its economical and greener characteristics. However, catalytic pathways of this reaction process on unactivated sp<sup>3</sup> carbons of reactants have not been well studied yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp<sup>3</sup>)–H bond activation with amino acids as transient ligands has been systematically conducted. The theoretical calculations showed that higher angle distortion of C(sp2)-H bond over C(sp3)-H bond and stronger nucleophilicity of benzylic anion over its aromatic counterpart, leading to higher reactivity of corresponding C(sp<sup>3</sup>)–H bonds; the angle strain of the directing rings of key intermediates determines the site-selectivity of aliphatic ketone substrates; replacement of glycine with β-alanine as the transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that β-alanine is indeed a more efficient transient ligand for arylation of β-secondary carbons of linear aliphatic ketones than its glycine counterpart.<br><br>

Peptide Modifications: Versatile Tools in Peptide and Natural Product Syntheses

Synlett ◽  
2019 ◽  
Vol 30 (11) ◽  
pp. 1289-1302 ◽  
Author(s):  
Phil Servatius ◽  
Lukas Junk ◽  
Uli Kazmaier
Keyword(s):  
Amino Acids ◽  
Natural Product ◽  
Bond Activation ◽  
Bond Formation ◽  
Side Chain ◽  
Peptide Backbone ◽  
Claisen Rearrangements ◽  
The Past ◽  
Allylic Alkylations ◽  
Peptide Modifications

Peptide modifications via C–C bond formation have emerged as valuable tools for the preparation and alteration of non-proteinogenic amino acids and the corresponding peptides. Modification of glycine subunits in peptides allows for the incorporation of unusual side chains, often in a highly stereoselective manner, orchestrated by the chiral peptide backbone. Moreover, modifications of peptides are not limited to the peptidic backbone. Many side-chain modifications, not only by variation of existing functional groups, but also by C–H functionalization, have been developed over the past decade. This account highlights the synthetic contributions made by our group and others to the field of peptide modifications and their application in natural product syntheses.1 Introduction2 Peptide Backbone Modifications via Peptide Enolates2.1 Chelate Enolate Claisen Rearrangements2.2 Allylic Alkylations2.3 Miscellaneous Modifications3 Side-Chain Modifications3.1 C–H Activation3.1.1 Functionalization via Csp3–H Bond Activation3.2.2 Functionalization via Csp2–H Bond Activation3.2 On Peptide Tryptophan Syntheses4 Conclusion

ChemInform Abstract: Non-Coordinating-Anion-Directed Reversal of Activation Site: Selective C-H Bond Activation of N-Aryl Rings.

ChemInform ◽  
2016 ◽  
Vol 47 (45) ◽  
Author(s):  
Dawei Wang ◽  
Xiaoli Yu ◽  
Xiang Xu ◽  
Bingyang Ge ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Site Selective ◽  
Activation Site

Carbon Dioxide-Driven Palladium-Catalyzed C–H Activation of Amines: A Unified Approach for the Arylation of Aliphatic and Aromatic Primary and Secondary Amines

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 519-524 ◽  
Author(s):  
Michael Young ◽  
Mohit Kapoor ◽  
Pratibha Chand-Thakuri ◽  
Justin Maxwell ◽  
Daniel Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Bond Activation ◽  
Secondary Amines ◽  
Activation Process ◽  
Unified Approach ◽  
Benzylic Amines ◽  
Palladium Catalyzed ◽  
Group A ◽  
Directing Group ◽  
Site Selective

Amines are an important class of compounds in organic chemistry and serve as an important motif in various industries, including pharmaceuticals, agrochemicals, and biotechnology. Several methods have been developed for the C–H functionalization of amines using various directing groups, but functionalization of free amines remains a challenge. Here, we discuss our recently developed carbon dioxide driven highly site-selective γ-arylation of alkyl- and benzylic amines via a palladium-catalyzed C–H bond-activation process. By using carbon dioxide as an inexpensive, sustainable, and transient directing group, a wide variety of amines were arylated at either γ-sp3 or sp2 carbon–hydrogen bonds with high selectivity based on substrate and conditions. This newly developed strategy provides straightforward access to important scaffolds in organic and medicinal chemistry without the need for any expensive directing groups.1 Introduction2 C(sp3)–H Arylation of Aliphatic Amines3 C(sp2)–H Arylation of Benzylamines4 Mechanistic Questions5 Future Outlook

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