A concise asymmetric synthesis of aminocyclitols, such as diastereomeric 2‐deoxystreptamine analogues and conduramine A, is described. The Pd‐catalyzed asymmetric desymmetrization of meso ...1,4‐dibenzolate enables the synthesis of highly oxidized cyclohexane architectures. These scaffolds can potentially be used to access new aminoglycoside antibiotics and enantiomerically pure α‐glucosidase inhibitors.
Very synthetic! Pd‐catalyzed asymmetric desymmetrization enables a concise synthesis of aminocyclitols, such as diastereomeric 2‐deoxystreptamine analogues and conduramine A (see scheme, Bz=benzoyl, Boc=tert‐butyloxycarbonyl, TFA=trifluoroacetic acid).
Magnesium-catalyzed enantioselective aldol between ethyl diazoacetate and aromatic, aliphatic, and α,β-unsaturated aldehydes affords α-diazo-β-hydroxy-esters in high enantioselectivities. Aldol ...adducts resulting from this asymmetric transformation are versatile intermediates toward the synthesis of several ester containing chiral building blocks.
Recent advances in targeted covalent inhibitors have aroused significant interest for their potential in drug development for difficult therapeutic targets. Proteome-wide profiling of functional ...residues is an integral step of covalent drug discovery aimed at defining actionable sites and evaluating compound selectivity in cells. A classical workflow for this purpose is called IsoTOP-ABPP, which employs an activity-based probe and two isotopically labeled azide-TEV-biotin tags to mark, enrich, and quantify proteome from two samples. Here we report a novel isobaric 11plex-AzidoTMT reagent and a new workflow, named AT-MAPP, that significantly expands multiplexing power as compared to the original isoTOP-ABPP. We demonstrate its application in identifying cysteine on- and off-targets using a KRAS G12C covalent inhibitor ARS-1620. However, changes in some of these hits can be explained by modulation at the protein and post-translational levels. Thus, it would be crucial to interrogate site-level bona fide changes in concurrence to proteome-level changes for corroboration. In addition, we perform a multiplexed covalent fragment screening using four acrylamide-based compounds as a proof-of-concept. This study identifies a diverse set of liganded cysteine residues in a compound-dependent manner with an average hit rate of 0.07% in intact cell. Lastly, we screened 20 sulfonyl fluoride-based compounds to demonstrate that the AT-MAPP assay is flexible for noncysteine functional residues such as tyrosine and lysine. Overall, we envision that 11plex-AzidoTMT will be a useful addition to the current toolbox for activity-based protein profiling and covalent drug development.
Process development for a multi-kilogram-scale synthesis of GDC-0022, an inhibitor of retinoic acid receptor-related orphan receptor γ (RORc), is described. Delivery of the active pharmaceutical ...ingredient (API) relied on diastereoselective preparation of a six-membered sultam building block, as well as execution of its benzylation under heterogeneous conditions. Investigation and optimization of a challenging late-stage palladium-catalyzed C–N coupling of a bicyclic amine were likewise central to synthetic efforts. Understanding of this key reaction, as well as the development of API salt forms and isolations, ultimately enabled a successful reaction at 8.0 kg scale, utilizing 1.0 mol % XantPhos–Pd–G2 as precatalyst and, in turn, preparation of >5.0 kg of GDC-0022 tosylate salt for preclinical needs.
Oncogenic KRAS mutations were identified decades ago, yet the selective inhibition of specific KRAS mutant proteins represents an ongoing challenge. Recent progress has been made in targeting certain ...P-loop mutant proteins, in particular KRAS G12C, for which the covalent inhibition of the GDP state via the Switch II pocket is now a clinically validated strategy. Inhibition of other KRAS mutant proteins such as KRAS G13D, on the other hand, still requires clinical validation. The remoteness of the D13 residue relative to the Switch II pocket in combination with the solvent exposure and conformational flexibility of the D13 side chain, as well as the difficulties of targeting carboxylate residues covalently, renders this specific protein particularly challenging to target selectively. In this report, we describe the design and evaluation of potent and KRAS G13D-selective reversible inhibitors. Subnanomolar binding to the GDP state Switch II pocket and biochemical selectivity over WT KRAS are achieved by leveraging a salt bridge with D13.
Palladium(0)-catalyzed conditions for the α-arylation of sultams with aryl and heteroaryl iodides have been developed. Arylation of 3-substituted 1,3-propanesultams gave rise to high yields and high ...diastereomeric ratios, leading to the thermodynamically favored cis product. The arylation was broadly applicable to various electron-rich and electron-poor (hetero)aromatic iodides.
A sustainable second-generation process for GDC-0134 was developed with a particular focus on safety and greenness, while complying with strong specifications to supply pivotal clinical studies. ...Through these efforts, we discovered solvents to replace the solvents classified as substances of very high concern by the REACH regulation in two SNAr steps. We further established a safer and faster way to oxidize the sulfanyl to the sulfonyl intermediate by dosing H2O2 at higher temperatures, reducing accumulation while minimizing uncontrolled H2O2 decomposition. The reaction conditions for the Suzuki coupling and the second SNAr were modified to increase the selectivity in these two steps. A change in the solvent for the final crystallization allowed operation at higher concentrations and delivery of a highly pure active pharmaceutical ingredient (API). The new improved process reduced the process mass intensity by approximately 40% and was successfully used to produce 150 kg of GDC-0134.
Efforts toward the process development of reversible Bruton’s tyrosine kinase (BTK) inhibitor GDC-0853 (1) are described. A practical synthesis of GDC-0853 was accomplished via a key highly ...regioselective Pd-catalyzed C–N coupling of tricyclic lactam 5 with 2,4-dichloronicotinaldehyde (6) to afford the C–N coupling product 3, a Suzuki–Miyaura cross-coupling of intermediate 3 with boronic ester 4 derived from a Pd-catalyzed borylation of tetracyclic bromide 7, to generate penultimate aldehyde intermediate 2 and subsequent aldehyde reduction and recrystallization. Process development of starting materials 5, 6, and 7 is also discussed.
A highly efficient and regioselective manufacturing route for the phosphoinositide 3-kinase β-sparing inhibitor taselisib was developed. Highlights of the synthesis include: (1) magnesium-mediated ...formation of a challenging cyclic amidine; (2) regioselective imidazole construction via alkylation/condensation with bromopyruvic acid; and (3) triazole formation with 2-isopropyl acetamidrazone to generate the key bromobenzoxazepine core intermediate. Subsequent highly efficient one-pot palladium-catalyzed Miyaura borylation/Suzuki cross-coupling/saponification, followed by a 1,1′-carbonyldiimidazole-mediated coupling with ammonia, led to the pentacyclic taselisib. This new synthetic approach provides a more efficient route to taselisib with a significant decrease in process mass intensity compared to the previous early development routes to the bromobenzoxazepine core. Finally, implementation of a controlled crystallization provided the active pharmaceutical ingredient with the desired polymorphic form.
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