Lewis Acid Catalyzed Diastereoselective Vinylogous Mannich Reaction Induced by O-Pivaloylated d-Galactosylamine as the Chiral Auxiliary: Stereoselective Synthesis of 6-Arylpiperidin-2-ones
derivatives, in the form of (S)-δ-amino-δ-arylpent-2-enoic ester, has been achieved in high yield via a vinylogous Mannich reaction, utilizing poly-O-pivaloylated d-galacosylamine as the chiral auxiliary. (S)-6-p-Tolylpiperidine-2-one can be stereoselectively synthesized from (S)-δ-amino-δ-arylpent-2-enoic ester by sequential hydrogenation of the double bond, cyclic lactam formation, and removal of
The diastereoselective formation of beta-N-glycosidically linked 3-indolyl methanamine derivatives 5 has been achieved with high yield via an aza-Friedel-Crafts reaction. The reaction was performed by using O-pivaloylated galactosylamine 1 as a chiral template and SnCl4 combining TBAI as catalyst in DCM at -50 degrees C. (C) 2012 Elsevier Ltd. All rights reserved.