Reductive aldol coupling of divinyl ketones via rhodium-catalyzed hydrogenation: syn-diastereoselective construction of beta-hydroxyenones.
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. [reaction: see text].
Han
Soo Bong
SB
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, USA.
Krische
Michael J
MJ
D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D002412:Cations / Q000737:chemistry; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D011312:Pressure; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D014753:Vinyl Compounds / Q000737:chemistry*
D000447:Aldehydes; D002412:Cations; D007659:Ketones; D014753:Vinyl Compounds; D012238:Rhodium