Novel Chiral Ligands, Diferrocenyl Dichalcogenides and Their Derivatives, for Rhodium- and Iridium-Catalyzed Asymmetric Hydrosilylation

Abstract

As chiral ligands for transition metal complex-catalyzed asymmetric reactions, a variety of novel chiral ferrocenyl chalcogen compounds, which possess planar chirality due to the 1,2-unsymmetrically disubstituted ferrocene structure, have been prepared from chiral ferrocenes. There are seven diferrocenyl dichalcogenides (4−10), nine alkyl or aryl ferrocenyl chalcogenides (11−19), two bis(ferrocenylseleno)alkanes (20 and 21), two 1-(phenylchalcogeno)-1-[2-(diphenylphosphino)ferrocenyl]ethanes (22 and 24), and two 1-(phenylchalcogeno)-1-[1‘,2-bis(diphenylphosphino)ferrocenyl]ethanes (23 and 25). 2,3-O,O‘-Isopropylidene-2,3-dihydroxy-1,4-bis(phenylchalcogeno)butanes (26−28) are also synthesized. The Rh(I) complex-catalyzed hydrosilylation of ketones with diphenylsilane in the presence of these chiral ligands including the reported [R,S;R,S]-bis[2-[1-(dimethylamino)ethyl]ferrocenyl] dichalcogenides (1−3), followed by hydrolysis with dilute HCl, affords the corresponding chiral alcohols (R-configuration) in mo...