Diastereoselective synthesis of dispirooxindoline fused [1,3]oxazines via Diels–Alder reaction of functionalized 1,2-dihydropyridines with (E)-1,3-dihydro-3-phenacylidene-2H-indol-2-ones

An efficient synthetic procedure for the complex dispirooxindoline fused [1,3]oxazines was successfully developed via Diels–Alder reaction of (E)-1,3-dihydro-3-phenacylidene-2H-indol-2-ones with 1,2-dihydro-2-oxospiro[3H-indole-3,2′-[2H,9aH-pyrido[2,1-b][1,3]oxazines], which were obtained from three-component reactions of pyridine and isatins with acetylenedicarboxylate or propiolate. 1H NMR data and single crystal structures indicated that this reaction has both high regioselectivity and diastereoselectivity.