RESUMO
One-pot syntheses of three new enantiopure heteroscorpionate ligands derived from (+)-camphor or (-)-menthone are described. The ligands are obtained by reacting pyrazoles derived from (+)-camphor or (-)-menthone with sodium hydride and thionyl chloride. Subsequent reactions with pyridine and various aldehydes afford the tripod ligands in multi-gram amounts. Especially the menthopyrazole based ligand 6 showed encouraging ee values up to 69% in the Cu(I) catalysed enantioselective cyclopropanation of styrene with ethyl diazoacetate.
Assuntos
Cânfora/química , Cobre/química , Mentol/química , Aldeídos/química , Catálise , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Cristalografia por Raios X , Ligantes , Conformação Molecular , Piridinas/química , Compostos de Sódio/química , Estereoisomerismo , Óxidos de Enxofre/químicaRESUMO
Reductive S-S bond cleavage of a disulfide precursor obtained from a pyridine-catalyzed Peterson-type reaction starting from camphorpyrazole , thionyl chloride and 2-methyl-2-(methyldithio)propionaldehyde yields 2,2'-bis(camphorpyrazol-1-yl)-2-methylpropane-2-thiol (HSiprbpm3cam, ); the first zinc complexes bearing this ligand exhibit kappa3 coordination of the ligand.
