Evans asymmetric induction procedur

During a synthesis of the immunosuppressant Discodermolide, Schreiber and co-workers,S9 used a procedure of Evans and Gauche-Prunet160-161 to create a benzylidene acetal with high 1,3-asymmetric induction via addition of an alkox-ide to benzaldehyde followed by intramolecular conjugate addition of the resultant hemiacetal derivative. Thus, treatment of 86.1 [Scheme 3.86] with benzaldehyde and catalytic potassium hexamethyldisilazide provided benzylidene acetal 86.2 as a single isomer in 73% yield. 

Evans auxiliaries proved their efficiency furthermore a procedure that permitted remote asymmetric induction in aldol additions of P-ketoimide 238 through titanium and tin enolates. Remarkably, Evans and coworkers experienced that... 

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