Investigations Directed at Catalytic Carbon−Carbon and Carbon−Oxygen Bond Formation via C−H Bond Activation

Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal ortho-, distal meta- and para-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(sp2)-H functionalization via reversible imine formation. By overruling facile proximal C-H bond activation by imine-N atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.

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Carbon Dioxide-Mediated C(sp2)–H Arylation of Primary and Secondary Benzylamines

10.26434/chemrxiv.7138088.v2 ◽

2018 ◽

Author(s):

Mohit Kapoor ◽

Pratibha Chand-Thakuri ◽

Michael Young

Keyword(s):

Carbon Dioxide ◽

Transition Metal ◽

Bond Activation ◽

Bond Formation ◽

Carbon Bond ◽

Chelate Effect ◽

Free Amine ◽

Carbon Carbon Bond ◽

New Strategy ◽

Metal Catalyzed

Carbon-carbon bond formation by transition metal-catalyzed C–H activation has become an important strategy to fabricate new bonds in a rapid fashion. Despite the pharmacological importance of ortho-arylbenzylamines, however, effective ortho-C–C bond formation from C–H bond activation of free primary and secondary benzylamines using PdII remains an outstanding challenge. Presented herein is a new strategy for constructing ortho-arylated primary and secondary benzylamines mediated by carbon dioxide (CO2). The use of CO2 is critical to allowing this transformation to proceed under milder conditions than previously reported, and that are necessary to furnish free amine products that can be directly used or elaborated without the need for deprotection. In cases where diarylation is possible, a chelate effect is demonstrated to facilitate selective monoarylation.

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Formation of Carbon-Oxygen Bond Mediated by Hypervalent Iodine Reagents Under Metal-free Conditions

Mini-Reviews in Organic Chemistry ◽

10.2174/1570193x17999200807140943 ◽

2020 ◽

Vol 17 ◽

Author(s):

Ayesha Jalil ◽

Yaxin O Yang ◽

Zhendong Chen ◽

Rongxuan Jia ◽

Tianhao Bi ◽

...

Keyword(s):

Natural Products ◽

Bond Formation ◽

Building Blocks ◽

Review Article ◽

Hypervalent Iodine ◽

Metal Free ◽

Bioactive Natural Products ◽

The Past ◽

Oxygen Bond ◽

Privileged Scaffolds

: Hypervalent iodine reagents are a class of non-metallic oxidants have been widely used in the construction of several sorts of bond formations. This surging interest in hypervalent iodine reagents is essentially due to their very useful oxidizing properties, combined with their benign environmental character and commercial availability from the past few decades ago. Furthermore, these hypervalent iodine reagents have been used in the construction of many significant building blocks and privileged scaffolds of bioactive natural products. The purpose of writing this review article is to explore all the transformations in which carbon-oxygen bond formation occurred by using hypervalent iodine reagents under metal-free conditions

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Mechanism and Selectivity Control in Ni- and Pd-Catalyzed Cross-Couplings Involving Carbon–Oxygen Bond Activation

Accounts of Chemical Research ◽

10.1021/acs.accounts.1c00050 ◽

2021 ◽

Author(s):

Shuo-Qing Zhang ◽

Xin Hong

Keyword(s):

Bond Activation ◽

Selectivity Control ◽

Oxygen Bond

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Peptide Modifications: Versatile Tools in Peptide and Natural Product Syntheses

Synlett ◽

10.1055/s-0037-1612417 ◽

2019 ◽

Vol 30 (11) ◽

pp. 1289-1302 ◽

Cited By ~ 4

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

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