Diastereo- and enantioselective hydrogenative aldol coupling of vinyl ketones: design of effective monodentate TADDOL-like phosphonite ligands.
We report the first enantioselective reductive aldol couplings of vinyl ketones, which were achieved through the design of a novel monodentate TADDOL-like phosphonite ligand. Specifically, hydrogenation of commercially available methyl vinyl ketone (MVK) or ethyl vinyl ketone (EVK) in the presence of aldehydes 1a-7a using cationic rhodium catalysts modified by chiral TADDOL-like phosphonite ligands AP-I and AP-IV produces aldol adducts 1b-7b and 1c-7c with excellent control of relative and absolute stereochemistry. The absolute stereochemical assignments of the aldol adducts are made in analogy to that determined for the 5-bromophthalimido derivative of aldol adduct 1b and the 2-bromo-5-nitrobenzoate of 3b, which were established by single-crystal X-ray diffraction analysis using the anomalous dispersion method.
Bee
Cisco
C
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, USA.
Han
Soo Bong
SB
Hassan
Abbas
A
Iida
Hiroki
H
Krische
Michael J
MJ
D002384:Catalysis; D018360:Crystallography, X-Ray; D004148:Dioxolanes / Q000737:chemistry; D006865:Hydrogenation; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry*; D008024:Ligands; D000432:Methanol / Q000031:analogs & derivatives / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D012238:Rhodium / Q000737:chemistry; D013237:Stereoisomerism
D004148:Dioxolanes; D007659:Ketones; D008024:Ligands; D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; C516101:alpha,alpha,alpha',alpha'-tetraaryl-1,3-dioxolane-4,5-dimethanol; D012238:Rhodium; D000432:Methanol