Intramolecular Diels–Alder reactions of α,β-unsaturated oxime ethers as 1-azadienes: synthesis of [c]-fused pyridines

The intramolecular hetero-Diels–Alder reaction of α,β-unsaturated oxime ethers as the diene with acetylenic dienophiles, readily prepared from salicylaldehyde derivatives, is described as a rapid and versatile route to [c]-annelated pyridines in modest to good yields.