Catalytic, Asymmetric Synthesis of the Carbacephem Framework

Guzzo, Peter R.; Miller, Marvin J.

doi:10.1021/jo00096a031

Cited by 54 publications

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“…Recently, Xue et al [32] performed the synthesis of an enantiomerically pure (R)-b 2 -homoaspartate derivative by a stereoselective alkylation of a Bn-and Z-protected chiral b-homoglycine-oxazolidinone with tert-butyl bromoacetate. In our approach, we started from the commercially available succinic and glutaric anhydrides, which were ring-opened by refluxing in toluene with t BuOH, and catalytic amounts of 4-(dimethylamino)pyridine (DMAP), Et 3 N, and N-hydroxysuccinimide (NHS) [54] to give the monoesters 1 and 2 in 70 and 24% 7 ) yield, respectively (Scheme 2). N-Acylation of the chiral oxazolidinone (R)-DIOZ with the LiCl-activated [55] pivaloyl mixed anhydrides of 1 and 2 gave the desired acyloxazolidinones 3 and 4, respectively, in excellent yields.…”

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confidence: 99%

Enantioselective Preparation of β²‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Lelais

Campo

Kopp

et al. 2004

Helvetica Chimica Acta

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S)-b 2 -Homoamino acids with the side chains of Asp, Glu, Asn, and Gln have been prepared and suitably protected (N-Fmoc, CO 2 t Bu, CONHTrt) for solid-phase peptide syntheses. The key steps of the syntheses are: N-acylation of 5,5-diphenyl-4-isopropyl-1,3-oxazolidin-2-one (DIOZ) with succinic and glutaric anhydrides (Scheme 2), alkylation of the corresponding Li-enolates with benzyl iodoacetate and Curtius degradation (Scheme 4), and removal of the chiral auxiliary (Scheme 5). In addition, numerous functional-group manipulations (CO 2 H > CO 2 t Bu, CO 2 Bn > CO 2 H, CbzNH 3 FmocNH, CO 2 H 3 CO 2 NH 2 3 CONHTrt; Schemes 2, 4, 5, and 6) were necessary, in order to arrive at the four target structures. The configurational assignments were confirmed by X-ray crystal-structure determinations (Scheme 2 and Fig. 3). The enantiomeric purities of a b 2 hAsn and of a b 2 hGln derivative were determined by HPLC on a Chiralcel column to be 99.7 : 0.3 and > 99 : 1, respectively (Fig. 4). Notably, it took up to twelve steps to prepare a suitably protected trifunctional product with a single stereogenic center (overall yield of 10% from DIOZ and succinic anhydride)! Part of the Master Thesis (Diplomarbeit) of S. K., ETH-Z¸rich, 2003. 5 ) With the exceptions of Fmoc-b 3 hHis(Trt)-OH and Fmoc-b 3 hCys(Trt)-OH, all −proteinogenic× b 3 -amino acids, which can be prepared by ArndtÀEistert homologation of the corresponding a-amino acids, are commercially available.compounds for their use in solid-phase b-peptide synthesis is the Fmoc protection of the b-amino group, and the t Bu or Trt protecting group on the side chains. Thus, we thought that 3-acyl-DIOZ derivatives of succinic and glutaric acids could serve as precursors for the corresponding b 2 -homoaspartic and b 2 -homoglutamic acids, respectively. The amino functionality would be introduced either by a diastereoselectiveMannich-type reaction (cf. bond 1 in Fig. 1) or by a carbalkoxymethylation, followed by Curtius degradation (connections 1 2 in Fig. 1), to give the desired amino acid skeleton, which could be further elaborated by protecting-group exchange (Scheme 1). Scheme 1. Retrosynthetic Analysis for the Preparation of the b 2 -Amino Acids with Asx and Glx Side ChainsHelvetica Chimica Acta ± Vol. 87 (2004) 1547 Fig. 2. Target b 2 -amino acid derivatives Scheme 2. Nucleophilic Ring Opening of the Succinic and Glutaric Anhydrides ( 3 1 and 2), N-Acylation of (R)-DIOZ to Form the Acyloxazolidinones 3 and 4, Respectively, and X-Ray-Crystal Structure of 3Helvetica Chimica Acta ± Vol. 87 (2004) 1548 7 ) The reaction was rather messy and the formation of polymerization products were observed.

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confidence: 99%

Enantioselective Preparation of β²‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Lelais

Campo

Kopp

et al. 2004

Helvetica Chimica Acta

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“…The b 3 -amino acid p-nitroanilides 11a and 11b were prepared from 15a and 15b, respectively, as shown in Scheme 3. In particular, the N-Boc protecting groups of 15a and 15b were removed on treatment with trifluoroacetic acid (TFA) and the resulting amine TFA salts were coupled to succinic acid mono-tert-butyl ester, 38,39 in the presence of N-ethyl-N¢-(3-dimethylaminopropyl)carbodiimide (EDCI) and 1-hydroxy-7-azabenzotriazole (HOAt), to give 16a and 16b, respectively. Hydrolysis of the constituent tert-butyl esters with TFA then gave 11a and 11b.…”

Section: Synthesis Of B 3 -Amino Acid Derivativesmentioning

confidence: 99%

Fluorinated β²- and β³-Amino Acids: Synthesis and Inhibition of α-Chymotrypsin

Peddie

Pietsch

Bromfield³

et al. 2010

Synthesis

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The synthesis of a series of a-fluorinated b 2-and b 3-amino acid derivatives is described. Stereoselective fluorination at the a-carbon of the b 3-amino acids was achieved by deprotonation with lithium diisopropylamide followed by treatment with N-fluorobenzenesulfonimide. Fluorination of b 2-amino acids employed the chiral auxiliary (4R)-4-benzyl-2-oxazolidinone. The a-fluorinated amino acids and their non-fluorinated precursors were found to competitively inhibit a-chymotrypsin.

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“…The mixture was stirred at -78 °C for 30 min, then mono-tertbutylsuccinate 39 (1 g, 5.7 mmol) dissolved in 10 mL of THF was added dropwise. The reaction vessel was warmed to 0 °C, stirred at this temperature for two hours, and cooled again to -78 °C before N-(3-bromopropane-1-yl)pyrrole (1.49 g, 7.9 mmol) 40 was added dropwise.…”

Section: Reagents and Materialsmentioning

confidence: 99%

Electrosynthesis and catalytic activity of polymer-nickel particles composite electrode materials

Melki¹,

Zouaoui²,

Bendemagh³

et al. 2009

J. Braz. Chem. Soc.

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Materiais de eletrodo de compostos poliméricos de níquel foram sintetizados a partir da redução eletroquímica de cátions ou complexos de níquel(II), incorporados por troca iônica ou por complexação, em vários tipos de filmes finos de polipirróis carboxilatos que recobriam eletrodos de carbono preparados por eletropolimerização oxidativa. A atividade eletrocatalítica e a estabilidade desses diferentes compostos foram avaliadas pela hidrogenação eletrocatalítica de cetonas e enonas em eletrólitos aquosos. Os melhores resultados foram obtidos usando-se compostos poliméricos de níquel sintetizados pela eletrorredução dos íons níquel(II) complexados em filmes de policarboxilatos, que são caracterizados por uma alta atividade catalítica e uma boa estabilidade operacional.Nickel-polymer composite electrode materials have been synthesized using various strategies, all comprising the electrochemical reduction of nickel(II) cations or complexes, incorporated by either ion-exchange or complexation into various poly(pyrrole-carboxylate) thin films coated by oxidative electropolymerization onto carbon electrodes. The electrocatalytic activity and the stability of the different composites have been then evaluated in the course of the electrocatalytic hydrogenation of ketones and enones in aqueous electrolytes. The best results were obtained using nickel-polymer composites synthesized by electroreduction of nickel(II) ions complexed into polycarboxylate films, which are characterized by a high catalytic activity and a good operational stability.

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Catalytic, Asymmetric Synthesis of the Carbacephem Framework

Cited by 54 publications

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Enantioselective Preparation of β²‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Enantioselective Preparation of β²‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Fluorinated β²- and β³-Amino Acids: Synthesis and Inhibition of α-Chymotrypsin

Electrosynthesis and catalytic activity of polymer-nickel particles composite electrode materials

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Catalytic, Asymmetric Synthesis of the Carbacephem Framework

Cited by 54 publications

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Enantioselective Preparation of β2‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Enantioselective Preparation of β2‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Fluorinated β²- and β³-Amino Acids: Synthesis and Inhibition of α-Chymotrypsin

Electrosynthesis and catalytic activity of polymer-nickel particles composite electrode materials

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Enantioselective Preparation of β²‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains

Enantioselective Preparation of β²‐Amino Acids with Aspartate, Glutamate, Asparagine, and Glutamine Side Chains