An efficient entry to highly substituted chiral 2-oxopiperazines from α-amino acids via iodocyclization

Corannulene Amino Acid-Derived Water-Soluble Amphiphilic Buckybowls as Broad-Spectrum Membrane Targeting Antibacterial Agents

To date, the use of corannulene has been restricted in the area of material science, but its application in biomedical research has yet to be established due to its nonsolubility in an aqueous environment and synthetic infeasibility. Herein, we detail the development of a new family of highly curved π-conjugated corannulene-containing unnatural α-amino acid (CAA) derivatives to overcome this challenge. These CAAs have been extended as novel constituents for the synthesis of corannulene-containing water-soluble cationic peptides (CCPs), which display inhibitory activity against broad-spectrum pathogenic bacteria along with drug-resistant bacteria via a membrane-damaging mechanism. Importantly, several of the synthesized peptides were found to be appreciably nonhemolytic against hRBCs and noncytotoxic against mammalian 3T3 cells. In vivo efficacy studies of the potent and least cytotoxic peptide 6a demonstrated clearance of bacteria from the spleen, liver, lung, and blood of mice infected with S. aureus ATCC 25923.

A Synthetic Overview of Benzoxazines and Benzoxazepines as Anticancer Agents

Benzoxazines and benzoxazepines are nitrogen and oxygen-containing six and seven-membered benzo-fused heterocyclic scaffolds, respectively. Benzoxazepines and benzoxazines are well-known pharmacophores in pharmaceutical chemistry, which are of significant interest and have been extensively studied because of their promising activity against various diseases including their wide range of anticancer activity. Several reports are known for synthesizing benzoxazine and benzoxazepine-based compounds in the literature. Herein this review provides a critical analysis of synthetic strategies towards benzoxazines and benzoxazepines along with various ranges of anticancer activities based on these molecules that have been reported from 2010 onwards. This review also focuses on the structure-activity relationship of the benzoxazine and benzoxazepine scaffolds containing bioactive compounds and describes how the structural modification affects their anticancer activity.

Tyrosine-Derived Novel Benzoxazine Active in a Rat Syngenic Mammary Tumor Model of Breast Cancer

In continuing efforts of improving benzoxazepine derivatives as an anti-breast cancer agent, a new chemical entity, benzoxazine, was designed from scaffold morphing. Structure-activity relationship studies revealed that H, -OMe, -CF₃, and -F were well tolerated on R₁ and R₂ positions of ring A, and R² as -CH₂CH₂N(CH₂)₄ (N-ethyl pyrrolidine) and -CH₂CH₂N(CH₂)₅ (N-ethyl piperidine) chains on ring D increased activities (Series B, Figure 3). 13d selected as a lead compound (IC₅₀: 0.20 to 0.65 μM) induces apoptosis, cell cycle arrest, and loss of mitochondrial membrane potential in breast cancer cells. Compound 13d was formulated into 13d-f using cyclodextrin to improve its solubility for a pharmacokinetic, in vivo efficacy study. Both 13d and 13d-f regressed tumor growth at concentrations of 5 and 20 mg/kg better than tamoxifen without any mortality in a rat syngenic mammary tumor model. Collectively, our data suggest that tyrosine-derived novel benzoxazine 13d could be a potential lead for the treatment of breast cancer and hence deserve further in-depth studies.

Synthesis of the Nonribosomal Peptide Phevalin and Analogs

Phevalin, a cyclic nonribosomal peptide produced by Staphylococcus aureus, has intriguing biological properties. A synthetic route to access phevalin and similar pyrazinone natural products tyrvalin, leuvalin, phileucin, and a few synthetic analogs is described. The reaction sequence involves a one-pot carbamate deprotection/imine formation/aerobic oxidation to form the pyrazinone-containing products.

Synthesis of enantiomerically enriched indolines and tetrahydroisoquinolines from (S)-amino acid-derived chiral carbocations: an easy access to (3S,4R)-demethoxy-3-isopropyl diclofensine

Enantiomerically enriched indolines and tetrahydroisoquinolines were synthesized in high yields from easily accessible (S)-amino acid-derived chiral carbocations.

Microwave assisted [RuCl2(p-cymene)2]2 catalyzed regioselective endo-tandem cyclization involving imine and alkyne activation: an approach to benzo[4,5]imidazo[2,1-a]pyridine scaffold

A microwave assisted efficient route to the synthesis of benzimidazole fused heterocycles through metal catalyzed endo-cyclization strategy involving imine and alkyne activation has been developed.