A concise α-amino acid-based synthetic approach to [1,4]oxazepin-2-ones from Baylis–Hillman adducts

An original two-step process for the synthesis of [1,4]oxazepin-2-ones starting from Baylis–Hillman (BH) adducts is reported. The protocol involves a nucleophilic substitution of the acetates of BH adducts with renewable natural α-amino esters followed by base-catalyzed intramolecular Michael addition. These sequential reactions are operationally simple, performed under ambient conditions, and give 81–93% yields of the target [1,4]oxazepin-2-ones. Thus, the present invention opens up a new aspect for the synthetic utility of BH adducts.