Discovery of (Dihydro)pyrazine N-Oxides via Genome Mining in Pseudomonas
摘要:
Overexpression of the Pseudomonas virulence factor (pvf) biosynthetic operon led to the identification of a family of pyrazine N-oxides (PNOs), including a novel dihydropyrazine N,N'-dioxide (dPNO) metabolite. The nonribosomal peptide synthetase responsible for production of (d)PNOs was characterized, and a biosynthetic pathway for (d)PNOs was proposed. This work highlights the unique chemistry catalyzed by pvf-encoded enzymes and sets the stage for bioactivity studies of the metabolites produced by the virulence pathway.
Thiocarbonyl Surrogate via Combination of Sulfur and Chloroform for Thiocarbamide and Oxazolidinethione Construction
作者:Wei Tan、Jianpeng Wei、Xuefeng Jiang
DOI:10.1021/acs.orglett.7b00819
日期:2017.4.21
An efficient and practical thiocarbonyl surrogate via combination of sulfur and chloroform has been developed. A variety of thiocarbamides and oxazolidinethiones have been established, including chiral thiourea catalysts and chiral oxazolidinethione auxiliaries with high selectivity. Meanwhile, pesticides Diafenthiuron (an acaricide), ANTU (a rodenticide), and Chloromethiuron (an insecticide) were
<i>N</i>-Chlorosuccinimide-Promoted Oxidative Decarboxylation of α-Amino Acids in Aqueous Alkaline Medium
作者:M. S. Ramachandran、D. Easwaramoorthy、V. Rajasingh、T. S. Vivekanandam
DOI:10.1246/bcsj.63.2397
日期:1990.8
Kinetics of oxidation of twelve α-amino acids (AA) by N-chlorosuccinimide (NClS) in aqueous alkaline media have been studied and compared with those of N-bromosuccinimide (NBS) oxidation. Analysis of the results shows that the observed rate of oxidation is first-order in [oxidant] and zero-order in [substrate]. The rate of oxidation increases with increase in [OH−]free in [NClS], the exception being the amino acids having β-alkyl substituent such as valine, leucine etc. Perusal of the results shows that NC1S/NBS reacts with α-amino acid anion to produce α-amino acyl hypohalite which then decomposes in the rate-determining step to give the products. The intermediate α-amino acyl hypohalite is identified by UV-visible absorption spectra. Glycine behaves differently from other amino acids in both oxidants. The proposed mechanism is consistent with the observed kinetics.
A highly efficient in situ N-acetylation approach for solid phase synthesis
作者:Koushik Chandra、Tapta Kanchan Roy、Johnny N. Naoum、Chaim Gilon、R. Benny Gerber、Assaf Friedler
DOI:10.1039/c3ob42096e
日期:——
We describe a new general N-acetylation method for solid phase synthesis. Malonic acid is used as a precursor and the reaction proceeds by in situ formation of a reactive ketene intermediate at room temperature. We have successfully applied this methodology to peptides and non-peptidic molecules containing a variety of functional groups. The reaction gave high yields compared to known acetylation methods
Discovery of (Dihydro)pyrazine <i>N</i>-Oxides via Genome Mining in <i>Pseudomonas</i>
作者:Ashley M. Kretsch、Gina L. Morgan、Jillian Tyrrell、Emily Mevers、Isabelle Vallet-Gély、Bo Li
DOI:10.1021/acs.orglett.8b01944
日期:2018.8.17
Overexpression of the Pseudomonas virulence factor (pvf) biosynthetic operon led to the identification of a family of pyrazine N-oxides (PNOs), including a novel dihydropyrazine N,N'-dioxide (dPNO) metabolite. The nonribosomal peptide synthetase responsible for production of (d)PNOs was characterized, and a biosynthetic pathway for (d)PNOs was proposed. This work highlights the unique chemistry catalyzed by pvf-encoded enzymes and sets the stage for bioactivity studies of the metabolites produced by the virulence pathway.
Pyrazine alkaloids via dimerization of amino acid-derived α-amino aldehydes: biomimetic synthesis of 2,5-diisopropylpyrazine, 2,5-bis(3-indolylmethyl)pyrazine and actinopolymorphol C
作者:Sandhya Badrinarayanan、Jonathan Sperry
DOI:10.1039/c2ob06935k
日期:——
of amino acid-derived alpha-amino aldehydes provides a short, biomimetic synthesis of several 2,5-disubstituted pyrazine natural products. The alpha-amino aldehyde intermediates were generated in situ by the hydrogenolysis of their Cbz-derivatives. It was found that a judicious choice of reaction solvent facilitated hydrogenolysis, dimerization and oxidation to the natural product in a one-pot operation