- Evaluation of the Synthetic Potential of an AHBA Knockout Mutant of the Rifamycin Producer Amycolatopsis mediterranei
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Supplementing an AHBA(-) mutant strain of Amycolatopsis mediterranei, the rifamycin producer, with a series of benzoic acid derivatives yielded new tetraketides containing different phenyl groups. These mutasynthetic studies revealed unique reductive properties of A. mediterranei towards nitro- and azidoarenes, leading to the corresponding anilines. In selected cases, the yields of mutaproducts (fermentation products isolated after feeding bacteria with chemically prepared analogs of natural building blocks) obtained are in a range (up to 118 mg L-1) that renders them useful as chiral building blocks for further synthetic endeavors. The configuration of the stereogenic centers at C6 and C7 was determined to be 6R,7S for one representative tetraketide. Importantly, processing beyond the tetraketide stage is not always blocked when the formation of the bicyclic naphthalene precursor cannot occur. This was proven by formation of a bromo undecaketide, an observation that has implications regarding the evolutionary development of rifamycin biosynthesis.
- Bu?yszko, Ilona,Dr?ger, Gerald,Klenge, Anja,Kirschning, Andreas
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supporting information
p. 19231 - 19242
(2016/01/26)
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- Regio- and chemoselective enzymatic N-oxygenation in vivo, in vitro, and in flow
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(Chemical Equation Presented) Action by the para: Evaluation of the nitro-group-forming N-oxygenase AurF in vivo, in vitro, and immobilized as a fusion protein with simply H2O2 as oxidant (peroxide shunt) reveals para-regioselective oxygenation of aromatic amines (see scheme). This effect includes the selective oxygenation of diamino compounds.
- Winkler, Robert,Richter, Martin E. A.,Knuepfer, Uwe,Merten, Dirk,Hertweck, Christian
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p. 8016 - 8018
(2007/10/03)
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- A convenient copper-catalyzed direct animation of nitroarenes with 9-alkylhydroxylamines
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O-Alkylhydroxylamines, particularly O-methylhydroxylamine, aminate nitroarenes in the presence of a strong base and a copper catalyst to give aminonitroarenes in good yields, ortho- or para-Animation with respect to the nitro group takes place, and in some cases the ortho-aminated product is preferentially obtained. With 3-substituted nitrobenzenes where the substituent has a lone pair of electrons, preferential amination occurs at the 2-position to give the sterically most congested 3c-f, 14 and 22g.
- Seko, Shinzo,Miyake, Kunihito,Kavvamura, Norio
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p. 1437 - 1444
(2007/10/03)
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