Synthesis of C-glycosylated amino acids by hetero-Diels-Alder addition of ethyl 2-nitrosoacrylate to exo-glycals

C-Glycoamino acids bearing a variety of sugar moieties were prepared by the hetero-Diels-Alder addition of ethyl 2-nitrosoacrylate to exo-glycals. The reaction proceeds smoothly to yield spirocyclic oxazines that can be converted into useful products by several hydrogenolytic techniques.