An inexpensive carbohydrate derivative used as a chiral auxiliary in the synthesis of α-hydroxy carboxylic acids

Yu, Hongwu; Ballard, C. Eric; Boyle, Paul D.; Wang, Binghe

doi:10.1016/s0040-4020(02)00871-2

Cited by 27 publications

(9 citation statements)

References 83 publications

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“…α-Hydroxy or alkoxy acids are biologically important compounds, and they can be used as auxiliaries or synthons for the synthesis of chiral ligands. − However, the methods for preparation of these compounds are limited. Derivatives of mandelic acid or atrolactic acid are generally prepared by oxidation of the α-carbon of α-arylcarbonyl compounds or by reduction of α-dicarbonyl compounds.…”

Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

Hama

Hartwig

2013

J. Org. Chem.

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The intermolecular α-arylation of esters by palladium-catalyzed coupling of aryl bromides with zinc enolates of esters is reported. Reactions of three different types of zinc enolates have been developed. α-Arylation of esters occurs in high yields with isolated Reformatsky reagents, with Reformatsky reagents generated from α-bromo esters and activated zinc, and with zinc enolates generated by quenching lithium enolates of esters with zinc chloride. The use of zinc enolates, instead of alkali metal enolates, greatly expands the scope of the arylation of esters. The reactions occur at room temperature or at 70 °C with bromoarenes containing cyano, nitro, ester, keto, fluoro, enolizable hydrogen, hydroxyl or amino functionality and with bromopyridines. The scope of esters encompasses acyclic acetates, propionates, and isobutyrates, α-alkoxyesters, and lactones. The arylation of zinc enolates of esters was conducted with catalysts bearing the hindered pentaphenylferrocenyl di-tert-butylphosphine (Q-phos) or the highly reactive dimeric Pd(I) complex {[P(t-Bu)3]PdBr}2.

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Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

Hama

Hartwig

2013

J. Org. Chem.

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“…α -Arylation of Acyclic α -Alkoxy Esters. Hydroxy or alkoxy esters are important biological compounds, and much effort has been spent to develop methods to prepare them. − α-Aryl, α-hydroxy esters are an important subset of these compounds, and their synthesis remains challenging . We envisioned the α-arylation of a hydroxy ester derivative as a rapid route to these compounds.…”

Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed Arylation of Trimethylsilyl Enolates of Esters and Imides. High Functional Group Tolerance and Stereoselective Synthesis of α-Aryl Carboxylic Acid Derivatives

2004

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A general procedure for the palladium-catalyzed arylation of trimethylsilyl enolates of esters and imides is reported. In the presence of ZnF2 or Zn(O-t-Bu)2 as an additive, the trimethylsilyl enolates of esters, including those bearing alpha-alkoxy derivatives, underwent arylation in high yield with high functional group tolerance. This arylation chemistry was extended to ester derivatives bearing chiral auxiliaries to form new tertiary stereocenters. The arylation of imides bearing the Evans auxiliary proceeded with selectivities up to 90% de. Further, the arylation of the ketal developed by Ley provided alpha-aryl glycolates with excellent diastereoselectivities (90 to >98% de). This reaction provides a convenient route to the synthesis of enantiopure alpha-aryl-alpha-hydroxy esters. Reactions conducted with Zn(O-t-Bu)2 as an additive occurred at room temperature to give enhanced diastereoselectivities with both chiral reagents. Mechanistic studies showed that the reaction conditions are neutral enough that the observed diastereomeric ratios reflect kinetic selectivities.

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“…Mono-or di-O-isopropylidenated fructopyranoses and fructofuranoses can be suitably modified at unprotected hydroxy groups, affording useful intermediates or starting synthetic blocks for the preparation of various carbohydrate derivatives. Many of them are analogues of significant biologically active compounds (Chery & Murphy, 2004;Izquierdo et al, 2002;Tatibouë t et al, 2000;Furneaux et al, 1993) and are also used for detailed structural studies including X-ray analysis (Yu et al, 2005;Ataie et al, 2000;Yu et al, 2002;Ď urík et al, 2001).…”

Section: Commentmentioning

confidence: 99%

3-O-Benzoyl-1,2-O-isopropylidene-β-D-fructopyranose

et al. 2005

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In the structure of the title compound, C16H20O7, the five‐membered 1,3‐dioxolane ring is disordered with two different positions, A and B (1/1); it adopts the OT4 conformation slightly distorted towards E4 for molecule A, and the 1E conformation distorted towards 1TO for molecule B. The pyranose ring adopts an almost ideal 1C4 conformation. The three‐dimensional packing is stabilized by strong intermolecular O—H⋯O interactions and weak C—H⋯O hydrogen bonds.

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An inexpensive carbohydrate derivative used as a chiral auxiliary in the synthesis of α-hydroxy carboxylic acids

Cited by 27 publications

References 83 publications

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

Palladium-Catalyzed Arylation of Trimethylsilyl Enolates of Esters and Imides. High Functional Group Tolerance and Stereoselective Synthesis of α-Aryl Carboxylic Acid Derivatives

3-O-Benzoyl-1,2-O-isopropylidene-β-D-fructopyranose

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