Novel tricyclic bridged heterocyclic systems can be readily prepared from sequential 1,4- and 1,2-addition reactions of allyl and 3-substituted allylsilanes to indolizidine and quinolizidine α,β-unsaturated N-acyliminium ions. These reactions involve a novel N-assisted, transannular 1,5-hydride shift. Such a mechanism was supported by examining the reaction of a dideuterated indolizidine, α,β-u...

The present work describes the preparation of a novel series of compounds based on the structure of goniothalamin (1), a natural styryl lactone with known cytotoxic and antiproliferative activities against a variety of cancer cell lines. A focused library of 17 goniothalamin analogues displaying the 5-methyl-2,5-dihydrofuran-2-one motif were prepared, and their cytotoxicity evaluated. While the...

N-Methyl-N-((trimethylsilyl)methyl)aniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic α,β-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two major re...

Thalassospiramides comprise a large family of lipopeptide natural products produced by Thalassospira and Tistrella marine bacteria. Here we provide further evidence of their nanomolar inhibitory activity against the human calpain 1 protease. Analysis of structure-activity relationship data supported our hypothesis that the rigid 12-membered ring containing an α,β-unsaturated carbonyl moiety is ...

Thirteen fatty acids were identified from the pulps of four Tunisian Ziziphus jujuba ecotypes (Sfax, Choutrana, Mahres and Mahdia), using capillary gaseous chromatography method. These oils presented 8.31% to 12.35% of dry weights. Compared to the other ecotypes, Mahres and Choutrana were the richest of the oleic acid. The palmitic acid was the most important compound of the Sfax ecotype. Unsat...

α,β-Unsaturated amidines can be synthesized in high yield by rhodium(II) carboxylate catalyzed 1,2-H shift following denitrogenation of α-diazo amidines. Using a large ligand and an electron-poor N-sulfonyl group results exclusive Z-selectivity excellent suppressing side reactions involving intramolecular oxygen transfer.

Two fluorescent probes, m-PSP and p-PSP , for sulfite and/or sulfide were constructed by connecting a pyridinium ion to a coumarin fluorophore through an α,β-unsaturated ketone. The presence of the pyridinium salt promoted the nucleophilic addition of sulfite and sulfide to the α,β-unsaturated ketone, which could be visualized by dramatic changes in the solution's color and fluorescence intensi...