The farnesoid X receptor (FXR) is a nuclear receptor that acts as a master regulator of bile acid metabolism and signaling. Activation of FXR inhibits bile acid synthesis and increases bile acid conjugation, transport, and excretion, thereby protecting the liver from the harmful effects of bile accumulation, leading to considerable interest in FXR as a therapeutic target for the treatment of cholestasis and nonalcoholic steatohepatitis. We identified a novel series of highly potent non-bile acid FXR agonists that introduce a bicyclic nortropine-substituted benzothiazole carboxylic acid moiety onto a trisubstituted isoxazole scaffold. Herein, we report the discovery of 1 (tropifexor, LJN452), a novel and highly potent agonist of FXR. Potent in vivo activity was demonstrated in rodent PD models by measuring the induction of FXR target genes in various tissues. Tropifexor has advanced into phase 2 human clinical trials in patients with NASH and PBC.

Since their discovery over five decades ago, quinolone antibiotics have found enormous success as broad spectrum agents that exert their activity through dual inhibition of bacterial DNA gyrase and topoisomerase IV. Increasing rates of resistance, driven largely by target-based mutations in the GyrA/ParC Quinolone Resistance Determining Region, have eroded the utility and threaten the future use of this vital class of antibiotics. Herein we describe the discovery and optimization of a series of 4-(aminomethyl)quinolin-2(1H)-ones, exemplified by 34, that inhibit bacterial DNA gyrase and topoisomerase IV and display potent activity against ciprofloxacin-resistant Gramnegative pathogens. X-ray crystallography reveals that 34 occupies the classical quinolone binding site in the topoisomerase IV-DNA cleavage complex, but does not form significant contacts with residues in the Quinolone Resistance Determining Region.

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The first total synthesis of (+)-serratezomine A is described. Key aspects of the synthesis include a) the first deployment of free radical-mediated vinyl amination -an intramolecular alkyne aminostannation -in a complex target synthesis, b) the use of a β-stannyl enamine as the lynchpin for convergent assembly of the natural product backbone, c) the use of an oxidative allylation promoted by cerium(IV) (CAN) to establish the all carbon quaternary chiral center with the proper configuration, and d) an intramolecular substitution reaction to form the sensitive bridging lactone. Overall, 15 steps (longest linear sequence) are required to prepare the natural product from a commercially available aldehyde, and assembly of the contiguous array of six stereocenters is accomplished with high stereocontrol.The Lycopodium alkaloids have provided some of the most intricately structured and stereochemically dense specimens among naturally occuring small molecules. 1 The attendant challenge for chemical synthesis, often combined with their promise as potential therapeutics, has led to broad interest in the total chemical synthesis of these targets. 2 Recent reports have detailed rather concise preparations of (−)-fawcettimine, 3 (+)-fawcettidine, 4 (−)-lycopodine, 5 lyconadin A and B, 6 and (−)-cernuine. 7,8 Importantly, valuable new chemical methods have been developed in nearly every case to solve specific synthetic challenges while also avoiding synthetic routes that would not address the important issue of supply. E-mail: jeffrey.n.johnston@vanderbilt.edu. Supporting Information Available: Preparations, spectral data, and structure elucidation for key intermediates. This material is available free of charge via the Internet at http://pubs.acs.org. Kobayashi isolated (+)-serratezomine A (1, as its trifluoroacetic acid salt) as part of a search for new therapeutics from the club moss L. serratum, from which the huperzine alkaloids were isolated. 9 The polycyclic structure merges a 5,6-fused ring system (an indolizidine) with a 6,6-spirocyclic ring and a bridging lactone. Kobayashi found that the lactone is subject to isomerization from O13 to O8, resulting in the thermodynamically favored fused γ-lactone. 10 Among the six contiguous stereogenic carbons, the axial alcohol at C8 -absent from the natural products listed above -sterically impinges upon the spirocyclic piperidine through a 1,3-diaxial interaction. Finally, all but two of the stereochemical elements overlap with a bridgehead or bicyclic union. We anticipated that these challenges might provide an opportunity to develop new chemistry to meet the goal of a convergent synthesis. In this Communication, we describe these developments in the context of the first total synthesis of (+)-serratezomine A. NIH Public AccessOur solution to the problem of convergency rested on the hypothesis that an exocyclic enamine of general type A (Figure 1), an unsaturated 2-methyl pyrrolidine, could provide a multiply nucleophilic C12 and serve as the synthesis lynchpin. The f...

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