Seven-membered heterocyclic rings constitute the core fragment of a number of bioactive compounds as well as natural products. In particular, 1,4-oxazepines have gained importance in synthetic organic chemistry since they are crucial moieties owing to their promising pharmaceutical activities such as anti-inflammatory, antipsychotic and antitumor properties. Spirocyclic compounds have also gained attention in modern organic synthesis because they are important class of molecules due to their frequent occurrence in numerous natural and non-natural products. Notably, they are considered as privileged structures with a broad range of biological activities. Combination of 1,4-oxazepine structure with a spiro unit may enhance the current activities or provide new medicinal properties. Thus the development of new methodologies for spiro-containing 1,4-oxazepines has attracted great attention from synthetic organic chemists. Recently, we have shown that upon treatment with zinc iodide and silver hexafluoroantimonate, spiro-bearing N-propargylic β-enaminones 1 afford spiro-containing 1,4-oxazepines 2 in good to high yields. The scope, limitations and mechanism of this new methodology will be discussed.

Synthesis of spiro-containing 1,4-oxazepines from N-propargylic β-enaminones

255th National Meeting (2018)

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