Organic Process Research & Development最新文献

The assessment and control of potential mutagenic impurities (PMIs) within pharmaceutical products are managed in accordance with the ICH M7 guideline “Assessment and control of DNA reactive (mutagenic) impurities in pharmaceuticals to limit potential carcinogenic risk”. This guidance highlights four control options that can be used to give assurance of control of PMIs to below a level of toxicological concern for the intended use. These control options range from testing to confirm that impurity levels within the active pharmaceutical ingredient or product are below an acceptable limit (ICH M7 Option 1 Control) to a control strategy that relies on process controls and scientific principles (e.g., purging) to demonstrate impurity presence to below a level of concern in lieu of analytical testing (option 4). While ICH M7 control option 4 is an established approach to justify that levels of a potential mutagenic impurity are below an acceptable limit, there have been health authority challenges that the use of ICH M7 control option 4 rationales is not appropriate for N-nitrosamines without included confirmatory analytical testing data to confirm absence. The reasons behind this lack of acceptance for ICH M7 control option 4 alone may include (i) a higher perceived potency for nitrosamines over other mutagenic impurities as they alert as part of the cohort of concern and (ii) inappropriate application of purge rationales such that, in some instances, confirmatory testing data highlighted higher levels for the impurity than had been predicted to be present. Through the inclusion of industry relevant case studies, this publication outlines that, while some nitrosamines may require control to lower levels than the ICH M7 threshold of toxicological concern, the concept of the ICH M7 option 4 control is scientifically justified when the properties for the nitrosamine are considered and an appropriate conservative purge rationale is applied.

A cocrystallization process of the active pharmaceutical ingredient apremilast with benzoic acid is explored in this work. The aim of the study is to adjust operating conditions during the crystallization to purposefully tune the dissolution properties of the final product. Understanding the cocrystallization is key to obtaining a consistent, high-quality product, as well as tuning other properties such as powder flowability or dissolution properties. It was discovered early in development that the studied cocrystallization process does not follow the common rules of crystallization. Better crystals were obtained at faster cooling rates and worse crystals at slower cooling rates. Interestingly, this can be explained by crystal collisions and a two-phase growth of the crystals. Standard operating conditions were further tested, resulting in different shapes and sizes of the product. Different types of produced crystals were tested in a dissolution apparatus and provided significantly modified dissolution profiles.

Imine reductase (IRED) enzymes catalyze the asymmetric reduction of cyclic imines and have recently gained attention due to their reductive aminase (RedAm) activity. Herein, we demonstrated their ability to control the two vicinal stereogenic centers in an N-heterocyclic system. By reversing their usual mode of action, the oxidative kinetic resolution (KR) of the rac-cis-1 piperidine intermediate of avacopan was used to leave the (2R,3S)-1 desired enantiomer untouched, whereas the undesired enantiomer was oxidized and tautomerized to enamine 4. The synthesis was improved by using alcohol dehydrogenase (ADH) for cofactor regeneration, and 4 was recycled by catalytic hydrogenation to rac-cis-1. Hence, KR was carried out on a 1 kg scale with 99.5% ee and 37.2 g/L/d space-time yield (STY). One cycle of recycling of 4 enamine was confirmed at the kg scale in 83.7% yield, which resulted after the bioconversion of (2R,3S)-1 with a total yield of 57.8% (theoretical maximum KR of 50%). Repetitive sequences of KR with ex situ recycling of 4 afforded an overall theoretical yield of 72%. Moreover, an enantiocomplementary enzyme was utilized for the dynamic kinetic reduction of 4 to (2R,3S)-1 with excellent diastereoselectivity.

The lipase-mediated oxidation of 2,5-diformylfuran (DFF) to 2,5-furandicarboxylic acid (FDCA) via peracid formation is a promising alternative to valorizing furans from biorefineries. In this chemoenzymatic reaction, Candida antarcticalipase B (CALB) uses hydrogen peroxide (H₂O₂) and ethyl acetate as an acyl donor to form peracetic acid in situ, which subsequently performs the oxidation of DFF to FDCA, via the intermediate 5-formyl-2-furancarboxylic acid (FFCA). This study explores the reaction en route to its industrial application, identifying strengths and limitations. First, the origin of DFF is considered since it can proceed from biorefineries either in organic media or in aqueous solutions. The reaction is assessed in ethyl acetate with different water contents, showing that oxidations can be achieved in wet nonaqueous media. Moreover, a mixture of ethyl acetate and tert-butanol improves the FDCA yield 2-fold. Subsequently, the reaction is conducted using a rotating bed reactor (RBR), which may enable straightforward downstream processing while showing hints for future scale-up. Once H₂O₂ dosage, rotating rate, and enzyme and substrate loadings are optimized, FDCA production of up to ∼27 g/L is achieved, yet still at low DFF selectivity (∼50%). To improve the atom economy of the reaction and enhance the option of organic media recycling, which saves significant CO₂ generation during incineration, an “acyl-donor-free” concept of the lipase-mediated oxidation of DFF to FDCA is proposed, which uses catalytic amounts of FDCA to be taken by the lipase to generate per-FDCA, to oxidize DFF to form the desired product subsequently. Overall, the enzyme-mediated oxidation of DFF to FDCA may become relevant in biorefineries if improvements in the enzyme stability (against H₂O₂ and peracids), as well as in process conditions (e.g., H₂O₂ and substrate addition, downstream, etc.) are adequately tuned.

The selective partial reduction of esters to the corresponding aldehydes has been a long-standing challenge in the field of chemistry due to rapid reaction kinetics, high exothermicity, and generation of unstable intermediates. Batch reactors, with their limited heat transfer capabilities, necessitate careful temperature control and prolonged dosing of DIBAL-H, typically at very low temperatures (−70 to −50 °C). This process, especially on a plant scale, can take several hours and often results in considerable over-reduction to the alcohol product despite the cryogenic conditions. As industries aim to increase productivity and efficiency, the transition from laboratory-scale processes to larger-scale manufacturing becomes crucial. Herein, we report a pilot-scale DIBAL-H reduction of an ester to the corresponding aldehyde with product output ranging from 0.72 to 1.2 kg/h using the benefits of continuous flow chemistry. Furthermore, we demonstrate the advantages of 3D metal printing in fabricating the flow reactor, heat exchangers, and static mixers, leading to a straightforward scale-up of this highly reactive and exothermic chemical process demanding excellent heat and mass transfer properties.