Imines derived from aryl/alkyl ketones

Imines derived from aryl/alkyl ketones can be reduced enantioselectively using the CuH-based catalytic system developed by Lipshutz. In general, high ees can be obtained (94—99% ee) using this procedure, but it is limited to the hydrosilylation of N-dixylylphosphinylimines such as (3.189). 

In general, catalysis by 84a and 85c resulted in good to excellent enantioselec-tivities in the reduction of lcetimines derived from methyl aryl ketones and aromatic amines (80, R1, R3 = aryl, R2 = Me), where the electronic effects of substituents in both aromatic groups did not show any significant influence [79, 80]. On the other hand, imines obtained from aliphatic amines (80, R3 = alkyl) gave virtually racemic products with 85a [80b]. In the reduction of non-aromatic imines, such as 80c, only catalyst 84a maintained high enantioselectivity (Table... 

The iV-alkyl and iV-aryl derivatives (Schiff bases, azomethines, anils) that can be obtained from aldehydes and ketones by use of primary amines are considerably more important than the unsubstituted imines. 

---