Mild and convenient one-pot synthesis of 1,3,4-oxadiazoles

A mild, general, convenient, and efficient one-pot synthesis of 2-phenyl-5-substituted-1,3,4-oxadiazoles is described. Both (hetero)aryl and alkyl carboxylic acids were efficiently condensed with benzohydrazide in the presence of TBTU to give diacylhydrazine intermediates. The latter underwent a smooth TsCl-mediated cyclodehydration reaction to afford 2-phenyl-5-substituted-1,3,4-oxadiazoles in good to very good yields.     

Indoles from Alkynes and Aryl Azides: Scope and Theoretical Assessment of Ruthenium Porphyrin-Catalyzed Reactions

A symbiotic experimental/computational study analyzed the Ru(TPP)(NAr)₂-catalyzed one-pot formation of indoles from alkynes and aryl azides. Thirty different C₃-substituted indoles were synthesized and the best performance, in term of yields and regioselectivities, was observed when reacting ArC≡CH alkynes with 3,5-(EWG)₂C₆H₃N₃ azides, whereas the reaction was less efficient when using electron-rich aryl azides. A DFT analysis describes the reaction mechanism in terms of the energy costs and orbital/electronic evolutions; the limited reactivity of electron-rich azides was also justified. In summary, PhC≡CH alkyne interacts with one NAr imido ligand of Ru(TPP)(NAr)₂ to give a residually dangling C(Ph) group, which, by coupling with a C(H) unit of the N-aryl substituent, forms a 5+6 bicyclic molecule. In the process, two subsequent spin changes allow inverting the conformation of the sp² C(Ph) atom and its consequent electrophilic-like attack to the aromatic ring. The bicycle isomerizes to indole via a two-step outer sphere H-migration. Eventually, a ′Ru(TPP)(NAr)′ mono-imido active catalyst is reformed after each azide/alkyne reaction.     

Identification of Broad-Spectrum MMP Inhibitors by Virtual Screening

Matrix metalloproteinases (MMPs) are the family of proteases that are mainly responsible for degrading extracellular matrix (ECM) components. In the skin, the overexpression of MMPs as a result of ultraviolet radiation triggers an imbalance in the ECM turnover in a process called photoaging, which ultimately results in skin wrinkling and premature skin ageing. Therefore, the inhibition of different enzymes of the MMP family at a topical level could have positive implications for photoaging. Considering that the MMP catalytic region is mostly conserved across different enzymes of the MMP family, in this study we aimed to design a virtual screening (VS) workflow to identify broad-spectrum MMP inhibitors that can be used to delay the development of photoaging. Our in silico approach was validated in vitro with 20 VS hits from the Specs library that were not only structurally different from one another but also from known MMP inhibitors. In this bioactivity assay, 18 of the 20 compounds inhibit at least one of the assayed MMPs at 100 μM (with 5 of them showing around 50% inhibition in all the tested MMPs at this concentration). Finally, this VS was used to identify natural products that have the potential to act as broad-spectrum MMP inhibitors and be used as a treatment for photoaging.     

3-(4-iodomethyl-2-oxo-1-azetidinyl)propynoic acidt-butyl ester: a new β-lactam derivative,synthesis of an ynamide by reaction of 4-iodomethylazetidin-2-one with the t-butyl ester of propiolic acid in the presence of copper(i)

The reaction of 4-iodomethylazetidin-2-one (2) with the t-butyl ester of propiolic acid (4) in the presence both of equimolar amounts of copper(I) and oxygen results unexpectedly in the fomation of the β-lactam ynamide 5. Its structure was suggested by spectroscopic data and confirmed by single-crystal X-ray analysis.     

Stereochemistry of allenic compounds : Absolute configuration of cycloallenols and cycloallenones

The absolute configuration of α-cycloallenols (3 and 4)as well as of α-cycloallenones(1)has been correlated to that of cyclic alkenols (2) by chemical transformations.     

Stereochimie de composes alleniques. Configuration relative des cyclononadiene-2,3 ols-1

The relative configuration of diastereomeric cyclonona-2,3-diene-1-ols, (1RS,aRS)², and (1RS,aSR), was determined by chemical methods, and confirmed by X-ray analysis of the phenylurethane derivative of the (1RS,aRS) isomer, 3a.