RESUMEN
Dihydropyridines are versatile building blocks for the synthesis of pyridines, tetrahydropyridines, and piperidines. Addition of nucleophiles to activated pyridinium salts allows synthesis of 1,2-, 1,4-, or 1,6-dihydropyridines; however, this process often leads to a mixture of constitutional isomers. Catalyst-controlled regioselective addition of nucleophiles to pyridiniums has the potential to solve this problem. Herein, we report that the regioselective addition of boron-based nucleophiles to pyridinium salts can be accomplished by the choice of a Rh catalyst.
RESUMEN
We report a rhodium-catalyzed asymmetric addition of aryl and alkenyl boronic acids to quinoxalinium salts that generates dihydroquinoxalines with high enantioselectivity. Functionalization of the reaction products, dihydroquinoxaline, allows the preparation of tetrahydroquinoxalines with various substitution patterns.
RESUMEN
Rhodium-catalyzed enantioselective addition of aryl and heteroaryl boron pinacol esters to pyridinium and quinolinium salts is developed for the synthesis of enantioenrichred dihydroheteroarenes. The methodology has enabled the synthesis of 2-heteroaryl-substituted dihydropyridines in high yield and ee, which provided efficient synthetic access to a nuphar alkaloid.
Asunto(s)
Alcaloides , Nuphar , Catálisis , Indicadores y Reactivos , Sales (Química)RESUMEN
Development of catalyst-controlled C-H hydroxylation could provide direct access to valuable synthetic targets, such as primary metabolites. Here, we report a new family of porous materials, comprised of 2-dimensional metalloporphyrin layers and flexible aliphatic linkers, and demonstrate C-H hydroxylation activity. We demonstrate that the stereochemistry of cis-decalin oxidation provides a useful tool for differentiating catalysis in from catalysis on porous materials, which is critical to leveraging the potential of porous materials for catalyst-controlled oxidation chemistry.