Ketone Reductase Biocatalysis in the Synthesis of Chiral Intermediates Toward Generic Active Pharmaceutical Ingredients

Highly Enantioselective Synthesis of Pharmaceuticals at Chiral-Encoded Metal Surfaces

Enantioselective catalysis is of crucial importance in modern chemistry and pharmaceutical science. Although various concepts have been used for the development of enantioselective catalysts to obtain highly pure chiral compounds, most of them are based on homogeneous catalytic systems. Recently, we successfully developed nanostructured metal layers imprinted with chiral information, which were applied as electrocatalysts for the enantioselective synthesis of chiral model compounds. However, so far such materials have not been employed as heterogeneous catalysts for the enantioselective synthesis of real pharmaceutical products. In this contribution, we report the asymmetric synthesis of chiral pharmaceuticals (CPs) with chiral imprinted Pt-Ir surfaces as a simple hydrogenation catalyst. By fine-tuning the experimental parameters, a very high enantioselectivity (up to 95 % enantiomeric excess) with good catalyst stability can be achieved. The designed materials were also successfully used as catalytically active stationary phases for the continuous asymmetric flow synthesis of pharmaceutical compounds. This illustrates the possibility of producing real chiral pharmaceuticals at such nanostructured metal surfaces for the first time.

Anthrol reductases: discovery, role in biosynthesis and applications in natural product syntheses

Covering: up to 2023Short-chain dehydrogenase/reductases (SDR) are known to catalyze the regio- and stereoselective reduction of a variety of substrate types. Investigations of the deoxygenation of emodin to chrysophanol has led to the discovery of the anthrol reductase activity of an SDR, MdpC involved in monodictyphenone biosynthesis of Aspergillus nidulans and provided access to (R)-dihydroanthracenone, a putative biosynthetic intermediate. This facilitated the identification of several MdpC-related enzymes involved in the biosynthesis of aflatoxins B1, cladofulvin, neosartorin, agnestins and bisanthraquinones. Because of their ability to catalyze the reduction of hydroanthraquinone (anthrols) using NADPH, they were named anthrol reductases. This review provides a comprehensive summary of all the anthrol reductases that have been identified and characterized in the last decade along with their role in the biosynthesis of natural products. In addition, the applications of these enzymes towards the chemoenzymatic synthesis of flavoskyrins, modified bisanthraquinones, 3-deoxy anthraquinones, chiral cycloketones and β-halohydrins have been discussed.

Enantioselective Transformations in the Synthesis of Therapeutic Agents

The proportion of approved chiral drugs and drug candidates under medical studies has surged dramatically over the past two decades. As a consequence, the efficient synthesis of enantiopure pharmaceuticals or their synthetic intermediates poses a profound challenge to medicinal and process chemists. The significant advancement in asymmetric catalysis has provided an effective and reliable solution to this challenge. The successful application of transition metal catalysis, organocatalysis, and biocatalysis to the medicinal and pharmaceutical industries has promoted drug discovery by efficient and precise preparation of enantio-enriched therapeutic agents, and facilitated the industrial production of active pharmaceutical ingredient in an economic and environmentally friendly fashion. The present review summarizes the most recent applications (2008-2022) of asymmetric catalysis in the pharmaceutical industry ranging from process scales to pilot and industrial levels. It also showcases the latest achievements and trends in the asymmetric synthesis of therapeutic agents with state of the art technologies of asymmetric catalysis.

Stairway to Stereoisomers: Engineering Short- and Medium-Chain Ketoreductases To Produce Chiral Alcohols

The short- and medium-chain dehydrogenase/reductase superfamilies are responsible for most chiral alcohol production in laboratories and industries. In nature, they participate in diverse roles such as detoxification, housekeeping, secondary metabolite production, and catalysis of several chemicals with commercial and environmental significance. As a result, they are used in industries to create biopolymers, active pharmaceutical intermediates (APIs), and are also used as components of modular enzymes like polyketide synthases for fabricating bioactive molecules. Consequently, random, semi-rational and rational engineering have helped transform these enzymes into product-oriented efficient catalysts. The rise of newer synthetic chemicals and their enantiopure counterparts has proved challenging, and engineering them has been the subject of numerous studies. However, they are frequently limited to the synthesis of a single chiral alcohol. The study attempts to defragment and describe hotspots of engineering short- and medium-chain dehydrogenases/reductases for the production of chiral synthons.

Biocatalysis: A smart and green tool for the preparation of chiral drugs

Over the last decades, biocatalysis has achieved growing interest thanks to its potential to enable high efficiency, high yield, and eco-friendly processes aimed at the production of pharmacologically relevant compounds. Particularly, biocatalysis proved an effective and potent tool in the preparation of chiral molecules, and the recent innovations of biotechnologies and nanotechnologies open up a new era of further developments in this field. Different strategies are now available for the synthesis of chiral drugs and their intermediates. Enzymes are green tools that offer several advantages, associated both to catalysis and environmentally friendly reactants. Specifically, the use of enzymes isolated from biological sources or of whole-cell represents a valuable approach to obtain pharmaceutical products. The sustainability, the higher efficiency, and cost-effectiveness of biocatalytic reactions result in improved performance and properties that can be translated from academia to industry. In this review, we focus on biocatalytic approaches for synthesizing chiral drugs or their intermediates. Aiming to unveil the potentialities of biocatalysis systems, we discuss different examples of innovative biocatalytic approaches and their applications in the pharmaceutical industry.

Biocatalysis for the asymmetric synthesis of Active Pharmaceutical Ingredients (APIs): this time is for real

INTRODUCTION

Biocatalysis has emerged as a powerful and useful strategy for the synthesis of active pharmaceutical ingredients (APIs). The outstanding developments in molecular biology techniques allow nowadays the screening, large-scale production, and designing of biocatalysts, adapting them to desired reactions. Many enzymes can perform reactions both in aqueous and non-aqueous media, broadening even further the opportunities to integrate them in complex pharmaceutical multi-step syntheses.

AREAS COVERED

This paper showcases several examples of biocatalysis in the pharmaceutical industry, covering examples of different enzymes, such as lipases, oxidoreductases, and transaminases, to deliver active drugs through complex synthetic routes. Examples are critically discussed in terms of reaction conditions, motivation for using an enzyme, and how biocatalysts can be integrated in multi-step syntheses. When possible, biocatalytic routes are benchmarked with chemical reactions.

EXPERT OPINION

The reported enzymatic examples are performed with high substrate loadings (>100 g L^-1) and with excellent selectivity, making them inspiring strategies for present and future industrial applications. The combination of powerful molecular biology techniques with the needs of the pharmaceutical industry can be aligned, creating promising platforms for synthesis under more sustainable conditions.

Ketoreductase-Catalyzed Access to Axially Chiral 2,6-Disubstituted Spiro[3.3]heptane Derivatives

The desymmetrization of a prochiral 6-oxaspiro[3.3]heptane-2-carboxylic acid derivative via biocatalytic ketoreductase-mediated reduction has provided access to both enantiomers in high ee. The axially chiral alcohol was converted to the corresponding ester alcohol, amino acid, and amino alcohol building blocks while high enantiopurity was maintained.

Shielding Effect of Nanomicelles: Stable and Catalytically Active Oxidizable Pd(0) Nanoparticle Catalyst Compatible for Cross-Couplings of Water-Sensitive Acid Chlorides in Water

Under the shielding effect of nanomicelles, a sustainable micellar technology for the design and convenient synthesis of ligand-free oxidizable ultrasmall Pd(0) nanoparticles (NPs) and their subsequent catalytic exploration for couplings of water-sensitive acid chlorides in water is reported. A proline-derived amphiphile, PS-750-M, plays a crucial role in stabilizing these NPs, preventing their aggregation and oxidation state changes. These NPs were characterized using ¹³C nuclear magnetic resonance (NMR), infrared (IR), and surface-enhanced Raman scattering (SERS) spectroscopy to evaluate the carbonyl interactions of PS-750-M with Pd. High-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDX) studies were performed to reveal the morphology, particle size distribution, and chemical composition, whereas X-ray photoelectron spectroscopy (XPS) measurements unveiled the oxidation state of the metal. In the cross-couplings of water-sensitive acid chlorides with boronic acids, the micelle's shielding effect and boronic acids plays a vital role in preventing unwanted side reactions, including the hydrolysis of acid chlorides under basic pH. This approach is scalable and the applications are showcased in multigram scale reactions.