Formation of functional cyclic nitrones via a new reaction intermediate, nitrosoketene and its development for the synthesis of nonproteinogenic amino acids

Thermolysis of isonitroso Meldrum's acid (5-hydroxyimino-2, 2-dimethyl-1,3- dioxane-4,6-dione) generated a new reaction intermediate, nitrosoketene, wh ich reacted with various ketones in aprotic solvent to form cyclic nitrones . These nitrones underwent 1,3-dipolar cycloaddition reactions with electro n rich olefins to give the corresponding isoxazolidine derivatives with hig h diastereoselectivity, which were converted to nonproteinogenic amino acid s such as allylglycine and cyclopentenylglycine. Nitrosoketene was detected by FT-IR spectroscopy.