Solvent-free synthesis of some ethyl arylglyoxylates

Xiang, Ji Ming; Li, Bao Lin

doi:10.1016/j.cclet.2008.10.003

Cited by 8 publications

(1 citation statement)

References 13 publications

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“…One involves the coupling of an organometallic reagent with ethyl chlorooxoacetate, but the drawback is that the commonly used organometallic reagents such as Grignard reagents are too reactive so the reaction has to be performed at very low temperatures or side products may be expected. The other is through the Friedel–Crafts acylation reaction of arenes with ethyl chlorooxoacetate. − This method suffers from a limited substrate scope because of issues of reactivity and selectivity associated with Friedel–Crafts acylation and the use of excess amounts of strong Lewis acids. A potentially more attractive method is the transition metal-catalyzed C–H acylation reaction with ethyl chlorooxoacetate as the acylating reagent.…”

Section: Introductionmentioning

confidence: 99%

Introducing an α-Keto Ester Functional Group through Pt-Catalyzed Direct C–H Acylation with Ethyl Chlorooxoacetate

et al. 2020

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Platinum-catalyzed selective C–H acylation of 2-aryloxypyridines with ethyl chlorooxoacetate provides an efficient way of introducing an α-keto ester functional group. The reaction is oxidant-free, additive-free, and, more significantly, free of any decarbonylative side reactions. The reaction tolerates a variety of substituents from strongly electron-donating to strongly electron-withdrawing groups. Double acylation is feasible for 2-phenoxypyridine and its derivatives with only one substituent at the para position. Although the reaction of 2-(2-methylphenoxy)pyridine with ethyl malonyl chloride did not produce the desired β-keto ester, the reaction with ethyl succinyl chloride proceeded smoothly to give the γ-keto ester. Ethyl chlorooxoacetate is much more reactive than ethyl succinyl chloride in this Pt-catalyzed C–H acylation reaction.

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Section: Introductionmentioning

confidence: 99%

Introducing an α-Keto Ester Functional Group through Pt-Catalyzed Direct C–H Acylation with Ethyl Chlorooxoacetate

et al. 2020

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ChemInform Abstract: Solvent‐Free Synthesis of Some Ethyl Arylglyoxylates.

Xiang

2009

ChemInform

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The Stereoselective Synthesis of 2‐Aryl‐2‐hydroxybutanoic Acid via Menthyl Chiral Auxiliaries

Xiang

2010

Helvetica Chimica Acta

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In the presence of titanium(IV) tetraethoxide ((EtO) 4 Ti), menthyl arylglyoxylates are prepared by transesterification of ethyl arylglyoxylates and natural (À)-(1R,2S,5R)-menthol. Using menthyl as a chiral auxiliary, the corresponding novel (R)-menthyl 2-aryl-2-hydroxybutanoates are synthesized by the addition of Et 2 Zn with menthyl arylglyoxylates. The structures of the products are characterized by IR and 1 H-and 13 C-NMR spectroscopy, mass spectrometry, and elemental analysis. The diastereoselectivities are analyzed by HPLC. The addition reactions are completed with good yields and high diastereoisomeric excess (de up to 95%), and, after hydrolysis, the (R)-2-aryl-2-hydroxybutanoic acids are obtained with high optical purities.Introduction. -The synthesis of chiral a-hydroxy compounds by the asymmetric addition of organometallics to aldehydes and ketones have extensively been reported [1]. We anticipate that a-keto esters will display a reactive intermediate similar to that of aldehydes and ketones [2]. Furthermore, the resultant a-alkyl-a-hydroxy esters are amenable to derivatization and useful starting components for the synthesis of pharmaceutical agents and natural products [3]. Diastereoselective addition of organometallic reagents to a-keto esters by means of a chiral auxiliary is a methodology to obtain chiral tertiary a-hydroxy carboxylic acids. Among various chiral auxiliaries employed for the stereoselective synthesis of tertiary alcohols, molecules based on a cyclohexane frame such as menthol (¼ 5-methyl-2-(1-methylethyl)cyclohexanol) are powerful, because they provide a higher asymmetric effect, and they are readily accessible natural products. Using menthol as the chiral auxiliary provides many advantages such as low cost, availability, good selectivity, and a tendency of intermediates to be crystalline [4].Here, we present a novel stereoselective synthesis of tertiary a-hydroxy carboxylic acids. First, ethyl arylglyoxylates (¼ 2-aryl-2-oxoacetates) were synthesized as described in the literature [5] [6]. Subsequently, the (À)-menthyl (¼ 5-methyl-2-(1-methylethyl)cyclohex-1-yl) arylglyoxylates were prepared by transesterification conditions with a catalyst of (EtO) 4 Ti. Finally, the diastereoselective addition to (À)-menthyl aketo esters employed organozinc or Grignard reagents to afford the a-hydroxy esters. The esters were saponified to afford the chiral tertiary a-hydroxy carboxylic acids. The synthetic route is illustrated in Scheme 1.

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Solvent-free synthesis of some ethyl arylglyoxylates

Cited by 8 publications

References 13 publications

Introducing an α-Keto Ester Functional Group through Pt-Catalyzed Direct C–H Acylation with Ethyl Chlorooxoacetate

Introducing an α-Keto Ester Functional Group through Pt-Catalyzed Direct C–H Acylation with Ethyl Chlorooxoacetate

ChemInform Abstract: Solvent‐Free Synthesis of Some Ethyl Arylglyoxylates.

The Stereoselective Synthesis of 2‐Aryl‐2‐hydroxybutanoic Acid via Menthyl Chiral Auxiliaries

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