Cost efficient synthesis of amides from oximes with indium or zinc catalysts

Allen, C. M. Van; Burel, Céline; Williams, Jonathan M. J.

doi:10.1016/j.tetlet.2010.03.048

Cited by 94 publications

(36 citation statements)

References 36 publications

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“…This is highlighted in the work reported by Mizuno, [6] Nolan [7] and our own group [8,9] (Scheme 1). Mizuno and co-workers reported a reusable supported rhodium hydroxide catalyst to work in this reaction in aqueous conditions, followed later by Nolan and co-workers reporting a gold/silver co-catalyzed reaction proceeding under solvent-free conditions.…”

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confidence: 64%

Mechanistic Studies into Metal‐Catalyzed Aldoxime to Amide Rearrangements

et al. 2011

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The metal-catalyzed rearrangement of aldoximes into primary amides is a completely atom economical synthetic method for the preparation of one of the most important functional groups in chemistry. There have been several reports of various metals successfully catalyzing this reaction, however, there are conflicting views as to the mechanism involved. Herein we report new experimental evidence to support the mechanism and whether this is universal to all catalysts reported or metal specific. We also describe our further studies into the mechanism of the nickel-catalyzed acylation of amines with aldoximes.Keywords: aldoximes; amides; mechanism; rearrangement The efficient synthesis of amide bonds is of great importance in both research and industrial chemistry due to the prevalence of this group in biologically active molecules, agrochemicals and polymer chemistry.[1] The metal-catalyzed rearrangement of aldoximes into primary amides offers a completely atom economical synthesis of this important chemical moiety. This reaction can also be run from the aldehyde oxidation level with the formation of the aldoxime occurring in situ when mixed with hydroxylamine.The first catalytic conditions for this rearrangement were reported by Chang and co-workers in 2003. [2] They found that Wilkinsons complex (at a catalyst loading of 5 mol%) efficiently catalyzed the conversion of a range of aldoximes into their corresponding primary amides at a temperature of 150 8C. Following this initial publication, reports of iridium, [3] ruthenium [4] and palladium [5] catalysts performing the rearrangement appeared in the literature detailing procedures at lower temperatures.Research efforts have more recently been focussed towards finding lower cost metal catalysts and procedures that can be run in the absence of undesirable organic solvents. This is highlighted in the work reported by Mizuno, [6] Nolan [7] and our own group [8,9] (Scheme 1). Mizuno and co-workers reported a reusable supported rhodium hydroxide catalyst to work in this reaction in aqueous conditions, followed later by Nolan and co-workers reporting a gold/silver co-catalyzed reaction proceeding under solvent-free conditions. We have shown that relatively inexpensive copper, zinc and indium salts are as effective as the precious transition metals at catalyzing aldoxime rearrangements. It has been proposed that the mechanism for this metal-catalyzed rearrangement proceeds via a discrete nitrile intermediate which is formed through dehydration of a coordinated oxime species. This is supported by the frequent detection of a small quantity of nitrile by-product on analysis of the crude reaction Scheme 1. Recently reported conditions for aldoxime rearrangements into primary amides.

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Mechanistic Studies into Metal‐Catalyzed Aldoxime to Amide Rearrangements

et al. 2011

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“…Other studies (e.g., ref. [21][22][23][24] have also reported varying degrees of success at utilising alternatives to precious metal catalysts. Potential PGM substitutes (outer ring) by major application (inner ring).…”

Section: Lower Substitute Performancementioning

confidence: 99%

Limitations to elemental substitution as exemplified by the platinum-group metals

Nassar

2015

Green Chem.

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Limitations to elemental substitution as exemplified by the platinum-group metals † N. T. Nassar Substitution is often touted as a potential solution to concerns regarding material supply restrictions, yet the degree to which substitution can abate these concerns has not been fully explored. This article examines the issue of elemental substitution by identifying potential substitutes for the platinum-group metals (PGMs) and highlighting factors that may limit substitution in each of their major commercial applications. The findings suggest that substitution is often not possible or is impractical due to various technical and economic reasons. When suitable substitutes are available they are often other PGMs or elements in close proximity to the PGMs on the periodic table, namely Ni, Co, and Au. In several cases, however, substitution has already occurred and further substitution may not be possible. Furthermore, the co-production of PGMs and their most promising potential substitutes from the same mineral deposits limits their ability to substitute for one another in the event of a supply disruption. The combination of these factors suggests that PGM substitution potential for current high-volume applications is limited and that further efforts are needed to develop new technologies that avoid the use of PGMs in order to significantly decrease our reliance on them in the future. † Electronic supplementary information (ESI) available. See

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“…1 Under the optimized set of reaction conditions, different ketoximes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) having varying structural features were reacted with TA to afford corresponding amides in excellent yields via Beckmann rearrangement. 1 Under the optimized set of reaction conditions, different ketoximes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) having varying structural features were reacted with TA to afford corresponding amides in excellent yields via Beckmann rearrangement.…”

Section: Resultsmentioning

confidence: 99%

Highly efficient synthesis of amides from ketoximes using trifluoromethanesulphonic anhydride

Kalkhambkar

Savanur

2015

RSC Adv.

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Trifluoromethanesulphonic anhydride (triflic anhydride: TA) has been successfully used as a reagent for Beckmann rearrangement in the conversion of a variety of ketoximes into amides without any additive or base. This reagent works well for the synthesis of a library of amides with excellent yields.a Reaction carried out using compound 12a (2.0 mmol) and Triic anhydride (2.0 mmol) in 5 mL of solvent, unless otherwise stated. b Conversion (%) of product based on GC analysis. c Isolated yield of pure product. d Reaction time in reux condition. e Conversion (%) of product in reux condition. f Isolated yield of pure product in reux condition. g Not isolated.This journal is

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Cost efficient synthesis of amides from oximes with indium or zinc catalysts

Cited by 94 publications

References 36 publications

Mechanistic Studies into Metal‐Catalyzed Aldoxime to Amide Rearrangements

Mechanistic Studies into Metal‐Catalyzed Aldoxime to Amide Rearrangements

Limitations to elemental substitution as exemplified by the platinum-group metals

Highly efficient synthesis of amides from ketoximes using trifluoromethanesulphonic anhydride

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