Ex-chiral pool synthesis of aminooxazepinones as conformationally restricted beta-amino acid analogs

Starting from natural asparagine, an efficient synthesis of the dibenzyl pr otected 6-amino-1,3-oxazepin-4-one (7) is reported. According to NMR based conformational studies, the lactam-bridged beta-amino acid analog (7) adopt s preferentially a twisted boat structure. The incorporation of the describ ed molecular scaffold to give a constrained beta-analog of the dopamine rec eptor modulating peptide Pro-Leu-Gly-NH2 is described as an application in the field of medicinal chemistry.