A Comprehensive Review on C-3 Functionalization of β-Lactams

Expanding the Chemical Space of Electrophilic β-Glycosyl β-Lactams through Photoinduced Diastereoselective Functionalization

Herein, we present a photoinduced diastereoselective C-3 functionalization of electrophilic β-glycosyl β-lactams. The developed protocol is simple, mild, and scalable and explores the use of 3-exomethylene β-lactams as reaction partners in a Giese type reaction. The key nucleophilic alkyl radical is generated by a photoinduced electron transfer process in the EDA complex formed by NHPI and Hantzsch esters. The diastereoselective hydrogen atom transfer to the β-lactam radical intermediate enables the synthesis of various N-phenyl β-glycosyl β-lactams.

Synthesis, Characterisation and Mechanism of Action of Anticancer 3-Fluoroazetidin-2-ones

The stilbene combretastatin A-4 (CA-4) is a potent microtubule-disrupting agent interacting at the colchicine-binding site of tubulin. In the present work, the synthesis, characterisation and mechanism of action of a series of 3-fluoro and 3,3-difluoro substituted β-lactams as analogues of the tubulin-targeting agent CA-4 are described. The synthesis was achieved by a convenient microwave-assisted Reformatsky reaction and is the first report of 3-fluoro and 3,3-difluoro β-lactams as CA-4 analogues. The β-lactam compounds 3-fluoro-4-(3-hydroxy-4-methoxyphenyl)-1-(3,4,5-trimethoxy phenyl)azetidin-2-one 32 and 3-fluoro-4-(3-fluoro-4-methoxyphenyl)-1-(3,4,5-trimethoxyphenyl)azetidin-2-one) 33 exhibited potent activity in MCF-7 human breast cancer cells with IC50 values of 0.075 µM and 0.095 µM, respectively, and demonstrated low toxicity in non-cancerous cells. Compound 32 also demonstrated significant antiproliferative activity at nanomolar concentrations in the triple-negative breast cancer cell line Hs578T (IC50 0.033 μM), together with potency in the invasive isogenic subclone Hs578Ts(i)8 (IC50 = 0.065 μM), while 33 was also effective in MDA-MB-231 cells (IC50 0.620 μM). Mechanistic studies demonstrated that 33 inhibited tubulin polymerisation, induced apoptosis in MCF-7 cells, and induced a downregulation in the expression of anti-apoptotic Bcl2 and survivin with corresponding upregulation in the expression of pro-apoptotic Bax. In silico studies indicated the interaction of the compounds with the colchicine-binding site, demonstrating the potential for further developing novel cancer therapeutics as microtubule-targeting agents.

The facile and efficient synthesis of novel monocyclic cis-β-lactam conjugates with a 1-methyl-1H-imidazole-2-thiol nucleus

We developed a facile and efficient synthesis of novel monocyclic cis-β-lactam conjugates with a 1-methyl-1H-imidazole-2-thiol nucleus through a ketene-imine [2+2] cycloaddition reaction of acyl chloride and different Schiff bases.

Synthesis, in vitro biological evaluation and in silico molecular docking studies of novel β-lactam-anthraquinone hybrids

Schiff bases from 2-aminoanthraquinone have been prepared by reaction with aldehydes and used to prepare novel β-lactam-anthraquinone hybrids via [2+2] ketene-imine cycloaddition (Staudinger reaction) reaction. In vitro antibacterial studies of all synthesized compound were carried out against three gram-positive strains Staphylococcus aureus (Methicillin-resistant strain), Enterococcus faecium (Vancomycin-resistant strain) and Bacillus subtilis, and two gram-negative strains Escherichia coli and Pseudomonas aeruginosa. These compounds were further evaluated for their in vitro antifungal activity against Candida albicans, Aspergillus niger and Trichophyton mentagrophytes. Hybrid compounds showed moderate to excellent antibacterial and antifungal activities. Surprisingly, among the tested compounds, some of them revealed equal antibacterial and antifungal properties and even better than standards. In addition, results demonstrated that the new hybrids are very promising antibacterial agents against resistant strains. Also molecular docking studies were carried out by Autodoc software. Penicillin-binding protein 2a (PDB ID: 1VQQ) from methicillin-resistant Staphylococcus aureus strain used as a target which good binding interactions were observed.