The Preparation of O-Phenylcarbamyl Benzohydroxamate Through the Lossen Rearrangement

Stolberg, Marvin A.; Tweit, Robert C.; Steinberg, George M.; Wagner‐Jauregg, Theodor

doi:10.1021/ja01608a074

Cited by 23 publications

(8 citation statements)

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“…[ 34 ] Very recently, different polymers bearing hydroxamate groups have been synthesized, possessing desirable chelating properties and biocompatibility for medical purposes, surface coatings, and material science. [ 35 ] For the Lossen rearrangement, it was assumed that an activating group such as O‐acylating, [ 36 ] O‐silylating, [ 37,38 ] or O‐phosphorylating [ 39 ] agent was necessary for the rearrangement to occur. In 1974, it was commonly known that a hydroxamic acid could rearrange in strongly alkaline solution.…”

Section: Methodsmentioning

confidence: 99%

Fully Renewable Non‐Isocyanate Polyurethanes via the Lossen Rearrangement

Filippi

Meier

2020

Macromol. Rapid Commun.

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In this work, a straightforward and efficient synthesis approach to renewable non‐isocyanate polyurethanes (NIPUs) is described. For this purpose, suitable and renewable carbamate monomers, possessing two double bonds, are synthesized from hydroxamic fatty acid derivatives via the Lossen rearrangement in a one‐step synthesis, and sustainable dithiols are synthesized from dialkenes derived from renewable feedstock (i.e., limonene and 1,4‐cyclohexadiene). Subsequently, the comonomers are polymerized with the highly efficient thiol–ene reaction to produce NIPUs with Mn values up to 26 kg mol−1 bearing thioether linkages. The main side product of the Lossen rearrangement, a symmetric urea, can also be polymerized in the same fashion. Important in the view of sustainability, the monomer mixture can also be used directly, without separation. The obtained polymers are characterized by NMR, attenuated total reflection‐infrared spectroscopy, differential scanning calorimetry, and size exclusion chromatography.

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Section: Methodsmentioning

confidence: 99%

Fully Renewable Non‐Isocyanate Polyurethanes via the Lossen Rearrangement

Filippi

Meier

2020

Macromol. Rapid Commun.

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“…The mixed anhydride has to be either prepared in a separate step or it can be generated in situ. The latter procedure has the disadvantage that the formed isocyanate can react with free hydroxamic acid to yield the corresponding O- carbamoylhydroxamate, which under the heating affords a symmetrically substituted derivative of urea. , Alternative procedures for the Lossen rearrangement avoiding this undesired self-dimerization are based on reactions of hydroxamic acids with dehydrating agents such as dicyclohexylcarbodiimide (DCC) , or carbonyldiimidazole (DCI) …”

Section: Introductionmentioning

confidence: 99%

“…The latter procedure has the disadvantage that the formed isocyanate can react with free hydroxamic acid to yield the corresponding O-carbamoylhydroxamate, which under the heating affords a symmetrically substituted derivative of urea. 3,4 Alternative procedures for the Lossen rearrangement avoiding this undesired self-dimerization are based on reactions of hydroxamic acids with dehydrating agents such as dicyclohexylcarbodiimide (DCC) 5,6 or carbonyldiimidazole (DCI). 7 The simplest approach has been shown recently: The rearrangement of aromatic hydroxamic acids can be easily achieved by heating with a base such as K 2 CO 3 .…”

Section: ■ Introductionmentioning

confidence: 99%

Metal-assisted Lossen Rearrangement

et al. 2012

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A new reaction mechanism for the Lossen rearrangement of hydroxamic acids catalyzed by basic salts is presented. It is shown that the rearrangement proceeds in metal complexes of deprotonated hydroxamic acids. The deprotonation can occur either at the oxygen atom (observed for the zinc complexes) or at the nitrogen atom (observed for the potassium complexes). Both anionic forms are characterized by infrared multiphoton dissociation spectroscopy. The rearrangements proceed from the reactive N-deprotonated metal hydroxamates and lead to metal carbamates. The mechanism is elucidated by computational chemistry, mass-spectrometric studies, and preparative experiments.

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“…There are unshared electron pairs on the atom adjacent to the nucleophilic center of these α‐nucleophiles. The hydrolysis of triester by α‐nucleophiles in different micellar media is a widely studied reaction . It has been observed that cationic micellar media accelerate the reactivity of α‐nucleophiles .…”

Section: Introductionmentioning

confidence: 99%

“…The hydrolysis of triester by a-nucleophiles in different micellar media is a widely studied reaction. [13][14][15][16][17][18][19][20][21][22][23] It has been observed that cationic micellar media accelerate the reactivity of a-nucleophiles. [24][25][26] Kinetic aspect of micellar catalysis [27,28] represents a significant contribution to the observed rate in this case of hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

Comparative studies on reaction of bis(p‐nitrophenyl) phosphate and α‐nucleophiles in cationic micellar media

Kumar

Satnami

Ghosh

et al. 2012

J of Physical Organic Chem

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We studied the cleave of bis(p‐nitrophenyl) phosphate (BNPP) over a pH range of 7.0–12.0 in the presence of cationic micelles of cetyldiethylethanolammonium bromide, cetyldimethylethanolammonium bromide, cetylpyridinium bromide, cetyltrimethylammonium bromide, and cetylpyridinium chloride by using different α‐nucleophiles, viz acetohydroxamate, benzohydroxamate, salicylhydroxamate, butane‐2,3‐dione monooximate, and α‐benzoin oximate ions. With the use of α‐nucleophiles in cationic micellar media, the hydrolytic cleavage of BNPP was found to be approximately 105‐fold faster than its spontaneous hydrolysis. All reactions followed pseudo‐first‐order kinetics. The effect of various concentrations of cationic micelles for the reaction of BNPP and α‐nucleophiles has been studied. The variation of kobs values of the reactions depends on the micellar structure, that is, head groups, hydrophobic tail length, and counter ion. Copyright © 2012 John Wiley & Sons, Ltd.

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The Preparation of O-Phenylcarbamyl Benzohydroxamate Through the Lossen Rearrangement

Cited by 23 publications

References 1 publication

Fully Renewable Non‐Isocyanate Polyurethanes via the Lossen Rearrangement

Fully Renewable Non‐Isocyanate Polyurethanes via the Lossen Rearrangement

Metal-assisted Lossen Rearrangement

Comparative studies on reaction of bis(p‐nitrophenyl) phosphate and α‐nucleophiles in cationic micellar media

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