87694-50-6Relevant articles and documents
A Flavin-Dependent Decarboxylase-Dehydrogenase-Monooxygenase Assembles the Warhead of α,β-Epoxyketone Proteasome Inhibitors
Zabala, Daniel,Cartwright, Joshua W.,Roberts, Douglas M.,Law, Brian J. C.,Song, Lijiang,Samborskyy, Markiyan,Leadlay, Peter F.,Micklefield, Jason,Challis, Gregory L.
, p. 4342 - 4345 (2016)
The α,β-epoxyketone proteasome inhibitor TMC-86A was discovered as a previously unreported metabolite of Streptomyces chromofuscus ATCC49982, and the gene cluster responsible for its biosynthesis was identified via genome sequencing. Incorporation experiments with [13C-methyl]l-methionine implicated an α-dimethyl-β-keto acid intermediate in the biosynthesis of TMC-86A. Incubation of the chemically synthesized α-dimethyl-β-keto acid with a purified recombinant flavin-dependent enzyme that is conserved in all known pathways for epoxyketone biosynthesis resulted in formation of the corresponding α-methyl-α,β-epoxyketone. This transformation appears to proceed via an unprecedented decarboxylation-dehydrogenation-monooxygenation cascade. The biosynthesis of the TMC-86A warhead is completed by cytochrome P450-mediated hydroxylation of the α-methyl-α,β-epoxyketone.
Synthesis and Structure-Activity Relationship of Xenocoumacin 1 and Analogues as Inhibitors of Ribosomal Protein Synthesis
Zumbrunn, Cornelia,Krüsi, Daniela,Stamm, Christina,Caspers, Patrick,Ritz, Daniel,Rueedi, Georg
supporting information, p. 891 - 897 (2020/12/15)
Ribosomal protein synthesis is an important target in antibacterial drug discovery. Numerous natural products have served as starting points for the development of antibiotics. We report here the total synthesis of xenocoumacin 1, a natural product that binds to 16S ribosomal RNA at a highly conserved region, as well as analogues thereof. Preliminary structure–activity relationship studies were aimed at understanding and modulating the selectivity between eukaryotic and prokaryotic ribosomes. Modifications were mainly tolerated in the aromatic region. Whole-cell activity against Gram-negative bacteria is limited by efflux and penetration, as demonstrated in genetically modified strains of E. coli. Analogues with high selectivity for eukaryotic ribosomes were identified, but it was not possible to obtain inhibitors selective for bacterial protein synthesis. Achieving high selectivity (albeit not the desired one) was thus possible despite the high homology between eukaryotic and prokaryotic ribosomes in the binding region.
Probing α-Amino Aldehydes as Weakly Acidic Pronucleophiles: Direct Access to Quaternary α-Amino Aldehydes by an Enantioselective Michael Addition Catalyzed by Br?nsted Bases
García-Urricelqui, Ane,de Cózar, Abel,Mielgo, Antonia,Palomo, Claudio
supporting information, p. 2483 - 2492 (2020/12/25)
The high tendency of α-amino aldehydes to undergo 1,2-additions and their relatively low stability under basic conditions have largely prevented their use as pronucleophiles in the realm of asymmetric catalysis, particularly for the production of quaternary α-amino aldehydes. Herein, it is demonstrated that the chemistry of α-amino aldehydes may be expanded beyond these limits by documenting the first direct α-alkylation of α-branched α-amino aldehydes with nitroolefins. The reaction produces densely functionalized products bearing up to two, quaternary and tertiary, vicinal stereocenters with high diastereo- and enantioselectivity. DFT modeling leads to the proposal that intramolecular hydrogen bonding between the NH group and the carbonyl oxygen atom in the starting α-amino aldehyde is key for reaction stereocontrol.
