Catalytic Asymmetric Synthesis of Unprotected β<sup>2</sup>-Amino Acids
作者:Chendan Zhu、Francesca Mandrelli、Hui Zhou、Rajat Maji、Benjamin List
DOI:10.1021/jacs.1c00249
日期:2021.3.10
Importantly, both aromatic and aliphatic β2-amino acids can be obtained using this method. Mechanistic studies are consistent with the aminomethylation to proceed via silylium-based asymmetriccounteranion-directedcatalysis (Si-ACDC) and a transition state to explain the enantioselectivity is suggested on the basis of density functional theory calculation.
Enantioselective synthesis of β-amino acids. 7. Preparation of enantiopure α-substituted β-amino acids from 1-benzoyl-2(S)-tert-butyl-3-methylperhydropyrimidin-4-one.1,2
Inexpensive natural α-amino acid L-asparagine was efficiently converted to either (R)- or (S)-α-alkylated β-amino acids in enantiomerically pure state. The key intermediate in this protocol is the enantiopure N,N-acetal pyrimidinone (S)-1, a masked chiral derivative of β-alanine.
Hydrogen Bond Enhanced Enantioselectivity in the Nickel-Catalyzed Transfer Hydrogenation of α-Substituted Acrylic Acid with Formic Acid
作者:Yaxin Sun、Chao Wang、Peng Yang、Jie-Yu Yue、Chang Xu、Jianrong Steve Zhou、Bo Tang
DOI:10.1021/acscatal.3c04187
日期:2023.11.3
asymmetric transferhydrogenation of α-substituted acrylic acids under mild conditions and avoided the use of high-pressure hydrogen gas was developed. The products included chiral β-amino acids and α-methyl carboxylic acids such as three nonsteroidal anti-inflammatory profens. Deuterium-labeling experiments and DFT studies pointed to an unconventional protonation of a metalacyclopropane complex formed by
?2- and ?3-Peptides with Proteinaceous Side Chains: Synthesis and solution structures of constitutional isomers, a novel helical secondary structure and the influence of solvation and hydrophobic interactions on folding
作者:Dieter Seebach、Stefan Abele、Karl Gademann、Gilles Guichard、Tobias Hintermann、Bernhard Jaun、Jennifer L. Matthews、J�rg V. Schreiber、Lukas Oberer、Ulrich Hommel、Hans Widmer
DOI:10.1002/hlca.19980810513
日期:——
the previously prepared β-peptides (35–39) showed NH/ND exchange rates (in MeOH at room temperature) with τ1/2 values of up to 60 days, unrivalled by short chain α-peptides. All β-peptides 1–7 were designed to be able to attain the previously described 31-helical structure (Figs. 1 and 2). CD Measurements (Fig. 4), indicating a new secondary structure of certain β-peptides constructed of β2- and β3-amino