Concise enantio- and diastereoselective synthesis of alpha-hydroxy-alpha-methyl-beta-amino acids

Reported here is an efficient procedure for enantio- and diastereoselective synthesis of purr beta -amino acids that display a tert-hydroxyl functiona lity in the alpha -position. Key steps include a catalytic asymmetric aldol reaction and a modified Curtius rearrangement to form oxazolidinone interm ediates, which are chemoselectively opened to furnish N-protected alpha -hy droxy-alpha -methyl-beta -amino acids. A modified work-up procedure of the: aldol reaction allows for recovery of up to 90% of bisoxazolinyl ligands f rom the catalysts. (C) 2001 Elsevier Science Ltd. All rights reserved.