Synthesis of β-amino α-hydroxy carboxylic esters from oxiranecarboxylic esters

Article abstract of DOI:10.1002/recl.19921110202

3-Aryl-3-azido-2-hydroxypropanoic esters, prepared from the corresponding 3-aryl-oxirane-2-carboxylic esters by ring opening with sodium azide, were reduced with tin(II) chloride dihydrate in methanol to give 3-amino-3-aryl-2-hydroxypropanoic esters in good yields.Under these conditions, halogen substituents in the aromatic rings were not affected.The nitro group, however, was partially reduced to the amino group.Treatment of aliphatic oxirane-2-carboxylic esters with acetonitrile in the presence of boron trifluoride etherate led to regiospecific formation of 2,4-dialkyl-2-oxazoline-5-carboxylic esters, resulting from reaction of the nitrile at C3.Acidic hydrolysis of these oxazoline-5-carboxylic esters gave the corresponding 3-(acylamino)-2-hydroxy carboxylic esters.With these two complementary methods, both aryl- and alkyl-substituted β-amino α-hydroxy acid derivatives are accessible.