A new method for the arylative cyclization of o-alkynylphenols with aryldiazonium salts via dual photoredox/gold catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives and offers an efficient approach to benzofuran derivatives. The scope of the transformation is wide, and the limitations are discussed. The reaction is proposed to proceed through a photoredox-promoted generation of a vinylgold(III) intermediate that undergoes reductive elimination to provide the heterocyclic coupling adduct.

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The gold(i) catalyzed cycloisomerization of an enynyl propargylic ester, featuring a 1,2-acyloxy migration/intramolecular cyclopropanation sequence, opens a straightforward access to the 5,7,3-tricyclic skeleton of neomerane sesquiterpenes. The first total synthesis of 5-epi-valeneomerin B in 12 steps with an overall yield of 5.3% is reported.

The synthesis, optical resolution through derivatization, characterization, and utilization of a new helical bis(phosphinite gold) complex derived from HELIXOL are described. By using an efficient cobalt catalyst, neither irradiation nor high catalytic loading was required to access the helicene of interest. The latter was phosphorylated to afford a new chiral ligand that was studied. Especially, treatment with AuCl(SMe2) gives a dinuclear gold complex that was used in cycloisomerization reactions.

This article discloses a study on a chiral bis-phosphorylatedhelical ligand in the palladium-catalyzed Tsuji-Trost allylation. The use of 2,15-bisphosphinite-[6]-helicenes revealed a remarkable ligand effect, in which the (R) and (S) isomeric products can be selectively formed as a direct function of the amount of ligand introduced. Investigation of the organometallic species involved through 31 P NMR spectroscopic analysis of a model complex and X-Ray diffraction analysis together with DFT calculations shed light on this phenomenon.

A series of pyridinium-betaine like molecules has been reported; one family of molecules is built with a benzimidazole core and a second one with a pyrimidine moiety. The title compounds were prepared by mixing 2-chlorobenzimidazole or 2-bromopyrimidine with the corresponding pyridines (pyridine, 4-tert-butylpyridine, 4-hydroxypyridine, potassium 4-trifluoroboratepyridine, 4-dimethylaminopyridine) in acetonitrile or DMSO at high temperatures. The novel compounds were characterized by spectroscopic methods. The UV-Vis. and fluorescence features are reported as well. Preliminary photoluminescence results showed broadband emissions as common feature ascribed to the compounds containing benzimidazole ring. Some of the spectra nearly span over the whole visible spectral range, which pave the way to real opportunities to design single-component panchromatic emitters.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

While studying the opening of an epoxide on a sugar-derived aziridine, we observed an unexpected formation of bicyclic compounds. The structure of these bicycles depends on the nature of the protecting group on the amine of the aziridine. This compounds appeared to be weak glycosidase inhibitors.