New multifunctional chiral phosphine (phosphine-amide type) LB8 and BINOL derivative co-catalyzed asymmetric aza-MBH reaction of 5,5-disubstituted cyclopent-2-enones 1 with N-sulfonated imines 2 afforded the corresponding optically active adducts 3 in good to outstanding yields with moderate to good ee's under mild conditions. The steric hindrance environment of BINOL derivatives as well as the nucleophilicity of the phosphorus center and the acidity of free OH which could significantly affect the stereochemical and chemical outcomes had been discussed, indicating the co-catalyzed system is very important to this particular asymmetric aza-MBH reaction.
Organic & Biomolecular Chemistry
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