A practical enzymatic procedure for the resolution of N-substituted 2-azabicyclo[2.2.1]hept-5-en-3-one

RNAs Containing Carbocyclic Ribonucleotides

Toward the goal of evaluation of carbocyclic ribonucleoside-containing oligonucleotide therapeutics, we developed convenient, scalable syntheses of all four carbocyclic ribonucleotide phosphoramidites and the uridine solid-support building block. Crystallographic analysis confirmed configuration and stereochemistry of these building blocks. Duplexes with carbocyclic RNA (car-RNA) modifications in one strand were less thermodynamically stable than duplexes with unmodified RNA. However, circular dichroism spectroscopy indicated that global conformations of the duplexes containing car-RNAs were similar to those in the unmodified duplexes.

Green Chemistry in the Synthesis of Pharmaceuticals

The principles of green chemistry (GC) can be comprehensively implemented in green synthesis of pharmaceuticals by choosing no solvents or green solvents (preferably water), alternative reaction media, and consideration of one-pot synthesis, multicomponent reactions (MCRs), continuous processing, and process intensification approaches for atom economy and final waste reduction. The GC's execution in green synthesis can be performed using a holistic design of the active pharmaceutical ingredient's (API) life cycle, minimizing hazards and pollution, and capitalizing the resource efficiency in the synthesis technique. Thus, the presented review accounts for the comprehensive exploration of GC's principles and metrics, an appropriate implication of those ideas in each step of the reaction schemes, from raw material to an intermediate to the final product's synthesis, and the final execution of the synthesis into scalable industry-based production. For real-life examples, we have discussed the synthesis of a series of established generic pharmaceuticals, starting with the raw materials, and the intermediates of the corresponding pharmaceuticals. Researchers and industries have thoughtfully instigated a green synthesis process to control the atom economy and waste reduction to protect the environment. We have extensively discussed significant reactions relevant for green synthesis, one-pot cascade synthesis, MCRs, continuous processing, and process intensification, which may contribute to the future of green and sustainable synthesis of APIs.

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.

Biocatalytic routes to anti-viral agents and their synthetic intermediates

An assessment of biocatalytic strategies for the synthesis of anti-viral agents, offering guidelines for the development of sustainable production methods for a future COVID-19 remedy.

Biocatalysis for synthesis of pharmaceuticals

Chirality is a key factor in the safety and efficacy of many drug products and thus the production of single enantiomers of drug intermediates and drugs has become important and state of the art in the pharmaceutical industry. There has been an increasing awareness of the enormous potential of microorganisms and enzymes (biocatalysts) for the transformation of synthetic chemicals with high chemo-, regio- and enatioselectivities providing products in high yields and purity. In this article, biocatalytic processes are described for the synthesis of key chiral intermediates for development pharmaceuticals.

Green access to chiral Vince lactam in a buffer-free aqueous system using a newly identified substrate-tolerant (−)-γ-lactamase

A novel (−)-γ-lactamase with high catalytic efficiency, strong substrate tolerance and environmental friendliness was identified for green access to chiral Vince lactam.

Discovery of a novel (+)-γ-lactamase from Bradyrhizobium japonicum USDA 6 by rational genome mining

A novel (+)-γ-lactamase used for the resolution of racemic γ-lactam from Bradyrhizobium japonicum USDA 6 was found as a result of sequence-structure guided genome mining. It consists of 409 amino acids, only 49% of which are identical to the amino acid sequences of the known (+)-γ-lactamase from Sulfolobus solfataricus. This is only the third (+)-γ-lactamase gene to be reported.

Carbocyclic Ribosylamines: Synthesis of 5-Substituted Carbocyclic β-Ribofuranosylamines

A synthesis of 5-substituted cyclopentylamine precursors for 5'-substituted carbocyclic nucleoside analogues was developed. We show that the stereochemistry of the OsO4-catalyzed hydroxylation of an apically brominated lactam, 7-bromo-2-azabicyclo[2.2.1]hept-5-en-3-one, can be controlled through the appropriate selection of the lactam N-H protecting group. Sterically large groups direct the hydroxylation to the exo-face of the olefin, yielding hydroxylation products that can be converted into analogues of carbocyclic ribosides. Conversely, a sterically small protecting group permits OsO4 approach from the endo-face, yielding hydroxylation products analogous to carbocyclic lyxosides. A key intermediate for carbocyclic sugar production, (1S,2S,3R, 4R,5S)-1-(tert-butyloxycarbonyl)amino-5-bromo-2,3-(dimethylmethylene)dioxy-4-hydroxymethylcyclopentane, was synthesized starting from a commercially available enantiomerically pure lactam, (1S)-(+)-2-azabicyclo[2.2.1]hept-5-en-3-one, in seven steps in an overall yield of 21%.

A facile synthesis of cis-4-amino-2-cyclopentene-1-methanol, a key intermediate for the synthesis of carbocyclic nucleosides

A number of carbocyclic nucleosides can be synthesized from (+/-)-cis-4-amino-2-cyclopentene-1-methanol (3). Carbocyclic amino alcohol 3 is a key intermediate that makes possible the efficient synthesis of the carbocyclic nucleosides. In this study we wish to report an efficient synthesis of carbocyclic amino alcohol 3 from inexpensive and readily available starting material. The synthetic route employed cyclopentadiene (4) as a starting material and proceeded in 38% overall yield through 6 steps involving a hetero Diels-Alder reaction and an aza-Claisen rearrangement.

Biocatalytic synthesis of intermediates for the synthesis of chiral drug substances

There has been an increasing awareness of the enormous potential of microorganisms and enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enantioselectivity. Chiral intermediates and fine chemicals are in high demand, both from the pharmaceutical and agrochemical industries, for the preparation of bulk drug substances and agricultural products. Biocatalytic processes have been described for the synthesis of chiral intermediates for beta3- and beta2-receptor agonists, antihypertensive drugs, antiviral agents, melatonin receptor agonists, anticholesterol and anticancer drugs, and drugs to treat Alzheimer's disease.

Industrial biocatalysis

The number of industrial processes for the synthesis of fine and commodity chemicals, pharmaceutical and agrochemical intermediates and drug substances utilizing biological catalysts continues to grow. The combination of new molecular biology techniques, such as directed evolution and pathway engineering, with new and efficient high-throughput screening methods is poised to bolster this field and further advance the contribution of biocatalysis to the chemical and the pharmaceutical industries.