Asymmetric Michael addition reactions of chiral Ni(II)-complex of glycine with (N-trans-enoyl)oxazolidines: improved reactivity and stereochemical outcome
摘要:
Application of the (N-trans-enoyl)oxazolidines as Michael acceptors in the kinetically controlled additions with a Ni(II)-complex of the chiral Schiff base of glycine with (S)-o-[N-(N-benzylprolyl)amino]benzophenone 1 was shown to be synthetically advantageous over the alkyl enoylates, allowing for remarkable improvement in reactivity and, in most cases, diastereoselectivity of the reactions. While the stereochemical outcome of the Michael additions of the aliphatic (N-trans-enoyl)oxazolidines with complex 1 depended on the steric bulk of the alkyl group on the starting oxazolidines, the diastereoselectivity of the aromatic (N-trans-enoyl)oxazolidines reactions was found to be controlled by the electronic properties of the aryl ring. In particular, the additions of complex 1 with (N-cinnamoyl)oxazolidines, bearing electron-withdrawing substituents on the phenyl ring, afforded the (2S,3R)configured products with synthetically useful selectivity and in quantitative chemical yield, thus allowing an efficient access to sterically constrained beta-substituted pyroglutamic acids and related compounds. (C) 1999 Elsevier Science Ltd. All rights reserved.
作者:Wayne Vuong、Fabricio Mosquera-Guagua、Randy Sanichar、Tyler R. McDonald、Oliver P. Ernst、Lei Wang、John C. Vederas
DOI:10.1021/acs.orglett.9b04216
日期:2019.12.20
Spin-labeled aminoacids (SLAAs) are often used to determine intermolecular distances and conformations in proteins via double electron-electron resonance. Currently available SLAAs can be difficult to incorporate selectively and have little resemblance to natural side chains in proteins. Enantioselective synthesis of three spin-labeled l-amino acids is described, starting from readily available 2
Rational Design and Synthesis of Modified Teixobactin Analogues: In Vitro Antibacterial Activity against <i>Staphylococcus aureus</i>
, <i>Propionibacterium acnes</i>
and <i>Pseudomonas aeruginosa</i>
作者:Vivian Ng、Sarah A. Kuehne、Weng C. Chan
DOI:10.1002/chem.201801423
日期:2018.6.26
Extensive antimicrobial susceptibility assessment against a panel of clinically relevant Staphylococcus aureus and Propionibacterium acnes strains led to the identification of the new lead compound, [Arg(Me)10,Nle11]teixobactin, with an excellent bactericidal activity (minimum inhibitory concentration (MIC)=2–4 μg mL−1). Significantly, the antimicrobialactivity of several of the teixobactin analogues against
[EN] NOVEL CYCLIC BORONATE INHIBITORS OF HCV REPLICATION<br/>[FR] NOUVEAUX INHIBITEURS DE BORONATE CYCLIQUES DE RÉPLICATION DU VIRUS DE L'HÉPATITE C
申请人:SMITHKLINE BEECHAM CORP
公开号:WO2009046098A1
公开(公告)日:2009-04-09
Compounds of formula (I) or a salt thereof are provided; wherein R1, R2, R3, R4, R6, R8, R20, R30, Y, Z and n are as defined in the description. Uses of the compounds as medicaments, and in the manufacture of medicaments for treating viral infection, especially HCV infection are also disclosed. The invention further comprises processes to make these compounds and pharmaceutical formulations thereof.
Total Synthesis of the Cyclic Depsipeptide YM-280193, a Platelet Aggregation Inhibitor
作者:Harveen Kaur、Paul W. R. Harris、Peter J. Little、Margaret A. Brimble
DOI:10.1021/ol503507g
日期:2015.2.6
first total synthesis of YM-280193, a cyclic depsipeptide that inhibits the ADP-induced aggregation of human platelets, is described. The monomer and dipeptide fragments were prepared using conventional chemistry and subsequently assembled by Fmoc-solid-phase peptide synthesis (Fmoc-SPPS). A late-stage novel bis-alkylation–elimination of cysteine on-resin was employed to introduce the unnatural N-methyldehydroalanine
Electrochemically Deprotonated Chiral Nickel(II) Glycinate in Stereoselective Nucleophilic Addition to Michael Acceptors: Advantages and Limitations
作者:Tatiana V. Magdesieva、Oleg A. Levitskiy、Yuri K. Grishin、Asmik A. Ambartsumyan、Mikhail A. Kiskin、Andrei V. Churakov、Konstantin K. Babievsky、Konstantin A. Kochetkov
DOI:10.1021/om500070n
日期:2014.9.22
the application of electrochemical techniques is the possibility of precise control of the concentration of a base and its in situ reaction with the complex. This opens up the possibility to carry out further functionalization of the anionic adduct formed in Michael addition via a successive one-pot reaction with the other electrophile. A one-pot cascade reaction of electrochemically deprotonated Ni(II)