A catalyticenantioselectiveStreckerreaction catalyzed by novel chiral lanthanum(III)−binaphthyl disulfonate complexes was developed. The key to promoting the reactions was a semistoichiometric amount of AcOH or i-PrCO2H, which takes advantage of HCN generation in situ. The corresponding cyanation products were obtained in high yields and with high enantioselectivities.
The JandaJEL™-supported bifunctionalcatalyst 3 (10 mol%) promoted the Strecker-type reaction of aromatic and α,β-unsaturated imines in excellent yields with 83–87% ee in the presence of tBuOH (110 mol%). The reactivity of 3 was comparable to the homogeneous analogue 1, and 3 could be recycled at least four times.
A general asymmetric Strecker-type reaction is reported, catalyzed by the Lewis acid-Lewis base bifunctionalcatalyst 1. The reaction of trimethylsilyl cyanide (TMSCN) with various fluorenyl imines, including n-aldimines and alpha,beta-unsaturated imines, proceeds with good to excellent enantioselectivities in the presence of a catalytic amount of phenol as additive (20 mol%) (catalytic system 1).