Samarium iodide-mediated Reformatsky reactions for the stereoselective preparation of β-hydroxy-γ-amino acids: synthesis of isostatine and dolaisoleucine

The synthesis of β-hydroxy-γ-amino acids via SmI(2)-mediated Reformatsky reactions of α-chloroacetyloxazolidinones with aminoaldehydes is reported. Diastereoselective coupling is demonstrated to depend on the absolute configuration of the Evans chiral auxiliary employed in the reaction, allowing erythro or threo products to be obtained selectively. The potential utility of the methodology is exemplified by the facile synthesis of biologically relevant N-Boc-isostatine (2b) and N-Boc-dolaisoleucine (3c).