A New Synthesis of Sulfur‐, Nitrogen‐ and Oxygen‐Containing Eight‐Membered Ring Lactams

Bi(NO3)3‐catalyzed ring expansion of five‐membered ring 1,4‐diketones in the presence of primary amines leads to eight‐membered ring lactams. When applied to starting materials with a tetrahydrothiophene or pyrrolidine moiety, tetrahydro‐2H‐1,4‐thiazocin‐3‐ones and hexahydro‐1,4‐diazocin‐2‐ones are obtained as representatives of these very rare heterocyclic systems. In the case of tetrahydrofuran derivatives, other reaction conditions are required and yields of tetrahydro‐2H‐1,4‐oxazocin‐3‐ones are very low.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)