1,2-Benzisoxazole compounds: a patent review (2009 - 2014)

3-Halo-5,6-dihydro-4H-1,2-oxazine N-oxides as synthetic equivalents of unsaturated nitrile oxides in the [3 + 2]-cycloaddition with arynes: synthesis of substituted 3-vinyl-1,2-benzisoxazoles

The reaction of 3-halo-5,6-dihydro-4H-1,2-oxazine N-oxides with arynes was studied. Arynes were generated from o-silylaryl triflates and underwent consecutive [3 + 2]-cycloaddition/[4 + 2]-cycloreversion with N-oxides leading to substituted 3-vinyl-benzisoxazoles in high yields. In the presented sequence, 1,2-oxazine N-oxides act as surrogates of rarely employed unsaturated nitrile oxides. A broad substrate scope was demonstrated. The influence of the substitution pattern of an aryne on the reaction outcome was determined. In the presence of bulky substituents, polycyclic 4,4a-dihydro-3H-benzofuro[3,2-c][1,2]oxazines were selectively formed. Mechanistic schemes for the observed reaction pathways were proposed. The synthetic utility of the products was demonstrated by their follow-up modifications.

Substitutional Diversity-Oriented Synthesis and In Vitro Anticancer Activity of Framework-Integrated Estradiol-Benzisoxazole Chimeras

Hybridization of steroids and other pharmacophores often modifies the bioactivity of the parent compounds, improving selectivity and side effect profile. In this study, estradiol and 3′-(un)substituted benzisoxazole moieties were combined into novel molecules by structural integration of their aromatic rings. Simple estrogen starting materials, such as estrone, estradiol and estradiol-3-methylether were used for the multistep transformations. Some of the heterocyclic derivatives were prepared from the estrane precursor by a formylation or Friedel–Crafts acylation—oximation—cyclization sequence, whereas others were obtained by a functional group interconversion strategy. The antiproliferative activities of the synthesized compounds were assessed on various human cervical, breast and prostate cancer cell lines (HeLa, MCF-7, PC3, DU-145) and non-cancerous MRC-5 fibroblast cells. Based on the primary cytotoxicity screens, the most effective cancer-selective compounds were selected, their IC₅₀ values were determined and their apoptosis-inducing potential was evaluated by quantitative real-time PCR. Pharmacological studies revealed a strong structure–function relationship, where derivatives with a hydroxyl group on C-17 exhibited stronger anticancer activity compared to the 17-acetylated counterparts. The present study concludes that novel estradiol-benzisoxazole hybrids exert remarkable cancer cell-specific antiproliferative activity and trigger apoptosis in cancer cells.

Identification of a bacteria-produced benzisoxazole with antibiotic activity against multi-drug resistant Acinetobacter baumannii

The emergence of multi-drug resistant pathogenic bacteria represents a serious and growing threat to national healthcare systems. Most pressing is an immediate need for the development of novel antibacterial agents to treat Gram-negative multi-drug resistant infections, including the opportunistic, hospital-derived pathogen, Acinetobacter baumannii. Herein we report a naturally occurring 1,2-benzisoxazole with minimum inhibitory concentrations as low as 6.25 μg ml-1 against clinical strains of multi-drug resistant A. baumannii and investigate its possible mechanisms of action. This molecule represents a new chemotype for antibacterial agents against A. baumannii and is easily accessed in two steps via de novo synthesis. In vitro testing of structural analogs suggest that the natural compound may already be optimized for activity against this pathogen. Our results demonstrate that supplementation of 4-hydroxybenzoate in minimal media was able to reverse 1,2-benzisoxazole's antibacterial effects in A. baumannii. A search of metabolic pathways involving 4-hydroxybenzoate coupled with molecular modeling studies implicates two enzymes, chorismate pyruvate-lyase and 4-hydroxybenzoate octaprenyltransferase, as promising leads for the target of 3,6-dihydroxy-1,2-benzisoxazole.

Synthesis and Biological Evaluation of Fused Tricyclic Heterocycle Piperazine (Piperidine) Derivatives As Potential Multireceptor Atypical Antipsychotics

Herein, a novel series of multireceptor ligands was developed as polypharmacological antipsychotic agents using the designed multiple ligand approach between dopamine receptors and serotonin receptors. Among them, compound 47 possessed unique pharmacological features, exhibiting high affinities for D₂, D₃, 5-HT_1A, 5-HT_2A, and 5-HT₆ receptors and low efficacy at the off-target receptors (5-HT_2C, histamine H₁, and adrenergic α₁ receptor). Compound 47 showed dose-dependent inhibition of apomorphine- and MK-801-induced motor behavior, and the conditioned avoidance response with low cataleptic effect. Moreover, compound 47 resulted nonsignificantly serum prolactin levels and weight gain change compared with risperidone. Additionally, compound 47 possessed a favorable pharmacokinetic profile with oral bioavailability of 58.8% in rats. Furthermore, compound 47 displayed procognition properties in a novel object recognition task in rats. Taken together, compound 47 may constitute a novel class of atypical antipsychotic drugs for schizophrenia.

Synthesis, antimicrobial and in vitro antitumor activities of a series of 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives

Three derivatives of substituted 1,2,3-thia- or 1,2,3-selenadiazole (4a–c) were prepared and characterized by different chemical techniques. These compounds were evaluated for their antimicrobial and antitumor activities. Compounds 4a (propenoxide derivative), 4b (carbaldehyde derivative), and 4c (benzene derivative) were active against the yeast-like fungi Candida albicans. Compound 4a was active against gram-negative Escherichia coli, and compound 4c was active against the gram-positive Staphylococcus aureus. For the antitumor activity, both compounds 4b and 4c were active against all tested tumor cell lines, namely, SW480, HCT116, C32, MV3, HMT3522, and MCF-7. The activity of compound 4c was greater than that of compound 4b and more than that of the reference antitumor 5-flourouracil against the SW480, HCT116, and MCF-7 tumor cell lines. In conclusion, a number of the prepared 1,2,3-thia- or 1,2,3-selenadiazole compounds showed promising antifungal, antibacterial, and in vitro antitumor activities. Further investigations are required to explore the mechanism by which active compound are inducing their cytotoxicity.