Regioselective and stereoselective glycidic oxirane ring opening: a new entry to optically pure α-alkyl α-hydroxy β-amino acid derivatives

The BF3·OEt2 catalyzed oxirane ring opening of glycidic esters or amides with acetonitrile afforded the corresponding 2-oxazolines under very mild conditions in good yields. The reactions are completely regioselective (the nitrogen attacks the β-carbon) and stereoselective (with inversion of configuration) starting from 2-alkyl or 2,3-dialkyl glycidic derivatives, but the stereoselectivity is lost and the regioselectivity is completely inverted from 2-aryl derivatives. The 2-oxazolines obtained are readily hydrolyzed into β-amino, α-hydroxy esters or amides.