Reprogramming of the NRPS/PKS assembly line is an attractive method for the production of new bioactive molecules. However, it is usually hampered by the loss of intimate domain/module interactions required for the precise control of chain transfer and elongation reactions. In this study, we first establish heterologous expression systems of the unique antimycin-type cyclic depsipeptides: JBIR-06 (tri-lactone) and neoantimycin (tetra-lactone), and engineer their biosyntheses by taking advantage of bioinformatic analyses and evolutionary insights.
View Article and Find Full Text PDFA large number of drug efflux transporters have been identified in Salmonella enterica serovar Typhimurium, and increased expression of these transporters confers drug resistance in this organism. Here we compared the respiration activities of the wild-type strain and a mutant with nine deleted transporters by phenotype microarray analysis. The mutant was susceptible to 66 structurally unrelated compounds including many antibiotics, dyes, detergents, antihistamine agents, plant alkaloids, antidepressants, antipsychotic drugs, and antiprotozoal drugs.
View Article and Find Full Text PDFA cobalt complex, [CoCl2(dpph)] (DPPH = [1,6-bis(diphenylphosphino)hexane]), catalyzes an intermolecular styrylation reaction of alkyl halides in the presence of Me3SiCH2MgCl in ether to yield beta-alkylstyrenes. A variety of alkyl halides including alkyl chlorides can participate in the styrylation. A radical mechanism is strongly suggested for the styrylation reaction.
View Article and Find Full Text PDFTreatment of alpha, beta-unsaturated carbonyl compounds or methyl propargyl ether with acylchlorobis(cyclopentadienyl)titanium in the presence of triethylamine and a copper salt in aqueous THF resulted in acylation of the carbon-carbon multiple bond, yielding the corresponding 1,4-diketones in good yields.
View Article and Find Full Text PDF[reaction: see text] Treatment of 6-iodo-1-hexene derivatives with trimethylsilylmethyl Grignard reagent in the presence of CoCl(2)(dppb) in refluxing THF affords Heck-type products, methylenecyclopentanes, in good yields.
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