Stereoselective Formation of <i>N</i>-Acyliminium Ion via Chiral <i>N</i>,<i>O</i>-Acetal TMS Ether and Its Application to the Synthesis of <i>β</i>-Amino Acids
see text] The highlystereoselectivesynthesis of beta-amino acids via the chiral 4-phenyloxazolidinone-controlled linear N-acyliminium ion reaction has been achieved by employing chiral N,O-acetal TMS ethers. In addition, the mechanism of the excellent stereochemical outcome has been elucidated. The oxazolidinone auxiliary plays a dual role in stereocontrol: the E/Z geometry control of the N-acyliminium