Oxidative N-Heterocyclic Carbene Catalysis

N-Heterocyclic carbene (NHC) catalysis is a by now consolidated organocatalytic platform for a number of synthetic (asymmetric) transformations via diverse reaction modes/intermediates. In addition to the typical umpolung processes involving acyl anion/homoenolate equivalent species, implementation of protocols under oxidative conditions greatly expands the possibilities of this methodology. Oxidative NHC-catalysis allows for oxidative and oxygenative transformations through specific manipulations of Breslow-type species depending upon the oxidant used (external oxidant or O2/air), the derived NHC-bound intermediates paving the way to non-umpolung processes through activation of carbon atoms and heteroatoms. This review is intended to update the state of the art in oxidative NHC-catalyzed reactions that appeared in the literature from 2014 to present, with a strong focus to crucial intermediates and their mechanistic implications

Whole-body radioiodine effective half-life in patients with differentiated thyroid cancer

Background: Radioactive 131I (RAI) therapy is used in patients with differentiated thyroid cancer (DTC) after total thyroidectomy for remnant ablation, adjuvant treatment or treatment of persistent disease. 131I retention data, which are used to indicate the time at which a 131I treated DTC patient can be released from the hospital, may bring some insights regarding clinical factors that prolong the length of hospitalization. The aim of this study was to investigate the 131I whole-body retention in DTC patients during 131I therapy. Methods: We monitored 166 DTC patients to follow the 131I whole-body retention during 131I therapy with a radioactivity detector fixed on the ceiling of each protected room. A linear regression fit permitted us to estimate the whole-body 131I effective half-life in each patient, and a relationship was sought between patients’ clinical characteristics and whole-body effective 131I half-life. Results: The effective 131I half-life ranged from 4.08 to 56.4 h. At multivariable analysis, longer effective 131I half-life was related to older age and extensive extra-thyroid disease. Conclusions: 131I effective half-life during 131I treatment in DTC patients is highly variable among patients and is significantly longer in older and in patients with RAI uptake in large thyroid remnants or in extrathyroidal disease that significantly prolongs the whole-body retention of 131I

Sintesi di composti ad attivita' antitumorale di origine naturale e di loro analoghi strutturali

Dottorato di ricerca in scienze chimiche. 8. ciclo. A.a. 1992-95. Relatore G. P. PolliniConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Recent Developments in General Methodologies for the Synthesis of α‑Ketoamides

The α-ketoamide motif is widely found in many natural products and drug candidates with relevant biological activities. Furthermore, α-ketoamides are attractive candidates to synthetic chemists due to the ability of the motif to access a wide range of functional group transformations, including multiple bond-forming processes. For these reasons, a vast array of synthetic procedures for the preparation of α- ketoamides have been developed over the past decades, and the search for expeditious and efficient protocols continues unabated. The aim of this review is to give an overview of the diverse methodologies that have emerged since the 1990s up to the present. The different synthetic routes have been grouped according to the way the α-ketoamide moiety has been created. Thus, syntheses of α-ketoamides proceeding via C(2)- oxidation of amide starting compounds are detailed, as are amidation approaches installing the α-ketoamide residue through C(1)−N bond formation. Also discussed are the methodologies centered on C(1)−C(2) σ-bond construction and C(2)−R/Ar bond-forming processes. Finally, the literature regarding the synthesis of α-ketoamide compounds by palladium-catalyzed double-carbonylative amination reactions is discussed

Exploring the Synergy Between HPTLC and HPLC-DAD for the Investigation of Wine-Making By-Products

Both environmental and economic issues are increasingly pushing for the revalorization of agri-food by-products, including those arising from wine industry. Wastes produced from wine-making processes are important sources of biologically active compounds, mainly phenolic acids and flavonoids, which could be re-used for several applications, for example as additive surrogates or new ingredients in foodstuffs and/or pharmaceuticals. Therefore, the development of methods aimed at isolating, characterizing and quantifying molecules present in winery by-products acquires considerable importance in view of their re-utilization on a large scale. In this connection, this study demonstrated that high-performance thin-layer chromatography (HPTLC) and high-performance liquid chromatography with diode array detection (HPLC-DAD) can operate in synergy for the investigation of pomace and seed materials arising from both white and red cultivars of Vitis Vinifera. By virtue of fingerprint profiling, mass spectrometry (MS) interfacing and band comparison method, HPTLC enabled detection and identification of phenolic acids, non-anthocyanic flavonoids and anthocyanins. On the contrary, only anthocyanins could be identified by HPLC-DAD, and their subsequent quantification showed that malvidin-3-O-glucoside (oenin) was the most abundant one. In parallel, HPTLC has allowed to detect and quantify proanthocyanidins (PAC), showing that only catechin was present in the test samples. Both quantitative analytical methods were validated in terms of linearity, detection and quantification limits and precision

Diastereoselective nitrocyclopropanation of 2,5-dihydrothiophene-3- carbaldehydes

An unprecedented domino Michael/alpha-alkylation reaction between 2,5-dihydrothiophene-3-carbaldehydes and bromonitromethane is presented. This process, efficiently catalyzed by DL-proline in the presence of MeOH/NaOAc system, provides access to novel 6-nitro-3-thiabicyclo[3.1.0]hexane-1-carbaldehyde derivatives in good yields with good to excellent diastereoselectivities

Research progress in the modification of quercetin leading to anticancer agents

The flavonoid quercetin (3,3,4,5,7-pentahydroxyflavone) is widely distributed in plants, foods, and beverages. This polyphenol compound exhibits varied biological actions such as antioxidant, radical-scavenging, anti-inflammatory, antibacterial, antiviral, gastroprotective, immune-modulator, and finds also application in the treatment of obesity, cardiovascular diseases and diabetes. Besides, quercetin can prevent neurological disorders and exerts protection against mitochondrial damages. Various in vitro studies have assessed the anticancer effects of quercetin, although there are no conclusive data regarding its mode of action. However, low bioavailability, poor aqueous solubility as well as rapid body clearance, fast metabolism and enzymatic degradation hamper the use of quercetin as therapeutic agent, so intense research efforts have been focused on the modification of the quercetin scaffold to obtain analogs with potentially improved properties for clinical applications. This review gives an overview of the developments in the synthesis and anticancer-related activities of quercetin derivatives reported from 2012 to 2016

Hagemann's ester: a timeless building block for natural product synthesis

none4The potential of Hagemann’s ester as a building block in the synthesis of complex and biologically active natural products is the topic of this report. Hagemann’s ester chemical transformations allowed the development of diverse and creative applications frequently entailing a wide range of new and modern chemistry. The collected material, covering the development of its chemistry from the very beginning up to the present time, has been organized in sections where the papers listed are discussed in chronological order. Sections 1 and 2 are dedicated to a short introduction and to a description of the different preparations of Hagemann’s ester. The alkylation of the vinylogous beta-keto ester system, the most common operation on the starting ester, has been discussed in detail in Section 3. Synthetic applications involving chemical modifications of the ester functionality, namely removal, preservation and elaboration, have been considered in Sections 4–6, while syntheses featuring Hagemann’s ester fragmentation into linear carbon chains are collected in Section 7. Finally, Section 8 has been dedicated to the preparation and synthetic applications of optically active Hagemann’s ester derivatives. For the sake of clarity, the carbon-atom fragments of the different synthetic targets coming from Hagemann’s ester or its analogues are marked in red.noneG.P. Pollini; S. Benetti; C. De Risi; V. ZaniratoPollini, Gian Piero; Benetti, Simonetta; DE RISI, Carmela; Zanirato, Vinici