Brønsted base (Et3N or DBU) catalyzed Michael addition of α-substituted α-isocyanoacetates to phenyl vinyl selenones followed by a Brønsted acid (PTSA) catalyzed domino oxidative cyclization afforded 1,3-oxazinan-2-ones in good to excellent yields. Enantio-enriched 1,3-oxazinan-2-ones were accessible using a Cinchona alkaloid-derived bifunctional catalyst for the first step. In this integrated one-pot process, the phenyl selenonyl group acted consecutively as an activator, a leaving group and a latent oxidant.