Synthesis of 1-Azaspiro[4.5]deca-1,3-dienes from N-Propargylic beta-Enaminones in Basic Medium

A facile, efficient and unprecedented method for the synthesis of spiro-2H-pyrroles is reported. When reacted with 1-ethynylcyclohexylamine, a, ss-alkynic ketones produced cyclohexane-embedded Npropargylic ss-enaminones, which in the presence of cesium carbonate underwent nucleophilic cyclization to afford 1-azaspiro[ 4.5] deca-1,3diene derivatives in good to excellent yields. This cyclization was found to be general for a variety of cyclohexane-embedded N-propargylic ss enaminones and demonstrated good tolerance to a broad range of aliphatic, aromatic and heteroaromatic groups with electron-withdrawing and electron-donating substituents. The decoration of pyrrole compounds with a spiro framework may exhibit potential for the synthesis of molecules of pharmacological interest.