Ferrocene-Based Secondary Alcohols via Asymmetric Hydrogenation

In the effort to synthesize Ugi’s amine, Chan and coworkers decided to apply Noyori-type rhodium reduction on ferrocenyl ketones to overcome the problems normally associated with this synthesis. As the authors mentioned, the use of a CBS-reduction protocol has been utilized for this synthesis, but a very high catalyst loading is needed (30-60 mol%), making it unattractive for large-scale applications. While the product shown is the methyl-substituted alcohol, aryl-substituted ketones were shown to be viable substrates giving products with >89% ee.