Vinylogous aldol reaction of heterocyclic silyloxy dienes. Application in synthesis

A versatile, readily accessible triad of 2-enoxy silane synthons derived from furan, pyrrole, and thiophene is presented. These heterocycles, in reacting with carbonyl and carbonyl- related acceptors, act as vinylogous nucleophile modules, giving rise to diverse, functionality- rich, γ-substituted α,β-unsaturated carbonyl constructs. These, in turn, are invaluable platforms onto which further functional elements and chirality may be introduced. A couple of appealing applications—the variable construction of a repertoire of carbasugars and a library of annonaceous acetogenin segments—have been chosen to illustrate the viability of this vinylogous aldol approach

Exploring the boundaries of vinylogous Mukaiyama aldol processes: stereoselective access to polyunsaturated homoallylic alcohols

Catalytic enantioselective vinylogous aldol reactions using extended enolates are of prominent value in synthetic organic chemistry. Here, we report our advances in the development of enantioselective bis-vinylogous and hyper-vinylogous Mukaiyama aldol reactions between a series of polyenylsilyloxy furans or polyenylsilyoxy indoles and aromatic aldehydes, realized by use of the enabling catalyst combination of silicon tetrachloride and Denmark’s chiral bis-phosphoramide base (R,R)-I. Several crucial issues such as the remote site-, enantio- and geometrical selectivity of the reaction will be highlighted, ultimately focusing on one main question: how far can we push the limits of the vinylogous reactivity transmittal?</i

Nuove metodologie d'accesso alla diversità molecolare: sintesi di biomolecole e loro insiemi per un utilizzo in agricoltura e terapia

La nostra metodologia totalmente sintetica ed altamente flessibile indirizzata alla costruzione di piccole molecole organiche chirali, sia individuali, sia in miscela fra loro, prevede l’utilizzo di una triade omogenea di reagenti nucleofili eterociclici contenenti, rispettivamente, ossigeno, azoto e zolfo

Sintesi totale di amminoacidi a base ciclitolica: un approccio orientato alla diversità

Amminoacidi carbociclici con funzionalità multiple installate sulle varie posizioni anulari, come le strutture polioliche 1-8 di questo studio, rappresentano un insieme molecolare omogeneo e, allo stesso tempo, variato, in cui ciascuna entità può essere vista sotto diverse angolazioni

Nuovi motivi azabiciclo [X.2.1] alcanici

Abbiamo intrapreso uno studio accurato avente come oggetto la reazione tra un reagente silossidienico a base pirrolica il N-(terzbutilossicarbonil)- 2-(terz-butildimetilsililossi)pirrolo (TBSOP, 1), e una serie di accettori chetonici di varia natura, simmetrici ed asimmetrici, enolizzabili e non, achirali prochirali e chirali prochirali enantiopur

Unlocking Access to Enantiopure Fused Uracils by Chemodivergent [4+2] Cross‐Cycloadditions: DFT‐Supported Homo‐Synergistic Organocatalytic Approach

The discovery of chemical methods enabling the construction of carbocycle‐fused uracils which embody a three‐dimensional and functional‐group‐rich architecture is a useful tool in medicinal chemistry oriented synthesis. In this work, an unprecedented amine‐catalyzed [4+2] cross‐cycloaddition is documented; it involves remotely enolizable 6‐methyluracil‐5‐carbaldehydes and β‐aryl enals, and chemoselectively produces two novel bicyclic and tricyclic fused uracil chemotypes in good yields with a maximum level of enantiocontrol. In‐depth mechanistic investigations and control experiments support an intriguing homo‐synergistic organocatalytic approach, where the same amine organocatalyst concomitantly engages both aldehyde partners in a stepwise eliminative [4+2] cycloaddition, whose vinylogous iminium ion intermediate product may diverge—depending upon conditions—to either bicyclic targets by hydrolysis or tricyclic products by a second homo‐synergistic trienamine‐mediated stepwise [4+2] cycloaddition

Direct vinylogous Michael addition of prochiral 3-alkylideneoxindoles to nitroolefins

3-Alkylidene-2-oxindoles represent a simple, yet enabling subfamily of indole alkaloids, and their ability to react as electron-poor acceptors has largely been investigated. In contrast, their utility as pronucleophilic synthons remains elusive. In this context, the present describes the successful execution of the direct, organocatalytic asymmetric Michael addition of prochiral 3-alkylideneoxindoles to nitroolefins

Sintesi di nuove strutture macrocicliche a ridotta libertà conformazionale

L'obiettivo della nostra ricerca consiste nella creazione di nuove strutture macrocicliche a ridotta libertà conformazionale che incorporino la sequenza consensus RGD per mezzo di una funzione γ-amminoacidica supportata da anelli ciclopentanici (Acpca), ossidrilati e non. Tali scaffold amminoacidici possono essere visti di fatto come mimetici dell’acido γ- amminobutanoico bloccato in una conformazione a W da un ponte α,γ-etilene o idrossietilene. La valutazione biologica in vitro dei ciclo-pseudopeptidi mediante test di binding verso i recettori αvβ3 e αvβ5 isolati, l’approfondito studio strutturale in soluzione via NMR e, infine, studi di docking eseguiti sulla struttura a raggi X del segmento extracellulare dell’integrina αvβ3 complessata con il composto di riferimento EMD121974 hanno completato il nostro studio