A series of novel functionalizedpiperidinederivatives were conveniently prepared by three‐component tandem aza‐Michael–Aldol reactions of α,β‐unsaturated enones with substituted sulfonamides in the presence of DBU. The structures of the compounds synthesized were characterized by spectral data and X‐ray crystal diffraction.
Reductive Aldol Coupling of Divinyl Ketones via Rhodium-Catalyzed Hydrogenation: syn-Diastereoselective Construction of β-Hydroxyenones
作者:Soo Bong Han、Michael J. Krische
DOI:10.1021/ol0624023
日期:2006.11.1
Catalytic hydrogenation of divinyl ketones 1a and 1e in the presence of diverse aldehydes 2a-e at ambient temperature and pressure using cationic rhodium catalysts ligated by tri-2-furyl phosphine enables formation of aldol products 3a-e and 5a-e, respectively, with high levels of syn diastereoselection. Through an assay of counterions (Rh(COD)(2)X), Rh(COD)(2)SbF6 is identified as the optimum precatalyst for reductive aldol couplings of this type. For para-substituted styryl vinyl ketones 1b-e, a progressive increase in isolated yield is observed for electron-releasing para substituents.