A biocatalytic approach for resolution of 3-hydroxy-3-phenylpropanonitrile with the use of immobilized enzymes stabilized with ionic liquids

Due to the growing importance of synthesizing active pharmaceutical ingredients (APIs) in enantiomerically pure form, new methods of asymmetric synthesis are being sought. Biocatalysis is a promising technique that can lead to enantiomerically pure products. In this study, lipase from Pseudomonas fluorescens, immobilized on modified silica nanoparticles, was used for the kinetic resolution (via transesterification) of a racemic mixture of 3-hydroxy-3-phenylpropanonitrile (3H3P), where the obtaining of a pure (S)-enantiomer of 3H3P is a crucial step in the fluoxetine synthesis pathway. For additional stabilization of the enzyme and enhanced process efficiency, ionic liquids (ILs) were used. It was found that the most suitable IL was [BMIM]Cl; a process efficiency of 97.4 % and an enantiomeric excess (ee%) of 79.5 % were obtained when 1 % (w/v) of that IL in hexane was applied and the process was catalyzed by lipase immobilized on amine-modified silica.

Recent Advances in Biocatalysis for Drug Synthesis

Biocatalysis is constantly providing novel options for the synthesis of active pharmaceutical ingredients (APIs). In addition to drug development and manufacturing, biocatalysis also plays a role in drug discovery and can support many active ingredient syntheses at an early stage to build up entire scaffolds in a targeted and preparative manner. Recent progress in recruiting new enzymes by genome mining and screening or adapting their substrate, as well as product scope, by protein engineering has made biocatalysts a competitive tool applied in academic and industrial spheres. This is especially true for the advances in the field of nonribosomal peptide synthesis and enzyme cascades that are expanding the capabilities for the discovery and synthesis of new bioactive compounds via biotransformation. Here we highlight some of the most recent developments to add to the portfolio of biocatalysis with special relevance for the synthesis and late-stage functionalization of APIs, in order to bypass pure chemical processes.

Shortening Synthetic Routes to Small Molecule Active Pharmaceutical Ingredients Employing Biocatalytic Methods

Biocatalysis, using enzymes for organic synthesis, has emerged as powerful tool for the synthesis of active pharmaceutical ingredients (APIs). The first industrial biocatalytic processes launched in the first half of the last century exploited whole-cell microorganisms where the specific enzyme at work was not known. In the meantime, novel molecular biology methods, such as efficient gene sequencing and synthesis, triggered breakthroughs in directed evolution for the rapid development of process-stable enzymes with broad substrate scope and good selectivities tailored for specific substrates. To date, enzymes are employed to enable shorter, more efficient, and more sustainable alternative routes toward (established) small molecule APIs, and are additionally used to perform standard reactions in API synthesis more efficiently. Herein, large-scale synthetic routes containing biocatalytic key steps toward >130 APIs of approved drugs and drug candidates are compared with the corresponding chemical protocols (if available) regarding the steps, reaction conditions, and scale. The review is structured according to the functional group formed in the reaction.

Application of Ketoreductase in Asymmetric Synthesis of Pharmaceuticals and Bioactive Molecules: An Update (2018-2020)

With the rapid development of genomic DNA sequencing, recombinant DNA expression, and protein engineering, biocatalysis has been increasingly and widely adopted in the synthesis of pharmaceuticals, bioactive molecules, fine chemicals, and agrochemicals. In this review, we have summarized the most recent advances achieved (2018-2020) in the research area of ketoreductase (KRED)-catalyzed asymmetric synthesis of chiral secondary alcohol intermediates to pharmaceuticals and bioactive molecules. In the first part, synthesis of chiral alcohols with one stereocenter through the bioreduction of four different ketone classes, namely acyclic aliphatic ketones, benzyl or phenylethyl ketones, cyclic aliphatic ketones, and aryl ketones, is discussed. In the second part, KRED-catalyzed dynamic reductive kinetic resolution and reductive desymmetrization are presented for the synthesis of chiral alcohols with two contiguous stereocenters.

Catalytic Lewis and Brønsted acid syn-diastereoselective benzylic substitutions of α-hydroxy-β-nitro- and α-hydroxy-β-azido-alkyl arenes

A series of alkyl and alkenyl p-methoxy arenes containing α,β-disubstituted diamino and amino alcohol groups were synthesized from β-nitro and β-azido benzylic alcohols in the presence of AuCl3 as catalyst. The formation of predominantly syn-disubstituted products were rationalized on the basis of mechanistic considerations and transition state models relying on A1,3-allylic strain. The products could have utility in the design of medicinally relevant compounds and as chiral ligands for asymmetric catalysis. A new synthesis of (+)-sertraline (Zoloft) was achieved.

Combination of organocatalytic oxidation of alcohols and organolithium chemistry (RLi) in aqueous media, at room temperature and under aerobic conditions

Organocatalysis and highly-polar s-block organometallic chemistry (RLi) work together in water, under air and at room temperature for the selective and ultrafast synthesis of tertiary alcohols.