Conversions of Cyclic Amines to Nylon Precursor Lactams Using Bulk Gold and Fumed Silica Catalysts

Bulk gold powder (∼50 μm) and alumina-supported gold catalyzed the oxidative dehydrogenation of 5-, 6-, and 7-membered cyclic amines to amidines. These amidines were hydrolyzed upon treatment with Aerosil 200 (fumed silica gel) and water, producing lactams in 42–73% yields and amines in 36–63% yields. The gold and Aerosil 200 catalysts could also be combined in a one-pot reaction to catalyze the conversion of cyclic amines to lactams in yields up to 51%.