Toure ´and Hall Scheme 6. Synthesis of trans-Jasmonic Acid Using a Noyori-type 3CR, by Yamamoto and Co-workers 23 Scheme 7. Synthesis of Indanomycin Using a Noyori-type 3CR, by Burke and Co-workers 25 Scheme 8. Synthesis of Incarvilline and Incarvine Using a Noyori 3CR, by Kibayashi and Co-workers 26,28

Using reverse transcriptase-PCR and degenerate oligonucleotides derived from the active-site residues of subtilisin͞kexin-like serine proteinases, we have identified a highly conserved and phylogenetically ancestral human, rat, and mouse type I membrane-bound proteinase called subtilisin͞kexin-isozyme-1 (SKI-1). Computer databank searches reveal that human SKI-1 was cloned previously but with no identified function. In situ hybridization demonstrates that SKI-1 mRNA is present in most tissues and cells. Cleavage specificity studies show that SKI-1 generates a 28-kDa product from the 32-kDa brain-derived neurotrophic factor precursor, cleaving at an RGLT2SL bond. In the endoplasmic reticulum of either LoVo or HK293 cells, proSKI-1 is processed into two membrane-bound forms of SKI-1 (120 and 106 kDa) differing by the nature of their N-glycosylation. Late along the secretory pathway some of the membrane-bound enzyme is shed into the medium as a 98-kDa form. Immunocytochemical analysis of stably transfected HK293 cells shows that SKI-1 is present in the Golgi apparatus and within small punctate structures reminiscent of endosomes. In vitro studies suggest that SKI-1 is a Ca 2؉ -dependent serine proteinase exhibiting a wide pH optimum for cleavage of pro-brainderived neurotrophic factor.

Tankyrase 1 and 2 have been shown to be redundant, druggable nodes in the Wnt pathway. As such, there has been intense interest in developing agents suitable for modulating the Wnt pathway in vivo by targeting this enzyme pair. By utilizing a combination of structure-based design and LipE-based structure efficiency relationships, the core of XAV939 was optimized into a more stable, more efficient, but less potent dihydropyran motif 7. This core was combined with elements of screening hits 2, 19, and 33 and resulted in highly potent, selective tankyrase inhibitors that are novel three pocket binders. NVP-TNKS656 (43) was identified as an orally active antagonist of Wnt pathway activity in the MMTV-Wnt1 mouse xenograft model. With an enthalpy-driven thermodynamic signature of binding, highly favorable physicochemical properties, and high lipophilic efficiency, NVP-TNKS656 is a novel tankyrase inhibitor that is well suited for further in vivo validation studies.

Imidazoles are an important group of the azole family of heterocycles frequently found in pharmaceuticals, drug candidates, ligands for transition metal catalysts, and other molecular functional materials. Owing to their wide application in academia and industry, new methods and strategies for the generation of functionalized imidazole derivatives are in demand. We here describe a general and comprehensive approach for the synthesis of complex aryl imidazoles, where all three C–H bonds of the imidazole core can be arylated in a regioselective and sequential manner. We report new catalytic methods for selective C5- and C2-arylation of SEM-imidazoles and provide a mechanistic hypothesis for the observed positional selectivity based on electronic properties of C–H bonds and the heterocyclic ring. Importantly, aryl bromides and low-cost aryl chlorides can be used as arene donors under practical laboratory conditions. To circumvent the low reactivity of the C-4 position, we developed the SEM-switch that transfers the SEM-group from N-1 to N-3 nitrogen and thus enables preparation of 4-arylimidazoles and sequential C4–C5-arylation of the imidazole core. Furthermore, selective N3-alkylation followed by the SEM-group deprotection (trans-N-alkylation) allows for regioselective N-alkylation of complex imidazoles. The sequential C-arylation enabled by the SEM-switch allowed us to produce a variety of mono-, di-, and triarylimidazoles using diverse bromo- and chloroarenes. Using our approach, the synthesis of individual compounds or libraries of analogues can begin from either the parent imidazole or a substituted imidazole, providing rapid access to complex imidazole structures.

Can classical and modern chemical C-H oxidation reactions complement biotransformation in the synthesis of drug metabolites? We have surveyed the literature in an effort to try to answer this important question of major practical significance in the pharmaceutical industry. Drug metabolites are required throughout all phases of the drug discovery and development process; however, their synthesis is still an unsolved problem. This Review, not intended to be comprehensive or historical, highlights relevant applications of chemical C-H oxidation reactions, electrochemistry and microfluidic technologies to drug templates in order to access drug metabolites, and also highlights promising reactions to this end. Where possible or appropriate, the contrast with biotransformation is drawn. In doing so, we have tried to identify gaps where they exist in the hope to spur further activity in this very important research area.

Oncogenic IDH1 and IDH2 mutations contribute to cancer via production of R-2-hydroxyglutarate (2-HG). Here, we characterize two structurally distinct mutant- and isoform-selective IDH1 inhibitors that inhibit 2-HG production. Both bind to an allosteric pocket on IDH1, yet shape it differently, highlighting the plasticity of this site. Oncogenic IDH1 mutation destabilizes an IDH1 "regulatory segment," which otherwise restricts compound access to the allosteric pocket. Regulatory segment destabilization in wild-type IDH1 promotes inhibitor binding, suggesting that destabilization is critical for mutant selectivity. We also report crystal structures of oncogenic IDH2 mutant isoforms, highlighting the fact that the analogous segment of IDH2 is not similarly destabilized. This intrinsic stability of IDH2 may contribute to observed inhibitor IDH1 isoform selectivity. Moreover, discrete residues in the IDH1 allosteric pocket that differ from IDH2 may also guide IDH1 isoform selectivity. These data provide a deeper understanding of how IDH1 inhibitors achieve mutant and isoform selectivity.

[reaction: see text] The synthesis and catalytic evaluation of palladium complexes containing imidazolyl carbene ligand of varying steric and electronic properties is reported. These complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines. The reaction is operationally simple; the complexes are insensitive to moisture.

High throughput screening and subsequent hit validation identified 4-isopropyl-3-(2-((1-phenylethyl)amino)-pyrimidin-4-yl)oxazolidin-2-one as a potent inhibitor of IDH1 R132H . Synthesis of the four separate stereoisomers identified the (S,S)-diastereomer (IDH125, 1f) as the most potent isomer. This also showed reasonable cellular activity and excellent selectivity vs IDH1 wt . Initial structure−activity relationship exploration identified the key tolerances and potential for optimization. X-ray crystallography identified a functionally relevant allosteric binding site amenable to inhibitors, which can penetrate the blood−brain barrier, and aided rational optimization. Potency improvement and modulation of the physicochemical properties identified (S,S)-oxazolidinone IDH889 (5x) with good exposure and 2-HG inhibitory activity in a mutant IDH1 xenograft mouse model. KEYWORDS: Mutant IDH1 inhibitor, allosteric inhibition, 2-HG, preclinical in vivo activity, 3-pyrimidin-4-yloxazolidin-2-one, chirality-defined potency H otspot heterozygous mutations in human cytoplasmic isocitrate dehydrogenase 1 (IDH1) at Arg 132 (R132*) have been identified in multiple cancer types, including acute myeloid leukemia (AML), glioma, chondrosarcoma, and cholangiocarcinoma. 1 These mutations have been shown to confer a neomorphic catalytic activity to produce high levels of intracellular R-2-hydroxyglutarate (2-HG) and effect downstream epigenetic markers on DNA and proteins. Recent clinical trials in AML patients with a specific inhibitor of IDH1 has shown clinical benefit, confirming the causal link between this genetic mutation, the production of 2-HG, and cancer.11 Efforts herein focused on the identification of compounds that could potentially target all classes of mutant-IDH1 tumors, including those in the brain.The substrate-binding site of mutant IDH1 is highly polar as defined by the amino acids lining the pocket (Figure 1), in addition to the active-site magnesium ion and NADPH cofactor. This suggests a low probability of being able to optimize a compound for potent binding to this site while also fulfilling the criteria most conducive to crossing the blood− brain barrier (BBB).12 It was decided to explore the identification of catalytic inhibitors with different mechanisms of action, which may bind distal to this polar substrate-binding site.High throughput screening was carried out with a NADPH fluorescence-based biochemical assay using IDH1 R132H homodimer protein, and orthogonal biochemical inhibition confirmation using an LCMS readout of 2-HG levels. Compounds 1a and 1b were identified as selective and functional inhibitors of IDH1R132H from this screen. Both 1a and 1b were screened as diastereomeric mixtures at the amine (Table 1, Am), which necessitated the independent synthesis of the four separate stereoisomers in order to determine the chiral preference for ligand binding. Potency was found to be most strongly dependent upon the chirality at the amine center (Am), . Amino acids lining the pocket are highl...