Organocatalytic C–H hydroxylation with Oxone<sup>®</sup>enabled by an aqueous fluoroalcohol solvent system

Adams, Ashley M.; Bois, J. Du

doi:10.1039/c3sc52649f

Cited by 61 publications

(38 citation statements)

References 45 publications

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“…Methods for efficient and selective alkyl C–H oxidation could streamline the synthesis of fine chemicals, natural products, and drug metabolites. 1 , 2 Despite rapid advances in the development of metal-catalyzed reactions 3 and reagents, 4 synthetically useful C(sp 3 )–H oxygenation chemistry is still in great demand. 5 , 6 Recently, radical reactions mediated by hypervalent iodine( iii ) reagents have emerged as viable means to oxygenate C(sp 3 )–H bonds under mild conditions.…”

Section: Introductionmentioning

confidence: 99%

A unified photoredox-catalysis strategy for C(sp³)–H hydroxylation and amidation using hypervalent iodine

et al. 2017

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Section: Introductionmentioning

confidence: 99%

A unified photoredox-catalysis strategy for C(sp³)–H hydroxylation and amidation using hypervalent iodine

et al. 2017

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“…Despite this challenge, upon reacting estrone derivative 178 with oxaziridine 179 , Du Bois and coworkers observe oxidation at the C11 methylene (Figure 30K). 212 However, the authors posit that this occurs via initial oxidation of the 3° C9–H bond due to resonance stabilization, followed by elimination to form the C9–C11 alkene. This alkene is subsequently transformed into the C11 ketone.…”

Section: C–h Oxidationmentioning

confidence: 99%

“…, , and orbs represent dominance of electronic, steric, and stereoelectronic factors respectively. 99,200,203–212 …”

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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“…[79] Indeed, the hydroxylation of the CÀHb ond wasa ccomplished by treatment with ac ommerciallya vailable alkyl trifluoromethyl ketone 48 combined with oxone as oxidant(Scheme20). [79] Addition of aw ater/hexafluoroisopropanol (HFIP) mixture as ac osolvent, according to Du Bois'sa pproach, [80] resultsi nd ecreasedr eaction times, expanded substrate scope, and enabled catalytic turnoveru nder conditions closer to the typical conditions for dioxirane-mediatedo xidations (e.g.,o xone/ NaHCO 3 ). Further,t hey also demonstrated that ah ighly valued characteristic of dioxirane reactivity is the full retentiono fs ite selectivity when used for the late-stage oxidation of highly complex, biologically relevant substrates.…”

Section: Site-selective Càhbond Oxyfunctionalization In Total Synthesmentioning

confidence: 99%

“…For example, the CÀ Hh ydroxylation of bile acid derivative 49 produced selective hydroxylation at the tert-C 5 ÀHp osition, which occurred with retention of configuration (Scheme 21). [80] Shortly after,i n1 999, Seto and co-workers reported the synthesis and biological evaluation of other Brassinolide analogs with extra hydroxyl groups at the C 14 and/orC 25 positions by using the same oxidant 1b (Scheme 22). [81] The presence of the ring lactone, in addition to the four acetylg roups, deactivates the steroid ring system,a nd reactivity is observed with TFDO only at the remote C 25 ÀHb ond position, whereas no oxidation is observed at the tertiary C 14 ÀH and C 17 ÀHp ositions, most likely deactivated by remote electron-withdrawing groups or steric effects of the ring system (Scheme 22 A).…”

Section: Site-selective Càhbond Oxyfunctionalization In Total Synthesmentioning

confidence: 99%

Continued Progress towards Efficient Functionalization of Natural and Non‐natural Targets under Mild Conditions: Oxygenation by C−H Bond Activation with Dioxirane

D’Accolti

Annese

Fusco

2019

Chemistry A European J

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The successful isolation and characterization of a dioxirane species in 1988 opened up one of the most attractive methods for the efficient oxidation of simple and/or structurally complex molecules. Dioxirane today rank among the most powerful tools in organic chemistry, with numerous applications in commercially important processes. They were quickly recognized as efficient oxygen transfer agents, especially for epoxidations and for a wide range of O‐insertion reactions into C−H bonds. Dioxirane possess catalytic activity and appear as highly (chemo‐, regio‐, and stereo‐) selective oxidants, despite their reactivity under mild and strictly neutral conditions being controlled by a combination of steric and electronic factors. In this review, we discuss some of the most recent and significant developments in the selective homogeneous and heterogeneous oxyfunctionalization of non‐activated C−H bonds in hydrocarbons of natural and non‐natural targets by using isolated dioxirane or, more generally, by using the ketones (i.e., the dioxirane precursors) as organocatalysts.

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Organocatalytic C–H hydroxylation with Oxone^®enabled by an aqueous fluoroalcohol solvent system

Cited by 61 publications

References 45 publications

A unified photoredox-catalysis strategy for C(sp³)–H hydroxylation and amidation using hypervalent iodine

A unified photoredox-catalysis strategy for C(sp³)–H hydroxylation and amidation using hypervalent iodine

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

Continued Progress towards Efficient Functionalization of Natural and Non‐natural Targets under Mild Conditions: Oxygenation by C−H Bond Activation with Dioxirane

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Organocatalytic C–H hydroxylation with Oxone®enabled by an aqueous fluoroalcohol solvent system

Cited by 61 publications

References 45 publications

A unified photoredox-catalysis strategy for C(sp3)–H hydroxylation and amidation using hypervalent iodine

A unified photoredox-catalysis strategy for C(sp3)–H hydroxylation and amidation using hypervalent iodine

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

Continued Progress towards Efficient Functionalization of Natural and Non‐natural Targets under Mild Conditions: Oxygenation by C−H Bond Activation with Dioxirane

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Organocatalytic C–H hydroxylation with Oxone^®enabled by an aqueous fluoroalcohol solvent system

A unified photoredox-catalysis strategy for C(sp³)–H hydroxylation and amidation using hypervalent iodine

A unified photoredox-catalysis strategy for C(sp³)–H hydroxylation and amidation using hypervalent iodine