CuOTf/PyBox system

CuOTf/PyBox System The first direct asymmetric addition of alkynes to imines, generated from aldehydes and amines in situ, was reported by using copper salts in the presence of chiral PyBox ligand (Scheme 5.2). The products were obtained in good yields and excellent enantioselectivities in most cases. When toluene was used as solvent, up to 93% yield and 99% ee were obtained. Up to 99.5% ee was obtained when the reaction was carried out in 1,2-dichloroethane. The reaction can also be performed in water smoothly, and good enantioselectivities (78-91% ee) were obtained. 

Similar to the CuOTf/PyBox system, the CuBr/QUINAP system also gave high enantioselectivities of the three component reactions to construct propargyl amines from aldehydes, amines, and alkynes (Scheme 5.6). In this system various aldehydes including aromatic aldehydes and aliphatic aldehydes could be used and a wide range of chiral propargyl amines were prepared in good yields and enantioselectivities. Mechanistic studies showed that the dimeric Cu/QUINAP complex is the catalytically active species that differs from the previous reaction. 

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See also in sourсe #XX -- [ ]

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