Stereoselective Synthesis of Ezetimibe via Cross-Metathesis of Homoallylalcohols and α-Methylidene-β-Lactams

Insights into the anticancer activity of chiral alkylidene-β-lactams and alkylidene-γ-lactams: Synthesis and biological investigation

Chiral alkylidene-β-lactams and alkylidene-γ-lactams were synthesized and screened for their in vitro activity against four human cancer cell lines (melanoma, esophageal, lung and fibrosarcoma carcinoma). Alkylidene-β-lactams were synthesized via Wittig reaction of diverse phosphorus ylides with benzhydryl 6-oxopenicillanate, derived from 6-aminopenicillanic acid. Moreover, novel chiral alkylidene-γ-lactams were synthesized through a multistep strategy starting from a chiral substrate (d-penicillamine). The in vitro assays allowed the identification of four compounds with IC₅₀ values < 10 μM for A375 cell line, and three compounds with IC₅₀ values < 10 μM for OE19 cell line. The effect of the most promising compounds on cell death mechanism, reactive oxygen species generation as well as the evaluation of their ability to act as MMP-9 inhibitors were studied. The reported results unveil the potential of alkylidene-β-lactams as anticancer agents.

Tailor-made amino acids in the design of small-molecule blockbuster drugs

The role of amino acids (AAs) in modern health industry is well-appreciated. Residues of individual AAs, or their chemical modifications, such as diamines and amino alcohols, are frequently found in the structures of modern pharmaceuticals. The goal of this review article, is to emphasize that, currently, tailor-made AAs serve as key structural features in many most successful pharmaceuticals, so-called blockbuster drugs. In the present article, we profile 14 small-molecule drugs, underscoring the breadth of structural variety of AAs applications in numerous therapeutic areas. For each compound, we provide spectrum of biological activity, medicinal chemistry discovery, and synthetic approaches.

β-Lactams as promising anticancer agents: Molecular hybrids, structure activity relationships and potential targets

β-Lactam, commonly referred as azetidin-2-one, is a multifunctional building block for synthesizing β-amino ketones, γ-amino alcohols, and other compounds. Besides its well known antibiotic activity, this ring system exhibits a wide range of activities, attracting the attention of researchers. However, the structurally diverse β-lactam analogues as anticancer agents and their different molecular targets are poorly discussed. The purpose of this review is 3-fold: (1) to explore the molecular hybridization approach to design β-lactams hybrids as anticancer agents; (2) the structure activity relationship of the most active anticancer β-lactams and (3) to summarize their antitumor mechanisms.

Iridium-Catalyzed Asymmetric Hydrogenation of γ- and δ-Ketoacids for Enantioselective Synthesis of γ- and δ-Lactones

A highly efficient asymmetric hydrogenation of γ- and δ-ketoacids was developed by using a chiral spiro iridium catalyst (S)-1a, affording the optically active γ- and δ-hydroxy acids/lactones in high yields with excellent enantioselectivities (up to >99% ee) and turnover numbers (TON up to 100000). This protocol provides an efficient and practical method for enantioselective synthesis of Ezetimibe.

Bypassing the stereoselectivity issue: transformations of Kinugasa adducts from chiral alkynes and non-chiral acyclic nitrones

An approach to β-lactams via a reaction between chiral copper acetylides and acyclic nitrones is reported. Electronic circular dichroism (ECD) in combination with NMR spectroscopy was used to determine the absolute configuration of all components of complex mixtures of azetidinones. Stereochemical preferences observed in the studied reactions are discussed and a model of a new reaction pathway supported by DFT conformational analysis is proposed. Subsequent transformations of the synthesized Kinugasa adducts followed by epimerization at the C-3 carbon atom led to trans-substituted azetidinones with improved stereoselectivity, mimicking a variety of important β-lactam structures. On the other hand, the oxidation of the furyl residue to the carboxylic group followed by oxidative decarboxylation with lead tetraacetate afforded the more thermodynamically stable trans-substituted 4-acetoxy azetidinone. The latter strategy is particularly attractive for the diastereomeric mixture in which isomers with the same configuration at the C-3 carbon atom dominate.

Formation of tetrasubstituted C–C double bonds via olefin metathesis: challenges, catalysts, and applications in natural product synthesis

Among the many types of transition-metal-catalysed C–C bond forming reactions, olefin metathesis is without a doubt one of the most thriving fields in modern organic synthetic chemistry.