Developing Amphetamine Certified Reference Materials: From Batch and Continuous-Flow Synthesis to Certification Protocol.

Certified reference materials (CRM) of amphetamine derivatives were produced through a simple, rapid and efficient synthesis in both batch and continuous-flow conditions, accompanied by the development of a comprehensive certification protocol for this class of substances. Our chemistry enabled the synthesis of MDA, MDMA, PMA and PMMA in two steps from safrole and estragole with overall yields of 38-61 % in 48 hours under batch conditions and 61-65 % in 65 minutes under continuous-flow conditions, followed by the development of a certification protocol for these materials through identity checking, homogeneity, stability, and characterization studies. Furthermore, as result of this work, a very pure CRM of MDA.HCl with 99.1±1.4 g/100 g of certified characterization value was produced. Considering the importance of supplying amphetamine calibrants for public security efforts in Forensic Chemistry, the potential therapeutical applications, and responding to the rising demand for the synthesis of CRM, this work presents a pioneering approach for the production of amphetamine and related compounds.

Concise two-step chemical synthesis of molnupiravir.

A concise synthesis of molnupiravir in a one-pot two-step approach starting from uridine is described. Formally, herein, two sets of one-pot two-reaction steps introducing simplicity for purifications and using chemically available reagents are presented. In this context, molnupiravir was obtained in up to 68% overall yield and multigram-scale. In addition, HPLC analysis showed the molnupiravir purity above 99%.

Lipase-catalyzed acylation of levoglucosan in continuous flow: antibacterial and biosurfactant studies.

Studies involving the transformation of lignocellulosic biomass into high value-added chemical products have been intensively conducted in recent years. Its matrix is mainly composed of cellulose, hemicellulose and lignin, being, therefore, an abundant and renewable source for obtaining several platform molecules, with levoglucosan (LG) standing out. This anhydrous carbohydrate can be acylated to obtain carbohydrate fatty acid esters (CFAEs). Here, these compounds were obtained via enzymatic acylation of LG, commercially obtained (Start BioScience®), with different acyl donors in continuous flow. Through the experimental design using a model reaction, it was possible to optimize the reaction conditions, temperature and residence time, obtaining a maximum conversion at 61 °C and 77 min. In addition, there was a productivity gain of up to 100 times in all comparisons made with the batch system. Finally, CFAEs were applied in tests of interfacial tension and biological activity. For a mixture of 4- and 2-O-lauryl-1,6-anhydroglucopyranose (MONLAU), the minimum interfacial tension (IFTmin) obtained was 96 mN m-1 and the critical micelle concentration (CMC) was 50 mM. Similar values were obtained for a mixture of 4- and 2-O-palmitoyl-1,6-anhydroglucopyranose (MONPAL), not yet reported in the literature, of 88 mN m-1 in 50 mM. For a mixture of 4- and 2-O-estearyl-1,6-anhydroglucopyranose (MONEST) and 4- and 2-O-oleoyl-1,6-anhydroglucopyranose (MONOLE), CMC was higher than 60 mM and IFTmin of 141 mN m-1 and 102 mN m-1, respectively. Promising data were obtained for minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of MONLAU against Staphylococcus aureus strains at 0.25 mM.

Computer Modeling Explains the Structural Reasons for the Difference in Reactivity of Amine Transaminases Regarding Prochiral Methylketones.

Amine transaminases (ATAs) are pyridoxal-5'-phosphate (PLP)-dependent enzymes that catalyze the transfer of an amino group from an amino donor to an aldehyde and/or ketone. In the past decade, the enzymatic reductive amination of prochiral ketones catalyzed by ATAs has attracted the attention of researchers, and more traditional chemical routes were replaced by enzymatic ones in industrial manufacturing. In the present work, the influence of the presence of an α,ß-unsaturated system in a methylketone model substrate was investigated, using a set of five wild-type ATAs, the (R)-selective from Aspergillus terreus (Atr-TA) and Mycobacterium vanbaalenii (Mva-TA), the (S)-selective from Chromobacterium violaceum (Cvi-TA), Ruegeria pomeroyi (Rpo-TA), V. fluvialis (Vfl-TA) and an engineered variant of V. fluvialis (ATA-256 from Codexis). The high conversion rate (80 to 99%) and optical purity (78 to 99% ee) of both (R)- and (S)-ATAs for the substrate 1-phenyl-3-butanone, using isopropylamine (IPA) as an amino donor, were observed. However, the double bond in the α,ß-position of 4-phenylbut-3-en-2-one dramatically reduced wild-type ATA reactivity, leading to conversions of <10% (without affecting the enantioselectivity). In contrast, the commercially engineered V. fluvialis variant, ATA-256, still enabled an 87% conversion, yielding a corresponding amine with >99% ee. Computational docking simulations showed the differences in orientation and intermolecular interactions in the active sites, providing insights to rationalize the observed experimental results.

Cannabidiol Discovery and Synthesis-a Target-Oriented Analysis in Drug Production Processes.

The current state of evidence and recommendations for cannabidiol (CBD) and its health effects change the legal landscape and aim to destigmatize its phytotherapeutic research. Recently, some countries have included CBD as an antiepileptic product for compassionate use in children with refractory epilepsy. The growing demand for CBD has led to the need for high-purity cannabinoids on the emerging market. The discovery and development of approaches toward CBD synthesis have arisen from the successful extraction of Cannabis plants for cannabinoid fermentation in brewer's yeast. To understand different contributions to the design and enhancement of the synthesis of CBD and its key intermediates, a detailed analysis of the history behind cannabinoid compounds and their optimization is provided herein.

Lipases of Endophytic Fungi Stemphylium lycopersici and Sordaria sp.: Application in the synthesis of solketal derived Monoacylglycerols.

Monoacylglycerols (MAGs) are amphiphilic compounds with wide range of applications such as emulsifiers, solubility agents, and chiral building blocks. These compounds are currently produced by chemical approaches involving alkaline glycerolysis or esterification under high temperatures and pressure, resulting in low yields and with by-products. Lipase-catalyzed processes have been alternative tools to provide more ecological approaches since MAGs can be obtained under milder reaction conditions and with higher selectivity. However, just a few papers have been explored the potential of endophytic fungi as lipase sources. In this work we summarized the screening of lipolytic activity of endophytic fungus S. lycopersici and Sordaria spp isolated from vegetal species collected in Jurubatiba Sandbank National Park, RJ, Brazil, as well as its applications as biocatalysts on the lipase-catalyzed synthesis of solketal 1-MAG derivatives. As a result, the crude enzymatic extract of S. lycopersici showed 98 U/mL and 110 U/mL of hydrolytic activity after 72 h and 96 h, respectively, against 74 U/mL (96 h) and, 86 U/mL (120 h) expressed by enzymatic extract of Sordaria spp.. Concerning the esterification activity, both crude enzymatic extracts and lyophilized fungi showed about 80 % conversion into ethyl oleate, in 100 min. On solketal derived 1-MAG synthesis, S. lycopersici both lyophilized and immobilized in polyurethane (PU) forms showed more than 75 % of conversion in the presence and absence of organic solvents. On MAG recycle assays, the PU biocatalyst could be reused after five reaction cycles while for the ethyl oleate synthesis, PU biocatalyst could be reused after six reaction cycles. Both microorganisms, immobilized in polyurethane, were successfully applied as biocatalysts in esterification reactions for solketal 1-MAG derivative production, in a solvent-free media.

Continuous-flow synthesis of dimethyl fumarate: a powerful small molecule for the treatment of psoriasis and multiple sclerosis.

Dimethyl fumarate (DMF) is a methyl ester of fumaric acid and has recently gained attention due to its use as a pro-drug in different pharmaceutical preparations, besides the low price of the final molecule and no active patents being available for the synthesis of DMF, the prices of multiple sclerosis treatment are still high. In our continuous effort for the development of process intensification strategies towards the synthesis of active pharmaceutical ingredients, here we present our work on a cascade methodology for dimethyl fumarate synthesis in short reaction times and quantitative yields.

Continuous-flow protocol for the synthesis of enantiomerically pure intermediates of anti epilepsy and anti tuberculosis active pharmaceutical ingredients.

Continuous-flow production of chiral intermediates plays an important role in the development of building blocks for Active Pharmaceutical Ingredients (APIs), being α-amino acids and their derivatives widely applied as building blocks. In this work we developed two different strategies for the synthesis of intermediates used on the synthesis of levetiracetam/brivaracetam and ethambutol. The results obtained show that methionine methyl ester can be continuously converted to the desired ethambutol intermediate by RANEY® Nickel dessulfurization/reduction strategy whereas levetiracetam/brivaracetam intermediates could be synthesized by both RANEY® Nickel (without H2) and Pd/C-H2 approach or by photochemical desulfurization.

Combination of the Suzuki-Miyaura Cross-Coupling Reaction with Engineered Transaminases.

The combination of enzymatic and chemical reaction steps is one important area of research in organic synthesis, preferentially as cascade reactions in one-pot to improve total conversion and achieve high operational stability. Here, the combination of the Suzuki-Miyaura reaction is described to synthesize biaryl compounds followed by a transamination reaction. Careful optimization of the reaction conditions required for the chemo- and biocatalysis reaction enabled an efficient two-step-one-pot reaction yielding the final chiral amines with excellent optical purity (>99 % ee) in up to 84 % total conversion. Key to the success was the protein engineering of the amine transaminases from Asperguillus fumigatus (4CHI-TA) where single alanine mutations increased the conversion up to 2.3-fold. Finally, the transfer to a continuous flow system after immobilization of the best 4CHI-TA variant is demonstrated.

Studies on the dynamic resolution of Crizotinib intermediate.

Crizotinib is an anti-cancer agent approved for treatment of non-small cell lung carcinoma. Retrosynthetic analysis revels 1-(2,6-dichloro-3-fluorophenyl)ethanol as an important intermediate, which can be made available by different biocatalytic approaches. Herein we report our results on the kinetic and dynamic resolution towards the desired chiral intermediate for Crizotinib synthesis. The results obtained show that very good conversions and high selectivity could be obtained for the kinetic resolution (45% conv. and E>200) while dynamic kinetic resolution under continuous-flow conditions afforded the desired product in 57% conversion and 98% e.e.

A Retrosynthesis Approach for Biocatalysis in Organic Synthesis.

For the planning of an organic synthesis route, the disconnection approach guided by retrosynthetic analysis of possible intermediates and the chemical reactions involved, back to ready available starting materials, is well established. In contrast, such concepts just get developed for biocatalytic routes. In this Review we highlight functional group interconversions catalyzed by enzymes. The article is organized rather by chemical bonds formed-exemplified for C-N, C-O- and C-C-bonds-and not by enzyme classes, covering a broad range of reactions to incorporate the desired functionality in the target molecule. Furthermore, the successful use of biocatalysts, also in combination with chemical steps, is exemplified for the synthesis of various drugs and advanced pharmaceutical intermediates such as Crispine A, Sitagliptin and Atorvastatin. This Review also provides some basic guidelines to choose the most appropriate enzyme for a targeted reaction keeping in mind aspects like commercial availability, cofactor-requirement, solvent tolerance, use of isolated enzymes or whole cell recombinant microorganisms aiming to assist organic chemists in the use of enzymes for synthetic applications.

Nanoencapsulated Lecitase Ultra and Thermomyces lanuginosus Lipase, a Comparative Structural Study.

Two commercially available and widely used enzymes, the parent Thermomyces lanuginosus lipase (TLL) and the shuffled phospholipase A1 Lecitase (Lecitase Ultra), were encapsulated in AOT/isooctane reverse micelles and evaluated regarding their structure and activity. Preparations were also tested as effective biocatalysts. Small-angle X-ray scattering (SAXS), electronic paramagnetic resonance (EPR), and fluorescence spectroscopy were the techniques applied to assess the effects of enzyme incorporation to a reverse micellar nanostructure. SAXS analysis showed that the radius of gyration (Rg) changed from 16 to 38 Å, as the water content (w0) increased. Elongated shapes were more commonly observed than spherical shapes after enzyme encapsulation. EPR studies indicated that enzymes do not participate in the interface, being located in the aqueous center. Fluorescence energy transfer showed that TLL is located in the water core, whereas Lecitase Ultra is closer to the interface. Enzymatic activity toward a standard esterification reaction endured after the enzyme was incorporated into the micelles. The activity of TLL for systems with w0 15 showed the highest conversion yield, 38% in 2 h, while the system with w0 10 showed the highest initial velocity, 0.43 µM/min. This last system had a Rg of 19.3 Å, similar to that of the TLL monomer. Lecitase Ultra showed the highest conversion yields in systems with w0 10, 55% in 2 h. However, the initial rate was much lower than that of TLL, suggesting less affinity for the substrates, which is expected since Lecitase Ultra is a phospholipase. In summary, we here used several spectroscopic and scattering techniques to reveal the shape and stability of TTL and Lecitase Ultra encapsulated systems, which allowed the selection of w0 values to provide optimized enzymatic activity.

Nanomicellar Formulation of Clotrimazole Improves Its Antitumor Action toward Human Breast Cancer Cells.

BACKGROUND: Although demonstrated as a selective anticancer drug, the clinical use of clotrimazole (CTZ) is limited due to its low solubility in hydrophilic fluids. Thus, we prepared a water-soluble nanomicellar formulation of CTZ (nCTZ) and tested on the human breast cancer cell line MCF-7 biology. METHODOLOGY/PRINCIPAL FINDINGS: CTZ was nanoencapsulated in tween 80 micelles, which generated nanomicelles of, approximately, 17 nm of diameter. MCF-7 cells were treated with nCTZ and unencapsulated DMSO-solubilized drug (sCTZ) was used for comparison. After treatment, the cells were evaluated in terms of metabolism, proliferation, survival and structure. We found that nCTZ was more efficient than sCTZ at inhibiting glycolytic and other cytosolic and mitochondrial enzymes. Moreover, this increased activity was also observed for lactate production, intracellular ATP content, ROS production and antioxidant potential. As a consequence, nCTZ-treated MCF-7 cells displayed alterations to the plasma membrane, mitochondria and the nucleus. Finally, nCTZ induced both apoptosis and necrosis in MCF-7 cells. CONCLUSIONS/SIGNIFICANCE: MCF-7 cells are more sensible to nCTZ than to sCTZ. This was especially evident on regard to antioxidant potential, which is an important cell defense against drugs that affect cell metabolism. Moreover, this water-soluble formulation of CTZ strengths its potential use as an anticancer medicine.

Lipases: Valuable catalysts for dynamic kinetic resolutions.

Dynamic kinetic resolutions have proven to be a useful method for the preparation of enantiopure compounds from racemates, leading to the formation of a single enantiomer in theoretically 100% yield. Because lipases are ubiquitous, versatile, stereoselective and robust biocatalysts, they have been successfully applied as co-catalysts in these reactions, being mostly combined with metals in the chemoenzymatic dynamic kinetic resolutions of alcohols and amines.

Expanding the toolbox of asymmetric organocatalysis by continuous-flow process.

Despite all the organic chemistry reaction methodologies already developed for the continuous-flow process, asymmetric synthesis is one that has gained less attention. Since the pioneering work of Barbas and MacMillan, organocatalysis has emerged as the third pillar of asymmetric catalysis. In this review, we present a survey of literature regarding the use of organocatalysis under continuous-flow conditions.

Active pharmaceutical ingredients for antiretroviral treatment in low- and middle-income countries: a survey.

Active pharmaceutical ingredients (APIs) are the molecular entities that exert the therapeutic effects of medicines. This article provides an overview of the major APIs that are entered into antiretroviral therapy (ART), outlines how APIs are manufactured, and examines the regulatory and cost frameworks of manufacturing ART APIs used in low- and middle-income countries (LMICs). Almost all APIs for ART are prepared by chemical synthesis. Roughly 15 APIs account for essentially all of the ARTs used in LMICs. Nearly all of the ART APIs purchased through the Global Fund for AIDS, TB and Malaria (GFATM) or the United States President's Emergency Plan for AIDS Relief (PEPFAR) are produced by generic companies. API costs are very important because they are the largest contribution to the overall cost of ART. Efficient API production requires substantial investment in chemical manufacturing technologies and the ready availability of raw materials and energy at competitive prices. Generic API production is practiced in only a limited number of countries; the API market for ART is dominated by Indian companies. The quality of these APIs is ensured by manufacturing under good manufacturing practice (GMP), including process validation, testing against previously established specifications and the demonstration of clinical bioequivalence. The investment and personnel costs of a quality management system for GMP contribute significantly to the cost of API production. Chinese companies are the major suppliers for many advanced intermediates in API production. Improved chemistry of manufacturing, economies of scale and optimization of procurement have enabled drastic cost reductions for many ART APIs. The available capacity for global production of quality-assured APIs is likely adequate to meet forecasted demand for 2015. The increased use of ART for paediatric treatment, for second-line and salvage therapy, and the introduction of new APIs and combinations are important factors for the future of treatment in LMICs. The introduction of new fixed-dose combinations for ART and use of new drug delivery technologies could plausibly provide robust, durable ART for all patients in need, at an overall cost that is only moderately higher than what is presently being spent.

The multicomponent Hantzsch reaction: comprehensive mass spectrometry monitoring using charge-tagged reagents.

A novel strategy for the ESI-MS monitoring of reaction solutions involving the alternate use of permanently charge-tagged reagents has been used for comprehensive mass spectrometry monitoring of the multicomponent Hantzsch 1,4-dihydropyridine reaction. By placing a charge tag on either, or both, of the two key reactants, ion suppression effects for ESI were eliminated or minimized, and comprehensive detection of charge-tagged intermediates was achieved. The strategy allowed the trapping and characterization of the important intermediates in the mechanism for 1,4-dihydropyridine formation.

Gasoline from biomass through refinery-friendly carbohydrate-based bio-oil produced by ketalization.

The introduction of biomass-derived compounds as an alternative feed into the refinery structure that already exists can potentially converge energy uses with ecological sustainability. Herein, we present an approach to produce a bio-oil based on carbohydrate-derived isopropylidene ketals obtained by reaction with acetone under acidic conditions directly from second-generation biomass. The obtained bio-oil showed a greater chemical inertness and miscibility with gasoil than typical bio-oil from fast pyrolysis. Catalytic upgrading of the bio-oil over zeolites (USY and Beta) yielded gasoline with a high octane number. Moreover, the co-processing of gasoil and bio-oil improved the gasoline yield and quality compared to pure gasoil and also reduced the amount of oxygenated compounds and coke compared with pure bio-oil, which demonstrates a synergistic effect.

Continuous flow synthesis of α-halo ketones: essential building blocks of antiretroviral agents.

The development of a continuous flow process for the multistep synthesis of α-halo ketones starting from N-protected amino acids is described. The obtained α-halo ketones are chiral building blocks for the synthesis of HIV protease inhibitors, such as atazanavir and darunavir. The synthesis starts with the formation of a mixed anhydride in a first tubular reactor. The anhydride is subsequently combined with anhydrous diazomethane in a tube-in-tube reactor. The tube-in-tube reactor consists of an inner tube, made from a gas-permeable, hydrophobic material, enclosed in a thick-walled, impermeable outer tube. Diazomethane is generated in the inner tube in an aqueous medium, and anhydrous diazomethane subsequently diffuses through the permeable membrane into the outer chamber. The α-diazo ketone is produced from the mixed anhydride and diazomethane in the outer chamber, and the resulting diazo ketone is finally converted to the halo ketone with anhydrous ethereal hydrogen halide. This method eliminates the need to store, transport, or handle diazomethane and produces α-halo ketone building blocks in a multistep system without racemization in excellent yields. A fully continuous process allowed the synthesis of 1.84 g of α-chloro ketone from the respective N-protected amino acid within ~4.5 h (87% yield).