Efficient and Selective Cu/Nitroxyl-Catalyzed Methods for Aerobic Oxidative Lactonization of Diols

Xie, Xiaomin; Stahl, Shannon S.

doi:10.1021/jacs.5b01036

Cited by 143 publications

(99 citation statements)

References 38 publications

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“…Recently we have exploited insights gained from these studies to develop four-electron oxidation reactions, including oxidative lactonization of diols via sequential oxidation of a primary alcohol followed by oxidation of an intermediate hemiacetal, 39 sequential dehydrogenation of primary amines to nitriles, 40 and oxidative coupling of primary alcohols and ammonia to nitriles (Figure 10). 40 These results complement numerous recent contributions by other groups in this area.…”

Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Copper-Catalyzed Aerobic Oxidations of Organic Molecules: Pathways for Two-Electron Oxidation with a Four-Electron Oxidant and a One-Electron Redox-Active Catalyst

2015

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Selective oxidation reactions have extraordinary value in organic chemistry, ranging from the conversion of petrochemical feedstocks into industrial chemicals and polymer precursors to the introduction of heteroatom functional groups into pharmaceutical and agrochemical intermediates. Molecular oxygen (O2) would be the ideal oxidant for these transformations. Whereas many commodity-scale oxidations of simple hydrocarbon feedstocks employ O2 as an oxidant, methods for selective oxidation of more complex molecules bearing diverse functional groups are often incompatible with existing aerobic oxidation methods. The latter limitation provides the basis for our interest in the development of new catalytic transformations and the elucidation of mechanistic principles that underlie selective aerobic oxidation reactions. One challenge inherent in such methods is the incommensurate redox stoichiometry associated with the use of O2, a four-electron oxidant, in reactions that achieve two-electron oxidation of organic molecules. This issue is further complicated by the use of first-row transition-metal catalysts, which tend to undergo facile one-electron redox steps. In recent years, we have been investigating Cu-catalyzed aerobic oxidation reactions wherein the complexities just noted are clearly evident. This Account surveys our work in this area, which has emphasized three general classes of reactions: (1) single-electron-transfer reactions for oxidative functionalization of electron-rich substrates, such as arenes and heterocycles; (2) oxidative carbon-heteroatom bond-forming reactions, including C-H oxidations, that proceed via organocopper(III) intermediates; and (3) methods for aerobic oxidation of alcohols and amines that use Cu(II) in combination with an organic redox-active cocatalyst to dehydrogenate the carbon-heteroatom bond. These reaction classes demonstrate three different pathways to achieve two-electron oxidation of organic molecules via the cooperative involvement of two one-electron oxidants, either two Cu(II) species or Cu(II) and a nitroxyl cocatalyst. They show the ability of Cu to participate in traditional organometallic steps commonly associated with precious-metal catalysts, such as C-H activation and reductive elimination, but also demonstrate the accessibility of reaction steps not typically associated with precious-metal catalysts, such as single-electron transfer. Many of the Cu-catalyzed reactions offer advantages over analogous two-electron oxidation reactions mediated by palladium or other noble metals. For example, carbon-heteroatom oxidative coupling reactions in the first two reaction classes noted above are capable of using O2 as the terminal oxidant, while analogous reactions with Pd commonly require less desirable oxidants, such as hypervalent iodine or electrophilic halogen sources. In addition, the alcohol and amine oxidations in the third reaction class are significantly more efficient and show much broader scope and functional group tolerance than related Pd-catalyzed reactions. Th...

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Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Copper-Catalyzed Aerobic Oxidations of Organic Molecules: Pathways for Two-Electron Oxidation with a Four-Electron Oxidant and a One-Electron Redox-Active Catalyst

2015

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“…Trichloroacetimidates 5 a and 5 b were first chosen as the target donors (Scheme a). Using Stahl's oxidative protocol, 3‐ O ‐benzyl protected allyl mannoside 1 was converted into lactone 2 , in which the C ‐4 hydroxyl group locates at our expected axial or pseudo‐axial position. After acylation, followed by deprotection of allyl group, hemiacetals 4 a and 4 b were prepared successfully.…”

Section: Methodsmentioning

confidence: 99%

“…Starting from the commercially available ethyl‐1‐thio‐α‐ d ‐mannopyranoside 7 , several 2,6‐lactone‐bridged thiomannosyl donors were easily prepared in practical total yields on a gram scale by a 3‐steps strategy. With the treatment of n ‐Bu 2 SnO and benzyl bromide, 7 was first regioselectively benzylated to give 3‐ O ‐benzylmannoside 8 , which was then oxidized to lactone 9 by using Stahl's protocol . The C ‐1 hydroxyl group in 9 was readily to be modified with different protecting agents, affording the desired 2,6‐lactone‐bridged thiomannosyl donors bearing various O ‐4 substituents.…”

Section: Methodsmentioning

confidence: 99%

Stereoselective β‐Mannosylation with 2,6‐Lactone‐bridged Thiomannosyl Donor by Remote Acyl Group Participation

Chen

Zhang

et al. 2019

Chemistry An Asian Journal

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Stereoselective β‐mannosylation has been recognized as one of the greatest challenges of carbohydrate chemistry. Herein, we described a practical method for stereoselective construction of β‐mannosides by using a 2,6‐lactone‐bridged thiomannosyl donor through the remote acyl‐group participation as well as the steric effect of O‐4 substituent. The two effects are enabled through the conversion of a regular mannopyranosyl 4C1 conformation into a 2,6‐lactone bridged conformation. The lactone donor could be readily prepared in three steps on a gram scale and the β‐mannosylation proceeded smoothly with high stereoselectivity for primary, secondary and tertiary alcohol acceptors. In addition, this strategy was successfully applied to the synthesis of a naturally occurring trisaccharide.

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“…3 Similar tactics have been used to oxidize amines to imines 4 or nitriles 5 (Scheme 1B) and for regioselective lactonization of diols. 6 Whereas Cu/TEMPO catalysts have been identified for the oxidative coupling of alcohols and amines to imines 7 or nitriles 8 (Scheme 1C), the highly appealing, complementary transformation involving oxidative coupling of alcohols and amines to carboxamides has been elusive (Scheme 1D). …”

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confidence: 99%

Practical Synthesis of Amides via Copper/ABNO-Catalyzed Aerobic Oxidative Coupling of Alcohols and Amines

2016

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A modular Cu/ABNO catalyst system has been identified that enables efficient aerobic oxidative coupling of alcohols and amines to amides. All four permutations of benzylic/aliphatic alcohols and primary/secondary amines are viable in this reaction, enabling broad access to secondary and tertiary amides. The reactions exhibit excellent functional group compatibility and are complete within 30 min – 3 h at room temperature. All components of the catalyst system are commercially available.

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Efficient and Selective Cu/Nitroxyl-Catalyzed Methods for Aerobic Oxidative Lactonization of Diols

Cited by 143 publications

References 38 publications

Copper-Catalyzed Aerobic Oxidations of Organic Molecules: Pathways for Two-Electron Oxidation with a Four-Electron Oxidant and a One-Electron Redox-Active Catalyst

Copper-Catalyzed Aerobic Oxidations of Organic Molecules: Pathways for Two-Electron Oxidation with a Four-Electron Oxidant and a One-Electron Redox-Active Catalyst

Stereoselective β‐Mannosylation with 2,6‐Lactone‐bridged Thiomannosyl Donor by Remote Acyl Group Participation

Practical Synthesis of Amides via Copper/ABNO-Catalyzed Aerobic Oxidative Coupling of Alcohols and Amines

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