A second-generation synthesis of CT1812, a sigma-2 receptor modulator (ligand), was developed from readily available starting materials to support late-stage clinical needs. An AIBN-induced thermal benzylic bromination in DCE was replaced by a visible-light-induced continuous flow process in MeCN operating at room temperature. High throughput screening was employed to overcome the unexpected challenges encountered in the hydrogenation of alkyne 13 in the penultimate step. The rationale for a polymorph switch from the originally developed monofumarate anhydrate to the more thermodynamically stable hemifumarate dihydrate is also described. The new convergent route proceeds in eight steps (longest linear sequence (LLS) = 6) as compared to the original med chem route (12 steps; LLS = 9) and has been successfully demonstrated on a 100 kg scale.
A novel continuous process is proposed for the synthesis of a macrocyclic sulfite of tetra(ethylene glycol), PEG4-MCSi, which is a precursor to the useful building block PEG4-macrocyclic sulfate, PEG4-MCS. The system at the core of this work is a set of cascaded continuously stirred tank reactors (portrayed aesthetically in the illustration) containing the reaction mixtures. The core features of this work are listed.
An enzyme catalyzed strategy for the synthesis of a chiral hydrazine from 3-cyclopentyl-3-oxopropanenitrile 5 and hydrazine hydrate 2 is presented. An imine reductase (IRED) from Streptosporangium roseum was identified to catalyze the reaction between 3-cyclopentyl-3-oxopropanenitrile 5 and hydrazine hydrate 2 to produce trace amounts of (R)-3-cyclopentyl-3-hydrazineylpropanenitrile 4. We employed a 2-fold approach to optimize the catalytic performance of this enzyme. First, a transition state analogue (TSA) model was constructed to illuminate the enzyme–substrate interactions. Subsequently, the Enzyme_design and Funclib methods were utilized to predict mutants for experimental evaluation. Through three rounds of site-directed mutagenesis, site saturation mutagenesis, and combinatorial mutagenesis, we obtained mutant M6 with a yield of 98% and an enantiomeric excess (ee) of 99%. This study presents an effective method for constructing a hydrazine derivative via IRED-catalyzed reductive amination of ketone and hydrazine. Furthermore, it provides a general approach for constructing suitable enzymes, starting from nonreactive enzymes and gradually enhancing their catalytic activity through active site modifications.
The development of a safe and scalable Pinnick oxidation of an aldehyde to a carboxylic acid in the late-stage synthesis of a BDK inhibitor candidate, PF-07208254, is reported. Extensive process safety testing revealed a large exotherm with significant heat accumulation during oxidant addition, which was minimized through careful control of oxidant dosing, and higher dilutions ensured complete solubility of the reactants. The role of atmospheric oxygen in generating sulfuric acid in the product stream, leading to partial decomposition, was identified. The optimized process was safely executed on a kilogram scale to deliver high-quality API for toxicology and clinical studies.
A fully continuous flow synthesis of 2-hydroxypyridine-N-oxide (HOPO), an important peptide coupling reagent used in a variety of pharmaceutical ingredient preparations, was designed, developed, and scaled up. The process involved the catalytic oxidation of 2-hydroxypyridine using hydrogen peroxide, followed by quenching and hydrolysis to obtain HOPO in an aqueous solution. A mixed fixed bed reactor was designed featuring a 3D-printed static mixer to achieve the complete conversion of the raw materials, and a continuous post-treatment process involving acid crystallization was developed to obtain a high-quality solid HOPO product. The continuous reaction process and post-treatment process resulted in >90% isolated yield with no need for additional separation and purification steps, thus avoiding an interruption of the continuous reaction. The scale-up process successfully achieved a production rate of 8 kg/day, making this synthesis method highly suitable for industrial applications.
A commercial route to adagrasib (1) was developed to support clinical and commercial needs. Yield was improved to 32% over six chemical steps. A doubly regioselective SNAr reduced consumption of a chiral intermediate, reaction optimization led to parts per million palladium catalysis, and a new method to deprotect Cbz-groups were developed to mitigate risk associated with benzyl iodide.
We report the successful manufacture of several >50 kg batches of a key intermediate via a Birch reduction that utilized liquified ammonia as well as lithium metal. With an eye toward continued scalability, we explored two alternative procedures to obtain the same intermediate: (1) an electrochemical reduction performed using continuous flow technology and (2) a ketalization approach that proceeds with olefin migration to give the target molecule. Both options were explored in detail and then demonstrated on a ≥100 g scale to assess the overall robustness. Ultimately, the olefin migration route appeared to be more promising and was demonstrated on a >1 kg scale to show the potential to avoid several unattractive aspects of the Birch reduction for future scale-up needs.
Protein engineering has made significant contributions to industries such as agriculture, food, and pharmaceuticals. In recent years, directed evolution combined with artificial intelligence has emerged as a cutting-edge R&D approach. However, the application of machine learning techniques can be challenging for those without relevant experience and coding skills. To address this issue, we have developed a web-based protein sequence recommendation system: STAR (Sequence recommendaTion via ARtificial intelligence). Our system utilizes Bayesian optimization as its backbone and includes a filtering step using a regression model to enhance the success rate of recommended sequences. Additionally, we have incorporated an in silico-directed evolution approach to expand the exploration of the protein space. The Web site can be accessed at https://www.FindProteinStar.com/.
Despite the growth of photoredox methods in academia, application of photoredox at scale in the pharmaceutical and fine chemical industries has been slow. In this report, a photoredox trifluoromethylation of a thiophenol was modified from the original literature report, and the mechanism was investigated to define the key scale-up parameters. The mechanistic insight was leveraged in the design and execution of two different reactor designs: an LED-based plug flow photoreactor and a laser-based continuous stirred tank photoreactor. In one of the first examples of commercial-scale photoredox chemistry, the process was scaled to provide over 500 kg of the desired intermediate and amended to fully continuous manufacturing.
In this work, an engineered ketoreductase, apKRED-9, derived from Acetobacter pasteurianus 386B was successfully immobilized on two platforms, namely, glutaraldehyde-activated amino polymer beads, LX1000 HA, and cofactor enriched poly(ethylenimine) (CEP) mediated coaggregation followed by glutaraldehyde cross-linking, respectively. The enzyme apKRED-9 immobilized on LX1000HA was evaluated in a packed bed reactor (PBR) for continuous-flow synthesis of (R)-tetrahydrothiophene-3-ol from 3-keto tetrahydrothiophene in an aqueous-isopropanol mixture, while the enzyme apKRED-9 immobilized on CEP was tested in batch mode until pilot scale for the same reaction. The long-term operational stability of the enzyme in both continuous-flow and batch modes was demonstrated, with high conversion of >99.0% and ee > 99.5% in both the cases. From the pilot-scale application of apKRED-9-CEP, (R)-tetrahydrothiophene-3-ol was obtained (118.0 g, GC purity 99.9%, chiral purity ee 99.9% and yield 76.3%). In the PBR flow reactor, the productivity in terms of space time yield (STY) 729 g L–1 d–1 was achieved with 64 h of continuous usage. Based on performance metrics, both platforms are scalable and reproducible, while CEP offers additional advantages on effective cost and adaptability to other enzymes.
d-Amino acids are important intermediates for the synthesis of β-lactam antibiotics and other vital pharmaceuticals, which can be synthesized by various methods including biocatalysis. In this work, we have demonstrated using immobilized multienzyme cofactor-driven cascade reaction for the synthesis of a model d-amino acid, (R)-2-amino-3-(2-bromophenyl)propanoic acid. In the present study, three enzymes, namely, d-amino acid amino transaminase from Bacillus cereus (bcDAAT), a d-lactate dehydrogenase (lhD-LDH) from Lactobacillus helveticus, and a formate dehydrogenase (cbFDH) from Candida boidinii, were successfully demonstrated in a practical and scalable immobilization protocol on glutaraldehyde-activated amino polymer beads LX1000HA. From the results, it was evident that the sequentially co-immobilized cbFDH along with the other two enzymes exhibited excellent stability at >90% for 10 cycles (150 h). Pilot-scale batches conducted at 50 g scale using the above immobilized multienzyme resulted in an overall isolated yield of 65% of (R)-2-amino-3-(2-bromophenyl)propanoic acid (～33 g white powder; HPLC purity, >99%; ee, 99.0%). The application of the immobilized enzyme was also evaluated in PBR continuous-flow reaction, in which a stable conversion of >95% for 36 h was achieved (space–time yield, 323.3 g L–1 day–1]. d-Amino acids are vital building blocks used in pharmaceuticals and fine chemicals. Hence, we believe that immobilized multienzyme cofactor-driven cascade reaction could be a potential manufacturing platform for d-amino acids.
A biocatalytic cascade to produce tert-butyl ((2R,4R)-2-methyltetrahydro-2H-pyran-4-yl)carbamate 6 has been demonstrated at the multikilogram scale. In this reaction, a racemic ketone is resolved by reducing the undesired ketone using a ketone reductase (KRED). The reduction is stereospecific for the 2-position of substrate (2S)-ketone leaving the (2R)-ketone unreacted. After the (2S)-ketone has been depleted, a transaminase is added to catalyze the enantioselective transamination of the ketone, resulting in formation of the (2R, 4R)-amine 6. The product is recovered from the aqueous reaction after Boc protection.
New route development activities toward ceralasertib (AZD6738) have resulted in the discovery of an efficient, acid additive-free, photoredox Minisci reaction. Mechanistic understanding resulting from LED-NMR reaction profiling, quantum yield measurements, and Stern–Volmer quenching studies have enabled optimization of the catalyst system, resulting in a significant enhancement in the rate of reaction. A large-scale continuous photoflow process has been developed, providing encouraging proof-of-concept data for the future application of this technology in the clinical manufacture of ceralasertib.
Ceralasertib is currently being evaluated in multiple phase I/II clinical trials for the treatment of cancer. Its structure, comprising a pyrimidine core decorated with a chiral morpholine, a cyclopropyl sulfoximine and an azaindole, makes it a challenging molecule to synthesize on a large scale. Several features of the medicinal chemistry and early development route make it unsuitable for the long-term commercial manufacture of the active pharmaceutical ingredient. We describe the investigation and development of a new and improved route which introduces the cyclopropyl moiety in a novel process from methyl 2,4-dibromobutyrate. Following construction of the pyrimidine ring, large-scale chlorination with phosphoryl chloride was performed with a safe and robust work-up. An SNAr reaction required an innovative work-up to remove the unwanted regio-isomer, and then a Baeyer–Villiger monooxygenase enzyme was used to enable asymmetric sulfur oxidation to a sulfoxide. A safe and scalable metal-free sulfoximine formation was developed, and then optimization of a Suzuki reaction enabled the manufacture of high-quality ceralasertib with excellent control of impurities and an overall yield of 16%.
Ceralasertib is currently being evaluated in multiple phase I/II clinical trials for the treatment of cancer. Its structure, comprising a pyrimidine core decorated with a chiral morpholine, a cyclopropyl sulfoximine and an azaindole, makes it a challenging molecule to synthesize on a large scale. Several features of the medicinal chemistry and early development route make it unsuitable for the long-term commercial manufacture of the active pharmaceutical ingredient. We describe the investigation and development of a new and improved route which introduces the cyclopropyl moiety in a novel process from methyl 2,4-dibromobutyrate. Following construction of the pyrimidine ring, large-scale chlorination with phosphoryl chloride was performed with a safe and robust work-up. An SNAr reaction required an innovative work-up to remove the unwanted regio-isomer, and then a Baeyer–Villiger monooxygenase enzyme was used to enable asymmetric sulfur oxidation to a sulfoxide. A safe and scalable metal-free sulfoximine formation was developed, and then optimization of a Suzuki reaction enabled the manufacture of high-quality ceralasertib with excellent control of impurities and an overall yield of 16%.
A two-stage flow process for cGMP manufacture of a commercially important carbapenem intermediate was developed. Stage 1 featured an intramolecular N–H insertion reaction catalyzed by an immobilized rhodium catalyst. In stage 2, phosphorylation of the resulting keto ester intermediate afforded the target, which was isolated in batch mode. The equipment design and process control strategy leading to validation of the process at the 100 kg scale are discussed.
This article details the approach to large-scale production of cyclobutane 2 by the continuous-flow [2 + 2] photocycloaddition of maleic anhydride and ethylene, including (1) focused reaction optimization and development of a robust isolation protocol, (2) the approach to equipment design and process safety, and (3) the results of commissioning tests and production runs delivering the target compound at throughputs exceeding 5 kg/day.
Herein we report a summary of the synthetic development of LY3202626 from the initial discovery route to a final route that was scaled to make 150 kg. Key developments include the use of a [3 + 2] cyclization to set the cis ring junction of the formed isoxazoline, a one-pot thiazine formation, and three different ways to install the aniline: (1) Cu-catalyzed azide coupling and reduction, (2) nitration and reduction, and (3) Buchwald coupling with acetamide.
The development of sustainable processes for the synthesis of new clinical candidates is a priority for every pharmaceutical company. The ultimate efficiency of a molecule’s synthesis results from a combination of the sequence of steps to assemble the molecule and the efficiency of each of the steps. While multiple approaches are available to aid the development of efficient processes, far fewer methods to guide route innovation have been described. Here we present a ‘green-by-design’ approach to route selection and development, assisted by predictive analytics and historical data. To aid the selection of more efficient strategies, we created a user-friendly web application, the ‘PMI Predictor’ (accessible from https://acsgcipr-predictpmi.shinyapps.io/pmi_calculator/), to predict the probable efficiencies of proposed synthetic routes before their evaluation in the laboratory. We expect that use of this app will bring greater awareness of sustainability during the initial phase of route design and will contribute to a reduced environmental impact of pharmaceutical production.
A simple and robust method for electrochemical alkyl C–H fluorination is presented. Using a simple nitrate additive, a widely available fluorine source (Selectfluor), and carbon-based electrodes, a wide variety of activated and unactivated C–H bonds are converted into their C–F congeners. The scalability of the reaction is also demonstrated with a 100 gram preparation of fluorovaline.
A simple and robust method for electrochemical alkyl C–H fluorination is presented. Using a simple nitrate additive, a widely available fluorine source (Selectfluor), and carbon-based electrodes, a wide variety of activated and unactivated C–H bonds are converted into their C–F congeners. The scalability of the reaction is also demonstrated with a 100 gram preparation of fluorovaline.
C–N cross-coupling is one of the most valuable and widespread transformations in organic synthesis. Largely dominated by Pd- and Cu-based catalytic systems, it has proven to be a staple transformation for those in both academia and industry. The current study presents the development and mechanistic understanding of an electrochemically driven, Ni-catalyzed method for achieving this reaction of high strategic importance. Through a series of electrochemical, computational, kinetic, and empirical experiments, the key mechanistic features of this reaction have been unraveled, leading to a second generation set of conditions that is applicable to a broad range of aryl halides and amine nucleophiles including complex examples on oligopeptides, medicinally relevant heterocycles, natural products, and sugars. Full disclosure of the current limitations and procedures for both batch and flow scale-ups (100 g) are also described.
Reductive electrosynthesis has faced long-standing challenges in applications to complex organic substrates at scale. Here, we show how decades of research in lithium-ion battery materials, electrolytes, and additives can serve as an inspiration for achieving practically scalable reductive electrosynthetic conditions for the Birch reduction. Specifically, we demonstrate that using a sacrificial anode material (magnesium or aluminum), combined with a cheap, nontoxic, and water-soluble proton source (dimethylurea), and an overcharge protectant inspired by battery technology [tris(pyrrolidino)phosphoramide] can allow for multigram-scale synthesis of pharmaceutically relevant building blocks. We show how these conditions have a very high level of functional-group tolerance relative to classical electrochemical and chemical dissolving-metal reductions. Finally, we demonstrate that the same electrochemical conditions can be applied to other dissolving metal–type reductive transformations, including McMurry couplings, reductive ketone deoxygenations, and epoxide openings.
Anhydrous tert-butyl hydroperoxide (TBHP) is a powerful oxidizing agent in many chemical transformations. Despite the versatility in organic reactions, the use of anhydrous TBHP has been greatly limited because of safety concerns over its shipping, handling, and storage, particularly on production scale. Herein we describe a membrane pervaporation method that allows the production of the anhydrous TBHP solution in continuous manner. The system consists of membrane modules in series that are made of perfluorinated polymer with very high gas permeability, allowing it to remove water efficiently. The pervaporation skid has been successfully implemented in production by continuously generating anhydrous 1.5 M TBHP solution in nonane at a rate of up to 100 mL·min–1 for more than 96 h, achieving the target of 0.15 wt % water. An integrated flow oxidation of a γ-butyrolactam substrate provides an efficient and diastereoselective synthesis of a key lactam intermediate for the preparation of a drug candidate targeting interleukin-1 receptor associated kinase 4 for the treatment of inflammation and oncology diseases.
DNA-encoded libraries (DEL)-based discovery platforms have recently been widely adopted in the pharmaceutical industry, mainly due to their powerful diversity and incredible number of molecules. In the two decades since their disclosure, great strides have been made to expand the toolbox of reaction modes that are compatible with the idiosyncratic aqueous, dilute, and DNA-sensitive parameters of this system. However, construction of highly important C(sp3)?C(sp3) linkages on DNA through cross-coupling remains unexplored. In this article, we describe a systematic approach to translating standard organic reactions to a DEL setting through the tactical combination of kinetic analysis and empirical screening with information captured from data mining. To exemplify this model, implementation of the Giese addition to forge high value C–C bonds on DNA was studied, which represents a radical-based synthesis in DEL.
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