Dichloropyrazinones are reacted with alkenolates or a Grignard reagent in order to tether a dienophilic side-chain at the 3-position. The compounds smoothly undergo intramolecular Diels -Alder reaction forming tricyclic ring systems. The reactions proceed completely stereoselective yielding only endo adducts. In the case of the alkenylpyrazinone, the core skeleton of the breviamides is obtained. (C) 2002 Elsevier Science Ltd. All rights reserved.