Book Description

The Diels-Alder reaction is a powerful C-C bond forming technique to effect the formation of unsaturated 6-membered rings from dienes and appropriate dienophiles. Monopropargylic diols cyclize under gold-catalyzed conditions to form cyclic dienol ethers, which may further react in the capacity of dienes in the Diels-Alder reaction. Likewise, the corresponding nitrogen heterocycles may be formed from substrates containing amine derivatives. Systems comprised of 5- and 6-membered unsaturated heterocycles with pendant vinyl groups forming the dienes were prepared from propargyl alcohols using gold(I)-catalysis. These dienes were trapped as their Diels-Alder adducts with several dienophiles including N-methylmaleimide and tetracyanoethylene. Herein we demonstrate the utility of a novel palladium-catalyzed spiroketalization in the total synthesis of the natural product acortatarin A, and report novel methods of preparing fused-ring heterocyclic systems employing a tandem gold-catalyzed cyclization / Diels-Alder methodology.