ipso-Iodocyclizationof Ethoxyethyl Ethers to Alkynes at the ortho-Position: AnEfficient Synthesis of Functionalized Spiro Compounds

An efficient approach to the synthesis of azaspiro compounds having dissymmetric dienone cores was achieved by ipso-iodocyclization of ethoxyethyl ether to alkynes. When the linker was an ether or an ester, domino iodocyclizaion/Diels―Alder reaction proceeded to afford the dimer, which can be transformed into the bridgehead-spiro connection ring system by a domino retro-Diels―Alder/Diels―Alder process.