Scope of one-pot synthesis of benzo[b]oxazolo[3,4-d][1,4]oxazin-1-ones^b.

^aReaction conditions: 8b–8r (1 mmol), 9a–9d (1.35 mmol), DIAD (1.5 mmol), PPh₃ (1.5 mmol), THF (8 mL), 0 °C–rt, 8 h for 11ab and 11ac, 6 h for 11ad and 11ae, 4 h for the others; then t-BuOLi (2.5 mmol), THF, rt, 1–3 h.

^bIsolated yields via column chromatography.

^cIsolated yields via trituration with MeOH and filtration.