Hypervalent Iodine(III) Organocatalysts

Significance

Several bis(iodoarene) compounds, such as 3, were designed and synthesized as organocatalysts for the oxidative spirocyclization of amide 1 to dienone 2. Bis(iodoarene) 3 exhibited high catalytic activity in this reaction and the cyclization product 2 could be isolated in 97% yield after 2.5 hours with 2 mol% catalyst. Using mono­iodoarene 4 rather than bis(iodoarene) 3 as the catalyst, only 52% yield of 2 was obtained after 12 hours even with a higher catalyst loading (10 mol%). A highly active hypervalent iodine(III) compound 5 was suggested to be generated in situ and this was proved in the stoichiometric ­reaction of 1 with preformed 5, where similar results were obtained under the same reaction conditions.