Amidic resonance not a barrier for transamidation of <i>N</i>-pivaloyl activated amides: catalyst, base and additive free conditions

Rajan, Ida Angel Priya Samuel; Kumar, Rajendran Saravana

doi:10.1039/d3ob00418j

Cited by 6 publications

(2 citation statements)

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“…In our earlier report, we established the single-crystal X-ray structure of N -pivaloylbenzamide. 34 It shows a planar structure and amidic resonance. The amide bond distance, 1.374 Å (Ph(O)C–N) and 1.405 Å ( t Bu(O)C–N), indicates that amidic resonance is slightly inclined towards the Ph(O)C–N bond.…”

Section: Resultsmentioning

confidence: 98%

“…Our group is actively involved in the transamidation and esterification of N -activated amides, and we recently reported the transamidation of planar and resonance stabilized N -pivaloyl activated secondary amides. 34,35 In continuation to our efforts, herein, we present a successfully developed generic, metal-free, and easily implementable catalytic method for the esterification of N -pivaloyl amides through a highly selective N–C(O) bond cleavage under one-pot conditions. After extensive screening, DABCO was found to be an effective catalyst.…”

Section: Introductionmentioning

confidence: 98%

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DABCO-catalyzed esterification of N-pivaloyl-activated amides

Samuel Rajan,

Rajendran

2024

Org. Biomol. Chem.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

DABCO-catalyzed esterification of N-pivaloyl-activated amides

Samuel Rajan,

Rajendran

2024

Org. Biomol. Chem.

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Electron Donor‐Acceptor Complex‐Assisted Photochemical Conversion of O‐2‐Nitrobenzyl Protected Hydroxamates to Amides

Gerogiannopoulou,

Mountanea,

Routsi

et al. 2024

Chemistry A European J

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The hydroxamic acid functionality is present in various medicinal agents and has attracted special interest for synthetic transformations in both organic and medicinal chemistry. The N‐O bond cleavage of hydroxamic acid derivatives provides an interesting transformation for the generation of various products. We demonstrate, herein, that O‐benzyl‐type protected hydroxamic acids may undergo photochemical N–O bond cleavage, in the presence or absence of a catalyst, leading to amides. Although some O‐benzyl protected aromatic hydroxamates may be photochemically converted to amides in the presence of a base and anthracene as the catalyst, employing O‐2‐nitrobenzyl group allowed the smooth conversion of both aliphatic and aromatic hydroxamates to primary or secondary amides in good to excellent yields in the presence of an amine, bypassing the need of a catalyst. DFT and UV‐Vis studies supported the effective generation of an electron donor‐acceptor (EDA) complex between O‐2‐nitrobenzyl hydroxamates and amines, which enabled the successful product formation under these photochemical conditions. An extensive substrate scope was demonstrated, showcasing that both aliphatic or aromatic hydroxamates are compatible with this protocol, affording a wide variety of primary and secondary amides.

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n‐Bu₄NI/K₂S₂O₈‐Mediated C−N Coupling Between Aldehydes and Amides

Liu,

Hee,

Sapir

et al. 2024

Eur J Org Chem

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n‐Bu4NI/K2S2O8‐mediated C‐N coupling between aldehydes and amides is reported. A strong electronic effect is observed on the aromatic aldehyde substrates. The transformylation from aldehyde to amide takes place exclusively when an aromatic aldehyde bears electron‐donating groups at either the ortho or para position of the formyl group, while the cross‐dehydrogenative coupling dominates in the absence of these groups. Both the density functional theory (DFT) thermochemistry calculations and experimental data support the proposed single electron transfer mechanism with the formation of an acyl radical intermediate in the cross‐dehydrogenative coupling. The n‐Bu4NI/K2S2O8 mediated oxidative cyclization between 2‐aminobenzamide and aldehydes is also reported, with four quinazolin‐4(3H)‐ones prepared in 65‐99% yields.

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Amidic resonance not a barrier for transamidation of N-pivaloyl activated amides: catalyst, base and additive free conditions

Abstract: Transamidation of twistless (τ = 4.54° and χN = 6.39°) and resonance stabilized N-pivaloyl activated amide is demonstrated in absence of catalyst, base and additive. The reactivity is comparable/better than...

Cited by 6 publications

References 33 publications

DABCO-catalyzed esterification of N-pivaloyl-activated amides

DABCO-catalyzed esterification of N-pivaloyl-activated amides

Electron Donor‐Acceptor Complex‐Assisted Photochemical Conversion of O‐2‐Nitrobenzyl Protected Hydroxamates to Amides

n‐Bu₄NI/K₂S₂O₈‐Mediated C−N Coupling Between Aldehydes and Amides

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Amidic resonance not a barrier for transamidation of N-pivaloyl activated amides: catalyst, base and additive free conditions

Abstract: Transamidation of twistless (τ = 4.54° and χN = 6.39°) and resonance stabilized N-pivaloyl activated amide is demonstrated in absence of catalyst, base and additive. The reactivity is comparable/better than...

Cited by 6 publications

References 33 publications

DABCO-catalyzed esterification of N-pivaloyl-activated amides

DABCO-catalyzed esterification of N-pivaloyl-activated amides

Electron Donor‐Acceptor Complex‐Assisted Photochemical Conversion of O‐2‐Nitrobenzyl Protected Hydroxamates to Amides

n‐Bu4NI/K2S2O8‐Mediated C−N Coupling Between Aldehydes and Amides

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Product

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n‐Bu₄NI/K₂S₂O₈‐Mediated C−N Coupling Between Aldehydes and Amides