(S)-2-(DIBENZYLAMINO)-3-PHENYLPROPANAL AS A CHIRAL AUXILIARY - A NEW STRATEGY FOR THE ASYMMETRIC-SYNTHESIS OF 2-SUBSTITUTED ALCOHOLS

The high levels of 1,2-stereocontrol observed in nucleophilic addition s to (S)-2-(dibenzylamino)-3-phenylpropanal (available in three high-y ielding steps from L-phenylalanine) can be converted to remote 1,4-ste reocontrol by a stereospecific rearrangement if the nucleophile is a v inyl anion equivalent. Ozonolysis of the product followed by reductive work-up returns an enantiomerically pure 2-substituted alcohol, along with the (S)-2-(dibenzylamino)-3-phenylpropan-1-ol precursor to the s tarting aldehyde, which functions as a chiral auxiliary. The sequence provides a new strategy for the use of aldehydes as chiral auxiliaries in the synthesis of chiral alcohols bearing oxygen-or carbon-based 2- substituents. (C) 1998 Elsevier Science Ltd. All rights reserved.