On the mechanism of the Dakin–West reaction

Dalla-Vechia, Luciana; Santos, Vanessa G.; Godoi, Marla Narciso; Cantillo, David; Kappe, C. Oliver; Eberlin, Marcos N.; Souza, Rodrigo O. M. A. de; Miranda, Leandro S. M.

doi:10.1039/c2ob26560e

Cited by 10 publications

(1 citation statement)

References 30 publications

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“…It is well known that salicylaldehyde (SA) has much strong luminescence under alkaline condition due to the deprotonation of phenolic hydroxyl group . Furthermore, the aldehyde group of D‐SA can react with OOH − via Dakin reaction, which has been widely applied in organic synthesis and optimization . However, few reports have been developed in luminescence senor.…”

Section: Introductionmentioning

confidence: 99%

Quenching of Salicylaldehyde‐based Luminescence Probe via Dakin Reaction: Approach for Highly Selective Detection of Hydrogen Peroxide

Tan

Yuan

Yin

et al. 2017

Bulletin Korean Chem Soc

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A novel assay for H 2 O 2 based on luminescence quenching is developed from the Dakin reaction between deprotonated salicylaldehyde (D-SA) and H 2 O 2 . Under alkaline condition, the phenolic hydroxyl group of SA is deprotonated, exhibiting good luminescence emission ability (λ ex = 433 nm, λ em = 508 nm). Luminescence of D-SA is quenched by H 2 O 2 in a concentration-dependent manner. Good linearity is obtained with a regression coefficient of 0.9989 in the range of 0.3~150 μM and a detection limit (LOD) is 30 nM. In addition, D-SA luminescence probe shows good biocompatibility and low cytotoxicity to HeLa cells through MTT assay. The feasibility for in vitro applications is demonstrated through confocal laser scanning microscopy.

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Section: Introductionmentioning

confidence: 99%

Quenching of Salicylaldehyde‐based Luminescence Probe via Dakin Reaction: Approach for Highly Selective Detection of Hydrogen Peroxide

Tan

Yuan

Yin

et al. 2017

Bulletin Korean Chem Soc

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From Catalysis to Lewis Base Catalysis with Highlights from 1806 to 1970

Vedejs

2016

Lewis Base Catalysis in Organic Synthesis

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The Enantioselective Dakin–West Reaction

et al. 2016

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Here we report the development of the first enantioselective Dakin-West reaction, yielding a-acetamido methylketones with up to 58 %eewith good yields.T wo of the obtained products were recrystallized once to achieve up to 84 %ee. The employed methylimidazole-containing oligopeptides catalyze both the acetylation of the azlactone intermediate and the terminal enantioselective decarboxylative protonation. We propose ad ispersion-controlled reaction path that determines the asymmetric reprotonation of the intermediate enolate after the decarboxylation.Even though the Dakin-West (DW) reaction dates back to 1928, [1] it is still one of the most effective synthetic procedures to prepare a-acylamido ketones from primary a-amino acids.[2] Generally,t he treatment of an amino acid with an acid anhydride and base,t ypically pyridine,a te levated temperature provides the desired product upon liberation of CO 2 (Scheme 1). Numerous modifications of the original reaction conditions were developed, [2] including catalytic variants, [3] broadening its scope and applicability.U nsurprisingly,the DW reaction found application in the preparation of a-acylamido ketones as valuable precursors for various biologically active compounds, [4] and even in Woodwards fundamental total synthesis of strychnine.[5] Remarkably,n o asymmetric variant has been developed to date,thus restricting the use of this important reaction in modern synthetic chemistry.According to the currently accepted mechanism, [6] the reaction of an amino acid with the anhydride leads to the Nacetyl derivative 1 and subsequently to the mixed anhydride 2 (Scheme 2). Cyclization of 2 provides the oxazol-5(4H)-one (azlactone) 3.S uch azlactones are acidic owing to the formation of resonance stabilized enolate 4 upon deprotonation. Subsequent acetylation may occur at the enolate oxygen atom (affording 5)ordirectly at the carbon atom to give 6. [7] However, 6 is exclusively produced under the typical DW reaction conditions because of concomitant O!Cacyltransfer (Steglich rearrangement).[8] Opening of 6 with acetic acid, formed in previous steps,t ot he mixed anhydride 7 and transacylation gives the b-keto acid 8, [6f] which is prone to decarboxylation upon deprotonation. This final reaction step affords the desired a-acetamido methylketone 10,l ikely via enolate 9.Other pathways,for example,the acylationof2 to directly give 7, [9] were discussed as well but have been shown to be rather improbable.I ti se vident from this mechanistic picture that the intermediacyo f4 and 9 (Scheme 2) leads to the observed complete racemization, making an asymmetric reaction ad ifficult endeavor. We surmized, however, that an enantioselective decarboxylative protonation [10] of 8 (via 9) would afford enantioenriched products.Herein we show that this is indeed possible with at ailor-made catalytic system.We chose synthetic oligopeptides as catalysts [11] as these should be well-suited for binding the amino acid derived intermediates,a sd emonstrated for such platforms in acyl tra...

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On the mechanism of the Dakin–West reaction

Cited by 10 publications

References 30 publications

Quenching of Salicylaldehyde‐based Luminescence Probe via Dakin Reaction: Approach for Highly Selective Detection of Hydrogen Peroxide

Quenching of Salicylaldehyde‐based Luminescence Probe via Dakin Reaction: Approach for Highly Selective Detection of Hydrogen Peroxide

From Catalysis to Lewis Base Catalysis with Highlights from 1806 to 1970

The Enantioselective Dakin–West Reaction

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