Paultheo von Zezschwitz

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The macrolactone archazolid is a novel, highly specific V-ATPase inhibitor with an IC(50) value in the low nanomolar range. The binding site of archazolid is presumed to overlap with the binding site of the established plecomacrolide V-ATPase inhibitors bafilomycin and concanamycin in subunit c of the membrane-integral V(O) complex. Using a semi-synthetic(More)
The investigation of V-ATPases as potential therapeutic drug targets and hence of their specific inhibitors is a promising approach in osteoporosis and cancer treatment because the occurrence of these diseases is interrelated to the function of the V-ATPase. Apicularen belongs to the novel inhibitor family of the benzolactone enamides, which are highly(More)
Two new alpha-pyridone metabolites, iromycins E and F, were isolated from cultures of strain Streptomyces sp. Dra 17, thus expanding the recently discovered iromycin family. The inhibitory potential on the mitochondrial respiratory chain was examined and revealed that iromycin metabolites block NADH oxidation in beef heart submitochondrial particles with(More)
The total synthesis of iromycin A (1a), a microbial metabolite combining a novel structure with an interesting biological activity as a NO synthase inhibitor, was accomplished using a flexible and highly convergent approach. Thus, the ring fragment was prepared as 6-bromomethylpyrone 27 by acylation of the respective beta-ketoester 13 and subsequent(More)
The new spiro[4.5]acetal okaspirodiol (4) was isolated from Streptomyces sp. Gö TS 19 as a secondary metabolite in yields up to 380 mg/L. The structure of this cryptic ketotetrol was elucidated by different methods including X-ray analysis, and its equilibration under mildly acidic conditions furnishing three additional isomers was thoroughly studied.(More)
The domino-type combination of consecutive palladium-catalyzed cross-coupling reactions with subsequent pericyclic transformations offers a very fast access to various oligocyclic skeletons. This Account highlights all-intramolecular, intra-intermolecular, and all-intermolecular organopalladation cascades leading to 1,3,5-hexatrienes, which undergo(More)
Rhodium(I)/Binap complexes catalyze highly enantioselective additions of methyl- and arylaluminum reagents to cyclic α,β-unsaturated N-tosyl ketimines. Depending on the solvent and substituents at the ring, the reaction occurs either in a 1,2-manner to deliver α-tertiary allylic amines or in a 1,4-manner to yield, after subsequent reduction, 3-substituted(More)
In copper(I)/phosphoramidite-catalyzed asymmetric 1,4-additions of dialkylzinc, N-sulfonyl imines are more reactive and furnish higher enantiomeric excesses than the respective cycloalk-2-enones. This enables formation of a quaternary stereocenter as well as a cis-selective addition to an imine derived from 5-methylcyclohex-2-enone. The 1,4-adducts can be(More)
Both, cis- and trans-3,4-disubstituted thiadiazolidines 5 and 6 can enantioselectively be obtained from thiadiazoles 2 which, in turn, are efficiently prepared from the respective 1,2-diketone by an improved protocol. An asymmetric ruthenium-catalyzed transfer hydrogenation followed by a diastereoselective hydride addition furnishes exclusively the(More)