Design, Synthesis, and Biological Evaluation of Structurally Rigid Analogues of 4-(3-Hydroxyphenyl)piperidine Opioid Receptor Antagonists

Biological Evaluation of 3-Azaspiro[Bicyclo[3.1.0]Hexane-2,5′-Pyrimidines] as Potential Antitumor Agents

A series of heterocyclic compounds containing spirofused barbiturate and 3-azabicyclo[3.1.0]hexane frameworks have been studied as potential antitumor agents. Antiproliferative activity of products was screened in human erythroleukemia (K562), T lymphocyte (Jurkat), and cervical carcinoma (HeLa) as well as mouse colon carcinoma (CT26) and African green monkey kidney epithelial (Vero) cell lines. The most effective among the screened compounds show IC50 in the range from 4.2 to 24.1 μM for all tested cell lines. The screened compounds have demonstrated a significant effect of the distribution of HeLa and CT26 cells across the cell cycle stage, with accumulation of cells in SubG1 phase and induced apoptosis. It was found, using a confocal microscopy, that actin filaments disappeared and granular actin was distributed diffusely in the cytoplasm of up to 90% of HeLa cells and up to 64% of CT26 cells after treatment with tested 3-azaspiro[bicyclo [3.1.0]hexane-2,5′-pyrimidines]. We discovered that the number of HeLa cells with filopodium-like membrane protrusions was reduced significantly (from 91% in control cells to 35%) after treatment with the most active compounds. A decrease in cell motility was also noticed. Preliminary in vivo experiments on the impact of the studied compounds on the dynamics of CT26 tumor growth in Balb/C mice were also performed.

Diastereoselective desymmetrization reactions of prochiral para-quinamines with cyclopropenes generated in situ: access to fused hydroindol-5-one scaffolds

Interesting desymmetric [3 + 2] annulation reactions between p-quinamines as prochiral N-donors and 2-aroyl-1-chlorocyclopropanecarboxylates facilitated by a base are reported. This successive double Michael reaction delivered a unique class of cyclopropane-fused hydoindol-5-one frameworks, each having four contiguous stereogenic centers, with three of them being fully substituted. Moreover, this method was found to provide acceptable chemical yields with promising diastereoselectivities (dr of up to ≤95 : 5) and to work with a variety of substrates. Importantly, a polycyclic tacrine analogue used to treat Alzheimer's disease was synthesized using our developed method.

Efficient One-Pot, Two-Component Modular Synthesis of 3,5-Disubstituted Pyrazoles

The pyrazole scaffold is one of the most prevalent and important tool in medicinal chemistry. Here, we report a method for preparing 3,5-diarylpyrazoles in good to excellent yield by reacting hydrazones of aryl aldehydes with substituted acetophenones in ethanol in the presence of dimethyl sulfoxide/cat. I₂/cat. HCl. The reverse process, reacting hydrazones of substituted acetophenones with aryl aldehydes under the same conditions, also provides 3,5-diarylpyrazoles in good to excellent yields. Reaction of hydrazones of aldehydes with 2'-aryloxy ketones in the presence of cat. HCl in ethanol and the catalyst-free reaction of phenacyl bromides with hydrazones of aldehydes in ethanol also gave good to excellent yields of 3,5-diarylpyrazoles.

Synthesis of CHF2-substituted 3-azabicyclo[3.1.0]hexanes by photochemical decomposition of CHF2-pyrazolines

A practical synthesis of CHF₂-substituted 3-azabicyclo[3.1.0]hexanes was developed for the first time. The key step was photochemical decomposition of CHF₂-substituted pyrazolines. This protocol has the advantages of simple operation, and mild conditions, as well as excellent functional group tolerance, giving the desired products in moderate to excellent yields.

A general and efficient method has been developed to synthesize CHF₂-substituted 3-azabicyclo[3.1.0]hexane derivatives via photochemical decomposition of CHF₂-pyrazolines.

Direct N–H/α,α,β,β-C(sp3)–H functionalization of piperidine via an azomethine ylide route: synthesis of spirooxindoles bearing 3-substituted oxindoles

A protocol for the direct functionalization of N–H/α,α,β,β-C(sp³)–H of piperidine without any metal or external oxidants is reported.