Highly Efficient Synthesis of New α-Arylamino-α′-chloropropan-2-ones via Oxidative Hydrolysis of Vinyl Chlorides Promoted by Calcium Hypochlorite

Ring-Closing Synthesis of Dibenzothiophene Sulfonium Salts and Their Use as Leaving Groups for Aromatic 18F-Fluorination

Herein, we report a novel intramolecular ring-closing reaction of biaryl thioethers that give access to highly functionalized dibenzothiophene sulfonium salts under mild conditions. The resulting precursors react regioselectively with [18F]fluoride to give [18F]fluoroarenes in predictable radiochemical yields. The strategy expands the available radiochemical space and provides superior labeling efficiency for clinically relevant PET tracers.

Novel Enantiopure Sigma Receptor Modulators: Quick (Semi-)Preparative Chiral Resolution via HPLC and Absolute Configuration Assignment

The identification of novel pan-sigma receptor (SR) modulators, potentially useful in cancer treatment, represents a new goal of our research. Here, we report on the preparation of novel chiral compounds characterized by a 3-C alkyl chain bridging an aromatic portion to a 4-benzyl-piperidine moiety. All of the studied compounds have been prepared both in racemic and enantiomerically-pure form, with the final aim to address the role of chirality in the SR interaction. To isolate and characterize enantiomeric compounds, high-performance liquid chromatography (HPLC) procedures were set up. A systematic analytical screening, involving several combinations of chiral stationary and mobile phases, allowed us to optimize the analytical resolution and to set up the (semi-)preparative chromatographic conditions. Applying the optimized procedure, the enantiomeric resolution of the studied compounds was successfully achieved, obtaining all of the compounds with an enantiomeric excess higher than 95%. Lastly, the absolute configuration has been empirically assigned to enantiopure compounds, combining the electronic circular dichroism (ECD) technique to the elution order study.

Synthesis and biological evaluation of new aryl-alkyl(alkenyl)-4-benzylpiperidines, novel Sigma Receptor (SR) modulators, as potential anticancer-agents

In the early 2000s, the Sigma Receptor (SR) family was identified as potential "druggable" target in cancer treatment. Indeed, high density of SRs was found in breast, lung, and prostate cancer cells, supporting the idea that SRs could play a role in tumor growth and progression. Moreover, a link between the degree of SR expression and tumor aggressiveness has been postulated, justified by the presence of SRs in high metastatic-potential cancer cells. As a consequence, considerable efforts have been devoted to the development of small molecules endowed with good affinity towards the two SR subtypes (S1R and S2R) with potential anticancer activity. Herein, we report the synthesis and biological profile of aryl-alkyl(alkenyl)-4-benzylpiperidine derivatives - as novel potential anticancer drugs targeting SR. Among them, 3 (RC-106) exhibited a preclinical profile of antitumor efficacy on a panel of cell lines representative of different cancer types (i.e. Paca3, MDA-MB 231) expressing both SRs, and emerged as a hit compound of a new class of SR modulators potentially useful for the treatment of cancer disease.

Lithium Halomethylcarbenoids: Preparation and Use in the Homologation of Carbon Electrophiles

α-Halomethyllithium carbenoids are useful homologating reagents which - reacting under proper reaction conditions as carbanions - enable the installation via nucleophilic addition of a reactive halomethyl fragment onto a preformed carbon-heteroatom bond. The pronounced thermolability represented - since seminal studies by Köbrich - the Achilles' heel of these reagents: the use of Barbier-type methodologies (i.e., the electrophile should be present in the reaction mixture prior to the formation of the carbenoid) was pivotal in order to suppress decomposition through α-elimination processes. Nowadays, the use of low temperatures (-78 °C) guarantees reliable procedures and, significantly, the employment of microreactor technologies allows external trapping to be performed even at higher temperatures as reported by Luisi. We will discuss the α-halomethyllithium-mediated homologations of a series of carbon electrophiles such as carbonyl compounds, imines, esters, Weinreb amides, and isocyanates.

Addition of lithium carbenoids to isocyanates: a direct access to synthetically useful N-substituted 2-haloacetamides

The addition of lithium carbenoids to isocyanates provides a versatile access to N-substituted 2-haloacetamides: the reaction tolerates the presence of variously functionalized substituents on the nitrogen atom, including sterically demanding ones and reactive halogens. No erosion of the enantiopurity was observed in the case of optically active isocyanates. One of the substrates prepared has been employed in Charette's type chemoselective addition of a Grignard reagent to access an α-chloroketone.