Binol Derived Bifunctional Amine Catalysts

Chiral Binol-Derived Bifunctional Amine Catalysts 

Sasai and coworkers reported that a chiral BINOL derived amine 16a catalyzed asymmetric aza MBH reaction of N tosyl imines with acrolein and alkyl vinyl ketones [22]. The corresponding aza MBH adducts were obtained in good to excellent yields with high enantiomeric excesses (Table 13.4). Replacing the tPr group with other substituents in amine 16a provided less effective catalysts regarding yield or enantioselectivity [23]. 

The catalyst 16a possesses two phenolic hydroxy groups and two nitrogen atoms. To clarify the role of each unit on the reaction, the monoprotected catalyst 16b with 

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Chiral Binol-Derived Bifunctional Amine Catalysts... 

Asymmetric addition of diorganozincs to aldehydes and ketones has been reviewed, focusing on bifunctional catalysts such as those prepared from salens or BINOLs. Regioisomeric chiral amine-sulfonamide organocatalysts give >99% yield and up to 98% ee in addition of diethylzinc to aldehydes. Switching between regioisomers effectively switches the direction of selectivity. Amino-acid-derived (15,l 5)-4,4 -biquinazoline primary amines catalyse ethylation of aryl aldehydes in up to 95%... 

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