Reductive Aldol Coupling of Divinyl Ketones via Rhodium-Catalyzed Hydrogenation: syn-Diastereoselective Construction of β-Hydroxyenones
journal contributionposted on 23.11.2006, 00:00 by Soo Bong Han, Michael J. Krische
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)2X), Rh(COD)2SbF6 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.
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presenceReductive Aldolambient temperatureHydrogenationsubstituentcounterionreductive aldol couplingsRhhydrogenationConstructionprecatalyststyryltypeDivinyl Ketonesassayaldehydes 2cationic rhodium catalysts ligatedformationphosphinetridivinyl ketones 1HydroxyenonesCatalyticaldol products 3syn diastereoselectionpara1 e