Asymmetric Organocatalysts Supported on Vinyl Addition Polynorbornenes for Work in Aqueous Media

Producción CientíficaIn an effort to identify novel polymer architectures suitable for the covalent supporting of catalysts, L–proline derivatives have been immobilized onto rationally designed vinyl addition polynorbornene (VA-PNB) resins through copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. The fully saturated VA-PNB resins have been found to be optimal catalyst supports, the resulting proline-functionalized resins behaving as very active, easily recoverable and highly reusable organocatalysts for the asymmetric direct aldol reaction of benzaldehydes with ketones in aqueous media. The obtained results show that the combination of modular, VA-PNB resins with proline derivatives through triazole linkers represent a promising strategy for the immobilization of organocatalytic species.Ministerio de Economía, Industria y Competitividad (CTQ2013-48406-P)Ministerio de Economía, Industria y Competitividad (CTQ2012-38594-C02-01)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA373A11-2)Generalitat de Catalunya (Grant 2014SGR827

Palladium Catalyzed Diaryl Sulfoxide Generation from Aryl Benzyl Sulfoxides and Aryl Chlorides

Diaryl sulfoxides are synthesized from aryl benzyl sulfoxides and aryl chlorides via three sequential catalytic cycles all promoted by a NiXantPhos-based palladium catalyst. The key step is <i>S</i>-arylation of a sulfenate anion. An air- and moisture-stable precatalyst derived from NiXantPhos efficiently facilitates the transformation. Various functional groups, including those with acidic protons, were tolerated. This method can also be extended to methyl and dibenzyl sulfoxides substrates