Oligonucleotide therapeutics (ONTs) are poised to become a third pillar of modern medicine. However, the practical and large-scale synthesis of ONTs and their constituent nucleoside analogue (NA) building blocks remains a major challenge. As each of the NA units must be individually designed and tailored to enhance the desired ADMET properties of the ONT, identifying economic, flexible, and scalable syntheses of these compounds is of critical importance. To date, the field has relied almost exclusively on carbohydrates as starting materials for NA synthesis. While these compounds are enantiopure and share common structural and stereochemical features with NAs, their conversion into NAs often requires challenging, low-yielding, and expensive synthetic campaigns. As a result, a large fraction of the ONT chemical space remains underexplored, and the full impact of chemical modification on the pharmacokinetic properties of the ONTs remains poorly understood. Here, we present a streamlined platform to produce NAs that will improve access to precision-edited ONTs. This approach uses achiral starting materials and relies on a dual organocatalyst, one-pot process to furnish a key class of ONT building blocks: the RAvIN (rapid access to value-added innovative nucleosides) ketones (RKs). Notably, RKs can incorporate appropriately protected natural nucleobases as well as nucleobase analogues, be made on scale in 2-4 steps with carbohydrate-like levels of enantiomeric purity, and are readily diversified to create the next-generation NAs required to improve the pharmacokinetic properties of the ONTs. Finally, we demonstrate the versatility and potential of this methodology in a totally noncarbohydrate synthesis of the all-MOE-modified 18mer ONT Nusinersen.

Nucleoside analogs (NAs) are essential as antiviral and anticancer therapies. Despite decades of focused medicinal chemistry efforts, their related chemical space remains underexplored, mainly owing to their lengthy, single-molecule-oriented syntheses that lack the flexibility required to generate NA libraries. Here we report a flexible, robust, and efficient platform for the high-throughput synthesis of NAs using a photoredox coupling strategy. This approach produces both carbon- and nitrogen-linked NAs and unifies the synthesis of several disparate NA classes, including 4'-thio, 4'-imino, and ProTides, all from a simple, scalable intermediate. Using this platform, we demonstrate the production of a diverse NA library and identify several hit compounds with anti-HIV-1 activity. We expect that this newly developed approach to NAs will inspire and support drug discovery efforts in this area.

Heteroaryl-functionalized chiral cyclopropanes are commonly found in pharmaceutically relevant molecules, yet their synthesis through catalytic asymmetric cyclopropanation presents multifaceted challenges concerning enantioselectivity, safety, and scalability. Herein, we report a homogeneous catalytic asymmetric cyclopropanation method by merging chiral pyridine bis-oxazoline (PyBox)-cobalt catalysts with readily accessible zinc carbenoids. This method enables facile access to chiral cyclopropanes bearing pyridyl, pyrimidyl, and other nitrogen-containing heterocyclic substituents with high enantioselectivities. Mechanistic studies support the direct transmetalation of the zinc carbenoid to the cobalt catalyst which then participates in cyclopropanation through a redox-neutral CoII catalytic cycle. The high enantioselectivity, homogeneity, and compatibility with various green solvents render this method amenable to scale up and application across diverse heteroaryl substrates.

Immune cells expressing the adenosine A2A receptor (A2AR) and A2B receptor (A2BR) present in an adenosine-rich tumor microenvironment have suppressed effector functions, such as proinflammatory cytokine release, antigen presentation, and others, making them inert to cancer cells. Simultaneous blockade of the downstream effects mediated by both receptor subtypes with a dual inhibitor has the potential to reverse adenosine-mediated suppression of tumor immune surveillance as either a single-agent treatment or in combination with other immunotherapy agents such as anti-PD-1/PD-L1 monoclonal antibodies. This publication describes the discovery and optimization of a novel series of potent and selective dual A2AR/A2BR antagonists, resulting in compound 46 (MK-1088) being identified for progression to human clinical studies.

Protein arginine methyltransferase 5 (PRMT5), a SAM-dependent type II methyltransferase implicated in chromatin regulation and cancer, is a highly sought-after target for small-molecule inhibitors. We report an (R,S)-selective vinylogous Mukaiyama aldol reaction enabled by a squaramide organocatalyst identified through HTE, delivering the product with good diastereoselectivity and excellent enantioselectivity. The reaction was translated to multigram scale and integrated into a convergent synthesis of a potent PRMT5 inhibitor, streamlining access to the active isomer and supporting biological and medicinal-chemistry studies.

Bridged nucleic acids (BNAs) are nucleoside analogues (NAs) in which the 2′‐alcohol is linked to the C4′‐position on ribose. In oligonucleotide therapeutics (ONTs), BNAs can impart beneficial properties, including enhanced stability, duplex melting temperatures, and tissue half‐lives. However, their lengthy syntheses challenge medicinal chemistry efforts and larger‐scale production. Here we demonstrate that a wide range of BNAs can be produced with various locking ring sizes and substitution patterns from a common thymine‐containing aldol product through cascade cyclization processes. Critically, several clinically relevant BNAs are now made available in as little as 3–5 steps. We expect these strategies will inspire and support medicinal and process chemistry efforts in this critical area for ONTs.

The Grignard reaction represents one of the most powerful carbon-carbon bond forming reactions and is the subject of continual study. Investigations of alkyl magnesium halide additions to β-hydroxy ketones identified a unique effect of the magnesium halide on diastereoselectivity, with alkylmagnesium iodide reagents demonstrating high levels of selectivity for the formation of 1,3-syn diols. Density functional theory (DFT) calculations and mechanistic studies suggest that the Lewis acidity of a chelated magnesium alkoxide can be tuned by the choice of halide, with the highest levels of diasteroselectivity achieved using alkyl magnesium iodide reagents. Exploiting this finding, we demonstrate that the diastereoselective addition of alkyl magnesium iodide reagents to ketofluorohydrins enables rapid access to naturally configured C4’-modified nucleosides. This work provides a platform to support antiviral and anticancer drug discovery and development efforts. The Grignard reaction represents one of the most powerful carbon-carbon bond forming reactions and is the subject of continual study. Here, the authors report a halide effect on the diastereoselectivity of 1,2-addition reactions to β-hydroxy ketones involving Grignard reagents, serving as a foundation for the rapid production of C4’-modified nucleosides with diversifiable positions at the nucleobase and C4’.

4'-Thionucleosides (thNAs) are synthetic nucleoside analogues that have attracted attention as leads for drug discovery in oncology and virology. Here we report a de novo thNA synthesis that relies on a scalable α-fluorination and aldol reaction of α-heteroaryl acetaldehydes followed by a streamlined process involving carbonyl reduction, mesylate formation and a double displacement reaction using NaSH. We demonstrate the multigram preparation of 4'-thio-5-methyluridine and highlight the production of purine and pyrimidine thNAs as well as C2'-modified thNAs.

Peptides may revolutionize the treatment of disease by combining the pharmacological benefits found in both large and small molecules into once-daily oral formulations. For decades, batch-mode solid-phase peptide synthesis (SPPS) has been employed throughout peptide drug discovery and development; however, numerous drawbacks have persisted despite advancements in the technology. Herein, we describe a continuous-flow (CF) SPPS workflow to optimize and deliver multigram quantities of peptide fragments, which are easily transformed to macrocyclic or linear peptide APIs. To develop this workflow, we leveraged a 10-amino acid peptide based on a recently disclosed macrocyclic peptide inhibitor of PCSK9. Compared with batch-mode SPPS, CF-SPPS enables rapid, data-rich optimization of peptide sequences with drastic reductions in development efforts, process execution timelines, and waste generation. To meet project demands and deliver multigram quantities, a hydraulically controlled CF-SPPS prototype was developed, which leverages small-scale optimization data to facilitate a seamless transition to larger deliveries of peptides.

Transaminases are choice biocatalysts for the synthesis of chiral primary amines, including amino acids bearing contiguous stereocenters. In this study, we employ lysine as a “smart” amine donor in transaminase-catalyzed dynamic kinetic resolution reactions to access β-branched noncanonical arylalanines. Our mechanistic investigation demonstrates that, upon transamination, the lysine-derived ketone byproduct readily cyclizes to a six-membered imine, driving the equilibrium in the desired direction and thus alleviating the need to load superstoichiometric quantities of the amine donor or deploy a multi-enzyme cascade. Lysine also shows good overall compatibility with a panel of wild-type transaminases, a promising hint of its application as a smart donor more broadly. Indeed, with this discovery in hand, we furnished a broad scope of β-branched arylalanines, including some bearing hitherto intractable cyclopropyl and isopropyl substituents, with high yields and excellent selectivities.

Abstract In the tumor microenvironment (TME), adenosine levels have been shown to be elevated relative to normal tissues. This increase in adenosine levels renders an immunosuppressive effect via direct effects on T cells via agonism of the A2A receptor and indirect effects via agonism of both A2A and A2B receptors on myeloid cells. With these observations as a backdrop, we sought to develop a dual A2A/A2B receptor antagonist with properties that would enable maintenance of high levels of target engagement of the A2A and A2B receptors even at trough concentration. Drawing on our organization’s significant prior experience developing A2A receptor antagonists for the potential treatment of Parkinson’s disease, we developed MK-1088, a highly potent A2A/A2B dual receptor antagonist that was purposefully designed to possess excellent selectivity over the related A1 and A3 receptors. This presentation will detail the discovery and development strategy that was employed to identify molecules that met the profile exemplified by this molecule. A single ascending dose study of MK-1088 in healthy human volunteers demonstrated our ability to achieve, at trough concentration, >99% target engagement (TE) at the A2A receptor and >90% TE at the A2B receptor. Details of the pharmacokinetics, safety, and tolerability from this study will be highlighted. Citation Format: Duane E. DeMong, Sheila Ranganath, Jared Cumming, Matthew Larsen, Yonglian Zhang, Christopher Plummer, Amjad Ali, Anthony Palmieri, Evan Barry, Pierre Daublain, Pranav Gupta, Manash Chatterjee, Jeremy Presland, Sebastian Schneider, Paul Ciaccio, Daniel Tatosian, Aaron Sather, Ben Turnbull, Steven Silverman, Harry Chobanian, Harini Krishnamurthy, Richard Wnek, Stephen Crowley, Alita Miller, Mark Ayers, Marlene Hinton, Jill Chrencik, Sylvie Rottey, Jennifer O'Neil. Discovery of the dual A2A/A2B receptor antagonist MK-1088 for the treatment of solid tumors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Optimizing Therapeutic Efficacy and Tolerability through Cancer Chemistry; 2024 Dec 9-11; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(12_Suppl):Abstract nr IA013.

Transaminases are choice biocatalysts for the synthesis of chiral primary amines, including amino acids bearing contiguous stereocenters. In this study, we employ lysine as a "smart" amine donor in transaminase-catalyzed dynamic kinetic resolution reactions to access β-branched noncanonical arylalanines. Our mechanistic investigation demonstrates that, upon transamination, the lysine-derived ketone byproduct readily cyclizes to a six-membered imine, driving the equilibrium in the desired direction and thus alleviating the need to load superstoichiometric quantities of the amine donor or deploy a multienzyme cascade. Lysine also shows good overall compatibility with a panel of wild-type transaminases, a promising hint of its application as a smart donor more broadly. Indeed, by this approach, we furnished a broad scope of β-branched arylalanines, including some bearing hitherto intractable cyclopropyl and isopropyl substituents, with high yields and excellent selectivities.

This chapter offers a comprehensive overview of stereogenic phosphorus compounds, which are molecules that feature a chiral center on the P-atom. As highly sought-after motifs in the pharmaceutical and materials industries—but not limited to—this treatise seeks to animate this fact with notable discoveries and applications in the field. While extensive methodology exists related to P(III) chirality, we will limit the discussion to P(V) in this chapter. Part 1 covers different synthetic strategies employed for accessing P(V) chiral molecules, including chiral separation, direct optical resolution, the use of chiral auxiliaries, chiral stoichiometric reagents, and recent discoveries in catalytic and enantioselective synthesis. Part 2 focuses on the historical significance of P(V) in therapeutics and introduces the applications of limonene-based P(V) reagents, Ψ and П. Finally, part 3 presents an overview of the utility of chiral P(V) compounds in the pharmaceutical industry and illustrates applications of the synthetic techniques discussed in the chapter to access clinical candidates containing these stereocenters.

Abstract Elevated adenosine levels present in the tumor microenvironment (TME) produce a net immunosuppressive effect through inhibition of T cell function by two mechanisms of action: Direct T cell effects via A2A receptor agonism and indirect T cell effects via agonism of A2A and A2B receptors on myeloid cells. Our team sought to identify a small molecule dual antagonist of the A2A and A2B receptors with the ability to decrease the immunosuppressive effects of adenosine in the TME and restore anti-tumor immune response. Drawing on our prior experience in the design of A2A receptor antagonists for the potential treatment of Parkinson’s disease, we developed a molecule with sub-nanomolar and single-digit nanomolar affinities for the A2A and A2B receptors respectively and greater than 100-fold selectivity over the related A1 and A3 receptors. A single dose assessment of this molecule in human subjects demonstrated the ability to achieve >99% target engagement (TE) at the A2A receptor and >90% TE at the A2B receptor at trough concentration. This presentation will, for the first time, describe the discovery and early clinical evaluation of this molecule, including disclosure of the structure, human pharmacokinetics, safety, and tolerability. Citation Format: Duane DeMong, Sheila Ranganath, Jared Cumming, Matthew Larsen, Yonglian Zhang, Christopher Plummer, Amjad Ali, Anthony Palmieri, Evan Barry, Pierre Daublain, Pranav Gupta, Manash Chatterjee, Vincent Giranda, Jeremy Presland, Sebastian Schneider, Paul Ciaccio, Daniel Tatosian, Aaron Sather, Ben Turnbull, Steven Silverman, Harry Chobanian, Harini Krishnamurthy, Richard Wnek, Roshi Afshar, Stephen Crowley, Alita Miller, Mark Ayers, Alan Whitehead, Marlene Hinton, Derek Chiang, Robert Orr, Jill Chrencik. Discovery and clinical evaluation of a potent and selective A2A/2B dual receptor antagonist [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr PR017.

α-heteroaryl acetaldehydes have become important building blocks in the synthesis of synthetic nucleosides. Novel organocatalytic cascades have enabled the rapid generation of nucleosides, which are valuable building blocks in the development of antisense oligonucleotides or as stand-alone antiviral and anticancer therapies, obviating the need for laborious synthetic routes relying on chiral pool starting materials and inefficient synthetic routes. This manuscript describes a robust and scalable protocol to α-heteroaryl acetaldehydes from readily available building blocks.

Nucleoside analogs are valuable commodities in the development of antisense oligonucleotides or as stand-alone antiviral and anticancer therapies. Syntheses of nucleoside analogs are typically challenged by a reliance on chiral pool starting materials and inefficient synthetic routes that are not readily amenable to diversification. The novel methodology described in this protocol addresses several longstanding challenges in nucleoside analog synthesis by enabling flexible and selective access to nucleoside analogs possessing variable nucleobase substitution, D- or L-configuration, selective protection of C3'/C5' alcohols and C2' or C4' derivatizations. This protocol provides direct access to C3'/C5' protected nucleoside analogs in three steps from simple, achiral starting materials and is described on both research (2.8 g) and process (30 g) scales for the synthesis of C3'/C5'-acetonide protected uridine. Using this protocol, proline catalyzes the fluorination of simple heteroaryl-substituted aldehyde starting materials, which are then directly engaged in a one-pot enantioselective aldol reaction with a dioxanone. Reduction, followed by intramolecular annulative fluoride displacement, forges the nucleoside analog. The three-step parent protocol can be completed in ~5 d by using simple mix-and-stir reaction procedures and standard column chromatographic purification techniques.

The synthesis of a key spiroamine building block for a medicinal chemistry program is described. Key innovations were a regioselective epoxide ring opening and a late-stage Pictet–Spengler reaction that was quickly optimized using Design of Experiments.