RESUMEN
2-Propargyl-1,3-dicarbonyl compounds have been carbonylated under oxidative conditions and with the catalysis of the PdI2/KI catalytic system to selectively afford previously unreported 2-(4-acylfuran-2-yl)acetamides in fair to good yields (54-81%) over 19 examples. The process takes place under relatively mild conditions and occurs via a mechanistic pathway involving Csp-H activation by oxidative monoamincarbonylation of the terminal triple bond of the substrates with formation of 2-ynamide intermediates, followed by 5-exo-dig O-cyclization (via intramolecular conjugate addition of the in situ formed enolate to the 2-ynamide moiety) and aromative isomerization.
RESUMEN
In this short review, we highlight the advancements in the field of palladium-catalyzed carbon dioxide utilization for the synthesis of high value added organic molecules. The review is structured on the basis of the kind of substrate undergoing the Pd-catalyzed carboxylation process. Accordingly, after the introductory section, the main sections of the review will illustrate Pd-catalyzed carboxylation of olefinic substrates, acetylenic substrates, and other substrates (aryl halides and triflates).
RESUMEN
A straightforward approach to new polycyclic heterocycles, 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones, is presented. It is based on the ZnCl2-promoted deprotective 6-endo-dig heterocyclization of N-Boc-2-alkynylbenzimidazoles under mild conditions (CH2Cl2, 40 °C for 3 h). The zinc center plays a dual role, as it promotes Boc deprotection (with formation of the tert-butyl carbocation, which can be trapped by substrates bearing a nucleophilic group) and activates the triple bond toward intramolecular nucleophilic attack by the carbamate group. The structure of representative products has been confirmed by X-ray diffraction analysis.
RESUMEN
Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H- as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts.
RESUMEN
The palladium-catalyzed carbonylation of 2-(propynylthio)benzimidazoles bearing a terminal triple bond leads to 2-methyl-1-thia-4a,9-diazafluoren-4-ones instead of the previously reported 3-methyl isomers, as unequivocally established by XRD analysis of a representative product. A correction is therefore provided here in order to rectify the previous erroneous assignment of the position of the methyl group. Moreover, the process has been generalized to substrates bearing an internal triple bond, which lead to 3-alkyl-2-methyl-1-thia-4a,9-diazafluoren-4-ones, whose structure was confirmed by XRD analysis of two representative derivatives.
RESUMEN
Invited for this month's cover are the collaborating groups at the University of Calabria (Unical, Italy)-Department of Chemistry and Chemical Technologies (CTC) and Department of Pharmacy and Health and Nutritional Sciences (PHNS), at the National Research Council (CNR, Italy), Institute on Membrane Technology (ITM), and at the Karlsruhe University of Applied Sciences (HSKA, Germany), Institute of Applied Research (IAR), which cooperated in the framework of the European Union's Horizon 2020 project "VicInAqua". The front cover shows the structure of an acryloxyalkyltrithylammonium (AATEA) cation, characterized by a polymerizable end, a long-chain alkyl linker, and a quaternary ammonium moiety. The bromide salts (AATEABs) have been synthesized by a two-step procedure carried out entirely under air without any need for chromatographic purifications. Some AATEABs have shown significant antimicrobial activity and represent useful precursors for the preparation of polymeric films with antimicrobial properties. Read the full text of the article at 10.1002/cplu.201700194.
RESUMEN
This study reports an efficient and practical synthetic approach for the synthesis of a particularly important class of polymerizable quaternary ammonium salts (PQASs), that is, acryloxyalkyltriethylammonium bromides (AATEABs), which may find application as antimicrobial coatings for commercial membranes with antifouling and anti-biofouling properties, to be used for wastewater treatment. The synthetic method is based on a simple two-step procedure from commercially available substrates, entirely carried out under air and without any need for chromatographic purification. All the newly synthesized AATEABs were tested for their antimicrobial activity, and the results showed that AATEABs bearing an alkyl chain of 11 and particularly 12â carbon atoms possessed significant activity against Gram positive bacteria and yeast strains.