An efficient entry to highly substituted chiral 2-oxopiperazines from α-amino acids via iodocyclization

A short and stereoselective route for the synthesis of 2-oxopiperazines is presented starting from different naturally abundant α-amino acids. The key synthetic steps involved amide coupling, Wittig reaction, HWE olefination, aza-Michael reaction, iodocyclization. This new pathway involving first report of iodocyclization to construct chiral substituted 2-oxopiperazines furnished final compounds in good yields.