The hetero-Diels–Alder addition of ethyl 2-nitrosoacrylate to electron-rich alkenes as a route to unnatural α-amino acids

A new method for the stereoselective synthesis of nonproteinogenic α-amino acids has been developed, which involves hetero-Diels–Alder addition of ethyl 2-nitrosoacrylate to electron-rich alkenes, such as enol ethers, enamines and allylsilanes, and a further two or three step manipulation of the resulting oxazines.