Diastereoselective construction of tetrahydropyridine fused bicyclic structures via three-component domino reaction.

The three-component reactions of enals, electron-deficient alkynes, and hydroxyl-functionalized primary amines for the highly diastereoselective construction of dihydro-3H-benzo[4,5]oxazolo[3,2-a]pyridines, hexahydropyrido[2,1-b][1,3]oxazines, and tetrahydro-2H-oxazolo[3,2-a]pyridines have been achieved. Domino formation of one C-C, two C-N, and one C-O bonds are furnished in these reactions. This bis-annulation protocol allows for the synthesis of fused heterocyclic products of high structural diversity with variation not only of appended fragments but also the ring size of the central backbone.