Development and Application of a New General Method for the Asymmetric Synthesis of syn- and anti-1,3-Amino Alcohols

A general method is described for asymmetric synthesis of both syn- and anti-1,3-amino alcohols. The first application of metalloenamines derived from N-sulfinyl imines is reported for the highly diastereoselective addition to aldehydes. The reduction of the product β-hydroxy N-sulfinyl imines 2 with catecholborane and LiBHEt₃ provides syn- and anti-1,3-amino alcohols with very high diastereomeric ratios. This method was found to be effective for a variety of substrates incorporating either aromatic or various aliphatic substituents. The convergent and efficient asymmetric syntheses of the two natural products, (−)-8-epihalosaline and (−)-halosaline, were also accomplished.