Formation of Functional Cyclic Nitrones via a New Reaction Intermediate, Nitrosoketene and Its Development for the Synthesis of Nonproteinogenic Amino Acids

Abstract

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