Remote Oxidation of Aliphatic C–H Bonds in Nitrogen-Containing Molecules

Howell, Jennifer L.; Feng, Kaibo; Clark, Joseph R.; Trzepkowski, Louis J.; White, M. Christina

doi:10.1021/jacs.5b10299

Cited by 181 publications

(151 citation statements)

References 29 publications

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“…13 More recently, we and others have leveraged this protonation strategy to achieve transition-metal catalyzed remote oxyfunctionalization of a more diverse variety of nitrogen-containing substrates, using K 2 PtCl 6 , 9 Fe(PDP), 14 and Mn/Ru-based catalysts. 15 However, all of these reactions exhibit limitations with respect to substrate scope and/or selectivity.…”

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confidence: 99%

Iron-Catalyzed Oxyfunctionalization of Aliphatic Amines at Remote Benzylic C–H Sites

et al. 2016

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We report the development of an iron-catalyzed method for the selective oxyfunctionalization of C(sp3)–H bonds in aliphatic amine substrates. This transformation is highly selective for benzylic C–H bonds that are remote (i.e., at least 3-carbons) from the amine functional group. High site selectivity is achieved by in situ protonation of the amine with trifluoroacetic acid, which deactivates more traditionally reactive C–H sites that are α-to nitrogen. The scope and synthetic utility of this method are demonstrated via the synthesis and derivatization of a variety of amine-containing biologically active molecules.

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confidence: 99%

Iron-Catalyzed Oxyfunctionalization of Aliphatic Amines at Remote Benzylic C–H Sites

et al. 2016

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“…( C ) Cycloheximine derivative (+)-260 is oxidized at C19–H, which is furthest away from the multiple EWGs of the molecule. 234 …”

Section: Figurementioning

confidence: 99%

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

2017

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The application of small molecules as catalysts for the diversification of natural product scaffolds is reviewed. Specifically, principles that relate to the selectivity challenges intrinsic to complex molecular scaffolds are summarized. The synthesis of analogs of natural products by this approach is then described as a quintessential “late-stage functionalization” exercise wherein natural products serve as the lead scaffolds. Given the historical application of enzymatic catalysts to the site-selective alteration of complex molecules, the focus of this review is on the recent studies of non-enzymatic catalysts. Reactions involving hydroxyl group derivatization with a variety of electrophilic reagents are discussed. C–H bond functionalizations that lead to oxidations, aminations, and halogenations are also presented. Several examples of site-selective olefin functionalizations and C–C bond formations are also included. Numerous classes of natural products have been subjected to these studies of site-selective alteration including polyketides, glycopeptides, terpenoids, macrolides, alkaloids, carbohydrates and others. What emerges is a platform for chemical remodeling of naturally occurring scaffolds that targets virtually all known chemical functionalities and microenvironments. However, challenges for the design of very broad classes of catalysts, with even broader selectivity demands (e.g., stereoselectivity, functional group selectivity, and site-selectivity) persist. Yet, a significant spectrum of powerful, catalytic alterations of complex natural products now exists such that expansion of scope seems inevitable. Several instances of biological activity assays of remodeled natural product derivatives are also presented. These reports may foreshadow further interdisciplinary impacts for catalytic remodeling of natural products, including contributions to SAR development, mode of action studies, and eventually medicinal chemistry.

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“…Within the range of practically promising catalyst systems studied, the Mn-aminopyridine catalysts (1) are used in very small amount (0.1 mol %; structurally similar Fe complexes are typically used in up to 15 mol % loadings [29][30][31][32][33][34]); (2) require a small (1.3 equiv.) excess of the green oxidant-commercially available 30% aqueous H 2 O 2 ; and (3) exhibit reasonably high yields in the oxidation of differently p-substituted cumenes, ensuring high cumyl alcohol selectivity [86].…”

Section: Initially Costas and Co-workers Reported That Complexes [(Mmentioning

confidence: 99%

“…First examples of non-heme-Fe-catalyzed oxidations appeared in early 1990s [24,28]; however, the breakthrough was achieved after 2007, when White with co-workers contributed a series of milestone works, presenting the bipyrrolidine-derived non-heme iron catalyst 1 ( Figure 1) and its structural analogs, ensuring reasonably high level of predictability in the selective oxidation of C(sp 3 )-H groups [29][30][31][32][33][34]. In competitive contribution, Costas and co-workers showed that the introduction of additional steric crowd at the pyridine moieties, as well as manipulating with the symmetry of the chiral ligand can divert the oxidation selectivity from 3° C(sp 3 )-H bonds to stronger 2° C(sp 3 )-H bonds, which is critical for the selective oxygenation of complex molecules such as natural products [35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

2016

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Non-heme iron(II) complexes are widespread synthetic enzyme models, capable of conducting selective C-H oxidation with H 2 O 2 in the presence of carboxylic acid additives. In the last years, structurally similar manganese(II) complexes have been shown to catalyze C-H oxidation with similarly high selectivity, and with much higher efficiency. In this mini-review, recent catalytic and mechanistic data on the selective C-H oxygenations with H 2 O 2 in the presence of manganese complexes are overviewed. A distinctive feature of catalyst systems of the type Mn complex/H 2 O 2 /carboxylic is the existence of two alternative reaction pathways (as found for the oxidation of cumenes), one leading to the formation of alcohol, and the other to ester. The mechanisms of formation of the alcohol and the ester are briefly discussed.

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Remote Oxidation of Aliphatic C–H Bonds in Nitrogen-Containing Molecules

Cited by 181 publications

References 29 publications

Iron-Catalyzed Oxyfunctionalization of Aliphatic Amines at Remote Benzylic C–H Sites

Iron-Catalyzed Oxyfunctionalization of Aliphatic Amines at Remote Benzylic C–H Sites

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

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