Asymmetric Synthesis of the HMG-CoA Reductase Inhibitor Atorvastatin Calcium: An Organocatalytic Anhydride Desymmetrization and Cyanide-Free Side Chain Elongation Approach

Assessing the structural stability and drug encapsulation efficiency of poly(ethylene glycol)-poly(L-lactic acid) nanoparticles loaded with atorvastatin calcium: Based on dissipative particle dynamics

Block polymer micelles have been proven highly biocompatible and effective in improving drug utilization for delivering atorvastatin calcium. Therefore, it is of great significance to measure the stability of drug-loading nano micelles from the perspective of block polymer molecular sequence design, which would provide theoretical guidance for subsequent clinical applications. This study aims to investigate the structural stability of drug-loading micelles formed by two diblock/triblock polymers with various block sequences through coarse-grained dissipative particle dynamics (DPD) simulations. From the perspectives of the binding strength of poly(L-lactic acid) (PLLA) and polyethylene glycol (PEG) in nanoparticles, hydrophilic bead surface coverage, and the morphological alteration of nanoparticles induced by shear force, the ratio of hydrophilic/hydrophobic sequence length has been observed to affect the stability of nanoparticles. We have found that for diblock polymers, PEG3kda-PLLA2kda has the best stability (corresponding hydrophilic coverage ratio is 0.832), while PEG4kda-PLLA5kda has the worst (coverage ratio 0.578). For triblock polymers, PEG4kda-PLLA2kda-PEG4kda has the best stability (0.838), while PEG4kda-PLLA5kda-PEG4kda possesses the worst performance (0.731), and the average performance on stability is better than nanoparticles composed of diblock polymers.

Asymmetric organocatalysis: an enabling technology for medicinal chemistry

The efficacy and synthetic versatility of asymmetric organocatalysis have contributed enormously to the field of organic synthesis since the early 2000s. As asymmetric organocatalytic methods mature, they have extended beyond the academia and undergone scale-up for the production of chiral drugs, natural products, and enantiomerically enriched bioactive molecules. This review provides a comprehensive overview of the applications of asymmetric organocatalysis in medicinal chemistry. A general picture of asymmetric organocatalytic strategies in medicinal chemistry is firstly presented, and the specific applications of these strategies in pharmaceutical synthesis are systematically described, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial, and antiparasitic agents, as well as several miscellaneous bioactive agents. The review concludes with a discussion of the challenges, limitations and future prospects for organocatalytic asymmetric synthesis of medicinally valuable compounds.

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.

Biocatalyzed Synthesis of Statins: A Sustainable Strategy for the Preparation of Valuable Drugs

Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are the largest selling class of drugs prescribed for the pharmacological treatment of hypercholesterolemia and dyslipidaemia. Statins also possess other therapeutic effects, called pleiotropic, because the blockade of the conversion of HMG-CoA to (R)-mevalonate produces a concomitant inhibition of the biosynthesis of numerous isoprenoid metabolites (e.g., geranylgeranyl pyrophosphate (GGPP) or farnesyl pyrophosphate (FPP)). Thus, the prenylation of several cell signalling proteins (small GTPase family members: Ras, Rac, and Rho) is hampered, so that these molecular switches, controlling multiple pathways and cell functions (maintenance of cell shape, motility, factor secretion, differentiation, and proliferation) are regulated, leading to beneficial effects in cardiovascular health, regulation of the immune system, anti-inflammatory and immunosuppressive properties, prevention and treatment of sepsis, treatment of autoimmune diseases, osteoporosis, kidney and neurological disorders, or even in cancer therapy. Thus, there is a growing interest in developing more sustainable protocols for preparation of statins, and the introduction of biocatalyzed steps into the synthetic pathways is highly advantageous—synthetic routes are conducted under mild reaction conditions, at ambient temperature, and can use water as a reaction medium in many cases. Furthermore, their high selectivity avoids the need for functional group activation and protection/deprotection steps usually required in traditional organic synthesis. Therefore, biocatalysis provides shorter processes, produces less waste, and reduces manufacturing costs and environmental impact. In this review, we will comment on the pleiotropic effects of statins and will illustrate some biotransformations nowadays implemented for statin synthesis.

Atorvastatin (Lipitor) by MCR

A concise and convergent synthesis of the atorvastatin, the best-selling cardiovascular drug of all time, is presented. Our approach is based on an Ugi reaction, which shortens the current synthetic route and is advantageous over the published syntheses.

Organocatalysts Derived from Unnatural α-Amino Acids: Scope and Applications

The organocatalytic properties of unnatural α-amino acids are reviewed. Post-translational derivatives of natural α-amino acids include 4-hydroxy-l-proline and 4-amino-l-proline scaffolds, and also proline homologues. The activity of synthetic unnatural α-amino acid-based organocatalysts, such as β-alkyl alanines, alanine-based phosphines, and tert-leucine derivatives, are reviewed herein. The organocatalytic properties of unnatural monocyclic, bicyclic, and tricyclic proline derivatives are also reviewed. Several families of these organocatalysts permit the efficient and stereoselective synthesis of complex natural products. Most of the reviewed organocatalysts accelerate the reported reactions through covalent interactions that raise the HOMO (enamine intermediates) or lower the LUMO (iminium intermediates).

Chiral Syn-1,3-diol Derivatives via a One-Pot Diastereoselective Carboxylation/ Bromocyclization of Homoallylic Alcohols

Chiral syn-1,3-diols are fundamental structural motifs in many natural products and drugs. The traditional Narasaka-Prasad diastereoselective reduction from chiral β-hydroxyketones is an important process for the synthesis of these functionalized syn-1,3-diols, but it is of limited applicability for large-scale synthesis because (1) highly diastereoselective control requires extra explosive and flammable Et₂BOMe as a chelating agent under cryogenic conditions and (2) only a few functional syn-1,3-diol scaffolds are available. Those involving halogen-functionalized syn-1,3-diols are much less common. There are no reported diastereoselective reactions involving chemical fixation of CO₂/bromocyclization of homoallylic alcohols to halogen-containing chiral syn-1,3-diols. Herein, we report an asymmetric synthesis of syn-1,3-diol derivatives via direct diastereoselective carboxylation/bromocyclization with both relative and absolute stereocontrol utilizing chiral homoallylic alcohols and CO₂ in one pot with up to 91% yield, > 99% ee, and >19:1 dr. The power of this methodology has been demonstrated by the asymmetric synthesis of statins at the pilot plant scale.

•

Diastereoselective carboxylation/bromocyclization

•

Mild conditions

•

Pilot-plant-scale synthesis of statins

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

A family of novel chloramphenicol base-amide organocatalysts possessing a NH functionality at C-1 position as monodentate hydrogen bond donor were developed and evaluated for enantioselective organocatalytic alcoholysis of meso-cyclic anhydrides. These structural diversified organocatalysts were found to induce high enantioselectivity in alcoholysis of anhydrides and was successfully applied to the asymmetric synthesis of (S)-GABOB.

Transition-metal-free synthesis of polysubstituted pyrrole derivatives via cyclization of methyl isocyanoacetate with aurone analogues

A transition-metal-free, operationally simple and atom-economic protocol that converts isocyanoacetates and aurones to 2,3,4-trisubstituted pyrroles catalyzed by NaOH was presented.

Stereocontrolled synthesis of rosuvastatin calcium via iodine chloride-induced intramolecular cyclization

A novel, stereoselective approach towards rosuvastatin calcium from the known (S)-homoallylic alcohol has been developed.

The total synthesis of calcium atorvastatin

A practical and convergent asymmetric route to calcium atorvastatin (1) is reported.

New chloramphenicol Schiff base ligands for the titanium-mediated asymmetric aldol reaction of α,β-unsaturated aldehydes with diketene: a short synthesis of atorvastatin calcium

Several novel chiral Schiff base ligands were prepared from a commercially available chloramphenicol base and applied to the titanium-mediated asymmetric aldol reaction of diketene with various α,β-unsaturated aldehydes.

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

The conjugate addition reaction has been a useful tool in the formation of carbon-carbon bonds. The utility of this reaction has been demonstrated in the synthesis of many natural products, materials, and pharmacological agents. In the last three decades, there has been a significant increase in the development of asymmetric variants of this reaction. Unfortunately, conjugate addition reactions using α,β-unsaturated amides and lactams remain underdeveloped due to their inherently low reactivity. This review highlights the work that has been done on both diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams.