Transannular Diels-Alder reactions on 14-membered macrocycles containing properly located diene and methyl-substituted dienophile units lead to ABC [6.6. 6] tricycles related to steroids. To study the influence of the olefin and diene geometry on the stereochemical outcome of the Diels-Alder reaction it was necessary to prepare macrocyclic trienes of well- defined stereochemistry. Eight different types of macrocyclic trienes might be obtained by ...