1,3-Dipolar Cycloaddition of Azomethine Ylides to Aldehydes: Synthesis of anti alpha-Amino-beta-Hydroxy Esters

A 1,3-dipolar cycloaddition reaction of azomethine ylides to aldehydes is described. The azomethine ylides, generated by thermal electrocyclic ring opening of aziridines, adds to aldehydes in good yields with moderate to good selectivities to furnish oxazolidines. The oxazolidines were subsequently hydrolyzed to the corresponding amino alcohols, giving the anti diastereomer as the major product.