- Zn- And Cu-catalyzed coupling of tertiary alkyl bromides and oxalates to forge challenging C?O, C?S, and C?N bonds
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We describe here the facile construction of sterically hindered tertiary alkyl ethers and thioethers via the Zn(OTf)2catalyzed coupling of alcohols/phenols with unactivated tertiary alkyl bromides and the Cu(OTf)2-catalyzed thiolation of unactivated tertiary alkyl oxalates with thiols. The present protocol represents one of the most effective unactivated tertiary C(sp3)? heteroatom bond-forming conditions via readily accessible Lewis acid catalysis that is surprisingly less developed.
- Gong, Yuxin,Zhu, Zhaodong,Qian, Qun,Tong, Weiqi,Gong, Hegui
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supporting information
p. 1005 - 1010
(2021/02/01)
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- Substrate derived peptidic α-ketoamides as inhibitors of the malarial protease PfSUB1
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Peptidic α-ketoamides have been developed as inhibitors of the malarial protease PfSUB1. The design of inhibitors was based on the best known endogenous PfSUB1 substrate sequence, leading to compounds with low micromolar to submicromolar inhibitory activity. SAR studies were performed indicating the requirement of an aspartate mimicking the P1′ substituent and optimal P1-P4length of the non-prime part. The importance of each of the P1-P4amino acid side chains was investigated, revealing crucial interactions and size limitations.
- Kher, Samir S.,Penzo, Maria,Fulle, Simone,Finn, Paul W.,Blackman, Michael J.,Jirgensons, Aigars
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supporting information
p. 4486 - 4489
(2015/02/19)
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- Anthranilimide-based glycogen phosphorylase inhibitors for the treatment of Type 2 diabetes: 2. Optimization of serine and threonine ether amino acid residues
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Optimization of the amino acid residue of a series of anthranilimide-based glycogen phosphorylase inhibitors is described leading to the identification of serine and threonine ether analogs. t-Butylthreonine analog 20 displayed potent in vitro inhibition of GPa, low potential for P450 inhibition, and excellent pharmacokinetic properties.
- Sparks, Steven M.,Banker, Pierette,Bickett, David M.,Clancy, Daphne C.,Dickerson, Scott H.,Garrido, Dulce M.,Golden, Pamela L.,Peat, Andrew J.,Sheckler, Lauren R.,Tavares, Francis X.,Thomson, Stephen A.,Weiel, James E.
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scheme or table
p. 981 - 985
(2009/08/15)
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- Convenient preparations of t-butyl esters and ethers from t-butanol
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A one-pot preparation of t-butyl esters and ethers is described that proceeds from the carboxylic acid or alcohol and t-butanol using only anhydrous magnesium sulfate and catalytic sulfuric acid as additional reagents. The method affords t-butyl esters and ethers in good yields and is applicable to a variety of substrates.
- Wright, Stephen W.,Hageman, David L.,Wright, Ann S.,McClure, Lester D.
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p. 7345 - 7348
(2007/10/03)
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- On the Preparation of β-Amino Acids from α-Amino Acids Using the Arndt-Eistert Reaction: Scope, Limitations and Stereoselectivity. Application to Carbohydrate Peptidation. Stereoselective α-Alkylations of Some β-Amino Acids
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The Arndt-Eistert homologation of α-amino acids was studied to determine the stereoselectivity in this reaction by chromatographic up-to-date analytical methods.While carbamate-protected phenylglycine was transformed to the corresponding β-amino acid methyl ester with a stereoselectivity of only 9:1, all other tested amino acid derivatives (Ala, Phe, Ser, Orn, tert-Leu and perhydro-azepine-2-carboxylic acid, suitably protected) were homologated with full retention of configuration (products 9-17).The intermediate diazo ketones 1-8 were purified and characterized by their NMR spectra.When nucleophiles derived from partially protected sugars were present during decomposition of the diazo ketones (derived from amino acids or dipeptides), a strong dependence of the yield (products 21-24) on the degree of steric hindrance of the nucleophilic OH group was observed.Two of the β-amino acids obtained from the homologation reaction were transformed to α-substituted (25-27, 31, 32) and α,α-disubstituted β-amino acid derivatives (28, 29) with excellent selctivities (in most cases, a single diastereoisomer was obtained). - Key Words: β-Amino acids, α-branched/Glycopeptides
- Podlech, Joachim,Seebach, Dieter
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p. 1217 - 1228
(2007/10/02)
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