Enantioselective Addition of Ketene Silyl Acetals to Nitrones Catalyzed by Chiral Titanium Complexes. Synthesis of Optically Active <i>β</i>-Amino Acids

Murahashi, Shun‐Ichi; Imada, Yasushi; Kawakami, Toru; Harada, Kazuhito; Yonemushi, Yoshiharu; Tomita, Naomi

doi:10.1021/ja0176649

Cited by 89 publications

(31 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…33 The first catalytic enantioselective addition of silyl ketene acetals to nitrones was achieved by using a complex formed from titanium isopropoxide, (S)-BINOL and 4-tert-butylcatechol (26). 57 By employing this catalyst, the S-enantiomer of the product was formed predominantly. Interestingly, replacement of the catechol unit in the catalyst by the D-mannitol derivative 27 created a complex containing two chiral ligands that promotes the reaction which afforded the R-enantiomer of the adduct preferentially (Scheme 11).…”

Section: Methodsmentioning

confidence: 99%

Mannich-Type Reactions of Nitrones, Oximes, and Hydrazones

Merino¹,

Tejero²

2011

Synlett

View full text Add to dashboard Cite

Mannich-type reactions with nitrones, oximes, and hydrazones provide efficient approaches to b-amino carbonyl derivatives with nitrogen functionality existing in an intermediate oxidation state, as in the cases of hydroxylamine and hydrazine derivatives. By employing chiral substrates and catalysts enantiomerically pure substances can be prepared by using these processes. 1 Introduction 2 Mannich-Type Reactions with Nitrones 2.1 Metal Enolates 2.2 Silyl Ketene Acetals 3 Mannich-Type Reactions with Oximes 4 Mannich-Type Reactions with Hydrazones 5 Concluding Remarks

show abstract

Section: Methodsmentioning

confidence: 99%

Mannich-Type Reactions of Nitrones, Oximes, and Hydrazones

Merino¹,

Tejero²

2011

Synlett

View full text Add to dashboard Cite

show abstract

“…The higher stability of ␤-amino acid peptides against peptidases also has drawn great interest in peptide chemistry (16). The significance of ␤-amino acids and their related molecules attracts increasing attention for the synthesis of ␤-amino acids (5,37,38,41), especially for the enantioselective synthesis of ␤-amino acids (26,28,30,40). Although recent reviews of the biocatalytic synthesis of ␤-amino acids elaborated a wide range of approaches, most of the methods dealt with the chiral resolution of precursors using hydrolytic enzymes (29).…”

mentioning

confidence: 99%

Cloning and Characterization of a Novel β-Transaminase fromMesorhizobiumsp. Strain LUK: a New Biocatalyst for the Synthesis of Enantiomerically Pure β-Amino Acids

Kim

Kyung

Yun

et al. 2007

Appl Environ Microbiol

View full text Add to dashboard Cite

A novel ␤-transaminase gene was cloned from Mesorhizobium sp. strain LUK. By using N-terminal sequence and an internal protein sequence, a digoxigenin-labeled probe was made for nonradioactive hybridization, and a 2.5-kb gene fragment was obtained by colony hybridization of a cosmid library. Through Southern blotting and sequence analysis of the selected cosmid clone, the structural gene of the enzyme (1,335 bp) was identified, which encodes a protein of 47,244 Da with a theoretical pI of 6.2. The deduced amino acid sequence of the ␤-transaminase showed the highest sequence similarity with glutamate-1-semialdehyde aminomutase of transaminase subgroup II. The ␤-transaminase showed higher activities toward D-␤-aminocarboxylic acids such as 3-aminobutyric acid, 3-amino-5-methylhexanoic acid, and 3-amino-3-phenylpropionic acid. The ␤-transaminase has an unusually broad specificity for amino acceptors such as pyruvate and ␣-ketoglutarate/ oxaloacetate. The enantioselectivity of the enzyme suggested that the recognition mode of ␤-aminocarboxylic acids in the active site is reversed relative to that of ␣-amino acids. After comparison of its primary structure with transaminase subgroup II enzymes, it was proposed that R43 interacts with the carboxylate group of the ␤-aminocarboxylic acids and the carboxylate group on the side chain of dicarboxylic ␣-keto acids such as ␣-ketoglutarate and oxaloacetate. R404 is another conserved residue, which interacts with the ␣-carboxylate group of the ␣-amino acids and ␣-keto acids. The ␤-transaminase was used for the asymmetric synthesis of enantiomerically pure ␤-aminocarboxylic acids. (3S)-Amino-3-phenylpropionic acid was produced from the ketocarboxylic acid ester substrate by coupled reaction with a lipase using 3-aminobutyric acid as amino donor.

show abstract

“…17 The catalytic asymmetric synthesis of optically active b-amino ester derivatives from benzyl nitrones and silicon enolates is reported. 18 This reaction is catalyzed by a chiral Ti(IV) complex, which is prepared from Ti(O i Pr) 4 , (S)-BINOL, and achiral phenols, to afford the desired adducts in high yields and enantioselectivities. Interestingly, the absolute configuration of the products are changed by additional achiral phenols.…”

Section: Use Of 22mentioning

confidence: 99%