Spirocyclization of keto-ynesulfonamides promoted by quaternary ammonium salts

Spirocyclization of keto-ynesulfonamides with quaternary ammonium salts was performed to access aza-spiro compounds. , Spirocyclization of keto-ynesulfonamides with quaternary ammonium salts was performed to access aza-spiro compounds. Exclusive E -configured 5- exo-dig compounds were isolated from keto-ynesulfonamides substituted by an aryl- or a vinyl group, whereas 6- endo-dig compounds were favored from terminal ynesulfonamides